Identification and status of design improvements to the NASA shuttle EMU for International Space Station application

Acra Asrronaurico Vol. 40. No. I I, pp.797405, 1997 0 1997 Published by Elsevier Science Ltd. All rights reserved

Pergamon

PII: 30094-5765(97)00132-X

Printed in Great Britain 0094-5765/98 $19.00+0.00

IDENTIFICATION AND STATUS OF DESIGN IMPROVEMENTS TO THE NASA SHUTTLE EMU FOR INTERNATIONAL SPACE STATION APPLICATION? RICHARD C. WILDE’, JAMES W. MCBARRON’ and JEFFREY J. FASZCZA’ ‘Hamilton Standard Space Systems International, Inc., 1 Hamilton Road, Windsor Locks, CT 06096-1010, U.S.A. LNASA Johnson Space Center, Space Suit Branch, Crew & Thermal Systems Division, Houston, TX 77058, U.S.A. (Received 8 March 1996)

Abstract-To meet the significant increase. in EVA demand to support assembly and operations of the International Space Station (ISS), NASA and industry have improved the current Shuttle Extravehicular Mobility Unit (EMU), or “space suit”, configuration to meet the unique and specific requirements of an orbital-based system. The current Shuttle EMU was designed to be maintained and serviced on the ground between frequent Shuttle flights. ISS will require the EMUS to meet increased EVAs out of the Shuttle Orbiter and to remain on orbit for up to 180 days without need for regular return to Earth for scheduled maintenance or refurbishment. Ongoing Shuttle EMU improvements have increased reliability, operational life and performance while minimizing ground and on-orbit maintenance cost and expendable inventory. Modification to both the anthropomorphic mobility elements of the Space Suit Assembly (SSA) as well as to the Primary Life Support System (PLSS) are identified and discussed. This paper also addresses the status of on-going Shuttle EMU improvements and summarizes the approach for increasing interoperability of the U.S. and Russian space suits to be utilized aboard the ISS. 0 1998 Published by Elsevier Science Ltd

1. INTRODUCIION

2. BASELINE -

NASA and industry have conducted a continuous program to improve safety and crew comfort and to reduce operating costs of the Shuttle EMU. This program -is an integral element of NASA’s overall activity to improve safety and reduce the cost of ongoing Shuttle operations. In 1989, NASA also baselined the Shuttle EMU to support assembly and maintenance of the Space Station. Thus Shuttledriven improvements to the EMU will also benefit Space Station EVA operations and support. In 1993, the historic space activity agreement between U.S. Vice President Gore and Russian Prime Minister Chernomyrdin included development of a common space suit system to be accomplished jointly by the two nations. This paper updates the status of the ongoing improvements to the EMU and discusses their benefit to Shuttle EVA operations, Station EVA support and interoperability with Russian EVA equipment.

IMPROVING THE EMU FOR SHUTTLE

The EMU, shown in Fig. 1, is a dynamic entity. It changes to incorporate improvements driven by the following:

tPaper IAA 95.10.1.02 presented at the 46th International Astronautical Congress, Oslo, Norway, 2-6 October 1995. 797

Extending the EMU on-orbit duration and maintenance capability to support the requirements of ISS assembly and maintenance missions. Capitalizing on technology improvements resulting from NASA investment. NASA undertakes technology development programs to improve technical capabilities, minimize cost and improve schedules in operational programs. For example, suit mobility and resizing improvements currently being implemented came from the ZPS/MK III space suit advanced technology development program. Accommodating the changing supplier base for l components and elements. 0 Addressing technical issues. For example, the planar hard upper torso (HUT) and dual seal SSA mobility bearings eliminate specific potential failure modes. Gloves are improved continuously for comfort and mobility. Crew comfort in cold environments is being addressed.

