NASA-TM-111836 /t/ .'

I I

AIAA-95-1 062

The Suitport's Progress

M. Cohen NASA Moffett Field, CA

Life Sciences and Conference April 3-5, 1995 / Houston, TX

For permission to copy or republish, contact the American Institute of Aeronautics and Astronautics 370 L'Enfant Promenade, SOW., Washington, D.C. 20024 AIAA-95-106;

THE SUITPORT'S PROGRESS

Marc M. Cohen* NASA-Ames Research Center Moffett Field, California

Abstract Origins of the Suitport NASA-Ames Research Center developed The Suitport Extravehicular Access Facility the Suitport as an advanced originated during the early phase of the to support a Space Station suit, Space Station Advanced Development based on the AX-5 hard suit. Several third Program. It grew from a recognition that the parties proposed their own variations the construction and operation of Space Station Suitport on the moon and . The Freedom (SSF) would require several Suitport recently found its first practical use thousand hours of EVA time (This finding as a terrestrial application in the NASA- has not changed much for the new design Ames Hazmat vehicle for the clean-up of for "Space Station Alpha." To make the best hazardous and toxic materials. In the Hazmat use of SSF crew time, it will become application, the Suitport offers substantial necessary to make the entire space suit improvements over conventional hazard donning and doffing, and airlock suits, by eliminating the necessicty to egress/ingress as safe, rapid, and efficient decontaminate before doffing the suit. as possible.

