Board of Directors CARL SAGAN BRUCE MURRAY President Vice President Director, Laboratory for Planetary Professor of Planetary Studies, Cornell University Science, California Institute of Technology LOUIS FRIEDMAN Letters to the Editor Executive Director HENRY TANNER Califomia Institute We encourage our members to write to us on topics related to the goals of The Planetary Society: THOMAS O. PAINE of Technology Former Administrator, NASA Continuing planetary exploration and the search for extraterrestrial life. Chairman, National JOSEPH RYAN Address them to: Letters to the Editor, 65 N. Catalina Avenue, Pasadena, CA 91106. Commission on Space O'MeJveny & Myers Board of Advisors DIANE ACKERMAN JOHN M. LOGSDON It is very disheartening to read that the leadership of our Society is lobbying Congress to kill the poet and author fj;~~o;~~;~~t~7:~~~i~ ISAAC ASIMOV space station program. ("A Space Station Worth the Cost: The Planetary Society Proposal," Senate author HANS MARK Chancel/or, Appropriations Committee testimony of Carl Sagan, Bruce Murray and Louis Friedman, reported RICHARD BERENDZEN University of Texas System in the July/August Planetary Report.) President, American University JAMES MICHENER As the originator of the dual-keel concept and the one who first presented it to NASA in May JACQUES BLAMONT author Scientific Consultant, Centre 1985, I know why this configuration was proposed and its capabilities. The primary reason to National d'Etudes Spatiales, MARVIN MINSKY France Donner Professor of Science, have two widely separated vertical keels was to provide the acreage necessary to assemble large Massachusetts Institute RAY BRADBURY of Technology spacecraft and to house upper stages for geosynchronous, lunar and interplanetary missions. poet and author PHILIP MORRISON This is precisely what is needed to outfit and launch a manned Mars mission. ARTHUR C. CLARKE Institute Professor, Massachusetts author Institute of Technology Life science experiments on the station will provide the understanding of long-term, microgravi CORNELIS DE JAGER PAUL NEWMAN ty impacts on human and plant physiology necessary to design manned vehicles for 400- and Professor of Space Research, actor The Astronomical Institute at 1,00O-day manned Mars missions. The nearly closed-loop environmental control and life support Utrecht. The Netherlands BERNARD M. OLIVER Chief. SETI Program, system on the space station will probe the technology issues and systems needed for either a lu FRANK DRAKE NASA/Ames Research Center Dean, Division of Natural nar base or a manned Mars mission. Sciences, University of SALLY RIDE California at Santa Cruz former astronaut ThE. easiest way to kill a program is to study it to death. Serious station studies have been per LEE A. DUBRIDGE ROALD Z. SAGDEEV formed several times in the last 20 years. You can never develop a design that will fully satisfy all former presidential Director, Institute for possible station users. Waiting for a new launch system or re-examining the requirements will not science advisor Space Research, Academy of Sciences of the USSR JOHN GARDNER result in a better design; it will just mean more delay. founder, Common Cause HARRISON H. SCHMID We have waited too long already. I believe that the membership of The Planetary SOCiety, despite former US Senator, NM THEODORE M. HES6URGH and former astronaut its leadership, would like to see a permanently manned US station before the end of this century. President Emeritus, University of Notre Dame LEWIS THOMAS CARL M. CASE, Boeing Aerospace Company, Huntsville, Alabama Chancellor, Memorial Sloan SHIRLEY M. HUFSTEDLER Kettering Cancer Center educator and jurist JAMES VAN ALLEN After reading Drs. Sagan, Murray and Friedman's testimony, I found myself with thoughts on their GARRY E. HUNT Professor of Physics, space scientist,United Kingdom University of Iowa arguments concerning the goals and implementation of the US space station. True, the US should adopt Mars exploration as a primary goal of our endeavors in space. False, the currently pro The Planetary Report (ISSN 0736-3680) is published six times yearly al the editorial offices of The Planetary Society, 65 North Catalina Avenue, posed space station, even with its weak definition and disturbing lack of public commitment, is Pasadena, CA 91106, (818) 793-5100. It is available to members of The Planetary Society. Annual dues are $20 in the US, $25 in Canada , and $30 not worth the cost. outside the US or Canada. The Planetary SOCiety leaders seem to be vocalizing an adage that a space station designed for Editor, CHARLENE M. ANDERSON; everyone satisfies no one. Such a philosophy is indicative of the inability of the participants to com Technical Editor, JAMES D. BURKE; Assistant Editor, DONNA STEVENS; promise on a design. While this problem is not unique to the scientific community, I feel that if we, Art Director. BARBARA SMITH as Society members, cannot be enlightened with the wisdom of compromise, then no one else will Viewpoints expressed in columns or edi10rials are those of the al:lthors and be willing to negotiate either. Advocating a "Mars or no space station" position is preposterous. g~ ;3~i~~~:.s~a~~88eg~e~~~t ~~~~~~ ~:C~:t:'lanetary Society, Its officers Justifying the space station has been difficult given its $18 billion price tag. Justifying a Mars In Canada. Second Class Mail Registration Number 9567 program that could cost more than $100 billion will be even more difficult. We should adopt a di vide and conquer strategy of space station, lunar settlement, then Mars exploration. To make real progress, you have to make hard decisions, even if a few of us don't like those decisions. COVER: This enhanced false color mosaic of CARLOS H. PEREZ, JR., Houston, Texas Landsat images covers a portion of the eastern Sahara. The Uweinat Mountain, 40 kilometers across, is the largest topographic prominence, Now that the Ride Report (Leadership and America's Future in Space) has affirmed that a Moon and causes a vast spindle-shaped, sand-free base should be America's next step into space, it is time for The Planetary Society's leadership to zone. The mountain rises at the borders of Egypt, abandon its self-destructive Mars-{)r-nothing policy. I find it greatly disturbing that the Society's Libya and Sudan. Smaller features also cause a dark, sand-free zone in their lee. Similar features Directors have spoken out strongly and harmfully against the space station and a Moon base in have been imaged by spacecraft orbiting Mars. the far-fetched hope of going to Mars first. The Mars-first initiative is inadequate as a goal for Photograph courtesy Farouk EI-Baz America's space program. GREG URBACK, North Hollywood, California Lets Reinvigorate the US Space Program
by Carl Sagan and Louis D. Friedman
as NASA lost its way? The space agency has been The current status of the United States' space program severely criticized by friends and foes, by insiders greatly concerns all who feel that exploration of the solar H and outsiders, for a string of unprecedented launch system is among the most exciting and inspiring undertak disasters-but also for lack of purpose and for the absence ings of our time. As the largest space interest group in the of a coherent, readily understandable, compelling explorato world, The Planetary Society has led the call for the country ry objective. Part of this criticism is misdirected. to set a goal that can help reinvigorate that program. NASA is responsible for reliable launches and for trailblazing Through congressional testimony, newspaper and magazine scientific exploration. It is not in the business of setting its own articles, and lectures, the Society's officers have suggested goals. The nation must do that, through Congress, and espe that the human exploration of Mars is a goal that could f~ cially through the President. NASA is a missio[}{)riented agen cos NASA's energy and imagination and pull it out of its cur cy; tell it what to do----even ask it for the Moon and the plan rent morass. ets-and frequently it has delivered on time and on budget. In the July/August Planetary Report, Carl Sagan, Bruce But part of the criticism is justified. It is NASA:s business to Murray and Louis Friedman, the Society's officers, present know what goals should drive the US space program, what ed their view of NASA's space station program. A sampling steps should be taken to reach those goals, and how to