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TMG cover (ortho-fabric)

‘TMG

_

extravehicular

Secondary 02 tanks

.._._

mobility

unit.

c-m

.*

-

TMG liner (neoprenene coated nylon ripstop)

-

-

Mini-workstation mounts

Pressure garment cover-restraint

insulation layers (aluminized mylar)

mounts

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--

FG1336001

P/SAFElUMMU mount

SAFEFWMU

ConnectIon for service and cooling umbilical

Pressure garment bladder (urethene coated nylon)

Extravehkular

SHUTTLE EXTRAVEHICULAR MOBILITY UNIT

NASA

shuttle

EMU for

international

799

space station application

Table I. Current EMU enhancements status

Enhancements

Testing Completed ‘93

. Extend EMU ground maintenance interval to 25 EVAs - Life support: Eliminate service for valves and selected filters within 25 EVAs and 180 days - SSA: Extend sanitation, mobility bearing service and suit inspection interval l Extend on-orbit operating life of limited life filters and gas trap . Delete muffler to reduce condensate carryover . Replace electrochemical CO? sensors with IR CO, Sensors . Implement dual seal SSA mobility bearings to eliminate potential Crit-I failure modes: Waist Shoulder @ye) wrist Upper arm . Improve sizing capability and provide ORU changeout for ground and Right by adding the following: Boot - sizing rings Leg length - adjustment link bracket Lower torso brief - repattern Arm length, upper - sizing rings Arm length, lower - cam bracket . Lower torque mobility joints for: Knee Upper arm Lower torso brief . Improved boot load strength and durability

l

Reducing life-cycle and operating costs. The same improvements for on-orbit maintenance reduction and suit resizing and extending on-orbit duration also reduce ground processing costs.

Flew ‘90 Flew ‘91 Fly GFY ‘96 Fly GFY ‘96 Fly GFY ‘96

Fly GFY ‘96

Flew ‘92

Two additional PLSS changes have been incorporated that extend the PLSS service interval. They are: Replaced the vent loop noise-reduction muffler with an orifice and vent tube assembly, as shown in Fig. 2. This change, flown since STS-45, reduces sublimator condensate carryover by reducing overall vent loop delta pressure drop, thus improving the sublimator slurper performance. This change also reduces overall power consumption. Replaced the present electrochemical CO, sensor with an IR transducer, shown in Fig. 3. This change, flown since STS-71, provides a more accurate CO2 detection system and does not require frequent recalibration [3].

Most of the EMU improvements to date have been incorporated into the EMU as a program of specific enhancements. Table 1 summarizes the current program of enhancements and updates their status reported previously [ 1,2]. The program to extend the EMU service interval to 25 EVAs without ground processing is complete. While primarily a Shuttle ground processing cost issue, this enhancement also supports ISS on-orbit mission duration and use. Accomplishments are as follows: Extended the crack/reseat interval for relief valves to 180 days. Completed 25 simulated chamber EVAs on a baseline Shuttle flight configuration PLSS. This testing certified the EMU to support six EVAs in ten days from Shuttle ISS-assembly flights and EVA-intensive flights such as STS-49 and STS-61 and supports EMU durations aboard ISS for up to 180 days. Completed extended maintenance certification testing to 84 h on dual seal waist and shoulder (scye) bearings.

Flew ‘92 Flew ‘92 Flew ‘95

Also, reliability and user friendliness of the EMU Space Suit Assembly are being enhanced. The following enhancements are in process or have already been flown. a Dual pressure seals in the suit mobility bearings at the waist, wrist, arm and scye, as shown in Fig. 4, eliminate a potential CRIT-1 failure INFRARED

FAN OUTLET

I

CELL BODY

IR SOURCE

\

PRINTED CIRCUIT BOARD ASSEMBLIES

ELECTRoNlCS MODULE

DETECTOR ASSEMBLY VALVE MODULE

Fig. 2. Vent tube replaces muffler.

W2512002

Fig. 3. Infrared CO2 transducer.

R. C. Wilde et al

800

ANDSECONDARY

LARGER

SCREWS

DUAL PRESSURE LIP SEALS SOLEANDHEEL DUAL

SEAL BEARING

DG2512003

DG2512004 Fig.

4.

Fig. 6. Enhanced boot assembly.

Dual seal smt mobility bearings.

mode. The waist and scye bearings have flown since STS-37 and -49. Lower torque joints in the knee, elbow and brief. shown in Fig. 5, make performing EVA easier for the crewmember. A more durable and stronger boot assembly. shown in Fig. 6, has flown since STS-37, -4.5 and -49. An enhanced sizing system consisting of a series of disconnects, sizing rings, and sizing brackets is in process, The sizing brackets, shown in Fig. 7, reduce the number of sizing rings by providing vernier length adjustment of the axial restraint lines in the arm, leg and thigh. Cam movement in the arm assembly restraint brackets

CURRENT

SliUTrLE

and adjustment links in the thigh brackets implement length changes. hancement also minimizes disassembly resize the SSA both on the ground and

Additional improvements are in development as funding permits but flight dates have not yet been established. Table 2 summarizes additional improvements that are currently in development.

