Education Product National Aeronautics and Space Administration Teachers Grades 5–12
Suited for S pac ewa l k i n g
ATeacher’s Guide with Activities for Technology Education, Mathematics, and Science Suited for Spacewalking—A Teacher’s Guide with Activities for Technology Education, Mathematics, and Science is available in electronic format through NASA Spacelink—one of the Agency’s electronic resources specifically developed for use by the educational community.
The system may be accessed at the following address: http://spacelink.nasa.gov Suited for Spacewalking
A Teacher’s Guide with Activities for Technology Education, Mathematics, and Science
National Aeronautics and Space Administration
Office of Human Resources and Education Education Division Washington, DC
Education Working Group NASA Johnson Space Center Houston, Texas
This publication is in the Public Domain and is not protected by copyright. Permission is not required for duplication.
EG-1998-03-112-HQ Deborah A. Shearer Acknowledgments Science Teacher Zue S. Baales Intermediate School This publication was developed for the National Friendswood, Texas Aeronautics and Space Administration by: Sandy Peck Writer/Illustrator: Clear Creek Independent School District Gregory L. Vogt, Ed.D. League City, Texas Crew Educational Affairs Liaison Teaching From Space Program Marilyn L. Fowler, Ph.D. NASA Johnson Space Center Science Project Specialist Houston, TX Charles A. Dana Center University of Texas at Austin Editor: Jane A. George Jeanne Gasiorowski Educational Materials Specialist Manager, NASA Educator Resource Center Teaching From Space Program Classroom of the Future NASA Headquarters Wheeling Jesuit University Washington, DC Wheeling, West Virginia
Reviewers: Dr. Peggy House Linda Godwin Director, The Glenn T. Seaborg NASA Astronaut Center for Teaching and Learning NASA Johnson Space Center Science and Mathematics Northern Michigan University Joseph J. Kosmo Senior Project Engineer Doris K. Grigsby, Ed.D. EVA and Spacesuit Systems Branch AESP Management and Performance NASA Johnson Space Center Specialist for Training Oklahoma State University Philip R. West Project Manager, EVA Tools Flint Wild for the International Space Station Technology Specialist NASA Johnson Space Center Teaching From Space Program Oklahoma State University Cathy A. Gardner Teacher Intern, Teaching From Space Patterson A. Biggs Silbernagel Elementary School Angelo A. Casaburri Dickenson, Texas Eva J. Farley James E. Pratt Joan Sanders Aerospace Education Specialists Oklahoma State University
Suited for Spacewalking—An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q
iii Table of Contents
National Education Standards...... 1 Introduction...... 5 Earth and Space ...... 7 The Outer Space Environment...... 9 Spacewalking History...... 11 The Space Shuttle EMU...... 17 Working In Space...... 31 EVAs on the International Space Station ...... 37 Future Spacesuits...... 39 Activities Designing Spacesuits for Mars...... 43 Introduction...... 44 Design Brief...... 47 Interface Control Document (Master)...... 49 Interface Control Document (Sample)...... 50 Teacher Tech Briefs...... 51 Exploration Briefs...... 63 Idea Bank...... 89 Glossary...... 95 References...... 97 NASA Educational Resources...... 99 Go for EVA!...... 101 Evaluation Reply Card...... Insert
Suited for Spacewalking—An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q
v National Education Standards
The activities set forth in this curriculum supplement address national standards for science and math- e m a t i c s , and the universals of tech n o l o gy for tech n o l o gy educa t i on . The matrices that foll ow specifica lly identify the standards by activity. The standards for science and mathematics in grades 4–8 and 9–12 have been com b i n e d . Universals of Technology International Technology Education Association, 1996*
*The Standards for Technology Education are still under development
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 1 National Science Education Standards
National Research Council, 1996 Grades 4–12
2 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q National Mathematics Standards
National Council of Teachers of Mathematics, 1989 Grades 4–12
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 3 Int r o d u c t i o n
Spa c e walking has cap t u r ed the imagination of at other subject area s , te a c hers of physi c al science ge n e ra t i o ns of chi l d r en and adults since science- and mathematics will find the Explorat i o n Brie f s fi c t i o n authors first placed their cha r acters on the and the Idea Bank useful as a source of activity ideas. Mo on . But true spacewalking did not actually begin The guide begins with brief discussions of the until the mid-1960s with the exploits of Alexei A. space envi r onm e n t , the history of spacewa l k i n g , Leon o v of the Soviet Union and Edward H.White II NASA's current spacesuit, and work that astronauts do of the United Sta t e s . Since those first tentative du r ing spacewa l k s . These are follo wed by a techn o l o g y pr obings outside a space cap s u l e , as t r onauts and cos- ed u ca t i o n design brief that cha l lenges students to mo nauts have logged thousands of hours on extrav e- design and build a spacesuit prot o t ype for an extrat e r - hicular activities, and some have even walked on the res t r ial envi r onment no human has ever visited before. su r face of the Moon. The stories of their missions in In the process of doing this, students will have to inves - space are fascinating, but just as interesting is the tigate the prop e r ties of that envi r onment and determi n e spacesuit techn o l o g y that made it possible for them what prot e c t i v e measures must be taken to permit a to “wa l k ” in space. fu t u r e explorer to work there safel y.Once accomp l i s h e d , Tod a y, spacesuits are used by astronauts on students will choose materials and technologies that can ma n y missions such as servicing the Hubble Spa c e be used for cons t r ucting and testing the prot o t yp e .T h e Telescope and re t ri eving satell i t e s . The new design brief is follo wed by Tea c her Tec h Brie f s that In t e rn a t i o nal Space Sta t i o n will depend upon astro- pr ovide a source of ideas on how to build spacesuit test nauts and cosmonauts to conduct over 1,200 hours ap p a r atus and by Explorat i o n Brie f s that provide activ- of spacewalks over the next sever al years to assemble it y fram ew o r ks to help students understand importa n t and maintain Space Sta t i o n comp on e n t s . Al t h o u g h topics in spacesuit design. no firm plans exist, NASA hopes to ret u r n to the The guide conc ludes with a glossary of terms , Mo o n to establish a permanent base and later begin suggested reading list, NASA educat i o nal res o u rc e s human surface explorat i o n of Mars. Ea c h of these in c luding electronic res o u rc e s , and an eva l u a t i o n ven t u r es places distinct demands on spacesuits sys- qu e s t i on n a i re . We would appreciate your assistance in tems and the tools astronauts use. im p r oving this guide in future editions by comp l e t i n g This publicat i o n serves as a guide for techn o l o - the fee d b a c k questionn a i r e electroni ca l ly or mailing gy educat i o n teache r s . While not specifical ly aimed the form to us.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 5 Me a s u r e m e n t unit for pressure may be unfamiliar to readers. A pascal is equal to a force of one newton exerted over This activity guide makes use of the metric system an area of one square meter. Because the pascal is a for measurement. However, British units for mea- relatively small unit, the more convenient unit of surement may be listed in materials and tools lists kilopascal (1,000 pascals) is used here instead. To when particular items are more easily found in convert kilopascals to the British-system unit of British measurement sizes. The pascal or metric pounds per square inch, divide by 6.895.
6 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Earth and Space
If we define an astronaut as som e one who t ra vels through space, eve ryone on Earth is an a s t ron a u t .E ven though we may be standing still on E a rth's surf a c e, we are actually tra veling thro u g h space at speeds of thousands of kilometers per h o u r. I n d e e d , our planet may be thought of as a spaceship on a never-ending voy a g e . As "astro- nauts" tra veling through space on the surface of E a rt h , we take for granted the complex env i ron- ment that sustains life . E a rt h’s gra v i t a t i onal attra c- t i on holds a dense atmosph e re of nitro g e n , ox y g e n , ca rb on diox i d e, and water vapor in a thick enve l o p e s u r rounding Eart h’s entire surf a c e . The weight of this atmosph e re exe rts pre s s u re, and its move m e n t s Earth as seen by the crew ofthe Apollo 17 Moon mission. d i s t ribute heat from the Sun to balance global tem- p e ra t u re s . Its gases filter out harmful ra d i a t i on and glass,plastic,and composites.Though far simpler in d i s i n t e g rate all but the largest meteoro i d s . E a rt h’s function than Earth’s environment, a spacecraft's a t m o s ph e re is a shell that protects and sustains the environment serves well for short missions lasting a l i fe forms that have ev o lved on its surf a c e . Wi t h o u t few days or weeks. On some flights, the shell is the atmosph e re’s pro t e c t i on , l i fe as pre s e n t ly deliberately opened and the astronauts pass through k n own would not be possible. an airlock to venture outside. When doing so, they When Earth astronauts leave the surface of must be protected by a still smaller and very spe- their planet and travel into space, they must carry c i a l i zed ve r s i on of their spacecra ft ca lled the some of their environment with them. It must be Extravehicular Mobility Unit (EMU).This smaller contained in a physical shell because their body spacecraft is composed of a spacesuit with a life- masses are too small to hold it in place by gravita- support system. It differs from the first spacecraft, tional attraction alone. The shell that is used is or mother ship, in its anthropomorphous (human) called a spacecraft—a rigid collection of metal, shape and its flexibility. Astronauts wearing EMUs
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 7 need to be able to move arms, hands, and legs to and service defective or worn-out satellites and perform an array of tasks in space. They must be other space hardware. The tasks of astronauts out- able to operate many types of scientific apparatus, side their mother ship are called extravehicular collect samples, take pictures, assemble equipment activities, or EVAs. and structures, pilot themselves about, and repair
8 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q The Outer Space Environment
Outer space is just what its name implies. It is gas molecules. The grav i t a t i o nal attrac t i o n of large the void that lies beyond the uppermost reaches of bodies in space, su c h as planets and stars, pu l ls gas the atmosphere of Earth and between all other molecules close to their surfaces leaving the space objects in the universe. Although it is a void, outer be t ween virtu a l ly empty. Some stray gas molecules are space may be thought of as an env i ron m e n t . found between these bodies, but their density is so low Radiation and objects pass through it freely. An that they can be thought of as prac t i ca l ly none x i s t e n t . unprotected human or other living being placed in On Earth,the atmosphere exerts pressure in all the outer space environment would perish in a few directions. At sea level, that pressure is 101 kilopas- brief, agonizing moments. cals. In space, the pressure is nearly zero. With vir- The principal envi r onmental cha ra c t e r istic of tually no pressure from the outside, air inside an outer space is the vacuum, or nearly total absence of unprotected human's lungs would immediately rush
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 9 out in the vacuum of space.Dissolved gases in body can climb to over 120° Celsius while the shaded fluids would expand, pushing solids and liquids side can plummet to lower than minus 100° Celsius. apart. The skin would expand much like an inflat- Maintaining a com f o rtable tempera t u re ra n g e ing balloon. Bubbles would form in the blood- becomes a significant problem. stream and render blood ineffective as a transporter Other envi r onmental factors encountered in of oxygen and nutrients to the body’s cell s . outer space inclu d e : mi c ro g ra v i t y, rad i a t i o n of electri- Furthermore, the sudden absence of external pres- cal ly charged parti c les from the Su n ,u l t raviolet rad i - sure balancing the internal pressure of body fluids and gases would rupture fragile tissues such as eardrums and capillaries.The net effect on the body would be swelling, tissue damage, and a deprivation of oxygen to the brain that would result in uncon- sciousness in less than 15 seconds. The temperature range found in outer space provides a second major obstacle.The sunlit side of objects in space at Earth's distance from the Sun
at i on , and meteoro i d s .M e t e o roids are ver y small bits of roc k and metal left over from the forma t i o n of the solar system and from the colli s i o ns of comets and as t e ro i d s . Though usually small in mass, these parti - cles trav el at ver y high velocities and can easily pene- tr ate human skin and thin metal. Eq u a l ly dangerou s is debris from previous space missions . A tiny paint chip trav eling at thousands of kilometers per hour can do substantial damage.
10 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Spacewalking History
The Extravehicular Mobility Unit worn during spacewalks by NASA’s Space Shuttle astronauts represents more than 60 years of development and testing of pressure suits in the U.S., Russia, France, Italy, Germany, and other countries. It all began with high-altitude flyers,and one of the first was an American, Wiley Post. Post, an aviation pioneer of the 1930s, was seeking to break high-altitude and speed records. Post, as well as others, knew that p ro t e c t i on against low pre s s u re was essential. T h rough experi e n c e, aviators had learned that Earth’s atmosphere thins with altitude. At 5,500 meters, air is onl y one-half as dense as it is at sea level . At 12,200 meters, the pres s u r e is so lo w and the amount of oxygen is so small that most living things peris h . For Wil e y Post to achi e ve the altitude rec o r ds he sought, he needed prot e c t i on . (P res s u ri z ed aircra f t cabins had not yet been devel - Aviation pioneer Wiley Post. oped.) Pos t ’s solution was a suit that could be pres - s u ri zed by his airplane engine’s supercha r g e r . difficult, but not impossible. To provide visibility, a First attempts at building a pressure suit failed viewing port was part of the rigid helmet placed since the suit became rigid and immobile when over Post’s head. The port was small, but a larger pressurized. Post discovered he couldn’t move inside one was unnecessary because Post had only one the inflated suit, much less work airplane controls. good eye! A later version succeeded with the suit constructed During the next 30 years,pressure suits evolved already in a sitting position. This allowed Post to in many ways and technical manufacturing help was place his hands on the airplane controls and his feet gained from companies that made armor, diving on the rudder bars. Moving his arms and legs was s u i t s , g a l o s h e s , and even girdles and corsets.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 11 Project Mercury
By the time NASA began the Merc u ry manned space flight program,the best full-pressure suit design consisted of an inner gas-bladder layer of neoprene-coated fabric and an outer restraint layer of aluminized nylon. The first layer retained pure oxygen at 34.5 kilopascals; the second layer prevented the first from expanding like a balloon. This second fabric restraint layer directed the oxy- gen pressure inward on the astronaut. The limbs of the suit did not bend in a hinge fashion as do human arms and legs. Instead, the fabric arms and legs bent in a gentle curve, which restricted move- ment. When the astronaut moved one of his arms, the bending creased or folded the fabric inward near the joints, decreasing the volume of the suit and increasing its total pressure slightly. Fortunately for the comfort of the Mercury astronauts,the Mercury suit was designed to serve only as a pressure backup if the spacecraft cabin decompressed. No Mercury capsule ever lost pressure during a mission, and the
Early spacesuit design. suits remained uninflated.
Designers learned in their search for the perfect suit that it was not necessary to provide full sea-level pressure. A suit pressure of 24.13 kilopascals (sea level–101 kilopascals) would suffice quite nicely if the wearer breathed pure oxygen. Supplying pure oxygen at this low pressure actually provides the breather with more oxygen than an unsuited person breathes at sea level.(Only one-fifth of the air at sea level is oxygen.) Var ious techniques were used for cons t ru c t i n g pre s s u r e garme n t s . Some approa c hes employed a rig i d la yer with special joints of rings or cables or some other device to permit limb movem e n t s . Others used non - s t re t c h fabrics—laced-up corset fashion. With the advent of pressurized aircraft cabins, comfort and mobility in the suit when it was u n p re s s u ri zed became prime objectives in suit design.The suit could then be inflated in the event Project Mercury astronauts.(Front row, left to right) Walter M.Schirra,Jr., that the aircraft cabin lost pressure. Donald K.Slayton,John H.Glenn,Jr.,M.Scott Carpenter. (Back row, left to right) Alan B.Shepard, Jr., Virgil I. Grissom,L.Gordon Cooper, Jr.