Definitions The Space Shuttle EMU suit and airlock AX-5 Ames Experimental Suit 5 systems pose several potential CCPS Command/Control Pressure Suit disadvantages for frequent and routine EMU Extra-Vehicular Mobility Unit Space Station operations. The shuttle EVA Extra-Vehicular Activity airlock would not be large enough to ft 3 cubic feet accommodate two crew members suiting up Hazmat Hazardous materials into the hard, rear-entry AX-5 as it is fairly IVA Intra-Vehicular Activity tight even for the soft, pull-on EMUs. m 3 cubic meters However, the solution for Space Station was clearly not to build a bigger airlock because PLSS Portable Life Support System that would only increase atmosphere loss, psi pounds per square inch pump-down time, power, and cooling. SSF Space Station Freedom STS Space Transportation System All Space Shuttle EMU suit maintenance (Space Shuttle) occurs on the ground. Perhaps the most Suitport An airlock design to allow rapid important departure from this practice is, that donning & doffing of a protective the SSF suit must be maintainable, suit through a rear hatch. resizable, and repairable on orbit. This V.E.R. Volumetric Efficiency Ratio requirement suggested a radical departure from the traditional "dumb can" airlock design. It would involve automated servicing, and the ability to conserve *Architect, Advanced Projects Branch, atmosphere and other consumables much Space Projects Division, Senior Member AIAA more efficiently than the EMU airlock system. Thus the problem definition for the Suitport involved considering strategies for Copyright © 1995 by the American Institute of Aeronautics and Astronautics, Inc. No conserving consumables. Secondarily, it involved additional considerations such as copyright is asserted in the United States under Title 17, U.S. Code. The U.S. potential for protection against outside contaminants. Government has a royalty-free license to exercise all rights under the copyright Strategies for AtmosDhere Loss - The loss claimed herein for government purposes. of atmosphere varies directly with the All other rights are reserved to the copyright volume of the airlock. There are two owner. strategies to handle this situation: to "sacrificetheatmosphere"fromtheairlock The Suitport seeks to resolve the dilemma of to vacuumandto saveon power,cooling pumpdown time versus power by saving on andcrewtimeORto "savetheatmosphere" all the variables. By reducing the pump andpaythecostinpower,cooling,time,and down volume by more than two orders of complexity.Undereitherstrategy,reducing magnitude, it saves substantially on power, the totalvolumeof the airlockatmosphere cooling, and pump down time. The volume contributesto savingson all the metrics, of air in the interstitial volume between the exceptperhapscomplexity.Theuseofvoid space suit hatch and the airlock hatch is so fillers can be a fairly inexpensiveway to small that it may become economical to reducethis pumpdownvolume Figure1 sacrifice it to without pumping it illustrates dramatically the inverse down. Table 1 shows a comparison of the relationshipbetweenelectricalpowerfor Suitport pump down volume against six airlockpumpdownandthetimerequiredto other candidate airlock designs. These pumpdownvariousairlockvolumesfrom1 metrics show the potential order of atmosphereintoastoragetankona 10to 1 magnitude improvements that the Suitport compressionratio.Thisgraphshowsthatto promises. 2 achieverapidpumpdownunderthe save the atmosphere approach for a large airlock Table 1. EVA Access Facility demands very large amounts of electrical Volumetric Efficiency Ratio (V.E.R.) power, compared to the then-anticipated SSF total capacity of 50 to 75 kW. For Suited Crew Volume = 0.22m 3 (8.0 ft3) example, to pump down a 300 ft3 airlock in for one crew member ten minutes would require about 25kW continuous during that period. It may also be Suited Crew Volume V.E.R. = possible to pump the airlock down to the Pump-Down Volume SSF cabin atmosphere. However, pumping to the cabin would pose potential hazards of AIRLOCK PUMP V.E.R. introducing external contamination into the OPTION DOWN station proper, because it would depend VOLUME upon filtration rather than upon physical m 3 (ft3) separation. A STS-Type .062 Comparative Analysis - The first step was to Airlock 3.63 (129) prepare comparative analyses of candidate (enlarged) , .087 airlock systems to support AX-5 suit STS Existing 2.59 (92) Airlock operations. 