1. AAE450 Senior Spacecraft Design Project Aquarius Mike Kowalkowski Week 2: January 25 th, 2007 Project Aquarius Power Engineering Habitat, Battery, and Rover Power Sizing

2. AAE450 Senior Spacecraft Design Project Aquarius HAB Power System Conceptual Design –Sustainable uninterrupted power supply for human use Assumptions & Trades –2x human factors req. Control systems & communications –Safety Factor 1.5 25% budget for peak loads P / M / V – 2 HAB Stations –Power: 100 kWe capacity –IMLEO Mass: 4650 kg –Volume: 57.5 m^3 Reactor and fuel cell fuel not included in mass / volume Fission Reactor Ga-As Solar Cells ISPP H 2 &O 2 1010 2020 REG

3. AAE450 Senior Spacecraft Design Project Aquarius Battery System Style & Sizing Satellite Batteries: –Power: 2 kWe Solar Battery Li-Ion Rechargeable (2hr) IMLEO Mass: 102 kg Volume: 7.3 m^3 –Scalable power density –Includes solar paneling Unmanned System Battery: –Power: 0.1~0.5 kWe Battery NaS Rechargeable (5 day) IMLEO Mass: 106 ~ 530 kg Volume: 0.07 ~ 0.35 m^3 –No theoretical long term storage loss –Assume nominal solar chg. Mars Rover (Manned): –Power: 15kWe & PMAD Regenerative Fuel Cell –12 hour fuel budget Li-Ion Rechargeable (1hr) IMLEO Mass: 265 kg Volume: 2.0 m^3 –Fuel weights neglected, but ~100 kg in situ fuel needed Based on utilization of efficient cryogenic storage –(10% dry mass budget)

4. AAE450 Senior Spacecraft Design Project Aquarius Backup Slides Week 2 Readiness Level

5. AAE450 Senior Spacecraft Design Project Aquarius HAB Power Budget Power budget –20 kWe to sustain life support systems (Courtesy: Kate Mitchell) –20 kWe to sustain control systems, communications, and peaking demands –25% total margin PMAD losses –8.3% power budget (Courtesy: Larson & Pranke) Resistance losses –2% power budget (Courtesy: Larson & Pranke) Unexpected demand –14.7% power budget

6. AAE450 Senior Spacecraft Design Project Aquarius HAB M / V Calculations Primary System –PMAD & Nuclear PMAD mass ~ 11.1 kg/kW e 1 Also require wiring budget ~ 0.5 mt / HAB –Battery bank regulation system 1 Li-ion rechargeable batteries –150 Wh / kg specific energy –Battery 88% efficient –Density 260 Wh/L –0.168% discharge/month NaS batteries –132 Wh/kg specific energy –Battery 86% efficient –Density 160 Wh/L –0% discharge/ month Secondary System –Direct fuel cell system 1.4 kWe/kg dry mass 2 1.5 W e /cm^3 density 2 Fuel / oxidizer containment tanks 3 Baseline 200 kg fuel / day / 50 kWe 1 –Solar cells 1 GaAs system specific mass 2.05 kg/m^2 Solar flux is 593 W/m^2 4 Efficiency of solar panels 18.5% Efficiency of array ~ 75% from table 2-6 1

7. AAE450 Senior Spacecraft Design Project Aquarius Calculations Calc. Theory from Human Spaceflight: Mission Analysis and Design, Larson & Pranke pgs. 660-663 – MATLAB code to come shortly

8. AAE450 Senior Spacecraft Design Project Aquarius HAB Power Systems Trade Study Solar / Windmill / Flywheel Distribution –Currently used in Antarctica Extreme environment proven operation –You pay a mass penalty for a flywheel & windmill to sustain power Windmillling & flywheeling are viable options, but they come at a cost of approximately 2 mt 1,5 Utilized during wind storms; Mars has 1% atmosphere, but power from wind is a function of velocity cubed 5 Only 4x faster wind for same power req 5 Magnetic flywheel is still unproven technology –Nuclear power system (EP) available on surface has excess capacity – no additional IMLEO mass from existing architecture for HAB.

9. AAE450 Senior Spacecraft Design Project Aquarius Power Systems Trade Study Battery Power vs. Regenerative Fuel Cell –Fuel cells are advantageous for Martian surface because of low dry mass and high fuel content on the surface. –Higher battery recharge efficiency make them optimal for space use, especially with solar satellite arrays. –Primary batteries are order of magnitude lighter than rechargeable batteries and could be advantageous for short term taxi missions

10. AAE450 Senior Spacecraft Design Project Aquarius Cited References 1 Larson, Wiley J. and Linda K. Pranke. Human Spaceflight, Mission Analysis and Design. Ch. 20. McGraw Hill. 2 “PEM Fuel Cell Cost Status.” Carlson, Eric, et al. November 2005. Available online. http://www.fuelcellseminar.com/pdf/2005/Thursday- Nov17/Carlson_Eric_392.PDF http://www.fuelcellseminar.com/pdf/2005/Thursday- Nov17/Carlson_Eric_392.PDF 3 "The status of handling and storage techniques for liquid hydrogen in motor vehicles." Peschka, W. International Journal of Hydrogen Energy, Vol. 12 Issue 11, pgs. 753-764, 1987. 4 “Atmospheric Climate.” University of Washington. Fall 2002. Available online. http://www.atmos.washington.edu/2002Q4/211/notes_greenhouse.html http://www.atmos.washington.edu/2002Q4/211/notes_greenhouse.html 5 “Conceptual Design of a Martian Power Generating System Utilizing Solar and Wind Energy.” Zimmerman, David, et al. University of Houston. Available online. http://www.lpi.usra.edu/publications/reports/CB-979/houston.pdf http://www.lpi.usra.edu/publications/reports/CB-979/houston.pdf