LOWER ARM

LOWER ARM SECTION ENHANCED

ARM

DG2512005

Fig. 5. Enhanced EMU SSA arm.

and leg This eneffort to in orbit.

Fig. 7. Length adjustment brackets.

NASA shuttle EMU

for

international

801

space station application

Table 2. Additional Shuttle EMU improvements status

Improvement l

Improve crew thermal comfort at low metabolic rates in cold environments - Understand crew thermal discomfort phenomenon - Concept EMU heating/heat loss control concepts - LCVG bypass - Thermal control undergarments - Improved glove insulation -Electrically heated glove fingertips a Planar HUT l ORU PLSSISOP. HUT and DCM

Shuttle missions are evolving toward colder environments, as more EVA work is conducted outside the shuttle payload bay. Improving crew thermal comfort at low metabolic rates at these colder environments is proceeding along four parallel paths. They are: l

l

l

l

Adding/conserving heat to the whole body. Studies are being conducted to define concepts for both actively heating the whole body and for minimizing overall heat loss from the EMU. These studies build on the understanding gained of the thermal discomfort phenomenon encountered during periods of low metabolic load in cold environments [5]. Evaluating a liquid cooling and ventilation garment (LCVG) bypass valve which shuts off cooling to the crewmember but retains the humidity control and electronics cooling functions of the life support system. The LCVG bypass valve flew as a development test objective (DTO) on STS-63 and STS-69. Evaluating thermal control undergarments (TCU). Additional body insulation in the form of long underwear for the upper torso, arms, lower torso and legs has been available as a crew preference item since STS-61. Warmer socks and boot liners flew on STS-69. Evaluating improved gloves. Finger tip heaters, drawing approximately 0.5 W each, along with an insulated, two finger mitten, flew on STS-69. Improvements to the glove thermal cover which added insulation to the fingertips and reduced torque refinements in the palm were flown on STS-6 I [4].

The original Shuttle EMU HUT configuration developed in 1978 had the arm attached via the shoulder bearing outer race which was integral with the HUT. This method of attachment has been termed “planar arm”. During development, this configuration proved unacceptable because some astronauts and test subjects experienced difficulty while donning. Interference occurred when the arms transitioned from vertical to horizontal as the HUT was entered (arms over head). At the time, designers needed to resolve this issue quickly to certify the EMU for the first Shuttle flight. The solution - pivot sockets - allowed the shoulder bearing to pivot relative to the HUT for donning purposes and then

Studied ‘93 Studied ‘95 Flew ‘95 Flew ‘93 Flew ‘93 Flew ‘95 In certification ‘95 In development ‘95

to pivot back to allow for optimum arm performance. The pivoted HUT configuration has been very successful and is one of the design features that provides the arm mobility and range in the EMU. However, this configuration also has some limitations. There are life critical, single point failure modes associated with this design, and the tolerances and necessary inspection associated with the pivot configuration have impacted cost and schedule. In addition, the composite pivot/bellows configuration has life limitations. In 1990, NASA Ames Research Center revisited the planar arm concept and modified a bottom entry HUT mock-up to incorporate planar arm openings. The evaluation suggested that a Shuttle bottom entry HUT with planar arm openings could have acceptable don/doff characteristics. In early 1991, Hamilton Standard and ILC Dover began an internal development effort building upon NASA’s work. Based on 12 years of accumulated program operating experience, an improved understanding of anthropometry, and the results of NASA’s development efforts on the MKIII and AX-5 advanced space suits, it was believed that the potential benefits of system safety and reduced component cost would justify the risk associated with reevaluating a planar configuration. Currently, NASA/JSC, Hamilton Standard and ILC are certifying the planar HUT design for implementation into NASA’s EMU flight program in the GFY 1997-1998 time period [6], when the current pivoted HUT inventory begins to go out of life. Since the EMU is designed for ground maintenance, a subassembly called the Short EMU (SEMU) consisting of the primary and secondary life support subsystems (PLSS/SOP), HUT, ams and Displays and Controls Module (DCM) has become a basic EMU building block. However, studies to reduce EMU cost-of-ownership have shown that time and money could be saved if disassembly of the Short EMU could be simplified. In 1994 Hamilton Standard concluded that disassembly could be simplified to the point where PLSS/SOP, HUT or DCM changeout on-orbit could be achieved. The current plan is to make these elements into orbit-replaceable units (ORUs). This capability requires no changes to the current inventory of PLSS/SOPs and DCMs and is compatible with the new planar HUT design. The ORU design adds less than 0.5 in to the front-to-back dimension of the