get of letters from members who do not share their opinion is its perspective understood by the President and Congress. printed on the opposite page. Its feeble response to the Paine Report of the National The Society's officers are delighted with this outpouring Commission on Space is illuminating. The report, which rec of concern for the space program, irrespective of whether ommends a bold series of steps mOving toward human ex members agree, disagree or just view the issues differently. ploration and settlement of the solar system, was requested The Planetary Society is a membership organization and we by the PreSident, and was submitted to him more than a care about and are influenced by our members' opinions, year ago. He has yet to say a word about it. suggestions and ideas about the future of the space program Neither has NASA. Instead, the agency selected a popular and of The Planetary Society. astronaut and let her issue the response, as a recommenda We encourage our members to continue to write and to tion to the agency's Administrator. This way NASA takes no create a dialog with the Society's officers on such topics as stand that might offend the distracted occupants of the the space station, the lunar base and the exploration of White House. Mars. We will carefully consider your opinions and will use The astronaut, Sally Ride, and her team issued a forthright your ideas to help form The Planetary Society's positions. and incisive study, critical of the present condition of the US To continue the dialog, we print here an Op-Ed piece by space program-and recommending a range of new initia two of our officers that appeared in the November 21, 1987 tives for the nation consistent with the Paine Report: sys issue of the Los Angeles Times. tematic study of Earth from space; robotic exploration of the Send your letters to: Members' Dialog, The Planetary solar system; an outpost on the Moon; and a program of Society, 65 N. Catalina Avenue, Pasadena, CA 91106. Mars exploration culminating in the first landing of humans on another planet. The report cites Mars as the "ultimate objective of human exploration." We concur. But there is a curious and revealing incongruity in the re bility for so doing-perhaps by those fearful that coopera port. Despite this "ultimate objective," Dr. Ride found the tive work on a great exploratory endeavor will make perpet Mars goal premature and claimed it would lead to a "waste ual strategic confrontation a less viable way of life for the ful space race" if undertaken now. How did this incongruity United States and the Soviet Union. But these political con come about? Reading the charge to the Ride panel, we find straints are likely to change as the present administration two unusual constraints on its deliberations: Do not consid prepares to leave office. er US-Soviet cooperation (or any other international cooper The planet Earth and the solar system exploration focus ation) on a mission of humans to Mars; and consider only of the Ride report will serve us well. quick (so-called sprint) missions. As nearly as we can tell, However, the lunar outpost-neither as exciting as robotic these are the only two mission-particular constraints im planetary exploration nor as practical as observing Earth as posed on the Ride panel from above. They are precisely the a planet, and far more expensive than either-is more prob opposite of what makes prudent space policy, and they lematical. We've been to the Moon; it neither stimulates pub straitjacket the possible recommendations. lic imagination nor provides the impetus for international co International cooperation, especially between the two su operation in space nearly as well as Mars does. The Ride re perpowers, is one of the principal justifications for a voyage port justifies a lunar base as a stepping stone to Mars. We're of humans to Mars. Congressional resolutions have cited it not so sure: Earth and Earth orbit are better and far easier as a rationale; it has been a major topiC of every symposium places to test the engineering systems, and the Moon's sur held on Mars exploration in the last several years; it broad face (with no atmosphere and no water) is so different from ens the scope of available technical talent and decreases Mars that science testing there is of limited relevance. But costs; and the Soviet Union appears to be amenable to the this will get sorted out as technologies and capabilities are proposal. Prohibiting the Ride panel from even conSidering developed by a reinvigorated NASA. joint missions to Mars severely undercuts the reason for go The goal of multinational exploration of Mars by humans ing. Similarly, a "quick" mission (by 2(05) of humans to Mars is the best way to achieve such a reinvigoration. We agree requires an expensive and perilous leap in technology incon with Dr. Ride's conclusion that human exploration of Mars sistent with prudent, steady evolution of flight programs, should take place early in the next century, after renewal of and forces a pessimistic assessment. American capabilities in robotic exploration of the solar sys Why the incongruity? Because of the constraints from tem and long-duration human flight. NASA now seems to rec above. And why the constraints? Since they make no techni ognize the need for such a revival. We look forward to the cal sense they must be political; perhaps they are a way to time when it will be able to lift its head-and again look to scuttle joint Mars missions without taking explicit responsi- the frontiers. 3 How a COI'OIIIJfII'8I wOlfcs ••• If you IooIc cloaely a' a star's Image Iomted by a typIcaIas"",1OIIIIca1 'elescope, you see he discovery of an Earth-like planet suggest that planets form naturally with the Utaf " resembles file picture a' file lower left orbiting another star would capture collapse of a protostellar nebula (the cloud of {A}-If has a very brig'" COfW, SWf'OIIIIded by T our imaginations and expand our sci dust and gas from which a star forms). Thus succ.sslvely fainter rings. If the telescope" entific frontiers. It would also foment new we believe that the circumstellar shells and aperture .. partly bIocIced by secondary mIr speculation on the existence and nature of disks could be directly related to planet for ror suppoI't trvues as shown, the Image will have bright "spikes" e1rfendlllg out from the extraterrestrial life. We know little enough mation. Second, our Sun is an ordinary star, _ pelpfHldlcuIar '0 file shadows 01 file about the relationships that may exist among like countless others in the galaxy. Lackirig trusses. If you IooIc ClII'efuI1y enough, you'll stars, planets and life. Once revealed, howev evidence to set the Sun apart in some funda notice Utaf fIIese .,.",kes" .. brfgM oaly er, this knowledge will change our view of the mental way, it's reasonable to proceed on the ..... they _ bdgIat """" Soth file ""'" universe. As David Black of NASA's Ames Re assumption that planets have formed about and the .".es .. file ,...", 01 file tIIIfrac. search Center has noted in these pages (The many solar-type stars. (See Eugene Levy's ar "on, or bending, oIligItt passing near an 0b Planetary Report, September/October 1984), ticle in the September/October 1984 Plane struction or close to the edge 01 the 'el. scope" primary or secondary mirror., we will never fully understand the origin and tary Report.) A coronagraplt does the 'rick 01 removing evolution of our planetary system-and of Ultimately, we want to answer several fun these unwanted feature.. First, an occulting life on Earth-until our knowledge is imbued damental questions: Are there Earth-like disk In ,he tel.scope" focal plane blocks out with a galactic perspective. Only then could planets that could support life as we know it? ,he bright COle of ,he star's image. Wha'" lett we describe star systems in general-and [s the mix of terrestrial (rocky) and jovian are the rings and ,he spike_nd ,he feeble our solar system in particular. (gas giant) planets in our system the rule or IIgh' of a planet, It fIIere is Oft8, circling the We may be on the verge of detecting large, the exception? What determines the distribu star {S}. To remove the dllfracted light {the "ngs Jupiter-like extrasolar planets. Several years tion of planets around a star? How old are and the sp'kes}, w. next creel., w"h a field ago, observers using the Infrared Astronomi planetary systems? Are they always about .ens, an image 