Crew Systems Design Project

Crew Systems Design Project

Scott Wingate

Kenneth Murphy

Leah Krombach

James Black

Mission Specifications

• Low-cost lunar mission

• Three 95 percentile males

• 10 day mission with 3 contingency days

• 3 days to Moon

• 4 days on Moon

• 3 days to return to Earth

• 4 EVAs

• 1500 kg maximum mass of crew and crew systems

Team A3 2 Crew Systems Design

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Outline

1. Mass/Volume Breakdown

2. Life Support Systems

a. Cabin Atmosphere

b. CO2 Scrubbing Trade Study

c. O2 Recovery Trade Study

d. Food, Water and Hygiene

e. Radiation Trade Study

f. Human Waste Management

4. EVA

a. Denitrogenation

b. Spacesuits Trade Study

5. Power Requirements

6. Final Capsule Design


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Mass/Volume Breakdown Crew System Item Quantity Total Mass (kg) Total Volume (cm^3)

95% male [1] 3 295.5 305,500

Food [8] 1 67.2 148,600

Orlan Model MK Suits [4] 3 324 340,000

LiOH Canisters for EVA [7] 12 76.8 84,096

Atmosphere control 1 50 112,500

Hammocks [5] 3 3.1 189,000

Clothes [1] 3 10.43 74,300

Hygiene 3 20 74,300

Water [1] 1 54 54,000

Water Tank [7] 5 16.35 54,500

EDC CO2 Collection [7] 1 33 60,000

Oxygen 1 44.34 15,700


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Mass/Volume Breakdown cont. Crew System Item Quantity Total Mass (kg) Total Volume (cm^3)

Nitrogen [7] 1 7.03 10,300

Nitrogen Tank [7] 1 4.86 10,300

Human Waste Bags [9] 39 1.56 ~0

Chairs 3 150 12,213

Urine Receptacle Hose [9] 1 1.7 0

Toe Bar [1] 1 1.5 0.41

VCD Water Regen. [7] 1 85.08 175,000

Oxygen Tank [7] 1 84.75 15,700

Total 1,331

Total Allotted 1,500

Margin 11.3%


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Cabin Atmosphere

• Kept at 10 psi except during EVA

• 73% Nitrogen and 27% Oxygen

• Chosen to avoid hypoxia and oxygen toxicity while

remaining under flamability limit

• Volume of pressurized capsule: 7.98 m^3

• Assume 1% cabin atmosphere per day lost to leaks


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Fig. 1 CO2 Scrubbing Systems vs. System Mass


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CO2 Collection System

• Regenerative Electro Depolarization Concentration

system was chosen

• For 13 day mission, regenerative system is less

massive than a non-regenerative system

• Regenerative

• Total Mass of 33 kg [7]

• Power consumption of 180 Watts [7]

• Non-regenerative (LiOH Canisters)

• Total Mass of ~75 kg [7]


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Fig. 2 O2 Recovery Systems vs. System Mass


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O2 Recovery System

• 95th percentile male requires 1.11 kg oxygen per day [6]

• Open loop includes:

• Mass of oxygen required per day for the crew

• 2 kg of tank per kg oxygen contained [7]

• Open loop system requires the smallest mass for a 13

day mission

• For mass optimization, open loop system was chosen


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Food, Water and Hygiene

• 95th percentile male drinks 4.2 kg of water per day [1]

• 95th percentile male eats 1.72 kg of food per day [8]

• Astronauts bring along a personal hygiene kit that

includes a toothbrush, toothpaste, dental floss, comb,

razor and other items

• Astronauts use rinseless shampoo and soap [10]

• Astronauts spit into washcloths after brushing teeth [10]

• NASA defines a long-term mission to be 14 days

• Therefore, shower not necessary for this mission


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Fig. 3 Water Recycling Systems vs. System Mass


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Water Recycling System

• 4.2 kg of water needed per day per person

• 2.28 kg of respiration/perspiration water condensed

from atmosphere per person per day

• 1.63 kg of water in urine collected per person per day [1]

• Vapor Compression Distillation (VCD) system was

chosen to recycle urine and condensation water

• System Mass 85.08 kg

• Requires 41 Watts

• Requires 0.175 m^3


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Radiation in Space

• Three major types

a. Galactic Cosmic Radiation

• About 40 micro Gy/day [3]

b. Trapped Radiation Belts

• Only applicable to low earth orbit [3]

c. Solar Particle Events

• About 1 Sv per year during major storm [6]

• Limits for a 25 year male

• About 0.5 Sv over a 10 year period


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Radiation Trade Study

Fig. 4 Total Mass of Shielding vs. Amount of Radiation for Water and Aluminum


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Radiation Shielding Trade Study

Water in Capsule Walls for Shielding

• About 2300 kg of water necessary shield entire

capsule from a Solar Particle Event as shown in

figure 5

• Assuming .5 Sv per year for mild radiation sickness

• Much more water than the 117 kg needed for open

loop system for 13 days

• Similar mass of aluminum provides same shielding

• Low chance of large SPE in 13 day mission


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Human Waste Management

• Due to short length of mission and limited space in

capsule, astronauts will use waste bags like the Apollo

missions

• Allotting for 1 bag per astronaut per day, 39 waste bags

will be taken

• All waste bags and trash will be dumped on EVAs to

save room and maintain cleanliness in the capsule

• Urine will be kept for H20 recovery system


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Extravehicular Activity (EVA)