1 The four airlock design .120 concepts that received the closest attention B Transit 1.86 (66) were: Aidock C Suitport w/ .014 (0.5) 16.0 A. An STS-Type Airlock enlarged to PLSS Seal accommodate the rigid AX-5 suit. C' Suitport No 2.28 (81) .098 B. A Transit Airlock, as an adaptation of PLSS Seal the STS airlock reduced by removing D Crewlock w/ .056 (2.0) 4.00 the suit servicing and don/doffing and Void Filler placing it inside the station. D' Crewlock No 1.49 (53) .150 C. The Suitport EVA Access Facility in Void Filler which the AX-5 rear entry disconnect mounts to the airlock hatch, creating an Strategies to Control Contamination - Two extremely small pump down volume in strategies exist for donning and doffing a the interstitial space between the suit rear hatch and the airlock hatch. protective suit without exposing the wearer to external contamination. These two D. The Crewlock developed by William strategies are "decontaminate before Haynes of the Aerospace Corp., which doffing" and "exit to a safe atmosphere." In uses conformal void fillers to minimize the decontaminate before doffing the pump down volume around the approach, decontamination must occur while space-suited crew member. the crew member is still in the suit, before opening its protective envelope. Current protective suits for hazardous material cleanupfollowthisapproach,as wouldthe that support productivity and safety current NASA Space Shuttle EMU suit in EVA operations, (should decontamination become (2) to develop advanced EVA necessary).Intheexit to a safe atmosphere airlock and servicing support system approach, the crew member can exit the suit mock-ups for high-pressure hard to a safe environment without space suits such as the AX-5 .... decontaminating first. The Suitport takes the exit to a safe atmosphere approach to an Cawthorn described "expected products": integrated systems level for both space operations and terrestrial applications. (1) an advanced EVA access facility combined airlock and servicing Figure 2 illustrates a storyboard showing the systems, operational scenario of how a crew member (2) an EVA suit servicing, donning would prepare the suit before routine and doffing, egress and ingress operations, don (enter) the suit, separate computer simulation .... the suit from the Suitport and egress the station airlock. The Suitport offers a This advanced airlock initiative came to a halt substantial improvement over the when NASA eliminated the Space Station conventional airlock technology. The crew suit from the budget. Instead, station member enters the rear-entry hatch of the planners proposed to stage EVAs out of the space suit through the Suitport. Closing the shuttle airlock to build the station, a scheme nesting suit rear hatch and Suitport hatch that proved inadequate and unworkable. together, it is necessary only to pump down Since that time, a there is a space station or vent off the very small amount of air in the airlock to support the space shuttle-type interstitial volume between the two hatches, EMU, but not an advanced suit. Without an less than .035 m 3 (1 ft3). Thus, the Suitport advanced station suit, there was no demand promises substantial savings in for an advanced Space Station airlock. atmosphere loss, crew time, electrical power, and pump cooling. The way the Suitport Third P6rty Adaptations seals the suit to the habitable "shirtsleeve" Since the Space Station Advanced atmosphere offers the additional advantages Development Program, a number of third for contaminant isolation and control. parties evaluated the Suitport and proposed applications for it. These ideas apply to Suitport Design - A patent for a Suitport , seeking to exploit the Extravehicular Access Facility characteristics that would make the Suitport describes the design idea in detail. 3 Figure advantageous for Space Station and the 3 shows a cross section through a dedicated NASA-Ames Hazmat program. Extravehicular Access module with a Suitport in it. Note the berthed connection Boeing Lunar Airlock Analysis - The Boeing to the SSF on the left and the "porch" on the Defense and Space Group in Huntsville AL right. Figure 4 shows a detail of an AX-5 type conducted an evaluation of several lunar suit mated to the Suitport. This cross airlock concepts on a variety of criteria. section identifies the interstitial volume Initially, they compared six candidate airlock requiring pump down as "43". designs, including the Suitport. 5 In their final assessment, they compared four Space Station "Transition Technology"- In design options: an STS-Type airlock, SSF the later phases of the Space Station "Crewlock," Suitport, and a "Doorlock" that Advanced Development Program, it they claim as their own. Although they appeared that the schedule-driven design prefer their own "Doorlock" for a Lunar process might require a rudimentary STS- surface application, still, they rated the type airlock before it would be possible to Suitport highest for dust mitigation and build an advanced system. Jimmy Cawthorn consumables resupply. 6 included an "EVA Access Facility" in this "transition technology" phase. 4 He It is important to avoid semantic confusion proposed" here. The "SSF Crewlock" is an entirely different design idea than Hayne's Crewlock. (1) to develop enhancements to the Ironically, the Boeing Doorlock derives Space Station IVA and EVA systems almost directly from Hayne's side-entry