01 the tel.sc..... aperture in cal Satellite (lRAS) discovered infrared radia the same age as the parent star? How are wIIlch the dllfracted ligItt 's now concentrat· tion from extensive shells or disks of material they created, and how do they evolve? What ed In brlgh' lines alOllfl file edges tha, pr0- encircling at least a dozen stars within 80 types of stars have planetary systems, and duced the diffrac'lon. H_, In the "pupil" lm light years of Earth. Scientists later imaged why? age, a s'op Is placed 110 as '0 mask olf those The search for extraterrestrial intelligence bright edg... one of these systems, Beta Pictoris, at visible WIlen the star {and its planets} are BfIIIln wavelengths. When coupled with two theo (SET!), supported by The Planetary Society brought Into focus, oaly a trac. of the star's retical considerations, these data become through Project META (see the July/August 4 IIg"t remains, wllil. the brig"'ne.. of any very interesting: First, star formation models 1987 Planetary Report) would benefit from nearby planet is undiminislJed {e}. ",... tnHlon: $.A. Smith N.w~cfe. even partial answers to these questions. signed to sean:ll for Owing to technical limitations, the .xtrasoIar P-" will prospects merely for detecting extrasolar half. to contend with planets used to be poor. Today the outlook is CIie zodiacal light, ...., far more promising. Many scientific and engi ..... file taint...... , of IIfIIrt IIIIIIIing from lower neering approaches now under serious rIgM to top left. (TIle scrutiny may someday carry us far beyond """." familiar ...... , of the first stages of detection. Let's consider light competing with some of the basic technical issues. the zodlacalllgltt In t1tIs In the visible spectrum (the wavelengths lmag. Is the Milky WaJ4} most strongly emitted by the Sun and Sun Dust concentrated In the ecliptic plane ,cfe. like stars) planets shine by reflected light. A fined by Earth's orWt planet is not very bright. Earth would have a about the SUn} Nffects visual magnitude of 28 if seen from 33 light visible sunlight, which years away, a distance that encompasses can be _In daIff, roughly 240 stars and provides a good cl_sIdes just after sunseforlle'-_ "search volume." (Magnitude is a measure of rise. Since the zodiac is stellar brightness; the higher the number the made up of constell. lower the brightness. With the unaided eye tlons that lie along the we can see only stars brighter than the fifth line of the ecllpHc,the magnitude.) A single object of magnitude 28 glow from tltis dust Is is just barely detectable by the 2(}{}.inch Hale called the zodiacal light. This dust also giv.. off Telescope on Mount Palomar. Infrared radiation, and But our parent star shines enormously so it will Interfere wltlt brighter-by about 13 billion times, and the Instl1llll"""""'lfen Sun and Earth are separated by only 150 mil thos. placed In Eart" lion kilometers. Using special techniques, we orfJit-tltat are searcft. can distinguish astronomical sources 33 light objects.ing for faint __ .xtrasolar_ years away separated by less than 150 mil lion kilometers, but only if the sources are about equally bright. Even a large planet such as Jupiter is only about one-billionth as bright as its parent star. With planets close to pictures of the planets. Jim Elliott of the Mas nounced tentative detections of extrasolar their central star, and given the enormous sachusetts Institute of Technology has exam planets around two (and possibly more) brightness differences, the detection of an ined how an image might be obtained using stars based on their ability to measure stel Earth-or even a Jupiter-becomes a major the edge of our Moon to block the central lar velocities as small as 10 meters per sec technological challenge. star's light. Other concepts would take mea ond. When we contemplate observations at in surements from which the existence of plan The most convincing demonstration on frared wavelengths, the situation changes. At ets might be inferred. For example, consider the existence of extrasolar planets would sufficiently long wavelengths, the radiation the transit of a planet across the disk of its come from actual images. At the Jet Propul we receive from a planet is dominated, not central star. If the planet's orbital plane hap sion Laboratory, scientists and engineers are by reflected light from its parent star, but by pened to lie edge-on to Earth, we could de studying several promising techniques. To its own incandescence, with an infrared tect the slight dimming of the star's bright discriminate between an exceedingly faint brightness that depends on the planet's tem ness as the planet passed in front of it. planet and its much brighter parent star rais perature and composition. The peak radia Another indirect approach makes use of es some problems, each calling for a special tion for Earth and for Jupiter occurs at in the observable fact that a massive planet will solution. frared wavelengths 40 to 80 times longer, re cause its star to move in a circle in response The first problem is simply the very bright spectively, than the wavelengths of visible to the planet's motion: Both the planet and central core of a star's image. If we had a light, where the Sun's output is most intense. the star move in orbits about their common large, optically perfect telescope, the image So, in the infrared, the star-to-planet bright center of mass. If our solar system were seen core would be very small, perhaps smaller ness ratio is much more favorable. For exam from stellar distances, the Sun's wobble in re than a planet's orbit. Still, the light from the ple, at 25 microns (a wavelength about 50 action to Jupiter would be just detectable by core would be so great that it would hide times longer than that of visible light), the an instrument like the Hubble Space Tele any nearby fainter image. So we would have star-to-planet brightness ratio for an Earth scope (HSl). This objective was used to de to get rid of the core image. would be 800,000 to 1, and only 100,000 to 1 fine one of the telescope's performance spec We can do this by introducing an opaque for a Jupiter. ifications. Using the HST's Wide FieldjPlane occulting disk into the telescope's focal Our solar system contains a potentially tary Camera, researchers will try to make plane, making it just large enough to block competing source of radiation-interplane such astrometric detections of extrasolar the image core, and leaving the rest of the tary dust concentrated in the ecliptic (the planets. field-of-view undisturbed. However, a faint plane defined by Earth's orbit about the The perturbations in a star's motion halo of starlight will remain due to diffrac Sun). This material is the source of the zodia caused by the gravitational pull of a massive tion-the bending of light around the edges cal light, which is simply sunlight reflected planet would be detectable as a shift in fre of the telescope's mirror. We can reduce by the dust. It is visible on very dark, clear quency (doppler shift) of spectral lines due these effects with a Lyot stop, named after nights·just before sunrise or just after sunset. to the absorption of light by atoms in the its inventor, Bernard Lyot. This ingenious de Uke the planets, this dust not only scatters star's atmosphere. Pierre Connes of France's vice works by blocking much of the light en the light of the Sun, it emits infrared radia Centre National de la Recherche Scientifique tering the telescope near its aperture's edge. tion. For certain measurements, this weak zo has devised an elegant spectrographic ap Originally used to study our Sun's corona, a diacal glow from our own system will limit proach to exploit this phenomenon. His con stellar coronagraph of this design (a tele the faintest objects that we can detect with cept involves measuring changes in a star's scope equipped with an occulting disk and a an Earth-orbiting telescope. velocity induced by planetary motions, using Lyot stop; see illustration) was successfully Researchers have advanced many ideas a laser for a frequency reference. used to image the vast circumstellar dust for detecting extrasolar planets (see the After a six-year observing program, Cana shell around Beta Pictoris (see the Novem September/October 1984 Planetary Report). dian astronomers Bruce Campbell, Gordon berjDecember 1984 Planetary Report). Some would use imaging systems to make Walker and Stephenson Yang