12 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Project Gemini
The six flights of the Merc u ry series were f o ll owed by ten flights in the Gemini pro g ra m . Suit designers were faced with new pro b l e m s . No t on ly would a Gemini suit have to serve as a pre s- s u re backup to the spacecra ft ca b i n , but also as an e s cape suit if ejection seats had to be fired for an a b o rted launch and as an EMU for extra ve h i c u l a r a c t i v i ty. To increase mobility and com f o rt of the suit for lon g - t e rm wear, designers departed from the Merc u ry suit con c e p t . Instead of fabric joints, t h ey chose a con s t ru c t i on that employed a bladder re s t rained by a net. The bladder was an anthro p o- m o rph i ca lly shaped layer of neopre n e - c o a t e d nyl on . That was cove red in turn with a layer of Te f l on®-coated nyl on netting. The netting, s l i g h t- ly smaller than the pre s s u re bladder, limited infla- Edward H. White’s historic spacewalk. t i on of the bladder and retained the pre s s u re load in mu ch the same way automobile tires retained the hours of EVA experience. Approximately one-half load in inner tubes in the days before tubeless tire s . of that time was spent merely standing up through The new spacesuit fe a t u red improved mobility in the open hatch. the shoulders and arms and was more com f o rt a b l e One of the most important lessons learned when worn unpre s s u ri zed during space flights last- during the Gemini program was that EVAs were ing as long as 14 days . not as simple as they looked. Moving around in The first Gemini astronaut to leave his vehicle space required a great deal of work.The work could (“go EVA”) was Edward White, II. White exited be lessened, h ow eve r, by extensive training on from the Gemini 4 space capsule on June 3,1965— E a rt h . The most effe c t i ve training took place just a few months after Leonov made the first underwater.Wearing specially-weighted spacesuits Soviet spacewalk. For a half-hour,White tumbled while in a deep tank of water gave later Gemini and rolled in space, connected to the capsule only by crew members adequate practice in maneuvers they an oxygen-feed hose that served secondary func- would soon perform in space. It was also learned tions as a tether line and a communication link with that a better method of cooling the astronaut was the capsule. Although the term “spacewalk” was required.The gas cooling system could not remove coined for the Gemini program, no actual walking heat and moisture as rapidly as the astronaut pro- was involved.On his spacewalk, White used a small duced them, and the inside of the helmet visor hand-held pro p u l s i on gun for maneuve ring in quickly fogged over making it difficult to see. space. When he pulled a trigger, the gun released jets of nitrogen that propelled him in the opposite Project Apollo direction.It was the first personal maneuvering unit used in space. Following Gemini, the Apollo program added Upon completion of the Gemini program, a new dimension in spacesuit design because actual NASA astronauts had logged nearly 12 additional spacewalks (on the surface of the Moon) were now
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 13 to occur for the first time. As with Merc u ry and Gemini space garm e n t s , Ap o llo suits had to serve as a backup pre s s u re system to the space ca p s u l e . Besides all owing flexibility in the shoulder and arm a re a s , t h ey also had to permit movements of the legs and waist. A s t ronauts needed to be able to bend and stoop to pick up samples on the Moon . Suits had to function both in micro g ra v i ty and in the one-sixth gra v i ty of the Moon's surf a c e . Fu rt h e rm o re, when walking on the Moon , Ap o ll o a s t ronauts needed the flexibility to roam fre e ly without dragging a cumbersome com b i n a t i on oxygen line and tether. A self-contained port a b l e l i fe - s u p p o rt system was needed. The Apollo spacesuit began with a garment that used water as a coolant. The garment, similar to long johns but laced with a network of thin- w a lled plastic tubing, c i rculated cooling water around the astronaut to prevent overheating.A multi-layered pressure garment was worn on top of Astronauts Harrison H.Schmitt (foreground) and Eugene A.Cernan practice the cooling suit. The innermost layer of this gar- sampling lunar sediment in a simulated Moon site constructed at the Kennedy ment was a comfort layer of lightweight nylon with Space Center in Florida.The Apollo 17 astronauts were the last humans to walk on the Moon. fabric ventilation ducts. On top of this was a layer of neoprene-coated nylon surrounded by a nylon helmet. Slipped over the top of the helmet was an restraint layer. This layer contained the pressure a s s e m b ly consisting of sun-filtering visors and inside the suit. Improved mobility was achieved by adjustable blinders for sunlight protection. The bellow-like joints of formed rubber with built-in final items of the Apollo spacesuit were lunar pro- restraint cables at the waist, elbows, shoulders, tective boots, a portable life-support system, and wrist, knees, and ankles. On top of the pressure custom-sized gloves with molded silicone-rubber layer were five layers of aluminized Mylar® for heat fingertips that provided some degree of fingertip protection, mixed with four spacing layers of non- sensitivity in handling equipment. woven Dacron®. Above these were two layers of The life - s u p p o rt sys t e m , a back p a ck unit, Kapton and beta marquisette for additional thermal pr ovided oxygen for breathing and pres s u ri za t i on , p ro t e c t i on and a nonflammable and abra s i on - water for cooling, and radio commu n i ca t i o ns for protective layer of Teflon®-coated filament beta lunar surface excu r s i o ns lasting up to eight hours. cloth. The outermost layer of the suit was white Furt h e rm o r e, ba c k inside the lunar lander the life- Teflon® cloth.The last two layers were flame resis- su p p o r t system could be rec harged with more oxy g e n tant. In total, the suit layers provided pressure, and battery power for additional Moonwa l k s . se r ved as a prot e c t i o n against heat and cold, and pro- During the Apollo program, 12 astronauts tected the wearer against microme t e o r oid impacts spent a total of 161 hours of EVA on the Moon’s and the wear and tear of walking on the Moon. surface. Additional EVAs were spent in micrograv- Capping off the suit was a communications ity while the astronauts were in transit from the headset and a clear polycarbonate-plastic pressure Moon to Earth. During a total of four hours, one
14 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q John W. Young,Commander ofthe Apollo 16 lunar landing mission to the Descartes region,salutes the American flag as he jumps upward in the one-sixth Earth gravity on the Moon.Behind him are the lunar module “Orion” and the lunar roving vehicle. astronaut, the command module pilot, left the cap- gered the premature deployment of two of the six sule to retrieve photographic film. There was no solar panels, resulting in one being ripped away by need for the portable life-support system away from atmospheric friction. The second was jammed in a the Moon, as those astronauts were connected to partially opened position by a piece of bent metal. the spacecraft by umbilical tether lines supplying In orb i t , Sk ylab re c e i ved insufficient electri ca l them with oxygen. power from the remaining solar panels: the station was overheating because of the missing shield. Skylab Instead of scrapping the mission, NASA assigned the first three-astronaut crew the task of repairing NASA’s next experience with EVAs came dur- the crippled station.While still on board the Apollo ing the Skylab program and convincingly demon- c ommand module, Paul Weitz unsuccessfully strated the need for astronauts on a spacecraft. attempted to free the jammed solar panel as he Spacesuited Skylab astronauts literally saved the extended himself through the open side hatch. On Skylab program. board Skylab, the crew poked an umbrella-like Skylab was NASA’s first space station. It was portable heat shield through the scientific airlock to launched in 1973, six months after the last Apollo cover the area where the original shield was torn M o on landing. Trouble developed during the away. Later, on an EVA, the metal holding the launch when a micrometeoroid shield ripped away jammed solar arrays was cut, and the panel was from the station’s outer surface. This mishap trig- freed to open.During an EVA by the second Skylab
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 15 crew, an additional portable heat shield was erected tether, was worn on the chest, and an emergency over the first. oxygen package containing two supply bottles was The Skylab EMU was a simplified version of attached to the right upper leg. A simplified visor the Apollo Moon suits. There was no need for the assembly was worn over the pressure helmet. Lunar p o rtable life - s u p p o rt system because the crew protective boots were not needed.Skylab astronauts member was attached to the station by an umbilical logged 17.5 hours of planned EVA for film and tether that supplied oxygen and cooling water. An experiment retrieval and 65 hours of unplanned a s t ronaut life - s u p p o rt assembly, c onsisting of a EVA for station repairs. pressure-control unit and an attachment for the
16 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q The Space Shuttle Extravehicular Mobility Unit (EMU)
As NASA changed from launching astronauts on expendable rockets to the Space Shuttle system with its reusable orbiter and solid rocket boosters, spacesuit engineers began deve l o pment of a reusable EMU. Previously, all spacesuits were one- time garments. Spacesuits were custom-built to each astronaut’s body size. In the Apollo program, for example, e a ch astronaut had three custom suits—one for flight, one for training, and one for flight backup.Shuttle suits, however, are tailored from a stock of standard-size parts to fit astronauts with a wide range of measurements. In cons t r ucting the Shuttle spacesuit, de vel o p - ers were able to conc e n t r ate all their designs towa r d a single function— g oing EVA. Suits from earli e r manned spaceflight prog r ams had to serve mul t i p l e fu n c t i on s . Th e y had to provide backup pres s u r e in case of cabin pre s s u re failure and, on Gemini mi s s i on s , pro t e c t i o n if ejection became necessary du r ing launch .T h ey also had to provide an envi r on- ment for EVA in microg ra v i t y and in low grav i t y while walking on the Moon (Apo l lo missions ) . Sui t s we r e worn during lift off and ree n t r y and had to be com f o r table under the high-g forces experie n c e d du r ing accelerat i o n and decelerat i on . Shuttle suits ar e worn onl y when it is time to ven t u r e outside the or biter cab i n . At other times, cr ew members wear com f o r table shirts and slacks , or shorts . For launch
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 17 and reentry, special orange-colored flight suits with p re s s u re bladder layer of urethane-coated nyl on helmets are worn. and fabric layer of pre s s u re - re s t raining Dacron ® . A b ove the bladder and re s t raint layer is a liner of Many Layers Ne o p rene coated Nyl on Ripstop. This is follow e d by a seve n - l ayer thermal microm e t e o roid garm e n t The Shuttle EMU has 14 layers to prot e c t of aluminized Myl a r ® , laminated with Dacron ® as t r onauts on EVAs . The inner layers comp r ise the s c ri m . The outer layer of the suit is made of Ort h o - li q u i d - c o o l i n g - a n d - ve n t i l a t i o n garme n t . First come s Fa b ric which consists of a blend of Gort e x ® , a liner of Nylo n tricot over which is a layer of span- K evl a r ® , and Nomex® materi a l s . dex fabric laced with plastic tubing. Next comes the
1. Liquid Cooling and Ventilation Garment Liner (Nylon tricot)
2. Liquid Cooling and Ven t i l a t i o n Ga r ment Liner Outer Layer 14. Thermal (N ylon / Sp a n d e x ) Micrometeoroid Garment Cover (Ortho-Fabric) 3. Liquid Cooling and Ven t i l a t i o n Ga r ment Liner Water Tran s p o r t Tub i n g 7–13. Thermal Micrometeoroid Garment Liner (Multi-layered Insulation— Aluminized Mylar®)
6. Th e r mal Microme t e o ro i d 4. Pres s u r e Garment Bladder Ga r ment Liner (Neo p re n e (U rethane Coated Nylon ) Coated Nylo ng Ripstop)
5. Re s t r aint (Dacron®)
18 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Shuttle EMU End Items 2 . D i s p l a ys and Control Module (DC M ) Chest-mounted con t rol module containing all The Shuttle extra vehicular mobility unit c on t ro l s , a digital display, the external liquid, g a s , (EMU) consists of 18 separate items. Fully assem- and electri cal interf a c e s . The DCM also has the bled, the Shuttle EMU becomes a nearly complete p ri m a ry purge valve for use with the Se c on d a ry short-term spacecraft for one person. It provides Oxygen Pa ck . pressure, thermal and micrometeoroid protection, oxygen, cooling water, drinking water, food, waste collection,(including carbon dioxide removal),elec- trical power, and communications.The EMU lacks only maneuvering capability, but this capability can be added by fitting a gas jet-propelled Simplified Aid for Extravehicular Activity Rescue (SAFER) over the EMU ’s prim a r y life- s u p p o r t syst e m . On Ea rt h , the suit and all its parts , fu l ly assembled but 3 . EMU El e c tri cal Harness (EEH ) without SAFER, weighs about 113 kilogra m s . A harness worn inside the suit to provide bioin- Or biting above Earth it has no weight at all. It does, s t ru m e n t a t i on and com mu n i ca t i ons con n e c t i ons to how e ver , retain its mass in space, which is felt as the PLSS. resistance to a change in motion.
1. Primary Life-Support System (PLSS) Self-contained backpack unit containing an oxygen supply, carbon-dioxide-removal equipment, caution and warning system,electrical power, water-cooling equipment, ventilating fan, machinery, and radio.
4. Secondary Oxygen Pack (SOP) Two oxygen tanks with a 30-minute emergency supply combined,valve, and regulators.The SOP is attached to the base of the PLSS. The SOP can be removed from the PLSS for ease of maintenance.
5. Service and Cooling Umbilical (SCU) Connects the orbiter airlock support system to the EMU to support the astronaut before EVA and to provide in-orbit recharge capability for the PLSS.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 19 The SCU contains lines for power, communica- 9. Lower Torso t i on s , oxygen and water re ch a r g e, and water Spacesuit pants, boots, and the lower half of the drainage. The SCU conserves PLSS consumables closure at the waist.The lower torso also has a waist during EVA preparation. bearing for body rotation and mobility, and D rings for attaching a safety tether.
6.Battery Hard Upper Battery that supplies electrical power for the EMU Torso under- during EVA.The battery is rechargeable in orbit. neath fabric
7. Contaminant Control Cartridge (CCC) Cleanses suit atmosphere of contaminants with an integrated system of lithium hydroxide, activated Lower Torso charcoal, and a filter contained in one unit. The CCC is replaceable in orbit.
Reference Numbers 8–11.
10. Arms (left and right) Shoulder joint and shoulder bearing, upper arm bearings, elbow joint, and glove-attaching closure. 8. Hard Upper Torso (HUT) Upper torso of the suit, c omposed of a hard fiber- 11. EVA Gloves (left and right) glass shell . It provides stru c t u ral support for Wrist bearing and disconnect, wrist joint, and fin- mounting the PLSS, DC M , a rm s , h e l m e t , I n - Su i t gers.The gloves have loops for attaching tethers for Drink Bag, EEH , and the upper half of the waist restraining small tools and equipment. Generally, cl o s u re . The HUT also has prov i s i ons for mount- crew members also wear thin fabric comfort gloves ing a mini-work s t a t i on tool ca r ri e r. with knitted wristlets under the EVA gloves.
20 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q 12.Helmet 14.Maximum Absorption Garment (MAG) Plastic pressure bubble with neck disconnect ring An adult-sized diaper with extra absorption mater- and ventilation distribution pad. The helmet has a ial added for urine collection. backup purge valve for use with the secondary oxy- gen pack to remove expired carbon dioxide.
15. Extravehicular Visor Assembly (EVA) 1 3 . Liquid Cooling-and-Ve n ti l a tion Garm e n t Assembly containing a metallic-gold-covered Sun- (LCVG) filtering visor, a clear thermal impact-protective Long underwear-like garment worn inside the visor, and adjustable blinders that attach over the pressure layer. It has liquid cooling tubes, gas venti- helmet. In addition, four small “head lamps” are lation ducting, and multiple water and gas connec- mounted on the assembly; a TV camera-transmitter tors for attachment to the PLSS via the HUT. may also be added.
16.In-Suit Drink Bag (IDB) Plastic water-filled pouch mounted inside the HUT. A tube projecting into the helmet works like a straw.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 21 17.Communications Carrier Assembly (CCA) known as caisson disease, are produced by the for- Fabric cap with built-in earphones and a micro- mation and expansion of nitrogen gas bubbles in phone for use with the EMU radio. the bloodstream when a person breathing a normal air mixture at sea-level pressure is exposed to a rapid drop in external pressure. In severe cases, the bends are characterized by pains in the joints, cramps, paralysis, and eventual death if not treated by gradual recompression.To prevent an occurrence of the bends, crew members intending to go EVA spend a period of time prebreathing pure oxygen. During that time, nitrogen gas in the bloodstream is replaced by pure oxygen. 18.Airlock Adapter Plate (AAP) Prior to prebreathing, the atmospheric pressure Fixture for mounting and storing the EMU inside of the entire orbiter cabin is depressed from the the airlock and for use as an aid in donning the suit. normal 101 kilopascals to 70.3 pascals while the p e rcentage of oxygen is slightly incre a s e d . Prebreathing begins when the crew members who plan to go EVA don a mask connected to an oxygen supply. A short hose permits them to continue their EVA preparations during this period.The length of time for cabin decompression and the time for prebreathing is related. Without any cabin decom- pression, prebreathing must last at least four hours. A prebreathe of 30 minutes is safe providing cabin decompression takes place at least 24 hours before the exit into space. By now, much of the dissolved nitrogen gas has been cleared from the EVA crew members,and they can remove their helmets. Later, when they don their spacesuits and seal the helmets, an additional Putting on the EMU 30 to 40 minutes of pure oxygen prebreathing takes place before the suits are lowered to their operating Putting on a Shuttle EMU is a relatively sim- pressure of 29.6 kilopascals. ple operation that can be accomplished in a matter Most of the EM U - d onning process takes of about 15 minutes.However, the actual process of place inside the airl o ck . The airl o ck is a cyl i n d ri ca l preparing to go EVA takes much longer.When chamber located on the orb i t e r’s mid-deck . O n e w o rking in the Shuttle ca b i n , c rew members h a t ch leads from the middeck into the airl o ck ,a n d breathe a normal atmospheric mix of nitrogen and a second hatch leads from the airl o ck out to the oxygen at 101 kilopascals. The suit’s atmosphere is u n p re s s u ri zed payload bay. pure oxygen at 29.6 kilopascals. A rapid drop from Before entering the hatch, but following their the cabin pressure to the EMU pressure could result initial prebreathing, the crew members put on the in a debilitating ailment that underwater divers m a x i mum absorb e n cy garment (MAG ) . T h e sometimes experience—the bends. The bends, also MAG is an adult-size diaper.
22 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q pro d u c t s — a r e contained by the insulation and pres - su r e layers of the suit and must be rem o ve d .C o o l i n g of the crew member is accomplished by circu l a t i n g chi l led water through the tubes. Ch i l ling the water is one of the functions of the Prim a r y Life- Su p p o r t System (PLSS). The PLSS device for water cooling and the tubing system are designed to provide cool- ing for physi c al activity that generates up to two mi ll i o n joules of body heat per hour, a rate that is c on s i d e red “ex t re m e l y vigoro u s . ” ( Ap p rox i m a t e ly 160 joules are released by burning a piece of new s p r int one centimeter square.) Ducting attache d to the LCV G ventilates the suit by drawing ven t i - lating oxygen and expired ca rb on dioxide from the su i t ’s atmosphe r e into the PLSS for purif i ca t i o n and rec i rc u l a t i on . Body perspirat i o n is also drawn away fr om the suit by the venting system and rec ycled in the water cooling syst e m . The intakes are locat e d near the hands and feet of the suit. Duc t s , run n i n g al o ng the arms and legs on the back of the LCV G cha n n e l , the ven t i l a t i o n gases to a circular junction on the back of the LCV G and into the torso ven t du c t . From there, the gases are ret u r ned to the PLSS via the LCCGV multiple water conn e c t o r .Puri f i e d oxygen from the PLSS reenters the suit throu g h another duct, mounted in the back of the helmet, that directs the flow over the astrona u t ’s face to co mplete the circu i t . The EMU electrical harness is attached to the HUT and provides biomedical and communica- tions hookups with the PLSS. The biomedical hookup monitors the heart rate of the crew mem- bers, and this information is radioed via a link with Spacesuit technician prepares to put on the Space Shuttle EMU by first don- ning the Liquid Cooling-and-Ventilation garment. the orbiter to Mission Control on Earth. Voice communications are also carried on this circuit. Next comes the Liquid Cooling-and-Ven t i l a t i o n Ne x t , s eve ral simple tasks are perf o rm e d . Ga r ment (LCVG ) . The LCV G has the general Antifog compound is rubbed on the inside of the ap p e a r ance of long underwe a r . It is a one-piece suit helmet. A wrist mirror and a small spiral-bound with a zippered front , made of stret c hable spandex 27-page checklist are put on the left arm of the fa b r ic laced with 91.5 meters of plastic tubing. Whe n upper torso. The wrist mirror was added to the suit the EMU is comp l e t e l y assembled, cooling and because some of the knobs on the front of the dis- ven t i l a t i o n become significant prob l e m s . Body heat, plays and control module are out of the vision range c ontaminant gases, and perspira t i on —a ll waste of the crew member. The mirror permits the knob
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 23 settings to be read. Setting numbers are written a fabric cap. After the crew member dons the EMU, backwards for ease of reading in the mirror. the cap is placed on the head and adjusted. Another task at this time is to insert a food bar When the tasks preparatory to donning the and a water-filled In-Suit Drink Bag (IDB) inside suit are completed,the lower torso, or suit pants,are the front of the HUT. The food bar of compressed pulled on.The lower torso comes in various sizes to fruit,grain,and nuts is wrapped in edible rice paper, meet the varying size requirements of different and its upper end extends into the helmet area near astronauts.It features pants with boots and joints in the crew member’s mouth. When hungry, the crew the hip, knee, and ankle, and a metal body-seal clo- member bites the bar and pulls it upward before sure for connecting to the mating half of the ring breaking off a piece to chew. In that manner, a small mounted on the hard upper torso. The lower torso’s piece of the bar remains extended into the helmet waist element also contains a large bearing. This for the next bite.It is necessary to eat the entire bar gives the crew member mobility at the waist, per- at one time, because saliva quickly softens the pro- mitting twisting motions when the feet are held in truding food bar, making it mushy and impossible workstation foot restraints. to break off. The IDB is placed just above the bar. Joints for the lower and upper torsos re p re s e n t Two sizes of bags are available and the one chosen an important advance over those of prev i o u s is filled with water from the water supply of the s p a c e s u i t s . E a rlier joint designs consisted of hard orbiter's galley prior to entry into the airlock. The ri n g s , b e ll ows-like bends in the pre s s u re bladder, largest bag contains nearly 1 liter of water. A plastic or cable- and pull ey-assisted fabric joints. T h e tube and valve assembly extends up into the helmet Shuttle EMU joints maintain nearly constant so that the crew member can take a drink whenev- volume during bending. As the joints are bent, er needed.Both the food bar and drink bag are held re d u c t i ons in volume along the inner arc of the in place by Velcro attachments. bend are equalized by increased volume along the During EVAs, the crew members may need outer arc of the bend. additional lighting to perform their tasks. A light- Long before the upper half of the EMU is bar attachment (helmet-mounted light array) is don n e d , the airlo ck ’ s Ser vice and Cooling Umbilical placed above the helmet visor assembly. Small built- (SCU) is plugged into the Displays and Cont ro l in flood lamps provide illumination to places that Module Panel on the front of the upper torso. Fiv e sunlight and the regular payload bay lights do not con n e c t i o ns within the umbilical provide the suit reach. The EVA light has its own battery system with cooling water, oxy g e n , and electric al powe r and can be augmented with a helmet-mountable fr om the Shuttle itself. In this manner, the cons u m - television camera system with its own batteries and ables stored in the Prim a r y Life- Su p p o r t Syst e m radio frequency transmitter. The camera’s lens sys- wi l l be cons e r ved during the lengthy preb re a t h i n g tem is about the size of a postage stamp. Through pe ri o d . The SCU also is used for battery and con- this system, the crew remaining inside the orbiter sumable rec harging between EVAs . and the mission controllers on Earth can get an The airlo c k of the Shuttle orbiter is onl y 1.6 astronaut’s eye view of the EVA action. During meters in diameter and 2.1 meters high on the inside. complicated EVAs, viewers may be able to provide When two astronauts prep a r e to go EVA, the space helpful advice for the tasks at hand. inside the airlo c k becomes crowde d . For storage pur- Next, the Communications Carrier Assembly poses and as an aid in donning and doffing the (CCA), or “Snoopy cap,” is connected to the EMU EMU , ea c h upper torso is mounted on airlo c k electrical harness and left floating above the HUT. adapter plates. Adapter plates are brac kets on the air- The CCA earphones and microphones are held by lo c k wall for supporting the suits’ upper torsos.
