Crew Systems Project ENAE 483 Fall 2012 Team A2: Douglas Astler Stephanie Bilyk Kevin Lee Grant McLaughlin Rajesh Yalamanchili
Presentation Overview Requirements and Assumptions Trade studies and life support systems selection Power requirements Atmosphere selection Denitrogenation Interior layout of vehicle configurations Sight lines for landing Ingress/egress for lunar surface operations design
Design Requirements Design a crewed spacecraft for a low-cost lunar mission The spacecraft is to be used for transporting the crew to low lunar orbit, where it will dock with a propulsion and landing module and land on the moon The spacecraft will be used as the base for lunar surface activities The spacecraft will support a crew of 3 for a 10-day nominal mission and three contingency days The spacecraft will be used for Earth re-entry
Assumptions The cabin will support 95th percentile males The maximum diameter is 3.57 m A half-cone angle of 25 degrees was used to maximize crew cabin volume; it became clear the diameter restriction would necessitate this half-cone angle Wall thickness of the outer shell is 10 cm The total mass allocation for crew and crew systems is 1500 kg
Trades Studies & Systems Selection CO2 collection system Water recycling system O2 and N2 storage system
CO2 Collection System Selection Considered: Lithium Hydroxide (LiOH) Calcium Hydroxide(Ca(OH)2) Two-Bed Molecular Sieve (2BMS) Four-Bed Molecular Sieve (4BMS) Solid Amine Water Desorption (SAWD) Silver Oxide (AgO2) For CO2 scrubbing systems, we selected the two-bed molecular sieve because of its low mass and low power requirement mass: 48 kg power: 77 W
CO2 Collection System Trade Study
Water Filtration System Selection Open-loop water required: 188.76 kg To lower mass, water filtration methods were considered multi-filtration (MF)2: 75 gallons/min would be processing 2.84 kg of hygiene water/person-day this is 0.001575 kg/(kg-day) 80.853 kg for the mission* reverse-osmosis (RO)3: 900 kg/hour would be processing 2.84 kg of hygiene water/person-day this is 0.28617 kg/(kg-day) 83.278 kg for the mission* Selected the multi-filtration system * Calculations at the end of the water trade studies
Water Filtration Trade Study
Water Filtration System Selection The addition of a distillation system was considered MF + Vapor Compression Distillation (VCD): 300 kg/100 kg of water processed would be processing 1.5 kg of urine water/person-day this is 13.50 kg/(kg-day) 37.353 kg for the mission MF + Vapor Phase Catalytic Ammonia Removal (VAPCAR): 550 kg/100 kg of water processed would be processing 1.5 kg of urine water/person-day this is 24.75 kg/(kg-day) 48.603 kg for the mission MF + Thermoelectric Integrated Membrane Evaporation (TIMES): 350 kg/100 kg of water processed would be processing 1.5 kg of urine water/person-day this is 15.75 kg/(kg-day) 39.603 kg for the mission The complete water recycling configuration selected: multi-filtration and VCR distillation * Calculations at the end of the water trade studies
Water Distillation Trade Study
Water System Trade Study Including both MF and VCD is beneficial for both the crews' health and mass budget:
Water System Calculations Filtration calculations: 2.84 kg of hygiene water to be filtered +2.84(3 crew members)(filtration system specific kg/kg-day) +({4.84 kg req. - 2.84 kg filtered} of water/person-day)(3 people)(13 days) Filtration + distillation calculations: 2.84 kg of hygiene water to be filtered +1.50 kg of urine to be distilled +2.84(3 crew members)(filtration system specific kg/kg-day) +1.50(3 crew members)(distillation system specific kg/kg-day) +({4.84 kg req. - 2.84 kg filtered-1.50 kg distilled} of water/person-day)(3 people)(13 days)
N2 and O2 System Selection Assuming open-loop atmosphere Considered high pressure gaseous storage and liquid storage After initial iteration showed that the system would be over mass requirements using all gaseous storage, we chose to use liquid storage for Nitrogen and gaseous storage for Oxygen Trace contaminant control system included in design
N2 and O2 Storage System Trade Study