R. C. Wilde et al

802

Table 3. EMU ISS attributes summary Accommodation within 1%

status as of E/30/95 EMU program need date (’

Attributellmnact

Flinht

ORU replacement and sizing

II/98

integrated airlock test

~ Develop on-orbit diagnosttc. replacement & reverificatton procedures using just station tools & resources EMU accommodation and physicalifuncttonal interface wtth ISS

I 1198

Integrated airlock test

2,,99

UF-I

2!99

UF-I

- Vertfy EMU don/doff, checkout and service m ISS airlock wtth servtce. performance. checkout equipment and ISS resources for 3 EMUs _ Assure EMU compattbility with ISS airlock interfaces Toxicology - Evaluate stericide, antifog lubricants and cleaning agents for ISS acceptability Battery safety - Evaluate EMU battery to current statton requirements

’

Space Station Joint Integration Schedule of 3/10/95.

EMU. Changeout can be performed with common hand tools and eliminates the need for shims and measurements currently required. The ORU PLSS/ SOP, HUT and DCM is currently undergoing system mock-up evaluation and is expected to be ready for flight in GFY 1998. 3. EMU REQUIREMENTS

FOR ISS

Three tables summarize additional attributes to be certified for using the EMU to support ISS operations. The tables list the attributes/impacts and show the ISS program milestone supported by implementation. They are: l l l

Table 3: Accommodation within ISS Table 4: Logistics support Table 5: External environments

The current expectation is that some EMU hardware changes will be required to meet the currently understood ISS requirements. Changes identified to date are: Battery modification to meet 180 day wet life on orbit. Micrometeorite protection may be modified to meet orbital debris requirement of the year 1999 and modifiable periodically thereafter to meet a deteriorating debris environment. NASA is also in the process of developing and procuring a metal oxide carbon dioxide scrubber for EMU use aboard ISS. This scrubber is

regenerable and would replace the single-use LiOH canister currently in use. ILC Dover has developed an antimicrobial fabric finish that extends the number of times crew worn items used between change out. This finish called TCHDE, in conjunction with a prescribed change out schedule of crew-worn items, eliminates the need for forced air drying of the EMU on-orbit between EVAs [7]. In addition, some suit protection may be added to specific vehicle propellant exposure risks. This could include materials changes to EMU suit materials for improved compatibility with hydrazine and nitrogen tetroxide. 4. EMU INTEROPERABILITY WITH THE RUSSIAN ORLAN-M

On September 2, 1993, U.S. Vice President Gore and Russian Prime Minister Chernomyrdin signed an historic space activity agreement that included the development of a common space suit system to be accomplished jointly by the two nations. As a consequence of this agreement, a working group was estabhshed by NASA JSC’s EVA and Crew Equipment Project Office under the direction of Astronaut G. David Low [S]. Basic objectives of the working group included developing a plan and approach for the implementation of the common space suit program and also developing a projected cost for the effort in order to obtain FY94 funding support. The working group

Table 4. EMU ISS attributes summary Logistics suuwrt Requirement Verify Verify

on-orbit duration w/o ground servicing 180 day duration with 16 EVAs No on-orbit CO1 transducer calibration & relief valve cycling 425 day/35 cycle day battery wet life 240 day/25 EVA secondary Or pack exposure EMU drying and microbial control txocedures

’ Space Station Joint Integration Schedule of 3/10/95

Status as of g/30/95 EMU program need date

’

Flight

2199

UF-I

3199

7A

NASA

shuttle

EMU for international

space station

803

application

Table 5. EMU ISS attributes summaw Status as of S/30/95

External environments

Debris Ionizing

environment Confirm Total

-

Particle

Thermal -

improve

’