24 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q With the lower torso donned and the orbiter nates the exposed and vulnerable ven t i l a t i o n and life- p roviding consumables to the suits, e a ch crew su p p o r t hoses of earlier EMU designs that could member “dives” with a squirming motion into the be c o me snagged during EVA. upper torso.To dive into it,the astronaut maneuvers The last EMU gear to be donned includes eye- under the body-seal ring of the upper torso and glasses if needed, the com mu n i ca t i ons ca r ri e r assumes a diving position with arms extended assembly (CCA), comfort gloves, the helmet with upward. Stretching out, while at the same time lights and optional TV, and EVA gloves. The two aligning arms with the suit arms, the crew member gloves have fingertips of silicone rubber that permit slips into the upper torso. As two upper and lower some degree of sensitivity in handling tools and body-seal closure rings are brought together, two other objects. Metal rings in the gloves snap into connections are made. The first joins the cooling rings in the sleeves of the upper torso. The rings in water-tubing and ventilation ducting of the LCVG the gloves contain bearings to permit rotation for to the Primary Life-Support System. The second added mobility in the hand area. The connecting connects the biomedical monitoring sensors to the ring of the helmet is similar to the rings used for the EMU electrical harness that is connected to the body-seal closure. Mobility is not needed in this PLSS. Both systems are turned on, and the crew ring because the inside of the helmet is large member then locks the two body-seal closure rings enough for the crew member’s head to move together, usually with the assistance of another crew around. To open or lock any of the connecting member who remains on board. rings, one or two sliding, rectangular-shaped knobs One of the most important features of the are moved to the right or the left. When opened, upper half of the suit is the HUT, or Hard Upper the two halves of the connecting rings come apart Torso. The HUT is a hard fiberglass shell under the easily. To close and lock, one of the rings slides part fabric layers of the thermal-micrometeoroid gar- way into the other against an O-ring seal.The knob ment. It is similar to the breast and back plates of a is moved to the right, and small pins inside the suit of armor. The HUT provides a rigid and con- outer ring protrude into a groove around the inside trolled mounting surface for the Primary Life- ring, thereby holding the two together. Support System on the back and the Displays and All suit openings have locking provisions that Control Module on the front. require a minimum of three independent motions In the past, du r ing the Apo l lo Moon missions , to open.This feature prevents any accidental open- do nning suits was a ver y lengthy process because the ing of suit connections. li fe - s u p p o r t system of those suits was a separate item. With the donning of the helmet and gloves, Be c ause the Apo l lo suits were worn during launch the spacesuits are now sealed off from the atmos- and landing and also as cab i n - p re s s u r e backu p s , a phere of the air lock. The crew members are being HUT could not be used. It would have been muc h supported by the oxygen, electricity, and cooling too uncomf o r table to wear during the high accelera- water provided by the orbiter. A manual check of ti o ns and decelerat i o ns of lift-off and ree n t r y. Th e suit seals is made by pressurizing each suit to 29.6 li fe - s u p p o r t system had to be attached to the suit kilopascals d. (The “d” stands for differential,mean- inside the lunar module. Al l conn e c t i o ns betwe e n ing greater than the air lock pressure.) Inside the air PLSS and the Apo l lo suit were made at that time lock, the pressure is either 70.3 or 101 kilopascals. an d , with two astronauts working in cramped quar- The suit’s pressure is elevated an additional 29.6 te r s , pre p a r ing for EVA was a difficult proc e s s . Th e kilopascals, giving it a pressure differential above Shuttle suit HUT eliminates that lengthy proc e d u r e the air lock pressure. Once pressure reaches the be c ause the PLSS is already attache d . It also elimi- desired level, the oxygen supply is shut off and the
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 25 digital display on the chest-mounted control mod- The Primary and Secondary ule is read. To assist in reading the display, an optional Fresnel lens inside the space helmet may Life-Support Systems be used to magnify the numbers. Some leakage of spacesuit pressure is normal. The maximum allow- A s t ronauts experienced their first real fre e d om able rate of leakage of the Shuttle EMU is 1.38 while wearing spacesuits during the Ap o ll o kilopascals per minute, and this is checked before M o onwalk EVA s , b e cause of a portable life - s u p- the suit is brought back down to air lock pressure. p o rt system worn on their back s . A ll other EVA s As the suit pres s u r e is eleva t e d ,c r ew members may up to that time were tied to the spacecra ft by the ex p e r ience discomf o r t in their ears and sinus cav i t i e s . u m b i l i cal-tether line that supplied oxygen and kept Th e y compensate for the pres s u r e change by swallo w- c rew members from dri fting away. In one sense, t h e in g , ya w n i n g , or pressing their noses on an optiona l tether was a leash, b e cause it limited move m e n t s sp o nge mounted to the left on the inside of the helmet a w ay from the spacecra ft to the length of the teth- rin g . Attempting to blow air through the nose when e r. On the Moon , h ow eve r, a s t ronauts were not pr essing the nose on the sponge forces air inside the ears h a m p e red by a tether and, in the later mission s , and sinus cavities to equalize the pres s u re . w e re permitted to dri ve their lunar rovers up to 10 During the next several minutes the two space- k i l ometers away from the lander. (That distance suits are purged of any oxygen/nitrogen atmosphere limit was imposed as a safe ty measure . It was deter- remaining from the cabin;this is replaced with pure mined that 10 kilometers was the maximum dis- oxygen. Additional suit checks are made while the tance an astronaut could walk back to the lander if final oxygen prebreathe takes place. a lunar rover ever broke dow n . ) The inner door of the air lock is sealed,and the Space Shuttle astronauts have even gre a t e r air lock pre s s u re bleed-down begins. A small f re e d om than the Ap o llo lunar astronauts beca u s e depressurization valve in the air lock latch is opened their EVAs take place in the micro g ra v i ty env i ron- to outside space, permitting the air lock atmosphere ment of space. T h ey do employ tethers when EVA s to escape. While this is taking place the EMU auto- center in and about the Sh u t t l e’s payload bay, b u t matically drops its own pressure to 66.9 kilopascals those tethers act on ly as safe ty lines and do not and leak checks are conducted. Failure of the leak p rovide life support . Fu rt h e rm o re, the tethers ca n test would require repressurizing the air lock, per- be moved from one loca t i on to another on the mitting the EVA crew to reexamine the seals of o rbiter along a slide wire, p e rmitting even gre a t e r their suits. distances to be cove re d . Final depressurization is begun by opening the The fre e d om of movement afforded to air lock depressurization valve. The outer air lock Shuttle astronauts on EVAs is due to the Pri m a ry hatch is then opened and the suited astronauts pre- L i fe - Su p p o rt System (PLSS) ca r ried on their pare to pull themselves out into the payload bay. As b a ck s . The PLSS, an advanced ve r s i on of the a safety measure, they tether themselves to the Ap o llo sys t e m , p rovides life support , voice com- orbiter to prevent floating away as they move from mu n i ca t i on s , and biom e d i cal telemetry for EVA s place to place by hand holds. It is at this point that lasting as long as seven hours. Within its dimen- they disconnect the orbiter Service and Cooling s i ons of 80 by 58.4 by 17.5 centimeters, the PLSS Umbilical from the EMU. The PLSS begins using c ontains five major groups of com p onents for life its own supply of oxygen, cooling water, and elec- s u p p o rt . Those are the ox y g e n - ve n t i l a t i n g, c on- tricity. The astronauts pull themselves through the d e n s a t e, fe e d w a t e r, liquid tra n s p o rt , and pri m a ry outer air lock hatch, and the EVA begins. oxygen circ u i t s .
26 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q The oxygen-ventilating circuit is a closed-loop picked up by the oxygen as it is drawn into the system. Oxygen is supplied to the system from the ducting built into the Liquid Cooling-and- primary oxygen circuit or from a secondary oxygen Ventilation Garment. A centrifugal fan, running at pack that is added to the bottom of the PLSS for nearly 20,000 rpm, draws the contaminated oxygen emergency use. The circulating oxygen enters the back into the PLSS at a rate of about 0.17 cubic suit through a manifold built into the Hard Upper meters per minute, where it passes through the Torso.Ducting carries the oxygen to the back of the Contaminant Control Cartridge. space helmet,where it is directed over the head and Carbon dioxide and trace contaminants are fil- then downward along the inside of the helmet tered out by the lithium hydroxide and activated front. Before passing into the helmet, the oxygen charcoal layers of the cartridge.The gas stream then warms sufficiently to prevent fogging of the visor. travels through a heat exchanger and sublimator for As the oxygen leaves the helmet and travels into the removal of the humidity. The heat exchanger and rest of the suit, it picks up carbon dioxide and sublimator also chill water that runs through the h u m i d i ty from the crew member’s re s p i ra t i on . tubing in the Liquid Cooling and Ve n t i l a t i on More humidity from perspiration, some heat from Garment (LCGV).The humidity in the gas stream physical activity, and trace contaminants are also condenses out in the heat exchanger and sublima-
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 27 Astronaut Joe Tanner works on the Hubble Space Telescope during the STS-82 mission.The curvature ofEarth and the Sun are over his left shoulder. tor. The relatively dry gas (now cooled to approxi- wa t e r - s t o r age tanks of the feedwater circuit and mately 13 degrees Celsius) is directed through a added to their supply for eventual use in the sublima- ca rb on dioxide sensor before it is re c i rc u l a t e d to r . In this manner, the PLSS is able to maintain suit through the suit. Oxygen is added from a supply cooling for a longer period than would be possible and regulation system in the PLSS as needed. In with just the tank’s original water supply. the event of the failure of the suit fan, a purge valve The function of the feedwater and the liquid in the suit can be opened. It initiates an open loop transport circuits is to cool the astronaut. Using the purge mode in which oxygen is delivered from both pressure of oxygen from the primary oxygen circuit, the primary and secondary oxygen pack. In this the feedwater circuit moves water from the storage mode, moisture and the carbon dioxide-rich gas are tanks (three tanks holding a total of 4.57 kilograms dumped outside the suit just before they reach the of water) to the space between the inner surfaces of Contaminant Control Cartridge. two steel plates in the heat exchanger and sublima- One of the by-products of the oxy g e n - ve n t i l a t - tor. The outer side of one of the plates is exposed ing circuit is moisture. The water produced by perspi- directly to the vacuum of space.That plate is porous rat i o n and breathing is withdrawn from the oxy g e n and, as water evaporates through the pores, the su p p l y by being condensed in the sublimator and is temperature of the plate drops below the freezing car r ied by the condensate circu i t . (The small amount point of water.Water still remaining on the inside of oxygen that is also car r ied by the condensate circu i t of the porous plate freezes, sealing off the pores. is rem o ved by a gas separator and ret u r ned to the oxy - Flow in the feedwater circuit to the heat exchanger ge n - v entilating system.) The water is then sent to the and sublimator then stops.
28 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q On the opposite side of the other steel plate is a circuit is used for suit pressurization and breathing. se c o nd chamber through which water from the liq- Two regulators in the circuit step the pressure down uid tran s p o r t circuit passes. The liquid tran s p o r t cir- to usable levels of 103.4 kilopascals and 29.6 kilo- cuit is a closed-loop system that is connected to the p a s ca l s . Oxygen coming from the 103.4-kilopas- plastic tubing of the LCVG . Water in this circu i t , cal regulator pre s s u ri zes the water tanks, and ox y- dri v en by a pump, ab s o r bs body heat. As the heated gen from the 29.6-kilopascal regulator goes to the water passes to the heat exchanger and sublimator, ventilating circ u i t . heat is tran s fe r r ed through the aluminum wall to the To insure the safet y of astronauts on EVAs , a chamber with the porous wall. The ice formed in the Sec on d a r y Oxygen Pac k (SOP) is added to the bot- po r es of that wall is sublimated by the heat direc t l y to m of the PLSS. The two small tanks in this syst e m into gas, pe r mitting it to trav el through the pores co ntain 1.2 kilograms of oxygen at a pres s u r e of into space. In this manner, water in the tran s p o r t 41,368.5 kilopascal s . The Sec on d a r y Oxygen Pac k ci r cuit is cooled and ret u r ned to the LCVG . Th e can be used in an open-loop mode by activating a cooling rate of the sublimator is determined by the purge valve or as a backup supply should the prim a r y wo r kload of the astrona u t . With a greater workl o a d , sy stem fall to 23.79 kilopascal s . The supply automa t - mo r e heat is released into the water loop, causing ice ica l ly comes on line whenever the oxygen pres s u r e to be sublimated more rap i d ly and more heat to be inside the suit drops to less than 23.79 kilopascal s . eliminated by the syst e m . If the Displays and Control Module (DCM) The last group of components in the Primary purge valve (discussed below) is opened, used-oxy- Life-Support System is the primary oxygen circuit. gen contaminants and collected moisture dump Its two tanks contain a total of 0.54 kilograms of directly out of the suit into space.Because oxygen is oxygen at a pressure of 5,860.5 kilopascals, enough not conserved and recycled in this mode, the large for a normal seven-hour EVA. The oxygen of this quantity of oxygen contained in the SOP is con- sumed in only 30 minutes.This half-hour still gives the crew member enough time to return to the o rb i t e r’s airl o ck . If ca rb on dioxide con t rol is required, the helmet purge valve may be opened instead of the DCM purge valve. That valve has a lower flow rate than the DCM valve. Displays and Control Module
The PLSS is mounted directly on the back of the Hard Upper Torso, and the controls to run it are mounted on the front. A small, irregularly-shaped box, the Displays and Control Module (DCM), houses a variety of switches, valves, and displays. Along the DCM top are four switches for power, feedwater, communications mode selection, and caution and warning. A suit-pressure purge valve projects from the top at the left. It is used for depressurizing the suit at the end of an EVA and can be used in an emergency to remove heat and
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 29 humidity when oxygen is flowing from both the a s t ronaut has the option of having the radio primary and secondary oxygen systems. Near the channel open at all times or only when needed. front on the top is an alpha-numeric display. A On a second platform, to the left, is an illumi- microprocessor inside the PLSS permits astronauts nated mechanical-suit pressure gauge. At the bot- to monitor the condition of the various suit circuits tom, on the front of the DCM, are additional con- by reading the data on the display. trols for communications volume, display lighting Stepped down from the top of the DCM, on a intensity, temperature control, and a four position small platform to the astronaut’s right, is a ventila- selector for controlling suit pressure in different tion-fan switch and a push-to-talk switch. The EVA operating modes.
30 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Working In Space
One of the great advantages of working in l i ft heavy objects upw a rd because the equal and space is that objects,including the astronauts them- opposite force is directed dow nw a rd through our selves, have no apparent weight. Regardless of the legs and feet to Earth itself. E a rth's inertia is so weight of an object on Earth, a single crew member g reat that its re s p onse to the dow nw a rd force is can move and position that object in orbit with ease i n f i n i t e s i m a l . In space, on the other hand, a s t ro- provided the crew member has a stable platform nauts do not have the advantage of having a plan- from which to work. et to stand on to absorb the equal and opposite The physics of working in space is the same as f o rce during work activities. As explained in the that of working on Earth. All people and things T h i rd Law of Motion , pushing on an object ca u s- c ontain matter and con s e q u e n t ly have mass. es the object and the crew member to float away Because of that mass, they resist any change in in opposite dire c t i on s . The rates at which the motion. Physicists refer to that resistance as inertia. c rew member and the object float away from each The greater the mass, the greater the inertia. other is determined by their re s p e c t i ve masses. Like on Eart h , to change the motion of For example, a massive satellite will move away objects in space re q u i res an applica t i on of forc e . mu ch more slow ly than the less massive astron a u t H ow mu ch the object moves is explained in part pushing on it. To gain advantage over objects, t h e by Sir Isaac Newt on's T h i rd Law of Motion . T h e spacesuited crew member must be bra c e d , law states that a force causing an object to move t h rough foot re s t ra i n t s , by a stable platform , s u ch one way is met with an equal and opposite force in as a massive and active ly stabilized Shuttle orb i t e r the other dire c t i on . The law is more familiarly or Intern a t i onal Space St a t i on . stated as, “For eve ry action there is an opposite and equal re a c t i on . ” The consequence of this law in EVA space is import a n t . A simple Earth task, s u ch as t u rning a nut with a wre n ch , can become quite dif- As Apollo spacesuits were being developed for ficult in space because the astronaut—and not the walking on the surface of the Moon,a special set of n u t — m ay turn . tools was designed to assist astronauts in their sam- Ap p l i ca t i on of force on Earth is easy beca u s e ple collecting task. The Apollo suits were stiff, and we plant our feet firm ly on the gro u n d . We ca n bending at the waist was difficult and awkward.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 31 The problem of picking up rocks and soil samples well. The tools are modified to make them easier was solved by creating long-handled sampling tools and safer to use in space. For example, the handles such as scoops and rakes. Because bulky spacesuit of tools are often enlarged so they will take less gloves made grasping difficult, tool handles were energy to hold. A spacesuit glove is similar to a made thicker than normal. thick leather welder's glove in bulk.Because the suit Today's spacewalkers have an extensive collec- glove is pressurized, the astronaut's fingers extend tion of EVA tools to employ during Shuttle and out when at rest. Closing the fingers around a tool International Space Station missions. Several crite- handle takes a continuous application of force. ria are used in creating useful tools for space flight. Quite simply, small-handled tools take more force Tools have to be easily gripped by astronauts wear- to hold than do large-handled tools. ing heavy gloves. The tools have to be safe to use To keep control of tools, each tool has some and reliable under temperatures that can vary by sort of tether or locking system. A socket wrench hundreds of degrees. Tools also need some sort of has a key that has to be inserted into a holder before attachment system so that if an astronaut should a socket can be installed at the end of the wrench. "drop" them,the tools will not float away. Colliding Once the key is removed, the socket is then locked with a socket wrench left in orbit by some earlier onto the wrench and cannot be removed without space mission could be disastrous. use of the key again.A short tether and clip enables In the planning phase of each mission,tools are the astronaut to hang on to the wrench in case it is selected on the basis of the jobs that must be done. d ro p p e d . T h e re is even a tether on the key. Specialized tools are often created when no existing Rechargeable power tools for driving bolts are also tool will do the job. Many of the tools found in a used by spacewalkers. traditional tool box on Earth are used in space as
STS-82 Astronaut Steven L.Smith holds a power ratchet tool as he prepares to replace some ofthe instruments on the Hubble Space Telescope.
32 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q EVA Tools
Bolt Puller Mechanical Fingers Hammer
Vise Grips
Safety Probe Tether
Allen Wrench
Small Cutter
Adjustable Wrench
The tools shown here are representative samples ofthe tools available to spacewalkers.Many EVA tools are standard Earth tools that have been modified for space use. Loops,to attach tethers,are added to prevent loss in orbit. For some tools,such as the adjustable wrench and probe, the handle has been enlarged to make grasp- ing with a spacesuit glove less tiring .