3 Crewlockwithvoidfillers. Table1 presents consumables resupply should rate much CaseandCapps'summaryoftheirfindings. higher than initial mass to orbit. The Boeing estimated difference between the Doorlock This Boeingstudy is the mostthorough at 1,368 kg and the Suitport at 1,904 kg is analysisofadvancedairlockoptionstodate. only 536 kg, or about 39% of the smaller It is fascinatingfor a multitudeof reasons. option. Table 1 suggests that the difference TheBoeingassessmentof theSuitportand in lifetime consumables resupply on Space theotherairlockoptionsis quiteprescient, Station or a Lunar Base for the Suitport over exceptforthefewpointsnotedbelow.They the Doorlock will amount to hundreds of are correctthatcomplexityis probablythe percent. For either the Suitport or the biggestsingle challengefor designinga Doorlock over the STS or SSF type , Suitport. Complexity affects suit the savings in consumables resupply will maintenanceaswell. Launchpackagingis amount to thousands of percent. Therefore, moredifficultto assess,as it dependsupon the consumables resupply criteria must one's presuppositionsof what should weigh much more heavily than initial mass to comprisea launchpackage. The Boeing orbit. analysisevokesthefollowingobservations: Dust Mitigation - On the Lunar or Martian surface, dust mitigation and control Table2. BoeingComparativeAnalysisof will be one of the most critical factors for safe FourAirlockOptions and efficient operations. All the non- fortheFirstLunarOutpost Suitport options require decontamination before the suited crew member can enter the airlock. In a contingency situation this delay could be dangerous, and in an emergency, it could be fatal. Only the Suitport allows the crew member to doff the suit and escape to a safe atmosphere without undergoing decontamination first. Hyperbarics - The Suitport patent { provides for a hyperbaric capability. 7 0. However, Boeing seemed to miss this provision in equating the Suitport to the Options\ _ _ = _ _ Modified STS and Doorlock, which provide Mass o 8 no hyperbarics. Modified "Off-the-Shelfness" - The purpose STS O ",,/ ',/ O O O O X 0 of the Suitport was to achieve order of magnitude improvements in airlock 1,749 kg performance. It is axiomatic that it could not SSF attain this goal by using "off-the-shelf" Crewlock* X O X 0 X X O _/ 0 hardware (of which little in fact exists). 2,843 kg New Comparison - If one adjusts the Suitport O X X _/ _/ X X X _/ comparison table to account for the 1,904 kg preceding comments -- hyperbarics, "off- the-shelfness," consumables resupply and Doorlock _J O _/ O _/ _J O X O dust mitigation -- the results look 1,368 kg substantially different. Table 3 shows this comparison revised to take into account the foregoing observations. Other than Legend for Table 2. correcting the one omission under _/= Good O = Fair X = Poor Hyperbarics, it does not alter any of Boeing's scoring. The outcome of this revision shows Boeing's Comparison Factors - The nine the Suitport in a dead heat with the "comparison factors" represent unweighted Doorlock. This new comparison brings the evaluation criteria. Yet for long term EVA Suitport into parity with the Doorlock. This operations, some criteria must receive more result recalls the result of a 1986 weight than others. From the perspective of assessment that found the William Haynes lifetime operating cost, surely minimizing Crewlock (Boeing Doorlock) best for an EMU-typesuitandtheSuitportbestforasuit developed his Command/Control Pressure witharearentryhatch.8 Suit (CCPS) as a complete integrated, architectural system for lunar EVA, including Ethan Cliffton: "The Indigenous Architecture helmet and visor design, backpack of Exploration," - As a subcontractor to modularity, controls and displays, and Martin Marietta Space Systems for Mars maintenance support. Figure 6 shows two exploration studies, Cliffton proposed views of the CCPS suit, including the rear mounting a pair of Suitports directly into the plane disconnect and backpack which would pressure wall of a Mars habitat. He interlock with a Suitport. Griffin explains his approached this application of the Suitport adaptation of the Suitport primarily in terms from the perspective of a Habitat designer, of dust control: with a focus upon what made the most sense for habitat design and operation. "A major feature of the CCPS is a Figure 5 shows a sketch of the "Operational dust-resistant design. All displays Plan" for this Mars Habitat. Cliffton hangs the are internal avoiding problems of suits completely outside the habitat, which dust buildup and except for the might expose the suits to excess backpack, all pressure joints remain "weathering." 9 intact until servicing, minimizing exposure to dust .... Another Table 3. Modified and Weighted Analysis of feature which holds promise is a seal Four Airlock Options Derived from the which mates directly to the module Boeing Analysis in Table 2. exterior allowing direct entry/exit without an airlock. This approach would not eliminate the airlock, but :_ eq for routine operation, would avoid e- e- X 0 [31 dust contamination. "10 •-_ "3 >, Griffin built a test suit flew it on the NASA- JSC KC-135 aircraft, in a simulated lunar