recently an- Recently, scientists working at the Perkin- 5 Elmer Corporation and at JPL developed the ideal by more than one-twentieth the to at least 33 light years, and to make multi mathematical tools to compute accurately wavelength of visible light, or around 100 spectral observations for determining plane the behavior of a stellar coronagraph and to times the diameter of an aluminum atom. tary temperatures and compositions. (Of the optimize it for planet detection. Their work (This factor of one-twentieth was the design 240 known stars within 33 light years, 58 are has shown that, in principle, most diffracted specification for the primary mirror of the similar to our Sun.) Diner's team is evaluat light from a circular aperture can be re Hubble Space Telescope.) ing a variety of system trade-offs. For exam moved, although perhaps one part in a mil However, even in a stellar coronagraph ple, to form direct images of planets at visi lion will get through to compete with the fee where the diffracted light is greatly reduced ble wavelengths, using the low-scatter-coron ble plapetary images that we seek. This esti by a Lyot stop, starlight scattered by the agraph approach, we would need a mirror mate is optimistic because it assumes that telescope's imperfections would still ob about 12 meters in diameter. To place it in the occulting disk, the Lyot stop and any oIr scure a very faint planet. Calculations show Earth orbit, such a large telescope would tical elements in the system are perfect. that, to reduce the effect of imperfections, have to consist of individual segments, like But, as we know, nothing is perfect. For ex the mirror must be 15 times smoother than the Keck Telescope being built in Hawaii, or ample, the surface of a telescope's main mir the HST mirror. With the Perkin-Elmer Cor the orbiting Large Deployable Reflector un ror will only approximate the shape the de poration, Rich Terrile of JPL is studying the der study at JPL. Positioning the segments to signer intended. One effect will be that some building of such a telescope about 1.5 me the extremely high precision required to de light that should have been directed into the ters in diameter. It could detect the brighter tect extrasolar planets would be a formi core of the star's image (where an occulting planetary companions of our nearest stellar dable challenge. disk would have blocked it) will instead aIr neighbors and could image circumstellar ma However, as we have seen, direct imaging pear as a halo of scattered light. Normally, terial. But to detect and characterize Earth in the infrared has some advantages. It skilled manufacturers can control residual er like planets out to 33 light years, we will need would require an even larger segmented mir rors well enough that the scattering is negligi a much larger and more exotic telescope. ror-about 50 meters in diameter-but due ble compared to the diffraction, which is A JPL group headed by Dave Diner is to the longer wavelengths and the more fa what we mean when we say that a certain studying several advanced telescope con vorable star/planet contrast, the poSitioning telescope is diffraction-limited. This often re cepts. The team is developing a method to of the segments need not be as precise. In quires that an optical surface not depart from image both jovian and terrestrial planets out this case, one technical challenge concerns cooling: The optics would have to be cooled to about -190 degrees Fahrenheit throughout the observations, otherwise heat from the telescope itself would block faint planetary signals. An alternative to a large reflector is inter ferometric imaging. An image of an extraso lar planetary system would be constructed by combining data from a set of paired tele scopes. Each pair contributes part of the im age. This technique has been used success fully to image many astronomical sources at radio wavelengths with the Very Large Array (left) in New Mexico. The advantage of this approach is that the total collecting area of the telescope can be smaller, thus redUCing the system's mass and the area to be cooled. One concept under study is a rotating array of telescopes in which the light from each el ement of a given pair is combined so as to The Very Large Array in New cancel the star's radiation. The quality of the Mexico (above] is a group of result is determined, among other things, by radio telescopes that can be the number of paired telescopes, the quality used simultaneously to 0b of the mirrors, and by how accurately each serve an astronomical object. element can be pointed, stabilized and con- . 8y carefully combining the trolled. Again, detailed trade-off analyses are radiation collected by each in progress to determine whether the merits of individual dish, researchers can reconstlVct an image as this approach will result in a practical design. if the entire area enclosed by The technical challenges for detecting and the array were a single, giant characterizing Earth-like and Jupiter-like ex aperture. This technique has trasolar planets out to 33 light years are for many advantages for detect· midable, but not insurmountable. Our recent ing and characterizing extra· progress suggests that we can mount a pro solar planets. gram that someday will tell us about the ori Photograp": JPI.JNASA gin and evolution of planetary systems, their relationships to stars, and the factors gov In this painting (right], NASA's erning extraterrestrial habitats in our galaxy. Large Deployable Reflector, now being studied at the Jet Propulsion Laboratory, is con· John F Appleby works in the Earth and Space StlVcted in Earth o"'it. This Sciences Division of the Jet Propulsion Labora type of telescope uses a seg· tory. His research interests include atmospheric mented primary mirror to modeling, remote sensing science and extra produce direct images of the solar planets. Arthur H Vaughan is a Senior source. This telescope is one Scientist and Supervisor of Optical Sciences at possible approach to the prob lem of finding and studying JPL and Institute Associate in Astronomy at extrasolar planets. the California Institute of Technology. 6 Painting: JPI.JNASA I know that ocean tides are generated by reach Jupiter, its speed at perihelion (speed it react chemically with the oceans? the gravitational pull of the Moon and the is magnitude of velocity; velocity is speed -RobertCasey,OradeIl,NJ SUIL It's easy to visualize a tidal bulge un and direction) should be about 39 kilometers der the Moon, but what causes the bulge per second. Earth goes around the Sun at Earth and Venus have similar abundances of on the opposite side ofEarth? about 30 kilometers per second. To gain the volatile (easily evaporated) elements and -Dale S. Smith, Ashland, OR additional 9 kilometers per second, Galileo hence, they have the potential for similar at will need a push from a rocket. This was to mospheres. In fact, if Earth had formed a few The tidal bulge under the Moon is easy to vi be the job of the Centaur upper stage that million miles closer to the Sun, its climate sualize because you probably have a mental would have launched Galileo from the shut might now resemble that of Venus. Luckily picture of the Moon pulling gravitationally on tle. When the Centaur was canceled, Galileo for humans and similar life-forms, Earth is far Earth itself; if it's going to raise the tidal bulge was left without a rocket powerful enough to enough away from the Sun that liquid water on the side of Earth facing the Moon, then it provide that extra 9 kilometers per second. can form and persist on our planet's surface. must pull harder on the water than on the Mission analysts came up with another tech As you correctly surmised, the oceans have Earth. Why? Distance is the key. The Moon is nique to supply the needed velocity. Galileo been very important to Earth's atmospheric closer to the water in the oceans than it is to would be launched toward Venus (the re evolution. They have helped keep Earth's at the solid Earth itself. If we ignore the fact that quired two or three kilometers per second mosphere relatively thin and its surface rela neither the Earth nor the Moon is perfectly velocity can be provided by the Inertial tively cool by allowing the removal of atmo spherical, we can think of the gravitational Upper Stage) so that when it swings by that spheric gases such as carbon dioxide (COz). force that the Moon exerts on the entire planet, its