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 33 On the Gemini 9 mission, a backpack maneu- vering unit was carried. However, problems with the unit prevented Gene Cernan from testing it. Foll o wing the Gemini prog ra m , the next space ex p e r iments that tested maneuver ing units for EVAs to o k place during the second and third manned Sky lab missions . The device was tested onl y inside the spacecra ft , but the experiment conf i r med that a ma n e u ve r ing device of that design was both fea s i b l e and desirable for future EVA use. Fiv e of the six as t r onauts who flew in those two missions accumu- lated a total of 14 hours testing the advanced devi c e , cal led the AMU, or Astronaut Maneuver ing Unit. The AMU was shaped like a large ver s i o n of a hi k e r ’s back p a ck . Built into the frame was a rep l a c e - able tank of comp r essed nitrogen gas. Con t r ols for the unit were placed at the ends of “ar m res t s . ” To Bruce McCandless II pilots the MMU in space for its first flight. mo ve, the astronaut worked rot a t i o nal and tran s l a - Astronaut Maneuvering Units ti o nal hand cont ro l s . Prop u l s i v e jets of nitrogen gas we r e released from various nozzles spaced arou n d Dur ing the first Ame ri c an EVA, Ed w a r d Whi t e the unit. The 14 nozzles were arranged to aim top- ex p e r imented with a personal prop u l s i o n devi c e , th e bo t t om , fr ont - b a ck , and rig h t - l e f t to produce six Hand-Held Maneuver ing Unit (HHMU). Th e de g r ees of free d o m in movem e n t . The AMU could HHMU tested by White was a three-jet maneuveri n g mo ve forwa r d and back, up and down , and side to gu n . Two jets were located at the ends of rods and si d e , and could roll , p i t ch , and yaw. With the 11 aimed back so that firing them pulled White forwa rd . ad d i t i o nal nozzles, pr ecise positioning with the A third jet was aimed forwa r d to provide a brak i n g AMU was far simpler than with the HHMU of the fo rc e . By holding the gun near his center of mass and Gemini prog ra m . The astronaut was surrounded by aiming it in the direc t i o n in which he wanted to trav - the unit, taking the guesswork out of determi n i n g el , he was able to propel himself forwa rd . Stopping that center of mass and making cont r ol muc h more accu- mo vement req u i r ed firing the center jet. The prop u l - rat e . The astronaut could move clo s e l y along the si v e force of the HHMU was produced by rel e a s i n g su r face of a curved or irreg u l a r ly-shaped object com p r essed oxygen from two small built-in tanks. without making contact with it. Although the HHMU worked as intended, it The AMU led to the MMU or manned had two disadvantages. To produce the desired m a n e u ve ring unit for use during early Sp a c e mo t i on , it had to be held as close to the astrona u t ' s Shuttle flights. It was designed to operate in the center of mass as possible. De t e r mining the center microgravity environment of outer space and under po s i t i o n was difficult because of the bulky spacesuit the temperature extremes found there. The MMU White wore and was a matter of guesswork and was operated by a single space-suited astronaut. ex p e ri e n c e . Furt h e rm o r e, pr ecise motions to posi- The unit featured redundancy to protect against ti o n an astronaut prop e r ly during an activity such as failure of individual systems. It was designed to fit se r vicing a satellite were difficult to achi e ve and over the life - s u p p o rt system back p a ck of the maintain and proved physi ca l ly exhausting. Shuttle EMU.
34 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q The MMU was approximately 127 centimeters operation,each tank fed one system of thrusters. At high,83 centimeters wide, and 69 centimeters deep. the direction of the astronaut, through manual con- When carried into space by the Shuttle, it was trol or through an automatic attitude-hold system, stowed in a support station attached to the wall of propellant gas moved through feed lines to varying the payload bay near the airlock hatch.Two MMUs combinations of 24 nozzles arranged in clusters of were carried on a mission with the second unit three each on the eight corners of the MMU. The mounted across from the first on the opposite pay- nozzles were aimed along three axes perpendicular load bay wall. The MMU controller arms were to each other and permit six degrees of freedom of folded for storage, but when an astronaut backed movement. To operate the propulsion system, the into the unit and snapped the life-support system astronaut used his or her fingertips to manipulate into place, the arms were unfolded. Fully extended, hand controllers at the ends of the MMU’s two the arms increased the depth of the MMU to 122 arms.The right-hand controller produced rotation- centimeters. To adapt to astronauts with different al acceleration for roll,pitch,and yaw. The left con- arm lengths, controller arms could be adjusted over troller produced acceleration without rotation for a range of approx i m a t e ly 13 centimeters. T h e m oving forw a rd - b a ck , u p - d ow n , and left - ri g h t . MMU was small enough to be maneuvered with Coordination of the two controllers produced intri- ease around and within complex structures. With a cate movements in the unit. Once a desired orien- full propellant load, its mass was 148 kilograms. t a t i on had been ach i eve d , the astronaut could Gaseous nitrogen was used as the propellant engage an automatic attitude-hold function that for the MMU.Two aluminum tanks with Kevlar® maintained the inertial attitude of the unit in flight. filament overwrappings contained 5.9 kilograms of This freed both hands for work. nitrogen each at a pressure of 20.68 kilopascals, The MMU was used on three Shuttle missions enough propellant for a six-hour EVA, depending in the mid 1980s. It was first tested by Bruce on the amount of maneuvering done. In normal McCandless and Robert Stewart on the 1984 STS
SAFER Propulsion Module
Stowed
Deployed
Hand Controller
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 35 November of 1984.The propulsion unit was used to retrieve two communication satellites that did not reach their proper orbit because of faulty propulsion modules. Joseph Allen and Dale Gardner captured the two satellites and brought them into the orbiter payload bay for stowage and return to Earth. M o re recent experiments with astron a u t m a n e u ve ring units took place on the 1994 STS-64 m i s s i on . A new dev i c e, ca lled the Simplified Aid for Extra vehicular activity Rescue (SAFER) was f l own by Mark C. Lee and Carl J. Meade a few meters away from their orb i t e r. S A F ER is a small- er unit than the MMU and is designed as a self- rescue device for use on the Intern a t i onal Sp a c e St a t i on . Although unlikely, an astronaut could b e c ome separated from the station during an EVA and a Shuttle not be available to re t ri eve the crew m e m b e r. In that eve n t , the crew member would use the pro p u l s i ve power of SAFER to re t u rn to the s t a t i on stru c t u re . SAFER fits over the portable life support system of the Shuttle EMU. A control module consisting of a joystick and display is stowed in the Mark C.Lee test flies the Simplified Aid for Extravehicular activity Rescue (SAFER) device during the STS-64 mission. bottom of SAFER. During operation, the control module is moved to the suit's front for easy access. 41-B mission. Taking turns, the two astronauts With the controls the astronaut can expel nitrogen flew the MMU out from the orbiter's payload bay gas through 24 nozzles that are fixed in different to a distance of about 100 meters and tested com- orientations around the device. An autopilot system plex maneuvers. On STS-41C, the next Shuttle is available to keep the astronaut at the same orien- mission, James Van Hoften and George Nelson tation for a limited period of time. SAFER features used the MMU to capture the Solar Maximum the same maneuverability as the MMU but because mission satellite and bring it into the orbiter's pay- its nitrogen tank only holds 1.4 kilograms of nitro- load bay for repairs and servicing. Their work gen gas, the total velocity change possible with the increased the life span of the satellite. The final unit is 3.05 meters per second. MMU mission was STS-51A that flew in
36 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q EVAs on the International Space Station
In recent yea r s , NASA has increased the fre- qu e n c y of extrav ehicular activity to prep a r e for the as s e m b l y of the Interna t i o nal Space Sta t i o n begin- ning in the late 1990s. Two recent extrao rd i n a r y Shuttle missions have demons t r ated the potential for EVA on the Space Sta t i on . These were the STS-61 and STS-82 missions in 1993 and 1997 in wh i c h astronauts conducted multiple spacewalks to se r vice the Hubble Space Tel e s c o p e . Dur ing each fl i g h t , cr ew members donned their spacesuits and co nducted EVAs in which they replaced instrum e n t s and installed new solar panels.Their servicing activ- ities req u i r ed extreme prec i s i o n and dexterit y durin g EVAs lasting more than seven hours. Similar efforts will be needed for the assembly of the International Space Station. During the nearly 40 American and Russian space flights to the station, astronauts and cosmonauts will log over 1,200 hours of EVAs.More hours of spacewalks are expected to be conducted during just the years 1999 and 2000 than were conducted during all previous US space flights. Spa c e walkers will assist in the assembly of the Space Sta t i o n by making all the conn e c t i o ns that req u i r e greater dexterit y than can be accomp l i s h e d with station rob o t s . These operat i o ns include joining STS-82 (1997) astron a uts Mark C. Lee (top) and Steven L. Smith (bottom) el e c t ri c al cables and fluid tran s f er lines and installi n g repair a worn area in the insulation of the Hub b le Space Tele s c o p e . De ta i l e d wo r k like this will be a frequent occurrence during the assembly and opertion of and deploying commu n i ca t i o n antennas. To do this, the International Space Stat i o n .
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 37 STS-76 astronaut Michael R. Clifford works with a restraint bar on the Docking Module ofthe Russian MIR space station.Similar docking modules (Pressurized Mating Adaptor) will be used on the International Space Station. sp a c e walkers will have to rem o ve locking bolts that assembly to the Space Station, attaching grapple se c u r ed comp o nents during launch to orbi t . fixtures to objects that have to be moved by the As the Space St a t i on ev o lve s , a s t ronauts will Space Station's robot arms, mounting tool kits, m ove com p on e n t s , s u ch as antennas, to the most adding batteries, and reconfiguring valves for fluid advantageous loca t i on s . For example, a com mu n i- transfer.Later, during the operational phase of the ca t i ons antenna may become blocked when addi- I n t e rn a t i onal Space St a t i on , s p a c ewalkers will t i onal station modules are joined to the stru c t u re . replace orbital replacement units (ORUs). These Sp a c ewalkers will have to tra verse the outside of are modular devices, such as the scientific instru- the modules and re p o s i t i on the antenna where it ments on the Hubble Space Telescope, that are w i ll be unblocked by modules, solar panels, a n d designed to be removed periodically and replaced other stru c t u re s . with improved or more advanced equipm e n t . Still other Space Station EVA assembly tasks O p e ra t i onal spacewalks will also take ca re of include removing of locking bolts for solar panels mounting external payloads that are brought up to and radiators, driving bolts that hold the truss the Space Station on the Space Shuttle.
38 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Future Space Suits
The current Extra vehicular Mobility Unit (EMU) and all its associated EVA systems are the result of many years of research and development. They now comprise a powerful tool for orbital operations, but they are not end-of-the-line equip- ment. Many improvements are possible; the space- suit of the future may look dramatically different from the Space Shuttle EMU. Advanced versions of the EMU are being stud- ied, including spacesuits that operate at higher pressures than the current EMU. The advantage of higher operating pressures is that virtually no time will be lost to prebreathing in preparation for EVA. To build an opera t i onal high-pre s s u re suit requires improved joint technology and integration of those joints into the suit.Under consideration are fabric and metal suits and suits with a hard external shell. Most of the technology needed for these suits has already been tested. One of the biggest chal- lenges is to make a highly mobile glove. At higher operating pressures, fingers of older-style spacesuit gloves become so increasingly stiff that finger dex- terity is severely reduced. Research to address this problem has led to the development of high-pres- sure gloves made with metal bands for knuckle and palm joints. These gloves show potential for use with future suits as well as with current suits, but there is still more work to be done. One line of The Mark III Hard Suit is modeled by a spacesuit engineer.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 39 Spacesuit technicians test the mobility ofa proposed hybrid suit design.
was a lengthy process because it involved lacing pieces together.Quick disconnect sizing inserts have been designed that greatly speed up and sim- plify the process.The new system involves threaded
A prototype ofa next-generation spacesuit is tested. q u i ck discon n e c t s , aluminum sizing ri n g s , a n d adjustable restraint lines.The capability of servicing research has explored incorporating robotic aids and resizing suits in space is vital for operations on into the glove such as motor and cable systems to the International Space Station. There, crew mem- provide grasping force at higher pressures. So far, bers will remain in space for months at a time, and such systems have not been successful because of EVAs will be routine events. With this and other the extra bulk added to the hands and arms of the improvements in design, spacesuits will be able to suit and because of the "what if" problem of a sys- be used 25 times on the International Space Station tem failing while the hand is clamped onto an over a period of 180 days before they have to be object. That could make it very difficult to release returned to Earth for major reservicing. the object. Another suit improvement is an electronic ver- Another improvement in suit design will per- sion of the checklist worn on the arm. The new mit servicing and resizing suits in orb i t . T h i s system,similar to a pocket electronic organizer, will improvement has already been tested on the STS- enable the spacewalker to run through complex 82 mission to service the Hubble Space Telescope. sequences at the touch of a button. The checklist The original design of the Space Shuttle EMU can be easily reprogrammed for new tasks. It may required the removal or the addition of sizing also have the capability of displaying television pic- inserts to lengthen or shorten legs and arms. This tures from external cameras.
40 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Other Worlds a Space Shuttle style spacesuit would weigh about 19 kilograms. The suit will operate in an environ- For the most part, the design of a spacesuit is ment in which there is an up and a down direction. based on the environment in which it operates. Circulatory pumps in the suit will face increased Space Shuttle spacesuits for use in Earth orbit are loads. Temperature extremes on the Moon will be designed to operate in a vacuum and microgravity. about the same as in orbit about Earth when in A spacesuit for use on the surface of the Moon or direct sunlight and in shade. However, when the Mars will require a different design. On the Moon, astronaut walks on the Moon,heat will be conduct- ed into or out of the suit via the feet. On Mars, a Space Shuttle style spacesuit would weigh about 43 kilogra m s , exhausting the astronaut who has to wear it for long periods of exploration. Consequently, lighter EMU structures will be need- ed to lessen the load a future Martian explorer will carry. In addition, the thin Martian atmosphere may provide too much pressure for a cooling subli- mator to work. Some other cooling strategy will have to be devised. Still another concern is to pro- vide protection from dust that is carried by Martian winds and will be kicked up by the explorers. On the Moon,lunar sediment is very angular and abra- sive but there is no atmosphere to stir it up. Until samples of the Martian sediment are returned to Earth,we won't know how abrasive it will be.These and other properties of the Moon and Martian environment provide interesting and exciting chal- lenges to spacesuit designers and builders. EVA
St a rting with Edward White II’s spacewalk in 1 9 6 5 , Am e ri can astronauts have logged many hun- d reds of hours of extra vehicular activity in space. M i s s i on planners corre c t ly foresaw the role EVA would play in future space mission s . The early Gemini experience was pri m a ri ly experi m e n t a l . Du ring the Ap o llo and Sk ylab pro g ra m s , EVA was c ri t i cal to success. With the Space Shuttle and the I n t e rn a t i onal Space St a t i on , it is even more cri t i ca l . By donning the EM U, an astronaut becomes a s m a ll , s h o rt - t e rm spacecra ft . Space-suited crew members can manipulate payl o a d s , make adjust- A future Martian explorer takes rock samples dangling offthe escarpment of m e n t s , repair broken part s , join pieces together, the Olympus Mons volcano.Pat Rawlings,SAIC.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 41 Future spacewalkers will roam the surface ofthe Moon and Mars.This picture, painted by artist Pat Rawlings ofSAIC,shows the first humans to explore the sur- face ofMars.The explorers, wearing spacesuits specially-designed for the Martian environment,are scouring the surface looking for clues to the planet’s history and evidence for signs oflife. and handle a host of other activities. Most impor- occur in the hard and unforgiving env i ronment of t a n t , t h ey bring with them the human ability to outer space. cope with unexpected or unusual situations that
42 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Activities–Designing Spacesuits for Mars Technology Education, Science, and Mathematics
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 43 Introduction: team, combines skills and content from science, mathematics, and technology. The challenge is to The steps spacesuit engineers and technicians fol- design and build a full-scale wearable model space- lowed in achieving a goal of creating reliable space- suit to be used to explore the surface of Mars. Since suit systems for exploration of the surface of the no human expeditions to Mars are planned for Moon and for construction and maintenance work many years, actual Martian spacesuits have not yet in Earth orbit were the same as those used in near- been built and there are no "right" answers. ly every technological endeavor: Consequently, this activity permits students to par- ticipate in "leading edge" research. Challenge Design and construct a protective garment that will The overview of the activity is contained in a permit humans to venture safely into outer space Design Brief format. It begins with a title and a and perform work. context statement (introduction) and is followed by a challenge to create a Martian spacesuit. This is Research followed by information on materials, equipment, Investigate the environment in which the garment procedures, and evaluation. The success of the will be worn and determine what protective mea- activity depends upon how well the students orga- sures must be employed. nize their work and communicate with each other. A computer with project software can be used to Management monitor the progress of the project or a flow chart Organize the effort into teams that design suit sub- can be constructed on a chalk or bulletin board. As s ystems and investigate and select appro p ri a t e an added aid to communication, Interface Control materials and technologies. Documents (ICD) are created as systems are designed.(Reproducible master on page 49. Sample Fabricate Prototypes Construct and assemble suit subsystems into the completed garment.
Evaluate Test the garment in a simulated space environment and make modifications where needed.
Manufacture Construct operational spacesuits.
Ongoing Evaluation Continue refining spacesuit subsystems to improve efficiency, reliability, versatility, and safety while lowering costs.
The pages that follow outline a multifaceted tech- nology education activity on spacesuits. This activ- Technology Education is a multi-disciplinary subject combining mathematics, ity, designed for an entire class to work on as a science, and technology.
44 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q document on page 50.) These documents are com- pr ints" for students to use. Rat h e r , th e y provi d e pleted by the teams. Critical details about systems, in f o rm a t i o n on one of many ways in which the task such as size, shape, and function, are recorded on can be accomp l i s h e d . Students will build an impact the form. The form has a grid where diagrams can test stand of their own design.TTBs aid you in facil- be made. ICD forms are then placed in a notebook itating the students' ideas. Foll o wing the TTBs is a and made available to all teams as a coordination se c t i o n on spacesuit testing apparatus used at the tool. An ICD master is provided. NASA John s o n Space Center. The apparatus are "o ne of a kind" devices created by follo wing the If desired, the project can be divided among several same design process students will use. classes (or even several schools) which will each have to work together. This is the way major NASA Exploration Briefs (EBs) are suggestions for activi- projects are divided between contractors and sub- ties that can be used to help students understand contractors located across the country. the nature of the environment for which they are designing a spacesuit. They provide background To support the activity, a colle c t i o n of Tea c her Tec h information and instructions for simple demonstra- Bri e f s (TTB) are inclu d e d . These brie f s provi d e tions and experiments that may be tried. A "bank" su g g e s t i o ns for your use when guiding students in of additional ideas follow the EBs. ac c o mplishing their tasks. For example, if student teams conc lude that high-speed parti c les (microme - The guide concludes with appendices that list te o r oids) are a problem in the Martian envi r onm e n t , res o u rc e s , su c h as NASA publicat i o ns and Interne t plans are provided for a device that measures impact web sites, wh e r e students can obtain more informa t i o n damage to materia l s . TTBs are not intended as "blue to help them in their res e a r ch and devel o p ment work.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 45 Design Brief Co n t ex t : Spacesuits are one of the important enabling technologies that have permitted humans to explore outer sp a c e . To survi v e the hostile envi r onm e n t , humans had to be cover ed with a prot e c t i v e shell as they exit- ed their spacecraft . This shell contained a part of Earth's surface envi r onment while remaining flexible and impervious to the unique hazard s , su c h as high-speed parti c le impacts, en c o u n t e r ed there .T h e s e req u i r ements meant that engineers and technicians had to spend long hours investigating and selecting ap p ro p r iate materia l s , finding ways of fabric ating and joining suit parts together, and providing operat - ing pres s u r e, pow e r , and commu n i ca t i o ns while assembling a garment that was tough but flexible. Th e task was achi e ved with such great success that astronauts and cosmonauts have safel y conducted thou- sands of hours of extrav ehicular activity.