• 4 EVAs while on the Moon

• Full cabin depressurization for each EVA

• 3 astronauts in space suits on each EVA

• Denitrogenation times of astronauts must be accounted

for pre-EVA

• Assume 90% atmosphere scavenging efficiency for

each full cabin depressurization


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Denitrogenation

• Tissue ratio of nitrogen is defined as: R = PN2 / Pambient [6]

• R = ~1.6 considered "safe" for astronauts [6]

• Given capsule atmosphere of 10psi, 73% N2, 27% O2

• Rcapsule= 0.73

• For space suits: "safe" values of PN2=1.6*Psuit

• The denitrogenation time for each suit is determined by

finding where PN2 in the tissue compartment with the

longest half-time equals the "safe" value of PN2


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Denitrogenation cont.

• Pre-breathe operations: pure oxygen.

• Use the Haldane equation to determine the change of

PN2 in tissue compartments

• Ten compartment tissue model

• Shortest half-time 5 minutes

• Longest half-time 360 minutes

• Fig. 5 shows the denitrogenation curves


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Fig. 5 Denitrogenation curves for each tissue compartment


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Space Suit Case Study

• All suits assumed to be 100% O2

• Denitrogenation times for each suit determined from

Fig. 7

Space suit Total

Mass (kg)

Operating

Pressure

(psi)

"Safe"

PN2 (psi)

Denitrogenation

Time (minutes)

Enhanced

Extravehicul

ar Mobility

Unit [4]

124.7 4.3 5.92 40

Apollo A7LB 96.2 3.7 6.88 120

Orlan Model

MK [5]

108 5.8 9.28 N/A

Fig. 6 Details of Possible Space Suits


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Fig. 7 Denitrogenation curves overlaid onto "safe" N2 partial pressures for each space suit


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Space Suit Case Study cont.

• Orlan Model MK space suit chosen for mission for the

following reasons:

• Denitrogenation not required due to higher operating

pressure

• Less massive than Enhanced EMU

• More current than Apollo A7LB

• Entering suit through the backpack allows astronaut

to get into suit by himself


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Fig. 8 Amount of EVA Days vs. System Mass of EVA CO2 Scrubbing Systems


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EVA CO2 Scrubbing

• Regenerative sytems: METOX

• Requires 3 METOC canisters per EVA

• 6 total canisters

• Each canister has mass of 14.5 kg 6.4 kg per

expendable canister [7]

• Requires 2 ovens at 48 kg each 6.4 kg per

expendable canister [7]

• Non-Regenerative systems

• 6.4 kg per expendable canister [7]

• LiOH canister system is mass optimized

• LiOH canister system was chosen


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Power Requirements

System Power Required (Watts)

(Maximum)

EDC CO2 Scrubbing System 180

VCD Water Regeneration

System

41

Atmospheric Control System 60

Orlan Model MK Spacesuit 54

Fig. 9 Power Requirements of Crew Systems


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Final Design Layout

• Outer Shell:

• 10 cm wall thickness

• Heat Shield

• Inner Pressure Vessel:

• Crew quarters

• Atmospheric and Capsule Controls

• Interstitial Space:

• Gas and water tanks

• Extra space for later additions


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Sight Lines


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Fig. 10 Sight Lines

Inner Pressure Vessel With Outer Shell Removed


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References

1. International Space Station Flight Crew Integration Standard (NASA–STD–3000/T) - SSP 50005,

Rev. C - Space Station Program Office, NASA Johnson Space Center, December 15,1999

2. Lange et. al., "Advanced Life Support Requirements Document" JSC-38571B, Sept. 2002

3. Badhwar, Gautam D. The Radiation Environment in Low Earth Orbit. Radiation Research, Vol.

148, No. 5, 1997

4. Reference Guide to the International Space Station. Washington, DC: National Aeronautics and

Space Administration, 2010. Print.

5. US Spacesuits. Chichester, UK: Praxis Publishing Ltd.. 2006. ISBN 0-387-27919-9

6. Akin, Dave. Lecture 10 CS/Aerospace Physiology, 2012

7. Akin, Dave. Lecture 11 CS/Space Life Support Systems, 2012

8. "HSF." HSF. N.p., n.d. Web. 17 Oct. 2012.

<http://spaceflight.nasa.gov/shuttle/reference/factsheets/food.html>.

9. Final Report on the 3-Month Alternate Access to Station (AAS) Performance Requirements Study,

Appendix G, 2002

10. "How Do Astronauts Eat in Space?" HowStuffWorks. N.p., n.d. Web. 17 Oct. 2012.

<http://science.howstuffworks.com/astronauts-eat-in-space1.htm>.


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http://en.wikipedia.org/wiki/Special:BookSources/0-387-27919-9

Documents

Crew Systems Design Project