trajectory will be bent into a more The carbon dioxide can dissolve in the Earth as being concentrated at the center of elongated ellipse-it will be given a "gravity ocean, where it forms carbonate rocks such the planet, which is about 4,000 miles further assist" from Venus (see the March/April 1982 as limestone. It can then be incorporated into away from the Moon than the water at its Planetary Report). That ellipse will be target Earth's crust. surface. So, the Moon pulls harder on the wa ed for Earth, where the spacecraft can re Carbon dioxide makes up over 95 percent ter at the surface than on Earth itself, raising ceive another gravity assist. Galileo will of Venus' atmosphere, but only about 0.03 a tidal bulge. Such a force, which is different swing by Earth once again, and with that final percent of Earth's present atmosphere. This at two separate points in a body and thereby push, it will have the 39 kilometer per second carbon dioxide, together with a small can cause a distortion of the body, is known speed that it needs to reach Jupiter. amount of water (H20), gives Venus a very ef as a differential force or (sensibly enough) a - WIWAM J. O'NEIL, Jet Propulsion Labor fective "greenhouse," leading to high surface tidal force. atory and LOUIS D. FRIEDMAN, The Planetary temperatures of about 460 degrees Celsius Now the explanation of the second tidal Society -hot enough to melt lead. bulge on the opposite side of Earth is fairly Earth's atmosphere seems to have varied straightforward. Since the Moon is closer to greatly over its history. One of many pieces Earth's center than to the water on the far I have noticed on maps of the Moon that of evidence of this variation made the news side, it pulls harder on Earth than on the wa the side facing Earth has many more large recently. Researchers discovered that an 80- ter. In effect, the Moon pulls Earth out from maria and fewer craters than the "far" million-year-{)Id piece of amber contained air under the water on the far side of the planet, side. Is this a result of the forces that bubbles that hold 50 percent more oxygen producing the second tidal bulge. caused the Moon to become gravitation than does our present atmosphere. If these -AlMA C. lOOK, Pomona College ally locked with Earth? air bubbles do indicate the state of the air 80 -Ronald Mallory, Huntington Beach, CA million years ago, then Earth's atmosphere had more oxygen, and presumably a higher GaIlleo will use a VenusEarthEarth gravi There are fewer craters on the maria because overall pressure, during the Cretaceous peri ty assist trajectory to gain the necessary the great floods of lava that formed them oc od- the era of the dinosaurs. This discovery, speed to reach Jupiter. What is the neces curred after the ancient bombardment that along with other studies indicating a warmer, sary speed to reach Jupiter? made the myriad craters on the highlands. thicker atmosphere at that time, have led to -Jeffrey S. Buch, Costa Mesa, CA During that bombardment, some very large the suggestion that large reptiles could fly impacts left what are called basins: depres more easily in the thicker atmosphere. The motions of objects in orbit about the Sun sions hundreds of kilometers in diameter sur With our recently acquired ability to dump are governed by Kepler's First Law of rounded by rings of mountains. The basins large amounts of pollution into our environ Planetary Motion: Objects orbiting the Sun on the Moon's near side are largely filled by ment, humans have a chance to make Earth a travel in ellipses. When a spacecraft is mare lavas, while those on the far side re little more like Venus. We cannot increase launched from Earth, it becomes, in effect, a main mostly empty. Whether this was a substantially the atmospheric pressure, but planet orbiting the Sun. Following Kepler's cause or an effect, during the tidal braking of we can change the abundance of minor ele . law, spacecraft travel on elliptical paths from the Moon into its current lock facing Earth, is ments that can have major effects on climate point to point in the solar system. To get unknown. and life. The burning of fossil fuels at its pro from Earth to Jupiter, Galileo must travel an -JAMES D. BURKE, Jet Propulsion Labomtory jected rate may cause the carbon dioxide ellipse whose perihelion (closest point to the abundance to double in the next century. Sun) is near Earth and aphelion (farthest This addition could raise Earth's average point from the Sun) is near Jupiter. The surface pressure of Venus' atmo temperature a couple of degrees and so sig The spacecraft's velocity at perhelion will be sphere is about 90 times that ofEarth, yet nificantly affect such things as agriculture determined by another of Kepler's Laws: Venus and Earth are about the same size and sea level. Orbiting bodies sweep out equal areas of and mass. Did Earth once have a thicker - JULIANNE MOSES, their ellipses in equal times. For Galileo to atmosphere? Where did the excess go?Did California Institute of Technoiogy
L-______~ ______~ 7 ALIEN LIFE-FoRMS AN
by James
hen we find "others" or they ural philosopher of the old school, simply scendants today are the swift, elegant find us, and we begin exchang tells us what he sees. But in the process tuna, swordfish and other teleost preda W ing snapshots, what will they he advances irresistibly the theme that tors of the sea. Meanwhile, life began its look like? In a delightful reverie the hu certain laws do govern plant and animal ascent onto the land. By the end of anoth man mind can range over the splendid di shapes. er hundred and fifty million years some versity of life on Earth and can create In this article, let us consider one re air-breathing dinosaurs had returned to imaginary beings that go beyond even gime where physical law reigns absolute the sea. Of these, one family, the icthyo the bizarre creatures seen in the open ly; namely, the realm of fast motion saurs, resumed the classic streamlined sea, along a coral reef, or in a good aquar through fluids. It is no accident that ev shape, while others with less need for ium. Ufe's molecular architectures have erything fast in the ocean, past or pre speed made more modest adjustments. enough intrinsic complexity that they can sent, looks like a fish. Engineers know In the wonderfuUy plastic habit of life, be, and are, arranged successfully by evo why: There is but one certain family of this whole cycle was repeated by the lution into millions of different shapes, permitted by fluid mechanics, mammals and even, with limitations, by forms-even here on Earth, where funda that gives minimum drag, hence lowest birds. Whales, dolphins, seals, otters and mentally all life is one. energy consumption, for a given speed. In penguins all display the same adaptation On another planet (or even on this one, water at animal speeds, and in air at forced by hydrodynamic law. as evolution slowly remodels animals and speeds up to those of most airliners, these Then came the thinker and builder, plants), endless further varieties of shape shapes are distinctly fishlike; rounded in man. For the first time in all the long are possible; for example, land locomo front, tapered at the rear, and a few times ages, the adaptation began to be extraso tion is here practiced with two, four, six, as long as they are wide, with fair, matico Instead of streamlining their own eight and "many" legs, but nothing now "streamlined" curvatures all along their gawky bodies, which would have en known prevents the use of three (kanga length. (Microorganisms, whose world is tailed the atrophy of other useful func roos), five (spider monkeys) or nine. Sci dominated by the viscosity, or stickiness, tions, humans invented boats. But wait: A ence-fiction authors have had and have of water, have a different drag problem, boat is pointy at the bow and broad near disseminated great fun with such possibil but even there a form of streamIining can the stern, very unlike a fish. This is be ities, and even some scientists have specu be observed.) cause it travels on the water surface, lated on the subject-on occasion going Thus, any animal whose competitive where wave drag and other considera so far as to say that evolution anywhere success is aided by fast movement under tions such as stability and dryness domi would naturally lead to a bipedal crea water tends to be shaped by evolution nate over classical underwater hydrody ture about two meters high with a brain into a streamlined form. On Earth (see il namics. To an engineer, the problem of at the top, two ears and two eyes! lustration) this has happened again and shape for a surface ship, a sailing yacht A wonderful monograph on the myriad again. A half billion years ago, creatures or a speedboat is immensely more com shapes of life, with a down-to-Earth per appeared that began the long and as yet plicated than that for a submarine. Fast spective and no nonsense about alien p0s unending story of the shark. A hundred submarines do look like sharks, fish, ic sibilities, is D' Arcy Thompson's classic, and fifty million years later, the first bony thyosaurs and whales and, as do these "On Growth and Form." Thompson, a nat- fish entered the fossil record; their de- animals, they perform superbly when