13A

to withstand

EV

and

IV

for year 2014 to

2199

UF-I

rate

3199

1A

3/99

7A

3199

7A

3199

IA

3199

7A

exposures

Atlantic

Anomaly

passes

thermal

comfort

compatibility

during

for

Develop loads -

ISS field

verify

translation

EVA

impacts

environments Solar

-

Atomic

passes at low

decontamination

work

procedures

for

and N?H,

intensities

procedure

EVA

-

nightside

and develop

compatibility

-

-

ability

probability

dose

MMH. UDMH. NH,

NIOd. Test

Other

verify

flux in South

-

-

-

no penetrations

Environment

Electromagnetic

Impact

to meet annual

radiation

Assess chemical -

Flight

l/W

ability

radiation

-

il

EMU program need date

attribute/impact

to limit

ability

when -

carrying

verify

exposure

to 137 V rn-

’

physiological

limit

at

> I.5

GHz

to withstand

stops from

electromagnetic

Space Station

crew

a 3 ft s-’

velocity

tools and

ISS replaceable

ability radiation

items

to withstand (UV)

oxygen Joint

Integration

Schedule

of 3/10/95.

provided a series of inputs toward the drafting of the comprehensive statement of work (SOW) between NASA and the Russian Space Agency (RSA). Of prime importance to the common space suit objective is enabling safe and efficient joint United States/Russian EVAs through development of a common EVA operations concept and harmonious EVA support protocols to be used on ISS. To reach the end goals of this program, the working group developed a phased approach which started with plans for conducting joint EVA operations and demonstrating interoperability capability between both nations using their respective EVA hardware systems. These phases would then lead to performing trade studies to define and determine the necessary level of commonality desired, and, finally, the implementation of commonality. The common space suit program approach contains the following phases: Phase I - Joint EVAs. EVAs being conducted simultaneously by United States astronauts using United States space suits and Russian cosmonauts using Russian space suits while operating from their respective airlocks. Phase II - Minimum interoperability. Both the United States and Russian EVA space suit systems must have compatible communications, foot restraints, and tethering systems (safety tethers and tool tethers), and a common operations concept. This includes preflight and real-time ground and flight operations. The goal is to demonstrate minimum interoperability by the beginning of the International Space Station assembly flights.

4. I, Current status During joint planning by NASA and RSA, it was determined that joint EVAs and minimum interoperability are basic requirements for ISS. Planning by NASA and RSA in January 1995 resulted in distributing elements of Phases I Joint EVA and Phase II Limited Interoperability into a series of

Shuttle Mission EVA Development Flight Tests. These are currently being planned in more detail. Figure 8 summarizes the planning status for these tests as of April 1995. When these flight tests are complete in 1997, it is expected that joint U.S.-Russian EVA and limited interoperability between the U.S. EMU and the Russian Orlan-M EVA Suit system will have been demonstrated. 4.2. Objectives l

l

Develop U.S./Russian interoperability for fundamental generic EVA tasks. Validate U.S./Russian interoperability, including common operations concepts and hardware elements for Space Station application.

4.3. Current Jlight planning The joint airlock for the U.S. segment of ISS is currently being designed. The joint airlock will be the .

STS-76(MIR-03)

Transfer

Passive Optical

Debris 3121196

Collector

Micrometeoroid payload Photo

Plate

Experiment

bay to MIR survey

experiment

Assy and Orbital

Polished

MIR

exterior

deployment

Evaluate

common

common

foot

Shuttle

module. and passive

configuration.

tether

restraint

leave on MIR

from

docking

and potentially

(U.S.

for potential

eval.

only,

later

Russian

eval).

.

Cargo

STS-80

Handling

ORU I l/7/96

.

STS-86(MIR-07)

ISS tools

(power

and rigid

tether).

Two

astronauts

cosmonauts 9/11/97

transfer MIR

Fig. 8. Current

demo

torque

egress shuttle Module crew

hi-use

multiplier

A/L

and

A/L.

Both

from

Shuttle

installs.

U.S.

two

crews to crew

STS-76 experiments plus optical

retrieves Shuttle

took.

egress MIR

Energy

Assy operattons,

operations,

and Russian

properties clock

Interface

and OTD

monitor

PLB.

from

Transfer

MIR

hydrogen

and stows in MASER

to MIR.

phase

I/II flight planning.