"--c C._m X c_ c ciu) gravity test. A photograph of the Griffin \o a3 o Design suit demonstrator on the KC-135 g appears in Figure 7. Aviation Week and 13_ r'- -r-- ._ Airlock_ I_ Space Technology described this test: _ x:: "_ _ "_- Options\ _ _- "The unit could plug into other & Mass _ _ 8 8 _, m m a _ vehicles, such as lunar rovers, and in Modified effect become the cockpit or cab of STS O _/ O O O O X O 10 the vehicle. The elimination of ingress/egress requirements for 1,749 kg SSF vehicles could become a huge advantage on the Moon where Crewlock* XXOXXO_O 7 highly abrasive dust is expected to 2,843 kg present a major challenge to surface operations. The life support system Suitport 0 X _J _/ X X _/ _ 13 backpack of the Griffin Design suit 1,9O4 kg would be on a door at the rear of the torso structure that would open to Doorlock _/ _ O _J _/ 0 X O 13 one side for ingress and egress." 11 1,368 kg NASA-Langley / Department of Energy Lunar Rover - M.D. Williams led a team at Table 3 Legend NASA-Langley and the DOE's Pacific "J =2 O=1 X=0 Northwest Labs (Battelle) who proposed a lunar rover that included two Suitports Griffin Design Lunar Surface Suit - Brand mounted on the rear bulkhead. Although Griffin of Griffin Design, developed a their illustration does not show the Suitport, prototype rear-entry space suit and airlock Williams et. al. describe their specific interface on the Suitport principle. Griffin adaptation of the Suitport to a Lunar Rover. suit from the Suitport and go to work. When "TheSuitportconceptplacesAX-5- reentering the Hazmat vehicle, the crew type hard suits outside the member backs his suit against the Suitport pressurized interior volume, and secures it to the hatch. He opens the attached directly to life support hatches and backs out of the suit without chargingand checkoutsystems. exposing himself or the vehicle interior to Entryisthrougha backpackdooron the contamination on the outside. However, thesuitthat lockstightagainstthe in the prototype, a tender does the latching pressurizedbulkhead. The suit and unlatching, not the person in the suit. itself can be shieldedby a form- To assist the suited person the Hazmat fittingcoverthatclosesoverit. This vehicle may have special hand rails or a rear Suitporthasthe highestvolumetric "porch" in the manner of the NASA- efficiencyof anytypetestedsofar, Langley DOE Lunar Rover. Figure 9 shows meaningminimal loss of interior an artist's sketch of an early concept for the atmosphereduringpumpdownfor Hazmat vehicle using its front-mounted entry and exit. It also prevents robotic arm to stop a toxic leak from an contaminationoftheinteriorbylunar overturned railroad tank car. dustthatadheres to the suits .... The Hazmat vehicle modifications will seal The two Suitports proposed for this the interior cabin to protect it from rover could be housed in the aft end contaminants in the external environment. It of the lab space. The area adjacent will have its own air-conditioning system. to the Suitport could house a The circular hatches through which the receiving station for surface driver and crew members can project their materials on one side and an heads, will be covered and sealed with clear enclosed hygiene facility on the polycarbonate domes. Although Popular other .... Mechanics referred to the Hazmat Vehicle as "the Cherno-Mobile," the entire effort so far Within the 2.4-m interior diameter of focuses on chemical hazards and does not the lab cylinder, two Suitports could address radiation. 13 be positioned side by side, leading to an exterior "porch" on the aft of This Hazmat vehicle promises several the rover." 12 improvements over current hazardous materials cleanup procedures. It offers an A view of this lunar rover appears in Figure 8 improved level of safety for the crew both in This figure shows the rear "porch" recalling the vehicle and wearing protective suits. It the EVA Access Facility module, with a gives the crew members the ability to spend robotic manipulator arm at the aft work much longer periods of time in the "hot station. Williams et al also provide a zone" without needing to retreat to rest or protective cover for the suit when not in use. decontaminate. The crew members may return to the vehicle for a break or to eat The NASA-Ames Hazmat Vehicle lunch. A furture version of the Hazmat The merits of the Suitport for keeping out vehicle may support a liquid cooling garment contamination made it desirable as a design system inside the suit, decreasing the heat solution for a hazardous materials clean-up stress on the crew member and increasing vehicle vehicle. Like the NASA Langley- the time he can work. The availability of the DOE idea, the NASA-Ames Hazmat vehicle Ames Hazmat technology will enable faster mounts two Suitports in the rear bulkhead. emergency response to hazardous material In 1994, Ames took delivery of an M577A3 accidents, and help the evaluation and armored personnel carrier on loan from FMC cleanup proceed more quickly and safely. If the NASA-Ames prototype proves corporation. Philip E. Culbertson, Jr., the lead designer for the Hazmat vehicle, is successful, many agencies will want one, making progress in adapting the Suitport to including federal, state, and regional it. The two Suitports will provide direct, rapid response teams, and perhaps some fire don/doff access to two protective suits. In departments also. The Suitport in the the ideal concept, a crew member will enter Hazmat vehicle exemplifies the reinvestment the suit through the rear entry, seal the two of advanced space technology to benefit nested hatches behind him, decouple the people on earth. Conclusion The Suitport derives from the application of a simple physical principle - minimizing the Structure, AIAA 93-0994, Aerospace pump down volume - to achieve an Design Conference, Irvine, CA improvement in airlock performance. In this respect, it is analogous to the economic 7 Cohen, (1989) op. cit., Figure 18D. payoff of weight savings. Several significant benefits follow from this innovation, 8 Cohen, Marc M., (1986, October 21) especially the advantages for contaminant "EVA Access Facility Presentation to Space control that Boeing, Griffin, NASA- Station Advanced Development Review" at Langley/DOE, andthe Ames Hazmat vehicle NASA-. hope to realize. The next step in the Suitport's progress should be to build a full 9 Cliffton, Ethan W., (1993, October 12) scale, pressurized proof of concept demonstrator. "The Indigenous Architecture of Exploration," announcement of lecture, PG&E Architectural Series.