8 D FUNCTIONS IN FLUIDS
D.Burke
deeply submerged. The long history of on the subject of dirigibles. Again, sci the planing hull, the jet engine? Well, seagoing vessels in some ways parallels ence-fiction writers have led the way, some bacteria have corkscrew tails driv the Darwinian evolution of life. Better imagining great shimmering argosies of en by electric motors, various animals adapted forms have gradually made earli soft, sentient beings cruising in alien at make use of hydrodynamic lift at the er ones extinct, while a few "living fos mospheres. Indeed, no physical law for water surface, and squids and octopi em sils" hang on in parts of the world where bids the existence of such creatures, and ploy pulsed jet propulsion. But there is they can survive, either because they can with the aid of Reynolds and other aero not, and apparently never has been on compete or because they are loved. dynamicists we can even figure out what Earth, a true animal equivalent of the What does all this suggest to us about they should look like, given knowledge or wheel or of the jet boat as used for tow the life forms of another planet? Wherev assumptions about the atmospheres in ing water skiers. Perhaps Darwinian evo er there is an ocean with creatures in it, if which they might live. However, biologi lution has no use for such energy-guz speed confers an evolutionary advantage, cal law may condemn such lovely crea zling frivolities ... but who is to assert this any fast-moving inhabitants of the deep tures to oblivion. Faster-flying animals, as a universal fact? On the surface of some will have the shapes of fish. If the ocean is alien birds, might eat them. Otherwise, strange lake or ocean, maybe nature, red not water, but some other liquid with dif we have to imagine the blimp-beings pro (or some locally more fashionable color) ferent density and viscosity, these alien tecting themselves as jellyfish do, which in tooth and claw, has yielded up, for fish may display different combinations makes them rather less attractive. flight or for pursuit, the planing hull-a of size and speed. Their shapes may differ Birds. Just as in the case of fish, but frightening prospect to be sure, but if slightly from those of fish on Earth, but with complications due to landing and such things do exist and we ever come to the governing physical laws will still have roosting, here evolutionary adaptation is know them, we will see at once how their forced them into the universal mold. (The forced by physical law. Time and again function follows from their form. Victorian physicist, Osborne Reynolds, on Earth, evolution has made an or As we continue to seek the origins of elucidated the relevant similarities; in his nithopter: at least two kinds of pterosaurs, the phenomenon we call life, we marvel honor, hydrodynamicists refer to the endless varieties of birds and insects, and at the results, past and present, of oppos Reynolds number as a descriptor of dif bats. finally, evolution yielded up a brain ing divergence and convergence as fering flow regimes.) This tendency of be powerful enough to imagine, analyze, de Earth's age-old stochastic game goes on. ings with different ancestry to assume sign, build and fly the airplane. No known Imagine the richness that would be similar shapes is called convergent evolu law of nature prevents all this from hap added by the discovery, anywhere, of an tion; in the endless shuffling of life's pos pening elsewhere, but aerodynamic laws other game in progress! Or even of one sibilities it is a trend counter to the diver do govern bird and airplane shapes. that ended long ago .... gent evolution that causes animals and Therefore, if heavier-than-air flying crea plants to radiate out and occupy every tures or artifacts are discovered in other James D. Burke, our Technical Editor, is a ~ible niche. atmospheres, we may find them startling member of the technical staff at JPL. If we expect to find fish, whales, possi ly familiar. These same ideas have been elegantly bly even brain-built submarines in some What about natural analogs of human woven into the texture of Arthur C. far-distant ocean, it is natural to speculate inventions such as the screw propeller, Clarke's new book, "2061: Odyssey Three. " by Farouk El-Baz
ur eyes were fixed on the day's climatic conditions, wind is the across the knobby terrain, it leaves display screens at NASA's Jet major agent of erosion, transporta sand-free lanes behind individual OPropulsion Laboratory, while tion and deposition of particulate knobs and a streaked pattern devel we anxiously awaited the first photo materials. ops. On the right is an area in the graphs of the planet Mars. The ex These two characteristics can also Cerberus region of Mars, which citement quickly disappeared with describe the hyper-arid deserts of displays the same kind of pattern. c. the arrival of the first images, be Earth. The shuttle imaging radar has A further ilIustraton of similari cause they showed nothing! Details revealed the now sand-buried cours ties is shown in Figure 3. In photo of the martian surface remained es of great rivers that once carried graphs of Mars, mixtures of rock veiled as image after blank image much water in the eastern Sahara. sizes were believed to be the result was transmitted by the Mariner 9 Archaeologic and geologic evidence of catastrophic events such as a spacecraft in its approach to the Red nearby in the Western Desert of flood or meteorite impact. However, Planet. For nearly two months, an Egypt supports the presence of in the Western Desert of Egypt we intense global dust storm raged in much surface water during several find similar mixtures that result from the atmosphere of Mars and shroud wet episodes in the geologic past. the natural decomposition of rocks ed its surface. Only the highest vol Today, however, the area is bone-dry, in the hyper-arid environment. canic peaks would peer through the where the sunlight falling on the A fourth example of similarities dust to be revealed by the vidicon sands is capable of evaporating 200 between the Western Desert of cameras aboard the automated times the amount of rainfall. As on Egypt and the surface of Mars is probe. Mars, only the wind reigns. even more instructive. When vesi Then, as Man·ner 9 became the Dunes are only one of the many cles (small pits in the rocks) were first spacecraft to orbit another plan features that are common to the first revealed by the Viking lander et on November 13, 1971, the dust deserts of Earth and Mars. Other cameras, geologists immediately settled and unveiled a desert-like analogies were confirmed by field thought of vesicular basalt. This is surface. Dunes littered the surface checking. For example, in the east a type of volcanic rock that occurs of Mars, particularly in polar regions. ern Sahara, there is a group of in many places on Earth, including They occured in groups forming mountains, with the largest called the vast tracts of the northwestern dune fields or as individual, crescent Uweinat. There are spindle-shaped United States. It is also among the shaped or barchanic forms. Thus, dark zones behind these topograph rocks that were returned from the the similarities between the wind ic prominences. The mountains Moon by the Apollo astronauts. blown features of Earth and Mars occupy the upwind part of the dark It is vesicular because, as the lava were first revealed. Five years later, areas and the spindle shapes are extrudes to the surface and very two Viking orbiters would bring sur bordered by light-<:olored material quickly chills, its gases have no time face