R. C. Wilde ei al UMBILICAL INTERFACE ASS””

” HAADUNE COMkiUNlCATldN 8 DATA, BAlTERY RECHARGE. OMAN: POWER (28 VDC)

EMU O2 SUPPLY (900 PSI)

EMU WATER FILL/DRAIN

IN

EMU/ORlAN-M COOLING WATER OUT

PI INTEI

iL \CES

ORIAN-M O2 SUPPLY 11-11----1ORLAN-M 0.2 SUPPLY

EMU 4

SUPPLY (900 PSI)

EMU WATER FILL/DRAIN

EMUIORLAN-M COOLING WATER IN

EMUKIRLAN-h4 COOLING WATER OUT

EMU: POWER (18.5 VDC), HARDLINE COMMUNICATION & DATA, BATTERY RECHARGE. ORtAN: POWER (28 VDC)

WASTE WATER PORT

REV MAY t 7, 1995

FG171SOOlcn

Fig. 9. ISS joint airlock umbilical interface assembly (preliminary).

base for scheduled U.S. EVA, and will also be able provide pre- and post-EVA support for the Russian Orlan-M. Figure 9 shows a current schematic diagram of the U.S.-supplied umbilical interface assembly (UIA) which transfers power and fluids to each country’s suits via their respective umbilicals. A Russian-supplied on-board suit control assembly (OSCA) located within the UIA will provide the required checkout capabilities, oxygen ventilation loop and purge gas supply functions to the Orlan-M. to

NASA is currently developing an in-suit Doppler ultrasonic bubble detector to evaluate an observation that astronauts and cosmonauts appear to be less prone to decompression sickness in orbit than on Earth. Studies by both Russian and U.S. investigators have predicted that decompression sickness during EVA would already have been encountered in flight, based on the results of ground-based studies. Flight tests using the Doppler device are currently planned to start as early as STS-80 in November, 1996 [9]. Depending on the outcome of the flight

NASA shuttle EMU for international space station application

experiments, prebreathe denitrogenation procedures may be shortened or simplified in the future.

5. CONCLUSIONS

The Shuttle EMU has already undergone significant enhancements to external service life and to reduce maintenance costs in the Shuttle program. Additional improvements are currently being made to the EMU to improve safety, crew comfort, and to further simplify maintenance. improvements EMU enhancements and currently operational or in process for the Shuttle program form the basis of the EMU to support ISS assembly and maintenance support. Additional EMU attributes will be certified for their role of supporting ISS assembly and maintenance operations. These fall within three broad areas: l Revised accommodation aboard Station, including interior environments l Extended operating life resulting from the EVA mission model for ISS assembly and support. 0 Operating safely in Station external environments that differ from Shuttle. Limited redesign and select retest are expected to meet ISSA EVA support requirements. Regarding U.S. and Russian EVA, Phase I Joint EVA and Phase II Minimum Interoperability are on the critical path of ISS assembly and operations. Detailed test objective planning for flight evaluation is currently in process.

AA 40/l I--c

l

805

An in-suit Doppler ultrasound device is currently in development to allow investigation of decompression sickness during EVA. Experiment results may allow shortening or simplifying pre-EVA de-nitrogenation procedures in the future. REFERENCES

1. Wilde, R., Higgins, W. and Lutz, G., Preparing EMCI for Space Station.

SAE Technical Paper 921343, July, 1992. 2. Balinskas, R., McBarron, J. and Spampinato, P., Shuttle Operational Enhancements. SAE Technical Paper 90 1317, July, 1990. 3. Lutz, G., Margiott, V., Murry, S. and Schaff, J., Development of an Infrared Absorption Transducer to Monitor Partial Pressure of Carbon Dioxide for Space Applications. SAE Technical Paper 932145, July, 1993.

4. Graziosi, D., Cadogan, D., Grahm, M. and Kosmo, J., Shuttle Space Suit Glove Thermal Protection and Performance Improvement Evolution. SAE Technical

Paper 941329, July, 1994. 5. Schneider, S., Margiott, V., Hodgson, E. and Lutz, G., Transient Aspects of Human Thermal Comfort in the Shuttle EMU. SAE Technical Paper 941381, July, 1994.

6. Stankiewicz, T., Dionne, S., Prouty, B. and Case, M., Redesign of the Shuttle Extravehicular Mobility Unit Hard Upper Torso to Improve Overall System Safety and Reduce Component Cost. SAE Technical Paper 932100,

July, 1993. Cloughlerty, M. and Slayer, J., Microbial Control of the Space Suit Assembly for Space Station Freedom. SAE Technical Paper 93210, July, 1993. Wilde, R., Abramov, I., McBarron, J. and Tehemikov, S., Options for Developing a Common Space Suit System. SAE Technical Paper 951671, July, 1995. KRUG Life Sciences, Risk Mitigation Experimental (RME 1309) In-Suit Doppler. Prototype Hardware Preliminary Design Review, September 6, 1995.