Ch a ll e n g e : Design and build a prot e c t i v e garment that will permit future space trav elers to explore the surface of Ma r s . The garment must protect the person inside from the hazar ds of the Martian envi r onment while remaining comf o r table to wear. Exc u r s i o ns on the surface will nomi n a l ly last 8 hours, but the garme n t wi l l have to function as long as 10 hours in emergency situations . The garment must be flexible enough to enable the wearer to walk up to 10 kilom e t e r s ,c o llect geologic samples, and operate a varie t y of tools and experimental apparat u s . Furt h e rm o r e, the garment's design must be rugged enough to permi t repeated use and be able to be serviced simply and quickl y. Al o ng with the garme n t , design a colle c t i o n of geologic sampling tools, su c h as roc k hammers, and a general set of tools for assembly and repair activ- it i e s . These tools should be easy to use while wearing the prot e c t i v e garme n t , be safe and rug g e d , an d in t e r face with a general purpose tool car r ier that must also be designed.
Proc e d u r e s : Select subcontractor teams to design and construct each of the garment's components, such as the helmet or gloves. Teams will coordinate their work with each other as materials for and sizes of the components are selected.
Ma t e ri a l s : Use whatever materials you find to cons t r uct the garment's comp on e n t s . Test these materials to ensure th e y will survi v e the Martian envi r onm e n t . Existing tools can be modified for use on Mars.
Ev a l u a ti o n : Co nduct periodic team eva l u a t i o ns of the prog r ess of the garment and tool design proc e s s . When all com p o nents are comp l e t e d ,i n t e g r ate them for a full test in a simulated Martian envi r onm e n t .E v a l u a t e the garment and tools on the basis of the crit e r ia presented in the context section.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 47 Interface Control Document Page Of
System Name: Team Members
Project No.
Date: Rev. No.
Briefly explain how this system functions. Interface Control Document Page 1 Of 1
System Name: Space Helmet Team Members
Project No. 8 Peter
Date: Nov. 22, 1997 Rev. No. 4 Kiesha
Helmet - 40 cm in diameter
Lights (3) Sun Visor
Window SAMPLE
Neck ring - 25 cm in diameter
SCALE: 1:5 MASS: 5 kg POWER REQUIREMENTS: 6 volts
In t e r face Cont r ol Documents are a commu n i ca t i o n tool that helps the various Martian Sur face Explorat i o n Suit design teams to coordinate with each other. This sample shows a design for a space helmet. The team wo r king on the upper torso will learn from this document how large the conn e c t i o n with the helmet has to be.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 49 Teacher Tech Brief Tensile Strength Test Strand
Context Pulley block (1 double, 1 triple) The different materials used in constructing the Cord for pulleys Space Shuttle EMU were chosen because they each Clamps (2 ) featured properties deemed desirable for spacewalk- Metric Ruler i n g. Depending upon their intended purp o s e, Pointer (stiff wire) material may have to withstand tears, punctures, Hose clamps (2 pcs ) temperature extremes, bending, abrasion, or any Lead weights (25 kg) combination of the above. Bucket Screwdriver Purpose Pipe wrench This test stand measures materials for their resis- Materials to be tested tance to tensile (stretching) forces. Eye Protection
Principle Operation Using the mecha n i c al advantage of a pulle y setup, te n - Obtain diffe rent fabric samples from re m n a n t sile forces are exer ted on test samples until they brea k . tables at fabric stores. Also ask students to bring in samples with which to work.Cut the material to be Materials and Tools Checklist tested into a rectangular strip 1 centimeter by 10 Wooden base (6" x 1" x 4') centimeters in size.The sample is held between two Threaded iron pipe (1 pc 3/4" x 2') clamps as shown in figure 1. Place a small number (2 pcs 3/4" x 3') of lead weights in the bucket to counterbalance the Pipe elbows (2 pcs ) weight of the clamp and pulle y assembly so that the Pipe flanges (2 pcs ) sample material is held uprig h t . Re c o r d the position Screws for flanges of the wire pointer on the rul e r . This is the zer o force Pulley (1 single) me a s u re m e n t . Gra d u a l ly add measured weights to
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 51
Pulley close-up view
the bucke t . The mecha n i c al advantage of the pulle y • The test stand can be modified for other ar r angement magnifies the actual pull (tensile force ) m a t e rials tests. on the sample five times. Re c o r d the tensile force • Students should wear eye pro t e c t i on when (the weight in the bucket multiplied by five) and the operating the apparatus. po s i t i o n of the pointer. The position of the pointer • Details on how to attach the clamps to the in d i c ates how muc h the fabric stret c hes as the force apparatus have not been provided because of the in c re a s e s . Add more weight and rec o r d the data. variety of clamping devices that could be used. Co ntinue this process until the sample breaks or you Students building the apparatus will have to run out of weights. Cr eate a grap h to demons t ra t e determine how this is done. the perfo r mance of the materia l . Extensions Tips • Co ntact manufacturers of "high-tech" fabrics and •An empty metal gallon-size paint bucket can be fibers for specificat i o n sheets on the prop e r ties of used to hold the lead weights. their prod u c t s . Some manufacturers may have • Used wheel-balancing lead weights can be web sites on the Interne t . Co nduct an Interne t obtained free or for little cost at tire stores. se a r ch using terms such as Kevlar® and Nome x ® . • In some materials, tensile strength varies with •Visit a sail maker's shop to learn about materials the direction the force is exerted. Compare cut being used for sail construction and how fabrics crosswise to the grain and on the bias. are stitched together for maximum strength. •For very strong fabrics (e.g. Kevlar®) test a •Learn about how fabrics are manufactured and narrower strip or even single strands and extrap- how different properties are achieved through olate the results to the force a one-centimeter fiber choice, weaving techniques, and coatings. wide piece could withstand. Check for videotapes in school video catalogs.
52 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Teacher Tech Brief Impact Resistance Tester
Gra p h i c Materials and Tools Checklist One of the hazar ds of spacewalking is the presence of Wooden base (6" x 1" x 2') sm a l l high-speed parti cl e s . These parti c les are call e d PVC plastic water pipe (3/4" x 10') mi c r ome t e o r oids and usually are smaller than a grai n Pipe elbows (2 pcs) of sand, ha v e a mass that is onl y a frac t i o n of a gram , Pipe flanges (1 pc) and trav el at speeds ranging from a few to as many as Screws for flange 80 kilometers per second . An astronaut struc k by a Bell wire mi c r ome t e o r oid could be severe l y injured . Furt h e rm o r e, Large eye screw the near-Earth space envi r onment has the additiona l Electronic project box pr oblem of space debris such as paint chips and metal On/off switch fr agments from old roc ket boosters and satelli t e s . Pilot light Being struc k by one of these parti c les is equally dan- Push button switch ge ro u s . As a cons e q u e n c e , spacesuits have to be con- 6 volt battery holder st r ucted from materials that are resistant to impacts. Wooden block (1" x 6" x 6") Center punch Pur pos e Screw driver This test stand measures the resistance of sample Meter stick ma t e r ials to impacts. Test materials Tape or pins Prin c i p l e The test stand consists of a towe r , made from pipe, Operation with an electromagnet near the top. A center punch Cut the material to be tested into a small square and (impactor) is suspended from the magnet and drop s tape or pin it on the test surface block (1" x 6" x 6" when the electric i t y is cut off. The center punch falls wooden block) . Af ter positioning the test materia l , into a test sample placed below. tu r n on the electromagnet and attach the impactor.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 53 Mathematics Equations
In physics, the energy of a moving object is called kinetic energy. The amount of that energy is related to the object’s mass and its speed. The equation below can be used to determine the kinetic energy of the falling center punch at the moment of its impact on the test surface. The answer will be in joules (unit of work equal to a force of one Newton exerted over a distance of one meter; in English units, a joule is approximately equal to 0.75 foot pounds). Electromagnet KE = 1/2 mv2
Impactor m = mass of impactor v = velocity at impact Tower (Two Meters Tall) To determine the velocity at the impact, use the following equation:
v = gt
g = the acceleration of gravity or 9.8m/second2 t = length of time the impactor fell
Distance Impactor Falls To determine the length of time the impactor falls.
6 Volt Power Test Surface Block use the following equation: Supply
t = 2d g
d = the distance the impactor fell, in meters
Measure the distance between the point of the elec- Sample Problem tromagnet and the test material. When the impactor d = 2 m and magnet stop swinging, turn off the electric cur- Impactor mass = 50 grams rent to release the impactor. As it falls, the impactor What is KE? will accelerate into the sample and make a dent or 2 even penetrate it. Evaluate the resistance to impacts v = 9.8m/s of various materials by comparing the damage done x 0.64s = 6.3m/s to them. Use a metric ruler for measuring the diame- KE = 1/2 x 0.05kg x (6.3m/s) 2 = 1.19 joules ter of the dent or hole.
54 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ Special Note Tips •Parts for the impactor design pictured in this In this simulation of m i c ro m e te o roid impact we are activity are available from hardware stores (pipe s u b s t i tuting an impactor with a large mass and low parts, screws, eye screw, center punch) and vel o c i ty for a micro m e te o roid with a small mass and a electronic parts stores (project box, switch,bat- high vel o c i ty. The reason for this can be seen in the first tery holder, pilot light, electromagnet wire). two equations on the previous page. Vel o c i ty is a • Make your electromagnet by wrapping electro- qu ad r atic factor while mass is a linear fac t o r. B e cau s e magnet wire about 400 times around a large eye o f this trad e, we can ach i eve similar damage to the sc r ew. When the magnet is electrified the blunt s u rf ace of a material being impac te d.Ho wever, end of the impactor will be held by the magnet. m i c ro m e te o roids usually vap o rize upon impac t . If t h e When the current is turned off, the magnet s u rf ace layer is penetra te d, the gas produced disperses on impactor will drop straight to the target. the material beneath. • Have students bring in various materials for testing such as fabrics and plastics. Encourage Safety Precautions students to create composite materials by com- 1 .A ll oper ators and observers must wear eye prot e c - bining two or more materials together. tion during drop s . • Ask students to keep a test log containing data fr om each test. En c o u r age students to pred i c t 2. The materials to be tested should be placed on the the amount of damage a sample will rec e i v e dur- test stand before the impactor is suspended from ing a test and comp a r e that to the actual res u l t s . the electrom a g n e t . Nothing but the material to be • Discuss the relative merits of the materials the tested should under the suspended impactor. students tested. For example, a thick layer of
Wiring Diagram for Power Supply Finished Power Supply
Leads To Electromagnet
Momentary Power Supply Off On Switch On
Arming Light On/Off Switch
6 Volts
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 55 steel would make an excellent micrometeoroid on the speed of the impactor as it falls. It will shield but would probably be too heavy and too be observed that the farther the impactor falls, inflexible to be of use in a Martian suit. the faster it falls. • B e f o re running tests on impact re s i s t a n c e, u s e E x p l o ra t i on Brief on Microm e t e o roids and Extensions Space Debris (p. 67) with the students to • The impactor can be dropped from any height i n t roduce the topic of spacesuits and impacts. when testing materi a l s . At what height should A fter your students have selected materials for the impactor be suspended to equal the their spacesuit, ch a llenge them to wrap a impact of a microm e t e o roid in space if the potato in their materials and see if the mate- m i c rom e t e o roid has a mass of 1x10-5 gra m s rials prevent penetra t i on in the drop test. and a ve l o c i ty of 8,000 meters per secon d ? R e fer to the potato astronaut activity for more Ve l o c i ty of 16,000 meters per second? (Yo u r i n f o rm a t i on . answers will depend upon the mass of the • A typi c al microme t e o r oid has a mass of 1x10-5 impactor you use.) gr ams and trav els at about eight kilometers per • How much kinetic energy is expended by the s e c on d .U p on impact, ap p r oxi m a t e l y three joules micrometeoroid above? of work is expended. • Challenge the students to combine the equa- • A drop tower is not necessary for this test. T h e tions on the previous page into simpler math- e l e c t romagnet can be suspended from a pull ey ematical statements. f rom the ceiling. The tow e r, h ow ever makes • How high should the impactor be before drop- the unit ve ry portable and eliminates any haz- ping to simulate the impact of a microme t e o ro i d a rds associated with attaching a pull ey to a with a mass of 1x10-5 grams and a vel o c i t y of high ceiling. eight kilometers per second? How high should • For younger students, begin studying the the impactor be suspended if the micromete- mathematics of the device with observations oroid's velocity is 16 kilometers per second?
56 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Teacher Tech Brief Abrasion Tester
Background an a l ysis of the sediments permitted scientists to cre- M a ny years before Ap o llo astronauts walked on ate simulated lunar sediments to use in experim e n t s . the surface of the Moon , s ome scientists speculat- Based on Viking studies of Mars and the discover y ed that lunar dust might pose a significant haza rd . of Martian meteorites in Ant a rc t i ca , scientists have Dust accumu l a t i ons in old craters could be quite also created simulated Martian sediments. Bo t h deep and swall ow up an unsuspecting astron a u t si m ulants have been used in a varie t y of tests, su c h that tried to cross on e . Lunar Su rveyor spacecra ft as fabric abras i o n and penetrat i o n of bearing seals. that landed on the Moon prior to the Ap o llo expe- Since astronaut stays on the Moon were limited to a d i t i ons showed that lunar dust (ca lled re golith or sediment) had on ly accumulated to the depth of a few centimeters and there f o re could not swall ow up astron a u t s . This did not mean that the sedi- ment was com p l e t e ly safe . Ra t h e r, the fineness of the sediment could pose a diffe rent kind of h a za rd—fouling equipment and suit com p on e n t s . Viking landers on Mars in the middle 1970s and the recent Pa t h f i n d e r / So j o u rner mission show e d that Mars also has a sediment coating that could foul equipment and suit com p onents of future M a rtian explore r s .
Tod a y, it is possible to study the effects of lunar sed- iment on materials because the Apo l lo astrona u t s ret u r ned home with samples. Rather than cons u m e valuable lunar sediment samples on materials tests,
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 57 da y or two ,Apo l lo spacesuit materials onl y had to Four casters s u rv i ve 10 to 20 hours of use. Fut u r e Marti a n Wood block stops ex p l o re r s , how e ver , wi l l remain on the planet for Fabric samples ma n y months to a year or more, and their suits will Masking tape need to be cons t r ucted of rugged materia l s . Martian sediment simulant
Purpose Operation This apparatus will measure the abrasion of fabrics The device shown on the previous page is a home- and other suit materials exposed to simu l a t e d made rock tumbler. It is constructed from a plastic Martian sediment. jar of the kind supplied to cafeterias and restaurants with various food stuffs such as relishes or mayon- Principle naise. A motor, pulley, and rubber band belt rotate Test samples are placed in a rock tumbler or a spe- the jar. The jar rests on inverted casters and is held cially constructed tumbler similar to the one shown in place with stops at the ends. Squares of fabric on the proceeding page. Simulated Martian sedi- samples are taped to the inside walls of the jar and ment is placed in the drum and the rotating motion a measured quantity of Martian sediment simulant causes the sediment to abrade the samples. is placed in the jar. The jar is allowed to rotate for a day or two and the fabric samples are removed for Materials and Tools Checklist c om p a ri s on with fresh samples. R e d d i s h - b row n Wooden base (12" x 24" x 1") volcanic rock used for landscaping can be used for Electric motor with pulley making Martian sediment simulant. Bags of the (use motor with low rpms) rock will have small amounts of abraded sediment Pulley belt at their bottoms or you can crush the rocks to a fine Plastic food jar (1 gallon) soil-like material. Be sure to wear eye protection and gloves. Use a hammer to smash the rocks. Sort out and discard the larger pieces to leave just the sandy to powdery material behind.
Tips •Look for an electric motor at an electric parts store. It may also be possible to find a suitable motor in an old appliance. Casters can be obtained at a hardware store. • Examine fabric samples for signs of wear such as tears and holes. If a sample is opaque, place it on the lighted stage of an overhead projector to look for holes and thin areas. • If solid materials are to be tested,do not test fab- rics at the same time. The solid materials may damage the fabric,making it difficult to interpret the results. Fabric abrasion tester in use at the NASA Johnson Space Center. The white drum contains an inflated cylinder made from the outer fabric ofa spacesuit. • Estimate the number of rotations of the "rock The drum also contains lunar sediment simulant. An electric motor with a pulley drives the drum. tumbler" jar by counting how many times the jar
58 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Apollo 16 astron a ut Charles M. Duke Jr. samples lunar regolith (sediment) next to the “house roc k ” in the lunar Descar tes highlands. Very fine sediment clings to his suit.
rotates in one minute. Multiply the number of minutes the jar has been rotated by the number of rotations per minute. • Mo r e student interac t i o n with the activity can take place if the motor-dri ven apparatus is replaced with just a jar. Ea c h day for a week or two , students spend a few minutes shaking and rotating the jar and counting the number of times.
Extensions
• Devise testing procedures to measure the abra- sion of the fabric on fabric in places on the space- suit where fabric rubs against itself (underarms, crotch, etc.).
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 59 NASA Spacesuit Test Apparatus
In addition to laboratory versions of the testing apparatus described in the Teacher Tech Briefs, NASA spacesuit engineers also employ the appara- tus shown on these two pages.
Bearing Tester Bearings and other joints are subjected to simulated lunar sediment to find out ifthe sediment degrades their performance. The wrist bearing inside the unit is rotated as simulated lunar sediment is poured over it.The white device in the tester is a winshield wiper motor that rotates the bearing.
Mechanical Boot Tester Checks book performance with a walking motion.
Waist Bearing Tester The waist bearing is placed through a series ofbends by this device.
60 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Sleeve and Leg Tester Inflated segments ofsleeves and legs are bent repeatedly by this device.
Spacesuit Robot The forces required to move suit arms and legs when the suit is pressurized are measured with this specialized robot.The robot is placed inside a suit.A gas- ket seals the neck ofthe suit.The suit is then pressurized through the robot’s “head.”Joints in the arm and leg ofthe black side ofthe robot are bent on command and the forces are measured. The white side ofthe robot is non- functioning. Only one side ofthe robot is needed for data and the white side serves only as balance.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 61 Exploration Brief Different Gravity
Context would weigh about 2/5ths as much on the surface of Gravity is an attractive force that all objects have for Mars. The reason for the difference is that the one another. It doesn't matter whether the object is Moon and Mars are less massive bodies than Earth a planet, a cannon ball, a feather, or a person. Each and they have smaller radii. Less mass reduces the exerts a gravitational force on all other objects amount of gravity experienced on the surface of the around it. Moon and Mars while the smaller radii increases it.