features of Mars into sharper on either side. to escape and so get trapped in focus. Then, on July 20, 1976, the The field checks allowed the com pockets. Thus, the rock acquires a first of the two Viking landers arrived parison of analogs of features in this spongy appearance. on the martian surface, seven years !lesert to those on the surface of A similar rock fabric that has no to the day after the Apollo 11 astro Mars. In the case of Hagar El-Garda, thing to do with volcanic activity oc nauts first set foot on the Moon. (Flgure 1, left) like the Uweinat curs in the Western Desert of Egypt On arrival at Chryse Planitia, the Mountains it has a spindle-shaped (Figure 4). Its pits were formed by "Golden Plain," the lander transmit sand-free zone in its lee. Sand forms perSistent wind erosion. Thus, the ted amazingly clear and sharp views the light-<:olored pattern on either rocks on Mars did not have to be of the martian surface. Several ex side. In the lee of the hill, where vblcanic, but could be any type of periments searched for traces of life there is no sand, the exposed ground rock pitted by the wind. or organic molecules, with negative is dark. These comparisons between the results. Images from both orbiters Figure 1, right, is an almost identi features of the hyper-arid Western and landers confirmed the Mariner 9 cal situation on Mars. In the same Desert of Egypt and parts of the conclusion that the heretofore am way, the wind distributes the partic surface of Mars suggest that aeolian biguous seasonal color changes on ulate material on either side of topo processes such as wind erosion Mars are not due to biological but graphic impediments, in this case, and deposition act Similarly on the rather to meteorological causes. two craters. The dark areas in the surfaces of both planets. This is but Photogeologic interpretations by lee represent the original surface one illustration of the many uses of numerous investigators confirmed and are surrounded by light-<:olored comparative planetology to better two basic characteristics of the sur dusty deposits. understand the environment of face of Mars: 1) It appears to have Another case is illustrated in Fig. Earth. hosted surface water in its past, and ure 2, where on the left is part of the in some cases valleys were formed desert southeast of the Uweinat Farouk El-Baz is Director of the Boston by fluvial erosion; and 2) under to- Mountain. As the wind moves 10 University Center for Remote Sensing. 'l,nre·(7Urer in upper leh is 20 kil& meters in diameter (right).
A mixture ofangular blocks ofvarying sizes on the desert surface in southwest· em Egypt Oelt) and in the Viking 2 landing site on Mars (right). The largest block in both cases is about
Wind."itted quart· zite in the Gilf Kebir region in the Western Desert ofEgypt Oeft) and vesicular rocks from the Viking 2 landing site. The largest blocks are about 30 centimeters
11 NelD~Reviews The Soviets in Space Sputnik began a continuing effort in the Soviet Union to be come the leading spacefaring nation. While the United States embarked on its manic.{\epressive approach to space (land ing a man on the Moon only to abandon the whole Apollo pro gram), the Soviets have kept a steady pace. Uttle is known in the United States about the impressive scientific and technical by Clark R. Chapman achievements of the USSR In 1987, for example, while the US was grounded, cosmonauts accumulated more than 7,500 hours in space, chiefly in the Mir space station. After years of frustrations, Soviet scientists now have a string of successful planetary missions to point to, and are about to embark on a series of impressive future missions that make the United States' modest Mariner Mark 0 and Planetary Observer mis believe that the most profound discovery of planetary sions seem relatively mundane. science during the Space Age has been our recognition For years, lack of knowledge in the West of the Soviet that interplanetary space is a shooting gallery and that space program was due to Russian secrecy. But for several we, on Earth, are the targets, just like the other planets. Since years now, they have been nearly as open as the Americans, Sputnik turned serious scientific attention toward space, it announcing launches in advance, broadcasting them live, has been proven that the Moon's craters were created by and finally reporting some of the tragedies that occurred in collisions with comets and asteroids. We have recognized earlier years. The continuing ignorance in America about the hundreds of impact craters on our own planet. And we have Soviet space program is now due mostly to lack of coverage found that the solid surfaces of every body in the solar sys in the American news media. A recent, highly readable sum tem (except those subject to extremely active geological mary of the present state of "glasnosting space" is Peter processes that erase even recent geological formations) are Pesavento's article in the October issue of Technology covered with impact craters. Finally, we have realized that Review, published by the Massachusetts Institute of comets and-asteroids, and their unseen smaller cousins, the Technology. meteorites, are bombarding us all the time; they may have caused extinctions of species and threaten catastrophe in Where Do We Go From Here? the future. One single scientist is responsible for most of this NASA, of course, has been mired in inactivity. Apart from the new perception of our planet and our solar system: Eugene obvious problems of getting the shuttle working again, there M. Shoemaker. has been little movement toward adopting long-range goals A particularly delightful article about Gene Shoemaker ap and beginning to take concrete steps to meet them. Around peared in the October 26th issue of The New Yorker, excerpt the time of the Challenger disaster, the National Commission ed from a new book of essays, First Light by Richard Preston, on Space attempted to set a future agenda for NASA, but on the general theme of the Mount Palomar Observatory. nothing much was done about it. More recently, Sally Ride Shoemaker thinks of himself chiefly as a geolOgist, but he was commissioned to outline some bold new initiatives; she will do practically anything to pursue his passion of learning issued her report in the late summer before leaving the about the cratering process. In this essay, Preston finds Gene space agency. This time NASA has taken at least a few small Shoemaker playing the role of astronomer, shivering in a steps towards trying to implement her recommendations. mountain-top observatory, taking photographic plates of The real proof of serious intentions, however, will be in the distant asteroids. President's budget, to be released about the time you are As a young man wanting to travel to the Moon, while it was reading this. A first test will be whether or not the Comet still the stuff of science fiction, Gene Shoemaker was attracted Rendezvous Asteroid Flyby (CRAF) mission is in the budget, to the crater south of Wmslow, Arizona; he proved that it was which it must be if it is to meet the time schedule of Sally truly due to an asteroidal impact. Nowadays it is difficult to Ride's recommendations. imagine that Meteor Crater's origin was ever in disput~you For a quick overview of the Ride Report, see the January can still pick up meteorites scattered on its slopes--but that 1988 issue of Astronomy magazine. The report is excerpted, just exemplifies the changed gestalt for which Gene including summaries of the four major initiatives: Mission to Shoemaker is largely responsible. He later led the research planet Earth, exploration of the solar system, outpost on the about lunar craters photographed by Rangers and Surveyors, Moon, and humans to Mars. The Ride Report is a bit ambigu and about craters imaged on outer-planet satellites by ous about whether these are to be regarded as competing Voyager. In the early 1970s, he turned his attention to the alternatives or as a unified program. I believe that America's skies, to the asteroids and comets that are responsible for the response to the challenge of space requires all four initiatives bombardment. He, his wife Carolyn, and their associates have to be undertaken: It is inconceivable that we should not aug been responsible for discovering most of the Earth-approach ment our nearly moribund planetary exploration program, ing asteroids known today. How they do it is chronicled in and we must also apply similar techniques to studying our Preston's essay. own planet. These are the least costly of the initiatives, and Preston writes about the origin of the asteroids, the they need to be started now. The lunar outpost, which Alvarez mass-extinction hypothesis, the Trojan asteroids out makes use of the space station, is a natural (if not essential) near Jupiter, and the significance of planetary cratering, all precursor to a piloted mission to Mars, as are the Mars mis within the context of late-night conversations with the sions within the solar system exploration option. Since I be Shoemakers on Palomar Mountain. Preston has the feel of lieve that we must embark on all four approaches to our fu an astronomer's existence exactly right: The cold, the pierc ture in space, [ am a bit disappointed in the divisive ques ing starlight, the red glow of LED numbers on the instrument tions posed in Astronomy's readers' poll. panel, and the disorienting rotation of the dome following the stars. The significance of Gene Shoemaker's scientific re Clark R. Chapman is a founding member of The Planetary search comes through strongly. Society. 12 by Louis D. Friedman