Radiation Shielding Least density of radiation shielding: 10 g/cm2 Rough estimate of surface area: 23.7 m2 Mass of radiation shielding: 2370 kg Conclusion: radiation shielding was clearly not possible within the mass budget and volume for the crew and crew systems
Power Requirements CO2 scrubbing: (77 W/kg)(3 kg) = 231 W Liquid Nitrogen tank: (9.037 W/person-day)(3 people) = 27 W Water filtration/mf2: 115 V, assuming a 1 A current --> 115 W Water distillation/vcd: (350 W/100 kg)(4.5 kg) = 16 W Trace contaminant control: (150 W)(3 people) = 450 W Total power required: 839 W
Atmosphere Conditions Selection Pressure: 10.9 psi (75 kpa) Percent O2: 25% The atmosphere was selected based on design space restricted by normoxic, hypoxic, flammability, and decompression sickness probability boundaries The time to complete denitrogenation for transfer to suit conditions was also considered during atmosphere selection
Denitrogenation We assumed a suit similar to NASA's Apollo A7LB EVA for suit mass estimation Mass per suit: 96.2 kg1 Originally tried using Space Shuttle Extravehicular Mobility Unit (EMU) suits but found mass was too high Denitrogenation must be performed from the selected atmosphere for a transition to suit conditions suit conditions: 5 psi and 80% O2
Denitrogenation Calculations Used Haldane's equation: Ptissue(t)=Ptissue(0)+[Palveoli(0) Ptissue(0)](1 e-kt) Palveoli(t)=[Pambient PH2O+{(1 RQ)/RQ}PCO2]Q Found our variables: Palveoli(0)=0 because Q=0 (we are pre-breathing 100% O2) Ptissue(0)=partial pressure of N2= 56.25 kpa Graphed the results using 6 tissue model
Time to Complete Denitrogenation
Denitrogenation Solution The tissue ratio R is defined by PN2/Pambient For our cabin atmosphere R = 0.75 Assuming a factor of two drop in Pambient is safe, an R of 1.5 is safe For our suit pressure (5 psi, or 34.47 kpa) which is our new Pambient and this R we found our PN2 to be 51.7 kpa The time it takes for the tissue with the longest half-life considered to reach this required PN2 to be safe is 14.55 minutes This is the minimum time for denitrogenation so to be safe we would recommend 20 minutes or more
Mass Estimates and Margin design category mass [kg] crew (3) 296 O2 (gaseous) 43 O2 tanks (gaseous) 87 N2 (liquid) 145 N2 tanks (liquid) 44 CO2 scrubbing: 2BMS 48 water: water, MF, VCD 37 food 33 seats 30 suits (Apollo) 289 trace contaminant control 300 total 1352 margin +148 (+9.9%)
Design and Configurations The design of the crew capsule has different configurations: 1) The chairs are reclined during take-off and re-entry, as well as for sleeping 2) The chairs are upright and facing the control station during lunar descent 3) The chairs collapse onto the floor space at the bottom: allowing room for the astronauts to take off/put on their EVA suits allowing room for the astronauts to stand in their suits and exit/enter through the door 4) The hatch opens out and down until it is horizontal; a ladder on the inside of the door extends down the surface
Takeoff and Re-entry Configuration The chairs are reclined during take-off and reentry, as well as for sleeping avionics and parachute stored at top
Landing Controls Configuration The chairs are upright and facing the control station during lunar descent seats upright for landing control panel door
Sightlines for Landing Three windows: one for each crew member
Ingress/Egress for Lunar Surface The seats are collapsed so the astronauts can easily walk out the door The hatch opens out and down until it is horizontal; 2 m tall, 1 m wide to allow for astronauts in suits to walk out Tension rods to support the open door A ladder stored on the inside of the door extends down to the lunar surface
Components and Storage O2, N2, and propulsion tanks are outside the pressure hull propulsion tanks fit between O2 and N2 tanks extra room for cargo transfer bags
References 1. "Apolo/Skylab A7L." Wikipedia, The Free Encyclopedia. Wikimedia Foundation, Inc. 7 Sept. 2012. Web. 17 Oct. 2012. <http://en.wikipedia.org/wiki/apollo/skylab_a7l> 2. Pure Aqua, Inc.. Pure Aqua, Inc., 2012. Web. 17 Oct. 2012. <http://www.pure-aqua.com/water-filters-industrial-commercial-media-filters-mf500.html> 3. Pure Aqua, Inc.. Pure Aqua, Inc., 2012. Web. 17 Oct. 2012. <http://www.pure-aqua.com/commercial-reverse-osmosis-systems-ro-200series.html>