The amount of the gravitational force between two Besides being altered by mass and distance, our per- objects is directly proportional to the product of ception of gravity's pull can also be altered by their two masses and inversely proportional to the motion. Gravity can be made to appear to increase square of the distance between their centers of by accelerating away from Earth, as in a rocket mass.This relationship is expressed in the equation liftoff or by riding on a centrifuge. Gravity can be below. M1 and M2 are the respective masses of the made to appear to decrease by falling.NASA calls two objects and r is the distance between their cen- the environment created by falling microgravity. ters of mass. G is the gravitational constant. You can get an idea of how this works by looking at m m f = G 1 2 the diagram on the next page. Imagine riding in an r2 elevator to the top floor of a very tall building. At the top, the cables supporting the car break, causing By referring to this equation, we can see that the the car and you to fall to the ground. (In this exam- f o rce of gra v i ty is not con s t a n t . The amount ple, we discount the effects of air friction on the depends upon local conditions. For example, an falling car.) Since you and the elevator car are astronaut walking on the surface of the Moon falling together, you feel like you are floating inside would weigh only 1/6th what he or she would the car. In other words, you and the elevator car are weigh on the surface of Earth.That same astronaut accelerating downward at the same rate due to grav-
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 63 ity alone.If a scale were present, your weight would the pump has to work against gra v i ty than if it not register because the scale would be falling too. w o rks in a micro g ra v i ty situation . On an Ap o ll o The ride is lots of fun until you get to the bottom! M o on landing mission , spacesuits were worn dur- NASA calls this floating condition microgravity. ing liftoff when high G (gra v i ty) forces were fe l t The condition is experienced in orbit and in transit b e cause of the accelera t i on . The suits were worn between planetary bodies. d u ring lunar walks where the gra v i ty was 1/6th that of Earth's gra v i ty. Fi n a lly, the suits were A s t ronauts experience many diffe rent gra v i ty w o rn in a micro g ra v i ty env i ronment duri n g e nv i ronments during space tra vel and these s p a c ewalks while they coasted back from the e nv i ronments make diffe rent demands on the M o on . Space Shuttle spacesuits are worn on ly in spacesuits they wear. When designing a spacesuit, m i c ro g ra v i ty during space walks in Earth orb i t . it is important to know in which gra v i ty env i ron- Suits worn on the surface of Mars may have to be ments the suit will be worn . For example, g re a t e r modified to function in the 2/5ths g that will be s t rain will be placed on fluid pumping systems if e x p e rienced there .
(A) The person in the stationary elevator car experiences normal weight.(B) In the car immediately to the right, weight increases slightly because of the upward acceleration. (C) Weight decreases slightly in the next car because of the downward acceleration.(D) No weight is measured in the last car on the right because of freefall.
64 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Investigation: Creating Extensions • Challenge students to come up with a way of Microgravity simulating the 2/5ths gravity of Mars. • Obtain a copy of the NASA curriculum Microgravity is easy to create. It is merely a matter supplement Microgravity—Activity Guide for of dropping objects.By falling, gravity's local effects Science, Mathematics, and Technology Education, are greatly reduced.That means that if two objects E G - 1 9 9 7 - 0 8 - 1 1 0 - H Q. The guide con t a i n s are falling together, gravity's influence on them plans and instructions for several additional becomes nearly zero. For example, if a heavy weight microgravity demonstrations. is suspended from an elastic cord, the cord will stretch out. If the cord is released, the weight and cord begin to fall to the floor.With gravity's effects greatly reduced, the cord immediately retracts to its relaxed length.The following activities are methods of creating microgravity in the classroom.
Materials and Tools Checklist Paper cup Masking tape Rubber band (thin) Several washers or nuts Scissors
Objective •To investigate microgravity.
Procedure St ep 1. Cut the rub b e r band and tie one end to the nuts or washers . The nuts or washers should be he a vy enough to stret c h the rub b e r band when suspended from the free end. St ep 2. Tape the free end of the rub b e r band to the inside of the cup. St ep 3. Hold the cup upside down. Slowly tur n the cup right side up so that the nuts or washers hang outside the cup. St ep 4. Drop the cup to the floor from eye level. Ob s e rve what happens to the wei g h t s . St ep 5. Discuss the implications of mi c ro g ravi t y on sp a cesuit design. For exa m p l e , how can fluids (w a t er cooling sys te m , gas circu l a t i o n , etc.) be mo v ed in microg ravi ty ?
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 65 Exploration Brief Micrometeoroids and Space Debris
Co n t ex t Re c e n t l y spacecraf t debris is of great conc e r n to space- As t r onauts on spacewalks are likely to encounter fast- cra f t engineers. Thousands of space launches have left mo ving parti c les cal led meteoroi d s . A meteoroid is usu- ma n y fragments of launch veh i cl e s , paint chi p s , and other al ly a fragment of an asteroid consisting of roc k and/or "space trash" in orbi t . Most parti c les are small, but they me t a l . It can be ver y large with a mass of sever al hun- tra v el at speeds of nearly 8,000 meters per second .T h e s e dr ed metric tons , or it can be ver y small—a microme t e - space-age parti c les have become a significant hazar d to or oid which is a parti c le smaller than a grain of sand. sp a c e c ra f t and to astronauts on extrav ehicular activities. Mi c r ome t e o r oids are usually fragments from come t s . Eve r y day Earth's atmosphe r e is struc k by milli o ns of Engineers have protected spacecraf t from microme t e - me t e o r oids and microme t e o ro i d s . Most never rea c h the or oids and space trash in a number of ways, in cl u d i n g su r face because they are vaporiz ed by the intense heat th i ck - w a l l cons t ru c t i o n and mul t i - l a yer shields cons i s t - ge n e r ated by the fric t i o n of passing through the atmos- ing of foil and hydro ca rb o n materia l s . A microme t e - phe re . It is rar e for a meteoroid to be large enough to or oid striking mul t i - l a yer shields disintegrates into su rv i v e the descent through the atmosphe r e and rea c h ha r mless gas that disperses on inner walls . Spa c e s u i t s solid Earth . If it does, it is cal led a meteorit e . pr ovide impact prot e c t i o n through various fabric - l a yer com b i n a t i o ns and strat e g i ca l ly placed rigid materia l s . In space there is no blanket of atmosphe r e to prot e c t sp a c e c ra f t from the full force of meteoroi d s . It was Although effec t i v e for parti c les of small mass, th e s e once believed that meteoroids trav eling at velocities up pro t e c t i v e strategies do little if the parti c le is large. It is to 80 kilometers per second would prove a great haz- es p e c i a l ly important for spacewalking astronauts to be ar d to spacecraft . How e ver , scientific satellites with car eful when they repair satellites or do assembly jobs me t e o r oid detection devices proved that the hazar d on the Interna t i o nal Space Sta t i on . A lost bolt or nut was minimal. It was learned that the majorit y of mete- could damage a future space mission through an acci- or oids are too small to penetrate the hull of spacecraft . dental colli s i on .( No t e : Low orbit tends to be cle a r er of Their impacts prim a ri l y cause pitting and "sandblast- pa rt i c les than higher orbits because low orbit parti cl e s ing" of the cover ing surfa c e . tend to decay and burn up in the atmosphe r e.)
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 67 Investigation Connections: Mathematics Refer to the "Potato Astronaut–Part One" activity Pea Shooter Meteoroids that follows.
The effects of high-speed micrometeoroid impacts Extensions can also be simulated with a "pea shooter." The •Tape two straws end to end. Does that increase shooter is actually a plastic milkshake straw. The the velocity of the projectile? projectile can be dried peas, popcorn, dried lentils, • Experiment with projectiles that have a greater etc. The object of the activity is to penetrate tissue mass than the pea. paper with the pro j e c t i l e . As with the Po t a t o • Add a second layer of tissue paper to the box to see Astronaut activity, the velocity of the impactor what effect the second layer has on penetrat i on . determines the penetration. • Is there any relationship between the ability to penetrate the tissue paper and the distance the Materials and Tools Checklist shooter stands from the box? Plastic milkshake straw Dried peas, popcorn, etc. Tissue paper (for wrapping presents) Cardboard box Tape Eye Protection
Objective •To compare the effect on tissue paper penetration between low and high speed projectiles.
Procedure Step 1. Cover the opening of a box with tissue paper. Stretch the paper tight. Step 2. Drop a pea or other projectile from a distance of approximately 1 meter on to the tissue paper. Does the pea penetrate? Step 3. While wearing eye protection, stand back a few meters from the box and blow the pea through the pea shooter at the tissue paper. Does the pea penetrate? (With a little prac - tice, the pea should penetrate the paper.) Step 4. Investigate what happens when more than one layer of tissue paper is used to cover the box opening.
Safety Precautions Students must wear eye protection. Caution stu- dents not to inhale through the straw.
68 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Investigation Connections:Mathematics The kinetic energy output of an impact, given in Potato Astronaut—Part One Joules, is calculated with the following equation:
2 The effects of high-speed micrometeoroid impacts KE = 1/2mv are simulated with a potato and a straw.Students hold the potato in one hand and stab it with the m = mass of impacting object other using a plastic milkshake straw. The penetra- v = velocity of impacting object tion depth into the potato relates to the speed of the stabbing action. A straw slowly pushed into the Note: The mass in this activity is actually the com- potato collapses. The plastic isn't strong enough to bined mass of the straw and the hand and forearm support the force exerted at the opposite ends of the driving it. straw. However, when the straw is thrust rapidly into the potato, the straw easily penetrates and passes through. The straw enters the potato before it has a chance to collapse. As it enters, the sur- rounding potato helps support the straw by shoring up its sides.
Materials and Tools Checklist Potato Plastic (milkshake-size) straw
Objective •To investigate the relationship between velocity and penetration depth when a potato is struck with a plastic straw.
Procedure Step 1. Hold a raw potato in one hand. (See illustra - tion.) While grasping the straw with the other hand, stab the potato with a slow motion. O b s erve how deeply the straw penetra tes the potato. St ep 2. Repeat the exp e riment but this time stab the po t ato with a fast motion. Ob s e rve how deeply the straw penetrat es the potat o . Co m p a r e your ob s e rvations with the results of st ep 1.
Safety Precautions Be careful to hold the potato as illustrated so that the straw does not hit your hand. Work gloves will provide additional protection.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 69 Investigation Extensions • Compare technologies for protecting astronauts Potato Astronaut—Part Two from micrometeoroid and space debris impacts to other protective technologies such as bullet-proof In part one of Potato Astronaut, students found vests, suits of armor, shields on power tools, and that "high speed" impacts enabled the plastic straw windshields on vehicles. How does the function to penetrate the potato without coll a p s i n g. d e t e rmine the form? (e.g. M o t o rcycl e Challenge the students to design a way to protect helmet–provide protection during crash . .. be the potato from damage caused by impacts using streamlined . .. comfortable to wear . .. protect just the materials they brought to the classroom. face from bug and rock impacts, etc.) Their solutions to the challenge should be flexible • E x p e riment with diffe rent fabrics and fabri c and light in weight. combinations for protective garments.
Materials and Tools Checklist Plastic (milkshake-size) straw Potato Tissue paper, notebook paper, handkerchiefs, rubber bands napkins, aluminum foil, w a x paper, plastic wrap, etc. Impact Resistance Test Stand (from Teacher Tech Brief )
Procedure Step 1. St udents design a method for prot ecting potat o as t ron a uts from damage caused by the plastic st raw when the straw is quickly stabbed into the potat o . Step 2. Aft er students have tes t ed a method for prote c t - ing a potat o , conduct a discussion to eval u a t e tec hnologies develo p e d . Re fine the constrai n t s for a prot ection sys t em (e.g . the materials used must toget h e r be no thicker than mm). Step 3. Have students redesign their system based on the refined constraints. Conduct additional impact tests with the straw. Step 4. Test pro tection sy s tems by using the an Impact Resistance Test Stand as described in the Teacher Tech Brief found earlier in the guide. Evaluate the effectiveness ofthe protec - tion systems developed.
70 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Exploration Brief Keeping Your Cool
Co n t ex t of the plate. As additional heated water runs across the It is not sufficient for the health and well-being of an pl a t e , the heat is absorbed by the aluminum and is as t r onaut just to be protected from the hazar ds of the co nducted to the exposed side. Th e r e the ice begins to env i r onment in which he or she is trying to work. It is su b l i m a t e , or turn direc t l y into water vapor and dis- also necessary to consider the cond i t i o ns that are cre- perses in space. Sub l i m a t i o n is a cooling proc e s s . ated by the suit itself. One of the most important of Add i t i o nal water passes through the pores , and free zes these cond i t i o ns is temperat u re . Suit insulation tech- as before. Con s e q u e n t l y, the water flowing across the nologies protect the astronaut from extreme high and plate has been cooled again and is used to rec i rc u l a t e lo w temperat u r es of the space envi r on m e n t .H ow ever , th r ough the suit to absorb more heat. the same insulation techn o l o g y also works to keep heat released by the astronaut's body inside Supplementing the EMU cooling system is an air the suit. To get an idea of what this is like, im a g i n e ci rc u l a t i o n system that draws perspirat i o n-laden air walking around in summer wearing a plastic bag. For fr om the suit into a water separat o r . The water is this rea s on , an active cooling system is employed . added to the cooling water res e r voir while the drier air is ret u r ned to the suit.Both the cooling system and the In Space Shuttle Extrav ehicular Mobility Units or air- circu l a t i o n system work together to cont r ibute to EMUs , the cooling system consists of a netwo r k of a comf o r table internal working envi r onm e n t . Th e sm a l l diameter water circu l a t i o n tubes that are held we a r er of the suit cont r ols the operating rates of the close to the body by a Spandex® body suit. He a t sy stem through cont r ols on the Display and Cont ro l released by the astronaut's body movements is tran s - Module mounted on the EMU che s t . fer r ed to the water where it is car r ied to a ref ri g e ra t i o n unit in the suit's backp a ck . The water runs across a Ob j e c ti ve po r ous metal plate that is exposed to the vacuum of • To investigate and experience the way the water outer space on the other side. Sma l l amounts of water cooling system in the Space Shuttle EM U pass through the pores where it free zes on the outside f u n c t i on s .
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 71 Siphon from ice Investigation water bucket Water Cooling—Part One
This demonstration shows the principle behind the operation of the Space Shuttle EMU liquid cooling garment.Instead of an internal heat source (the suit wearer), the heat is provided by a strong electric light bulb or flood lamp.
Materials and Tools Checklist Two coffee cans with plastic lids 4 meters of aquarium tubing Two buckets Two thermometers Duct tape Water flow to Water (solid and liquid) catch basin Heat source (light bulb and fixture) Hole punch Step 3. Place the two cans on a table top. Direct the Flood light and fixture light from a strong light bulb or flood light to fall equally fall on the two cans. The light Procedure should be no more than about 25 centimeters Step 1. Punch a hole near the bottom of the wall of a away from the cans. Fill a bucket with ice metal coffee can. The hole should be large water and elevate it above the two cans.Place enough to pass aquarium tubing through. the catch bucket below the two cans. Punch a second hole in the plastic lid ofthe can Step 4. Turn on the light. Observe and record the so that tubing can pass through it as well. temperatures on the two thermometers. After Punch another hole in the center of the lid so two minutes, again observe and record the that a thermometer will fit snugly into it. temperatures. Finally, punch a hole in the center of the sec - Step 5. Place the upper end of the aquarium tubing ond coffee can lid for another thermometer. into the ice water and suck on the other end of Step 2. Loosely coil the aquarium tubing and place it the tube to start a siphon flowing. Let the inside the first coffee can. Use bits of tape to water pour into the catch bucket. hold the coils to the walls and to keep them Step 6. Observe and record the temperature ofthe two spread out evenly.Pass the lower end of the cans at regular intervals for ten minutes. tube through the hole in the can wall and the upper end through the outer hole in the lid. Tips The lower tube should extend to the catch • If more than one student is going to start the bucket that will be placed below the can.The siphons with sucking on the end of the tube, upper end will have to reach to the bottom of make sanitary mouthpieces like those called for 2 the ice water bucket.That bucket will be ele - in the activity "O How Much?" vated above the can.Insert thermometers into • Color the water with food coloring to increase its each can. visibility in the siphons.
72 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Assessment Have students design a graph to display the data collected in step 6.
Extensions • How can the flow of icy water be cont ro l led? Find a wa y to maintain a constant temperat u r e inside the can with the tubing. Mo ve the light source closer to the can so that it is heated more than before. Try to maintain the internal temperat u r e at the same level as before. Investigation Water Cooling —Part Two
This demonstration permits students to experience the water cooling technology used in the Space Shuttle EMU.
Materials and Tools Checklist Two buckets 3 meters of aquarium tubing Water (solid and liquid) Ki t c hen size plastic garbage bag (one per student) the bags . (War m air in the bag was released and mo i s tu r e from pers p i r ation began evapo ra t i n g .) Procedures St ep 4. Se lect a student vol u n te e r for another exp e ri - Step 1. Distribute one plastic garbage bag to each me n t . Wrap the middle of the length of aq u a r i - student. Have students wearing long-sleeve um tubing around the bar e arm of the vol u n te e r shirts roll up one sleeve. se veral times. Step 2. Ask each student to place their bare arm inside Step 5. Start a siphon flow from the ice water bucket the bag and then gather the plastic so that it through the tube.Ask the student to describe fits closely along the entire length of the bag. for the rest of the class the sensations he or she Tell students to repeatedly make a fist or wave feels. (See note about mouthpiece in part 1.) their arm while it remains in the bag for a for two minutes. (Steps 1 and 2 can also be done Extensions with plastic gloves.) • Discuss how a liquid cooling garment could be Step 3. After two minutes, have students remove c on s t ructed that could operate con t i n u o u s ly their arms from the bags and observe any without siphons and buckets of ice water that sensations that come with their rem o va l . eventually run out. Discuss what students felt. Make sure they •What professions on Earth might find liquid understand that a spacesuit, like the plastic cooled garments useful? bag, retains body heat. Also discuss why their • Design and construct a liquid cooling garment ar ms suddenly felt cooler with the rem o v al of out long underwear or Spandex® running tights.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 73 Exploration Brief Absorption and Radiation
Context Materials and Tools Checklist The tempera t u re range of outer space and on plan- Coffee cans with plastic lids e t a ry bodies is affected by a wide range of factors. Thermometers In outer space, the tempera t u re on a surf a c e Flood lamp (optional) depends upon whether that surface is in sunlight Various colors of paint and if so, the angle of that surface to the Sun's rays . Foil, construction paper, etc. On a planetary body, the tempera t u re also vari e s Clock with the ambient atmosph e ric tempera t u re, w i n d s , Refrigeration (see step 6) and nearby surface materi a l s . For example, on E a rth tempera t u res can vary dra m a t i ca lly on a Objective summer day between asphalt parking lots and •To investigate the effect different colors, reflective g rassy bord e r s . surfaces, and different materials on radiant heat absorption and heat radiation. When designing spacesuits, it is important to account for the tempera t u re range of the env i ron- Investigation ment for which the suit is intended. Heating and cooling systems inside a suit can moderate temper- Surface Color a t u re s , but electric power to operate these sys t e m s limits the length of time the suit can be used before This activity investigates the affect surface color has re ch a r g i n g. One way to reduce the dependency of a on heat absorption and radiation. spacesuit heating/cooling system is to use materi a l s for suit con s t ru c t i on that have desirable therm a l Procedure p ro p e rt i e s . I f, for example, a suit is operated in a S tep 1. Paint the surf aces of s everal coffee cans in ve ry cold env i ron m e n t , good insulating materi a l d i f f erent colors such as white, bl ac k , gre e n , w i ll reduce the need for internal suit heating. or yel l o w.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 75 Investigation Insulating Layers
In this activity, students explore the insulative prop- erties of several materials.