WASI-DNGTON-"For want of a horse.... " In the launched until 1998 or 2000, but NASA has appear that OMB is giving it very low priority United States' space program, the horse is a been organizing advanced development and and trying to forestall any new initiatives in launch vehicle. With some six months before study team efforts to prepare for this mile the 1990s. space shuttle flights are said to resume, the stone mission. A welkoordinated, coopera The United States has not launched a plan United States is poised to reclaim its role in tive study at the Jet Propulsion Laboratory etary mission since Pioneer Venus was sent the exploration of space. The first launch and NASXs Johnson Space Center has a team on its way in 1978. If no decisions are made since the Challenger tragedy is scheduled to of NASA personnel, industry contractors and now to fund new programs, then the decade lift a Tracking and Data Relay (IDRS) satellite university scientists laying out the specifica of the 1990s will be just as empty. The United into Earth orbit in 1988. With the Hubble tions and requirements. States will not enter the 21st century as a Space Telescope, Magellan (a Venus-orbiting An expendable launch vehicle plan, finally deep-spacefaring nation. Planetary missions imaging radar), Ulysses (the European mission announced by NASA, now permits a greater require very long lead times and decisions to fly over the north pole of the Sun) and flexibility in planetary mission planning. being make in Washington today will affect Galileo (the Jupiter orbiter and probe) all figu Since the 1970s, all launches had been re planetary encounters in the next century. ratively on the launch pad and ready to go, stricted to the shuttle. Now backup launch Whether or not any US spacecraft are launched the United States is hoping that the next 18 vehicles and spacecraft are being prepared to visit other worlds in the next decade will be months will rejuvenate space science. If all for Gali/eo, CRAF and other future missions known when the President submits his budget goes well, 1989 could be the "year of space so that they will not be as vulnerable to single to Congress. Without a new start for CRAF and science" that we had hoped for in 1986. point failures or vagaries in launch schedul support for future exploration, such as the If shuttle flights resume smoothly, and ing. A Titan 3 is being planned as backup for Mars rover and sample return mission, we NASA acquires expendable launch vehicles the Planetary Observers (a proposed series can assume that there will be no American for its space science program, the future of of spacecraft based on Earth-orbiting satellite planetary encounters for a very long time. space exploration will brighten. NASXs space designs) and a Titan Kentaur could boost science program has used the three-year de the Comet Rendezvous Asteroid F1yby. Such Louis Friedman is the Executive Director of lay productively to lay the groundwork for an resiliency has been sorely needed since the The Planetary Society. exciting decade in the 1990s. The missions decision to abandon expendable launch now scheduled include: vehicles and to rely solely on the shuttle. Mars Observer-Unfortunately delayed from 1990 to 1992, the mission is now better Clouds on the Horizon defined, ensuring that NASA will obtain valu However, there are clouds on the horizon. Of Into the Computer Age able information about Mars. The Mars Ob most concern, of course, is the shuttle sched seroerwill be a precursor to landing and sam ule itself. Many independent analysts still As you no doubt noticed, the last ple return missions by robotic vehicles, and think that NASA is too optimistic in its pre issue of The Planetary Report was a little later human missions. A second spacecraft dicted rate of launchings. Magellan, sched late in getting to our members. With the has been added as a backup. If this mission uled for April 1989, will be only the fourth November/ December 1987 issue, we goes well, that spacecraft could be used as a launch of the revamped shuttle, and delays tried two new things: We converted to a Lunar Observer. with the new system are to be expected. computerized page-makeup system, and Comet Rendezvous Asteroid Flyby Gali/eo and Ulysses can hardly afford to be we expanded our special issues from (CRAf)-This important next step follOwing delayed again if their constrained launch win 24 to 32 pages. We did not plan to do the Halley's Comet encounters will be the dows (October of 1989 and 1990, respective both things at once, but with equipment first rendezvous with a comet. CRAF will ly) cannot be met. Thanks, in part, to efforts delays and the inexorable march of make detailed remote and on site measure by Planetary Society members in support of deadlines, we managed to prove that ments of a comet and its environment. This the Mars Obseroer, Congress urged NASA to Murphy's Laws do control the universe. mission will be the first of the Mariner Mark U make future planetary missions "dual com We hope to have better luck with series, a new class of modem spacecraft that patible"-that is, able to fly on either the future issues. Once we learn its idiosyn will be suitable for outer planet missions. shuttle or an expendable launch vehicle. cracies, the new computer system CRAF is scheduled for a new start in fiscal However, such dual compatibility does not should speed up production and help year 1989. We'll know if it gets this new start come cheaply, and the Mars Observer re us remain on schedule. after the President's budget is sent to Con mains in a precarious position since NASA is The expanded special issues will allow gress at the end of January. This would be reluctant to commit resources for an expend us to bring our members even more fea the first planetary new start in four years. able Titan rocket to launch it. The House tures on planetary exploration and the New Obseroatories-The Advanced X-Ray Science and Technology Committee, under search for extraterrestrial life. We will Astronomical Facility (AXAf) will observe the the leadership of Congressman Robert Roe soon be making some format changes universe at non-visible wavelengths, comple (D-NJ), has been particularly active in sup to make the magazine more readable, menting the deep-space investigations of the port of the Mars Obseroer. to bring you even more information, and Hubble Space Telescope. AXAF was submit The Reagan administration's budget diffi to display more spectacular spacecraft ted to the administration for a new start this culties also form a dark cloud looming over images and illustrations inspired by our fiscal year, and its fate will be unknown until the future. Some Washington observers of exploration of the planets. after the President's budget is revealed. space policy believe that the Office of Man So stick with us. While others shrink Advanced Technology Development for the agement and Budget cares little for the US or withdraw, we expand! Mars Rover and Sample Retum-Such an un planetary program and would willingly cut it L.-______~_ ... 13 manned mission will probably not be out entirely. While this is not likely, it does : ';"l~- I:,;) j~<:ur~ '::,;-.:;lr y>:~
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