10 Griffin, Brand N. (1990, Sept. 25-28) A Space Suit Designed for Lunar Construction and Exploration, AIAA 90-3885, AIAA Space Programs and Technologies Conference, References Huntsville, AL, p. 2.

1 Cohen, Marc M., & Bussolari, Steven, 11 Aviation Week & Space Technology, (1987, April) Human Factors in Space (1994, April 25) Vol. 140, No.17, "NASA Station Architecture II - EVA Access Facility: tests new suit design at equivalent of lunar A Comparative Analysis of Four Concepts for gravity," p 61. On-Orbit Space Suit Servicing, NASA TM 86856. 12 Williams, M. D., De Young, R. J., Schuster, G. L., Choi, S. H., Dagle, J. E., 2 Cohen, Marc M., (1985, December 3-6) Coomes, E. P., Antoniak, Z. I., Bamberger, J. A., Bates, J. M., Chiu, M. A., Dodge, R. E., "Introduction: Ames Space Station Architectural Research," in Cohen, Eichold and Wise, J. A., (1993, Nov.) Power &Heers, eds, Space Station Human Factors Transmission by Laser Beam from Lunar- Research Review, Vol. III, NASA CP 2426. Synchronous Satellite, NASA TM 4496, pp. 19-20. pp. 44-58.

3 Cohen, Marc M., US Patent 4,842,224, 13 11. Popular Mechanics, (1994, Feb.) (1989, June 27) Suitport Extra-Vehicular "Send in the Cherno-Mobile," p. 16. Access Facility.

4 Cawthorn, Jimmy M., (1986, July 7) "Space Station Transition Technology Recommendations," Space Station Program Office -- Advanced Development Office, NASA-JSC, p. 12.

5 Case, C., Capps, S., Ruff, T., McGhee, J., Roberson, R., (1992, August)"'Doorlock' Single-Crew Conformal Airlock for First Lunar Outpost Application," presentation by Boeing Advanced Civil Space Systems Group, Huntsville, AL.

6 Capps, S., & Case, C., (1993, Feb 16-19) A New Approach for a Lunar Airlock 50 I I I I !

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30_ 225 ft 3 z tJJ \ 300 ft 3 20_-

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Figure 1. EVA Access Facility Power versus Time for three airlock volumes, showing pumpdown from one atmosphere to a pressure vessel at 150 psi on a 10 to 1 compression ratio, analysis by Bernadette Squire Luna.

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Figure 2 EVA Access procedures using the Suitport, adapted from NASA TM-86856.

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Figure 3. Suitport in a dedicated module, from US Patent 4,842,224 _ su, 2 Operational Plan

Figure 5. Plan view of 2 Suitports mounted in Ethan Cliffton's Mars Habitat. Drawing courtesy of Ethan Cliffton, Architect.

Figure 6. Two views of Brand Griffin's CCPS, showing the rear entry disconnect (9) between the backpack and the suit's hard upper torso. Drawing courtesy of Griffin Design.

9 Figure4. DetailofSuitport showingrearplanedisconnect forboththeAX-5spacesuit's PLSSbackpackandthe Suitportinnerhatch, fromUSPatent4,842,224.

Figure7. Simulatedlunar gravityflighttestofthe GriffinDesignCCPSsuit on theNASA-JohnsonSpace Center'sKC-135aircraft. photocourtesyof Griffin Design.

10 Figure8. SideviewoftheproposedNASA-Langley/DOELunarRover, mountingtwoSuitportsintheaftbulkhead,fromNASATM-4496.

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Figure 9. Artist's rendering of the NASA-Ames Hazmat vehicle design, with two Suitports in the aft bulkhead, courtesy of Douglas Smith, NASA-Ames.

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