St ep 1. St ack different fabric s , pap e r, and foils, an d fold them into small envelo p e s . In s e rt a ther - mo m e t er and repeat the previous exp e riment to de t ermine the heat absorption and refl e c t i o n pro p e rties of di f f e rent material combinations. Step 2. Punch a small hole in the plastic resealable lid and insert a thermometer bulb to approxi - Extensions mately the middle of each can. • C onduct ch rom a t o g ra phy experiments on vari- Step 3. Place the cans in sunlight so that all are ous ink colors to see what their com p onent col- equally exposed. Immediately record the ini - ors are . B l a ck inks often consist of seve ral colors. tial temperature of each can. If you are doing The re a s on for mixing seve ral ink pigments is to the experiment inside, expose the cans to a make a darker black (more complete absorp t i on flood light. It is important that each can of light). (The Space Shuttle uses black heat receives the same amount of heat from the shield tiles on the bottom of the orbiter to quick- lamp. Measure and record the temperature of ly dissipate the heat produced when re e n t e ri n g the cans every minute. E a rth's atmosph e re . ) Step 4. Remove the cans from the heat source after 10 minutes and measure and record their tem - peratures again for the next 10 minutes. Graph your data. Relate the temperature rise and fall of each can to its surface color. Step 5. Change the surface material of the cans by wrapping them with aluminum foil, gray construction paper, or cloth.Repeat the exper - iment to find the best combinations of colors and surfaces for different environments. Step 6. Repeat the experiment by subjecting the cans to intense cold. The cans can be placed in a freezer or in a tub with ice water or a block of dry ice.
76 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Exploration Brief Getting the Right Fit
Context pre s s u ri ze d . An unpres s u ri z ed suit is slightly smalle r In spite of many decades of experience in develop- than when it is pres s u ri ze d . The suit must fit rig h t ing and evaluating spacesuits,they are still fatiguing when the crew member is in space. The microg ra v i t y to wear. The internal pressure of the suit creates resistance to movements of the arms, hands,or legs. Consequently, astronauts training for a spacewalk are encouraged to stay in excellent physical condi- tion by training on the ground for endurance and strength. After a spacewalk, crew members are allowed a day of rest before going out again.That is why missions,such as the multi-day servicing of the Hubble Space Telescope, have two EVA crews that alternate spacewalk days.
The exhaustion factor of spacesuits can be mitigated som e what by insuring that the suit the crew mem- ber will wear in space fits prop e r ly. It is essential that the position of suit joints prec i s e l y match the posi- ti o n of shoulders, el b ow s , wris t s , kn u ck l e s , kn e e s , and ankles. A misalignment of a mere centimeter in the arm length, for example, can lead to aching fingers after a sever al-hours spacewa l k i n g .
Getting the right fit is comp l i c ated by a number of fa c t o r s . It is important that the suit fits when it is
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 77 env i r onment experienced in Earth orbit affects the Procedure human body in many ways. One effect is spine Step 1. Construct a variety of spacesuit arm segments le n g t h e n i n g . In one G (grav i ty ) , the vert e b r ae of the by sawing off measured lengths of PVC plas - spine are close together but are kept separate by tic thin wall sewer pipe. (See the tip section rub b e r y disks that act as shock absorbe r s . In space, for information on where the sewer pipe and without the perce i v ed direc t i o nal force of grav i t y, th e other needed materials can be obtained.) Cut disks expand slightly, causing the vert e b r ae to move the pipe into segments 25, 50, 75, and 100 sl i g h t l y farther apart than they are when the crew mm long. Cut two of each size. Cut three member is standing upright on Earth . This spine- additional segments of the 50 mm length. lengthening causes the astronaut to get talle r , res u l t - Step 2. Create a suit elbow joint by connecting two of ing in arm joint misalignment. Spine lengthening in the 50 mm segments with a 25 cm piece of mi c ro g ra v i t y has to be accounted for when astrona u t s vinyl clothes dryer hose. Slip the hose ends ar e measured for their suits. The typi c al astrona u t over one end of each ofthe segments.It will be wi l l gain between 2 and 3 centimeters in height while necessary to the hose a small amount to accom - in space. plish this task. Fasten the hose to the segments with duct tape. To avoid the expensive and time-consuming proc e s s Step 3. Slip the cuff of one ofthe gloves over a 50 mm of creating custom-made suits for astrona u t s , as pipe segment. The fit may be tight but try to NASA did during the Apo l lo missions , suits with slide the ring in so that it just reaches the posi - i n t e rchangeable parts are used. D i f fe re n t - s i ze d tion of the wrist.Trim off the excess of the cuff upper and lower torsos are available, but arm and so that the glove can be affixed to the ring leg lengths are still difficult to match. NASA has with duct tape. solved this problem for the Shuttle EMU by creat- ing sizing inserts that are added or removed from Activity the restraint layer in the arms and legs to achieve Step 4. Provide the rings, joint, glove, measuring the right fit.The inserts are fabric rings of different tape, and duct tape to a group of students. Tell lengths that are laced into the arms and legs. the students to select one member of their Selecting the right combination of inserts insures group to serve as the astronaut. Their objec - the best fit possible. tive is to fit a suit arm to that astronaut.The students should begin by measuring the arm Objective and mapping the range of movement of the •To experience the measurement process used in arm without the suit. Use the Arm Range of sizing a spacesuit arm to fit different wearers. Movement Data Sheet for recording data. Step 5. The students should select the right combina - Materials and Tools Checklist tion of segments to use to construct the arm. PVC thin-wall sewer pipe (4 in. dia.) PVC rings are joined with pieces of duct tape. Saw (crosscut or hacksaw) Step 6. After completing the arm, the student group Measuring tape or ruler (metric) should test it by placing the "astronaut's" arm Duct Tape into the suit arm.They will then evaluate the Vinyl clothes-dryer hose arm by repeating the range of movement tests Scissors done before and by asking the astronaut how Thick rubber gloves comfortable the arm is to wear. If the fit is not Sand paper or knife comfortable or the range of movements are
78 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q restricted, the student group should adjust the •Use the saw to cut the sewer pipe.Have someone arm length by changing the lengths of the help you hold the pipe as you cut it. Use sand- PCV rings used.When the fit is comfortable, paper or a sharp knife to remove burrs left on the and the range of movement is acceptable, pipe segments after sawing. record the sizing data in the log chart that is •Duct tape pieces can be removed and used again provided. The sizing process can be repeated for joining segments. White duct tape can be with a different student. substituted for gray tape to improve the appear- ance of the arms or one inch wide masking tape Tips can be used. • All the materials for this guide can be obtained at •Actual arm measurements for spacesuit fitting larger hardware stores. Pick a thin wall sewer involve more measurements than just arm length pipe without holes in its sides. A 10 foot length and range of movement of the extended arm in of pipe is inexpensive and will provide material t h ree planes. Other necessary measure m e n t s for several sets of arms. include upper and forearm circumference, hand • A long sleeve shirt worn by the astronaut will and finger size, knuckle location, and movement reduce any possibility of pinching skin between of the forearm from the elbow. pipe segments.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 79 Arm Range of Movement Data Sheet
Subject Name: Arm Length cm (shoulder to elbow) Arm Length cm (elbow to wrist)
0 -30 30 X-Z Plane Movement Range:
0 to + -60 60 0 to -
-90 90
-120 120 90 60 120 -150 150 +180- 30 150 X-Y Plane Movement Range: 0 to + 0 to - 0 +180-
-30 -150
-60 -120 90 -90 60 120
30 150
Y-Z Plane Movement Range: +180 0 to + 0 - 0 to -
-30 -150
-60 -120 -90
80 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Extensions Measurements on the chart provide the range of •When fitting spacesuit components to astro- m e a s u rements between the 5th percentile nauts, more than 100 measurements are taken. ( 4 0 - year-old Japanese female) and the 95th Set up a measuring activity with students and percentile (40-year-old American male). These determine the class average for each measure- range measurements are projections to the year ment made. Because of certain sensitivities, you 2000 in a one-gravity environment. may wish to avoid girth measurements. Refer to • Create a computer spreadsheet to compile class the chart on the next page for data covering girth. data.
J E K F L G M H V N
S T
B
O A
I
R
C
D
U
P Q
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 81 Body Size Range Measurements
Based on 1989 Man-Systems Integration Standards, NASA-STD-3000
Category Minimum (cm) Maximum (cm)
A. Stature* 162.1 187.7 B. Vertical trunk dimension 64.3 74.4 C. Crotch height 74.4 91.9 D. Knee Height 32.3 38.9 E. Wrist to wrist distance 131.6 167.1 F. Elbow to elbow distance 85.9 106.2 G. Chest breadth 27.9 36.6 H. Head breadth 12.7 16.5 I. Hip breadth 32.3 38.9 J. Arm reach 80.5 94.2 K. Shoulder to wrist reach 62.2 73.7 L. Chest depth 21.3 27.7 M. Head depth 18.3 21.6 N. Chin to top of head 21.8 24.4 O. Hip depth 24.1 29.2 P. Foot length 21.1 27.4 Q. Foot width 8.9 10.7 R. Thigh circumference† 52.1 67.1 S. Biceps circumference (flexed) 27.4 36.8 T. Chest circumference 89.2 109.7 U. Instep NA 8.3 V. Head circumference 55.5 60.2
*Stature increases approximately 3 percent over the first three to four days in microgravity. Because almost all the change appears in the spinal column, other dimensions such as vertical trunk dimension increase proportionately.
† Thigh circumference will significantly decrease during the first day in orbit due to the shift of fluid to the upper torso.
82 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Exploration Brief
O2—How Much?
Context oxygen tanks still have to be con s t ructed from A typi c al extrav ehicular activity (EVA) lasts about 7 l i g h tweight materi a l s . Weight is not a problem in ho u r s . Dur ing that time, an astronaut perfo r ms a o rb i t , but it is a problem for Shuttle lift o f f. T h e number of activities, so me of which are ver y stren u - Space Shuttle can ca r ry on ly so mu ch mass to ou s . To make it possible to accomplish the mission, o rb i t . Lighter tanks means that additional payl o a d the spacesuit has to provide a steady and rel i a b l e can be ca r ri e d . oxygen supply for breathing and suit pres s u ri za t i on . The oxygen supply in the prim a r y life- s u p p o r t To reduce their weight tanks are made from thin- sy stem (PLSS) is contained in four oxygen tanks. w a ll metal shells that are wrapped with Kevl a r ® Two of the tanks are used as the prim a r y oxy g e n filaments and resin for stre n g t h . su p p l y and two for an emergency second a r y supply. The two prim a r y tanks each have a volume of 3,980 Objective cm 3. Th e y contain a total of 0.55 kilograms of •To measure the quantity of oxygen a person will oxygen at a pres s u r e of 5,860.5 kilopascal s . As this need under varying levels of activity oxygen circulates through the suit, it passes throu g h a rec ycling system that rem o ves ca rb on dioxi d e , Materials and Tools Checklist od o r s , and humidity. The two second a r y oxy g e n Two-liter soft drink bottle tanks have a volume of 1,460 cm3 and contain a 1 meter of flexible plastic tubing total of 1.19 kilograms of oxygen at a pres s u r e of (from a hardware or aquarium store) 41,368.5 kilopascal s . This supplies onl y enough oxy - Permanent marker gen for about 30 minutes because this oxygen is not Paper strips con s e r ved and rec ycle d . Cellophane tape Water Although the Shuttle spacesuit is used in Eart h Large pot or aquarium o rbit where the suit is in effe c t , w e i g h t l e s s , t h e
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 83 Procedure q u a n t i ty re q u i rement measurements and Step 1. Obtain the materials in the material list and record the numbers in the data table for "mod - begin by calibrating the 2 liter soft drink bot - erate work." tle. Stand the bottle upright and pour mea - Step 6. Repeat the procedure a third time, but have sured amounts of water into the bottle with a the students run in place for a minute or two beaker. Add 100 ml and mark the side of the before taking the measurements. Record the bottle at the top surface of the water. Repeat results under "strenuous exercise." this procedure until the bottle is filled. Step 7. Discuss possible ways to determine how much Step 2. Make paper mouthpieces by rolling a strip of air an average "student astronaut" will need paper around one end of the tube.Use a small on a 7-hour spacewalk in which the work strip of tape to hold the mouthpiece together. level will range from moderate to strenuous Make a new mouthpiece each time a different and calculate an answer from the data collect - person uses the apparatus. ed. Make sure the students realize that not Step 3. Partially fill a large pot or aquarium with only will the quantity of air taken in with water. Fill the bottle with water and invert it each breath changes but the breathing rate in the aquarium. Support the bottle by hold - will change with exercise. Determine what ing it with one hand around the neck. Insert the quantity would be if, instead of a normal the air hose into the bottle neck. Attach a air mixtu re, p u re ox y gen would be used. mouthpiece to the other end of the tube and (Normal air contains 20 percent oxygen.) have a student fully exhale a normal breath of air through the tube.Water will be driven out Extensions of the bottle. Read the volume of air trapped • De t e r mine the actual volume of oxygen car r ied in inside the bottle from the calibration marks the Shuttle spacesuit pri m a ry and secon d a ry placed on the bottle's side in step 1. oxygen supplies. Oxy g e n , under standard cond i - ti on s , has a mass of 1.327 kilograms per cubic Activity me t e r . (The prim a r y and second a r y oxygen sys- Step 4. Measure the air quantity required in normal tems contain a total of 1.74 kilograms of oxy g e n . b reathing by several vo l u n te er stu d e n t s . Divide that number by 1.327 to get the volume of Begin with the students at rest. With a fresh oxygen in cubit meters. Although the volume may mouthpiece on the tubing, have a student seem small, remember that oxygen is rec ycle d . ) inhale a normal breath of air and exhale the air through the tube. The student should do this several times. Measure the amount of air in the bottle and divide this quantity by the number of breaths.Record the quantity for "at rest" on a data table or computer spread sheet. Also measure and record how long it took for the test. Step 5. After recording "at rest" breathing require - ments, refill the bottle with water and have each student perform a moderate amount of activity such as lifting small barbells for a minute or two.After exercising, repeat the air
84 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Exploration Brief Keeping the Pressure On
Context Objective While pres s u r e is essential to astronaut survi v a l , th e •To demonstrate one method for creating a work- pre s s u r e exer ted by a spacesuit does not have to match able pressure inside a spacesuit. sea level pres s u r e on Earth . If the atmosphe r e inside a spacesuit is pure oxy g e n , a pres s u r e equal to about one Materials and Tools Checklist th i r d sea level pres s u r e (about 33 kilopascals) is suffi- 0.5 m ripstop nylo n (available in fabric stores ) ci e n t . How e ver , su c h low pres s u r es req u i r e a severa l Sewing machine hour oxygen pre b reathing period to eliminate Scissors ni t r ogen from the spacewalker's blood strea m . If a Long balloon higher suit operating pres s u r e can be achi e ved , an Bicycle pump with pressure gauge as t r onaut can don a suit and immediately exit the Small adjustable screw type, hose clamp sp a c e c ra f t for a spacewa l k . Tire valve Screwdriver Op e r ating pres s u r es inside spacesuits are achi e ved by cr eating some sort of pres s u r e shell around the astro- Procedure na u t . The shell can be made of rigid materials or a com- Step 1. Using two pieces of ripstop nylon,stitch a bag bi n a t i o n of fabrics provided they are nearly leakproo f . as shown in the pattern on the next page. The The pres s u r e layer of the Space Shuttle spacesuit encas e pattern should be doubled in size.For extra the astronaut inside a human-shaped bag which has an s tre n g t h , s t i t ch the bag tw i c e.Tu rn the inner layer of rubber and an outer layer of nyl on .T h e stitched bag inside-out. rubber contains the atmosphe r e and the nylo n preven t s S tep 2. Slip the nozzle of a long balloon over the the rubber from inflating beyond a pred e t e r mined size fat end of the tire va l ve. Slide the other end and shape. Once the suit is fully inflated, ad d i t i o nal gas o f the balloon inside the bag so the neck of pre s s u r e supplied to the suit pushes inwa r d on the the tire va l ve is aligned with the neck of as t r onaut providing a livable pres s u r e envi r onm e n t . the ba g.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 85 Magnified view of tire valve and clamp
Step 3. Slide the adjustable hose clamp over the bag and tire valve necks. Tighten the clamp until the balloon and bag are firmly pressed against the tire valve neck. This will seal the balloon and bag to the valve.
Activity Step 4. Connect the tire valve to the bicycle pump and inflate the balloon. The balloon will inflate until it is restrained by the bag. Additional pumping will raise the pressure inside the bal - loon. Check the tire pressure gauge on the pump (use separate gauge if necessary) and pressurize the bag to about 35 kilopascals One-half size pattern (5 pounds per square inch).The tire valve can be separated from the pump so that the bag for step 1 can be passed around among the students. Step 5. Discuss student observations of the stiffness of the pressurized bag. square inch). What prob - lems might an astronaut have wearing a pressurized spacesuit?
Extensions • C om p a re the tech n o l o gy for pre s s u ri z i n g spacesuits to the tech n o l o gy for pre s s u ri z i n g a u t omobile tire s .
86 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Exploration Brief Bending Under Pressure
Context contract with bending and building joints into the Maintaining proper pressure inside a spacesuit is restraint layer like ribs on vacuum cleaner hoses. essential to astronaut survival during a spacewalk.A lack of pressure will cause body fluids to turn to gas, Objective and resulting in death in a few seconds.While mak- •To observe how an external joint in a spacesuit ing spacewalks possible, pressure produces its own arm segment increases bendability of the segment. problems. An inflated spacesuit can be very difficult to bend. In essence, a spacesuit is a balloon with an Materials and Tools Checklist astronaut inside.The rubber of the balloon keeps in Two long balloons oxygen that is delivered to the suit from pressurized 3 heavy-duty rubber bands oxygen tanks in the backpack. But, as pressure inside the balloon builds up, the balloon’s walls Procedure b e c ome stiff, making normal bending motion s St ep 1. In f l a t e a long balloon and tie it off. The bal l o o n impossible. Lack of flexibility defeats the purpose rep r esents the pres s u r e blad d e r of a spacesuit arm. of the spacewalk–mobility and the ability to do Let students try to bend the balloon in the middle. work in space. St ep 2. In f l a t e a second long bal l o o n . As you are inflat - ing the bal l o o n , slip heavy- d u t y rub b e r ban d s Spacesuit designers have learned that strategically ov er the balloon at intervals so that as inflation placed breaking points at appropriate locations out- continues the balloon is pinched by the rub b e r side the pressure bladder (the balloon-like layer ban d s . It is easier to accomplish this by pre- inside a spacesuit) makes the suit become more inflating the bal l o o n . It may be necessary to bendable.The breaking points help form joints that do u b le the rub b e r band to pinch the bal l o o n bend more easily than unjointed materials. Other enough for the demonstrat i o n . Have stud e n t s techniques for promoting bending include stitching co m p a r e the force req u i r ed for bending this bal - folds into the restraint layer that spread apart and loon with the force needed for the first bal l o o n .
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 87 Extensions • Compare the stiffness of the balloons to other inflated structures such as air mattresses, inner tubes, beach balls, etc. •Use a Slinky® as an alternative to the rubber bands. Place the Slinky® on a desk top and pick up one end. Slip in the balloon and inflate it. As the balloon inflates, it will be pinched in a spiral pattern by the Slinky®. The pattern will achieve the same result as the rubber bands.
88 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Idea Bank
Use these ideas as suggestions for additional testing and measurement apparatus and for techniques that could be employed for constructing suit parts.
1. Suit Arm and Leg Bending Tester
Electric Motor Pulley
Reciprocating Rod
Inflated Arm Segment
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 89 2. Tethers 4. Connector Seal Test Place Martian sediment simulant or other dry sandy sediment in the jar.Place plastic tape over the zone where the lid comes together with the jar. Shake the jar several hundred times and then remove the tape to see if any sediment made its way through the jar and lid threads to stick to the tape.
3. Field of Vision Tester for Helmet Vision Design De t e r mine how muc h visibility is needed for a space suit helmet by measuring the field of vision of stu- de n t s . Two differ ent ways for doing this are shown .
5. Weightlifting Test for Right and Research an exercise routine that can be used to Left Views strengthen the upper body. This is the area of the body that receives the greatest workout during a s p a c ewalk in Earth orb i t . Design exe rcises for strengthening the lower torso and for planetary sur-
face exploration.
Omnidirectional test. Use clear plastic punch bowl and place dots at limit of vision.
90 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q 6.Measurements for Space Helmet
30 cm
7. Paper Maché Space Helmet glue and water or with premixed wallpaper paste. Inflate a large round balloon to a diameter greater Let each layer dry before applying the next one. than student heads. Cover the balloon with four When completely dry, deflate and remove the bal- layers of paper maché. Paper maché can be made loon and cut appropriate holes with a scissors.Paint with newspaper strips and a 50/50 solution of white as desired.
8. Visor Light Transmission Tester Co nnect a solar cell to a potentiometer and a mi ll a m m e t e r . These items are available from an elec- tr onic parts store. Adjust the potentiometer so a light so u r ce you are measuring does not driv e the needle off the scal e . Place potential space helmet visor mate- rial between the light source and the solar cell to evaluate the materia l ’s light-filtering prop e rt i e s .
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 91 9. Vacuum Experiment - 1 11. Vacuum Experiment - 3 Obtain an electric doorbell,push button, and door- C on s t ruct a marshmall ow astronaut out of re g u- bell transformer. Insert the wires to the doorbell lar size and mini marshmall ows and toothpick s . through a single-hole rubber stopper. The stopper Evacuate the bell jar and observe how the marsh- should fit the upper hole in the bell jar.Fill the rest m a ll ows expand. Living tissue will also inflate in of the stopper hole with hot glue from a hot-glue a vacuum because of gas bubbles forming in the gun to seal the wires in place. Evacuate the bell jar fluids of cell s . and ring the doorbell. While holding the button, gradually let air back into the jar. The bell cannot be h e a rd ringing when the jar is evacuated eve n though the clapper can be seen to be moving. This demonstration explains why spacesuits have 2-way radios. Sound is not conducted through a vacuum.
Doorbell To Transformer Note: The vacuum pump, vacuum plate, and bell jar needed for the activities on this page are common pieces
Push of science equipment found in many junior and senior Button high schools. This equipment is available from school science supply catalogs.
10. Vacuum Experiment - 2 12.Underwater Training Show how fluids like water boil when they are If a swimming pool is available, practice underwa- exposed to a vacuum. Place water in a beaker and ter EVA training. Have students wear a dive mask evacuate the bell jar. The demonstration will take place more rapidly if warm water is used. Place a thermometer in the beaker to record the boiling temperature.
92 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q and assemble PVC water pipe parts underwater. tially screwed into it,over the first student.The first Make a weighted panel that has bolts protruding student will find it difficult to turn the bolt with a from it.Use a chrome steel wrench to try to turn the wrench without spinning as well. Relate this to the bolts while free floating in the water. Make tools challenges astronauts have on spacewalks when appear weightless by attaching a string to the han- they try to do a similar job.To turn a bolt or move dles and to empty two liter soft drink bottles.Invite s ome massive object in space, an astronaut is a local SCUBA shop to participate in the activity. attached to a stable work platform. The shop owners might be willing to supply dive equipment and serve as safety divers during the 15.Glove Work simulation. Use rubber-coated work gloves from a hardware store to demonstrate the importance of spacesuit 13.Design A Tool gloves that are comfortable to wear. Have students Have students design and construct a prototype attempt to screw a bolt into a nut or assemble plas- multipurpose tool for use on spacewalks. The tool tic snap toys into a structure. Discuss how these should combine the functions of single purpose gloves can be improved to make them easier to use. tools such as hammers,screw drivers, wrenches,etc. The tool should also make provisions for attach- ment to tethers and easy gripping.
16. Neutral Buoyancy 14. Torque A s t ronauts simulate micro g ra v i ty for spacesuit Place a student on a swivel office chair or on a training in a deep swimming pool.Their spacesuits rotating platform like a child's Sit and Spin®. Have are specially weighted to produce neutral buoyancy. two other students hold a 2 by 4, with a bolt par-
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 93 You can investigate neutral buoyancy by creating a small submarine out of a plastic film canister, aquarium tubing, pennies, and hot glue. Punch tow holes at the base of the canister and a hole in the lid. Hot glue the end of the aquarium tube into the hole in the lid. Add several pennies to the canister so that when you place it in a water-filled aquarium, the canister just floats. Suck air out of the tube to cause the canister to sink. Try to get the canister to hover half way from the bottom to the surface.
17. Neutral Buoyancy - 2 Neutral buoyancy can also be investigated with a Cartesian diver.Fill a plastic soft drink bottle with water. Insert an eyedropper that is partially filled with water. Cap the bottle and squeeze the bottle's sides to increase the pressure in the bottle. The trapped air in the eyedropper will compress and the eye dropper will sink. Try to get the eyedropper to hover midway in the bottle.
94 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Glo s s a r y
AMU Astronaut Maneuvering Unit Apollo NASA project that landed astronauts on the Moon CCA Communications Carrier Assembly CCC Contaminant Control Cartridge Composite Material Substance derived by combining two or more materials such as glass fibers and epoxy DCM Displays and Control Module EEH EMU Electrical Harness EMU Extravehicular Mobility Unit EVA Extravehicular Activity; Extravehicular Visor Assembly Gemini NASA project that pioneered space flight technologies for spacecraft rendezvous and docking and spacewalking HHMU Hand-Held Maneuvering Unit HUT Hard Upper Torso IDB In-Suit Drink Bag ISS International Space Station Joule One newton meter or 1 kg • m2/s2 Kilopascal Metric pressure unit; one pound per square inch pressure equals 6.895 kilopascals Kinetic Energy Energy in motion LCVG Liquid Cooling-and-Ventilation Garment MAG Maximum Absorption Garment Microgravity An envi r onm e n t , pr oduced by free - f a ll , that alters the lo c al effects of grav i t y and makes objects seem weightless Micrometeoroid Ti ny part i cle of space debris (natural or art i f i c i a l ) ravling at high speed through space
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 95 MMU Manned Maneuvering Unit Mercury The NASA project that launched the first U.S. astronauts into space and demonstrated that humans could live and work in space ORU Orbital replacement unit PLSS Primary Life-Support System Regolith Sediment derived directly from igneous rock and not containing any organically-derived materials RMS Remote Manipulator System SCU Service and Cooling Umbilical Skylab First U.S. space station SOP Secondary Oxygen Pack SAFER Self-rescue rocket backpack device for use during spacewalks around the International Space Station Space Shuttle Reusable spaceship currently used for all U.S. manned space missions Spacewalk Extravehicular activity Sublimation Change of state of matter from a solid to a gas
96 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1 9 9 8 - 0 3 - 1 1 2 - H Q Ref e r e n c e s
All e n , J.P . with Mart i n ,M .( 1 9 8 4 ) , En t ering Space , An NASA (1973), Apo l l o ,EP- 1 0 0 , NASA Headquarte r s , Ast ron au t ’s Odyssey,Stew a rt , Tab o r i & Chang, Was h i n g t on , DC. New Yor k City, NY . NASA (1991), Go For EVA, Li f toff to Lea rn i n g Com p t on , W. & Bensen, C. (1 9 8 3 ) , Li ving and Seri e s . (Vid e o t a p e ) ,E d u ca t i o n Wor king Grou p , Wor king In Space , A His t o r y of Sk y l a b , NASA SP- NASA John s o n Space Center, Ho u s t on , TX. 4 2 0 8 , Scientific and Te ch n i cal Inform a t i on NASA (1987), The Early Yea r s : Me rcu r y to Apo l l o - Bra n ch , NASA Headquarte r s , Was h i n g t on , DC. Soy u z , In f o rm a t i o n Sum m a ri e s , PMS 001-A, Ko z l o s k i , L. (1 9 9 4 ) , U.S . Sp a ce Gear, Ou t fitting Th e NASA Kennedy Space Center, FL . As tron au t ,Sm i t h s onian Institution Pre s s , NASA (1970), The First Lunar Landing As Told by Was h i n g t on , DC. The Ast ron au t s ,EP- 7 3 , NASA Headquarte r s , Kuz n i k , F. (1 9 9 7 ) , Spacesuit Sag a : A Sto r y in Many Was h i n g t on , DC. Part s , Air & Spa c e , V1 2 N 3 . Vog t , G. (1 9 8 7 ) , Sp ac ew a l k i n g , Franklin Wat t s , New M a ch e ll , R. e d . ( 1 9 6 7 ) , S u m m a ry of G e m i n i Yor k City, NY . E x travehicular Activ i ty, NASA SP-149, Vog t , G. , Ro d g e r s , M. and War g o, M. (1 9 9 7 ) , Scientific and Tech n i c al Informa t i o n Division, Mi c ro g ravi t y - A Tea che r's Guide With Activi t i e s , Office of Te ch n o l o gy Ut i l i za t i on , NA S A Se c o n d a r y Level, EG - 1 9 9 7 - 0 8 - 1 1 0 - H Q , NAS A He a d q u a rt e r s , Was h i n g t on , DC. He a d q u a rt e r s , Was h i n g t on , DC. Moh l e r ,S.R . & John s on , B. H .( 1 9 7 1 ) , Wil e y Pos t , His Winnie Mae, and the Worl d ’s First Pres s u r e Suit, Smi t h s o nian Institution Pres s , Was h i n g t on , DC.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 97 NASA Resources for Educators
NA S A’s Central Ope ra tion of Resources for Ed u ca t o r s Regional Edu c ator Resource Centers of f er more educators access (CORE) was established for the national and international dis- to NASA educat i o nal materia l s . NASA has formed partn e r s h i p s tribution of NASA-produced educational materials in audiovi- with univer s i t i e s , mus e u m s , and other educat i o nal institutions to sual format.Educators can obtain a catalogue and an order form se r ve as reg i o nal ERCs in many states. A complete list of reg i on a l by one of the following methods: ERCs is available through CORE , or electroni ca l ly via the NAS A •NASA CORE Ed u ca t i o n Home Page at: ht t p : / / w w w. h q. n a s a . go v / e d u ca t i o n Lorain County Joint Vocational School 15181 Route 58 South NASA On-line Resources for Ed u ca t o r s p rovide current edu- Oberlin,OH 44074 ca t i onal inform a t i on and instru c t i onal re s o u rce materials to •Phone (440) 774-1051, Ext.249 or 293 t e a ch e r s , f a c u l ty, and students. A wide range of inform a t i on is •Fax (440) 774-2144 a v a i l a b l e, i n cluding science, m a t h e m a t i c s , e n g i n e e ri n g, a n d • E-mail [email protected] t e ch n o l o gy educa t i on lesson plans, h i s t o ri cal inform a t i on re l a t- • Home Page: http://spacelink.nasa.gov/CORE ed to the ae ronautics and space pro g ra m , c u r rent status re p o rt s on NASA pro j e c t s , n ews re l e a s e s , i n f o rm a t i on on NASA edu- Educator Resource Center Network ca t i onal pro g ra m s , useful softw a re and gra phics files. E d u ca t o r s To make additional informa t i o n available to the educat i o n com- and students can also use NASA re s o u rces as learning tools to mun i t y, the NASA Educat i o n Division has created the NAS A e x p l o re the Intern e t , accessing inform a t i on about educa t i on a l Ed u c ator Resource Center (ERC) netwo rk . ERCs contain a g ra n t s ,i n t e racting with other schools which are already on - l i n e, wealth of informa t i o n for educat o r s : pu b l i ca t i on s , refe re n c e and participating in on-line intera c t i ve pro j e c t s ,c om mu n i ca t i n g bo ok s , slide sets, audio ca s s e t t e s ,v i d e o t a p e s ,t e l e l e c t u re pro g ra m s , with NASA scientists, e n g i n e e r s , and other team members to co mputer pro g ra m s ,l e s s on plans, and teacher guides with activi- e x p e rience the excitement of real NASA pro j e c t s . t i e s .E d u cators may previ e w, co p y , or rec e i v e NASA materials at these sites. Be c ause each NASA Field Center has its own areas of Access these resources through the NASA Education Home ex p e rt i s e , no two ERCs are exactly alike. Pho ne cal ls are welcome Page: http://www.hq.nasa.gov/education if you are unable to visit the ERC that serves your geograph i c are a . A list of the centers and the reg i o ns they serve inclu d e s : NASA Television (NTV) is the Agency's distribution system for live and taped programs.It offers the public a front-row seat for AK, AZ, CA,HI,ID, MT, NV, OR, UT, I L ,I N ,M I ,M N ,O H ,W I launches and missions, as well as informational and educational WA,WY NASA Educator Resource Center NASA Educator Resource Center Mail Stop 8-1 programming, historical documentaries,and updates on the lat- Mail Stop 253-2 NASA Lewis Research Center NASA Ames Research Center 21000 Brook p a r k Road est developments in aeronautics and space science.NTV is trans- Mo f f ett Fie l d , CA 94035-1000 Cl e vel a n d , OH 44135-3191 mitted on the GE-2 satellite, Transponder 9C at 85 degrees Phon e : (415) 604-3574 Phon e : (216) 433-2017 West longitude, vertical polarization, with a frequency of 3880 CT, D E ,D C ,M E ,M D, M A ,N H , NJ , NY , A L ,A R, IA , LA ,M O ,TN megahertz,and audio of 6.8 megahertz. PA, RI, VT U.S . Space and Rocket Center NASA Educator Resource Lab o ra t o r y NASA Educator Resource Center for Mail Code 130.3 NASA Marshall Space Flight Center Apa r t from live mission cove ra g e, regular NASA Tel ev i s i o n pro- NASA Goddard Space Flight Center P.O . Bo x 070015 Gre e n b e l t , MD 20771-0001 Hu n t s v i ll e , AL 35807-7015 gr amming includes a Video File from noon to 1:00 pm, a NAS A Phon e : (301) 286-8570 Phon e : (205) 544-5812 G a ll e ry File from 1:00 to 2:00 pm, and an Educat i o n File from CO ,K S ,N E ,N M ,N D, O K ,S D,TX MS 2:00 to 3:00 pm (all times Eastern) . This sequence is repeated at JSC Educator Resource Center NASA Educator Resource Center Space Center Houston Building 1200 3:00 pm, 6:00 pm, and 9:00 pm, Mon d a y through Frid a y. Th e NASA Johnson Space Center NASA John C. Stennis Space Center NT V Educat i o n File fea t u r es prog r amming for teachers and 1601 NASA Road One Stennis Space Center, MS 39529-6000 Ho u s t on , TX 77058-3696 Phon e : (601) 688-3338 students on science, m a t h e m a t i c s , and tech n o l o gy. NA S A Phon e : (281) 483-8696 Te l ev i s i on prog r amming may be videotaped for later use. NASA Educator Resource Center F L ,G A ,P R,VI JPL Educat i o nal Out re a c h NASA Educator Resource Lab o ra t o r y Mail Stop CS-530 Mail Code ERL NASA Jet Propulsion Laborat o r y For more information on NASA Television,contact: NASA Kennedy Space Center 4800 Oak Grove Driv e NASA Headquarters, Code P-2, NASA TV, Washington, DC Kennedy Space Center, FL 32899-0001 Pas a d e n a , CA 91109-8099 Phon e : (407) 867-4090 Phon e : (818) 354-6916 20546-0001 Phone:(202) 358-3572 NTV Home Page: http://www.hq.nasa.gov/ntv.html KY, N C ,S C ,VA ,W V CA cities near the Center Virginia Air and Space Museum NASA Educator Resource Center for NASA Educator Resource Center for NASA Dryden Flight Research Center How to Access NASA's Education Materials and Services, NASA Langley Research Center 45108 N.3r d Str eet East 600 Settlers Landing Road Lan ca s t e r , CA 93535 EP-1996-11-345-HQ Ha m p t on , VA 23669-4033 Phon e : (805) 948-7347 Phon e : (757) 727-0900 x 757 This bro ch u re serves as a guide to accessing a vari e ty of NA S A VA and MD's Eastern Shores m a t e rials and services for educa t o r s . Copies are available NASA Educator Resource Lab Ed u ca t i o n Complex - Visitor Center t h rough the ERC netw o rk , or electron i ca lly via NA S A Building J-1 Sp a c e l i n k . NASA Spacelink can be accessed at the foll ow i n g NASA Wal lops Flight Fac i l i t y Wal lops Island, VA 23337-5099 a d d re s s : h t t p : / / s p ac el i n k . n a s a . go v Phon e : (757) 824-2297/2298
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 99 Grade Level Application Technology Education, K–8 Life Sciences, Physical Science, History
Go For EVA! Educational Videotape Series
Go For EVA! discusses how spacesuits protect astro- nauts from the hostile space envi r onm e n t , ex p l a i n s what the comp o nents of the spacesuit are, de s c ri b e s ho w the suit functions , and shows what types of work as t r onauts perfo r m while spacewa l k i n g .Act u a l footage of spacewalks–also known as Extrave h i c u l a r Activities (EVAs ) – i ll u s t r ate how spacesuits allo w as t r onauts to operate scientific apparat u s , as s e m b l e e q u i pment and stru c t u re s , pilot the Manned Ma n e u ve r ing Unit, take pictures , and service satel- lites and space hardw a re .
Length: 13:48
Image from the videotape Go for EVA! ofthe Liftoff To Learning Videotape Series. To obtain a copy of the Go For EVA! videotape and ac c om p a n ying Video Resource Gui d e , or for more Go For EVA ! is from the L i f t o f f to Learn i n g in f o rm a t i o n on the Li f t o f f to Learning Educat i o n a l Ed u c ational Vid e o t ape Serie s , wh i c h allo ws students to Vid e o t ape Serie s , co ntact your local Educator Resource study science, ma t h e m a t i c s , and techn o l o g y with Center or the NASA Central Operat i o n of Resource s cr ew members aboard Space Shuttle flights. for Educators (CORE ) . See page 99 for details.
Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG-1998-03-112-HQ • 10 1 Suited for Spacewa l k i n g 4. How did you use this guide? A Tea c h e r ’s Guide with Activities for Tec h n o l o g y o Background Information o Critical Thinking Tasks Education, Mathematics, and Science o Demonstrate NASA Materials o Demonstration o Group Discussions o Hands-On Activities TE A CHER REPLY CARD o Integration Into Existing Curricula o Interdisciplinary Activity o Lecture o Science and Mathematics To achieve Am e r i c a ’ s goals in Educational Excellence, it is NASA’s mission to develop supplementary instructional materials and curricula in science, math- o Team Activities Standards Integration ematics, and technology. NASAseeks to involve the educational community in o Other: Please specify: ______the development and improvement of these materials. Your evaluation and suggestions are vital to continually improving NASA educational materials. 5. Where did you learn about this guide? Please take a moment to respond to the statements and questions below. You can submit your response through the Internet or by mail. Send your o NASA Central Operation of Resources for Educators (CORE) reply to the following Internet address: o NASA Educator Resource Center http://ednet.gsfc.nasa.gov/edcats/teacher_guide o Institution/School System o Fellow Educator You will then be asked to enter your data at the appropriate prompt. o Workshop/Conference o Other: Please specify: ______Otherwise, please return the reply card by mail. Thank you.
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