1. AAE450 Senior Spacecraft Design Steve Kassab Week 1: January 18 th, 2007 Power Team RTGs, Fuel Cells ISPP

2. AAE450 Senior Spacecraft Design RTG and Fuel Cell Power Systems Radioisotope Thermoelectric Generators –Very inefficient, because of “waste” heat Source: www.nasa.gov Fuel Cells –Proton Exchange Membrane (50-75kW) mobile units Phosphoric Acid Fuel Cell (0.2-20MW) stationary ProjectElectricityHeatMass Cassini100W4400W55.5kg MSL110W2000W45kg *Robert Zubrin, The Case For Mars

3. AAE450 Senior Spacecraft Design In-Situ Propellant Production Waste heat from RTGs can help evaporate water in excavated regolith.5 kW-hr/kg extraction of water from regolith* –For 1 ½ years, ISPP would require about 2 kW to excavate 44,000kg of water –Zubrin assumed 1kW-hr/kg with 3% concentration by mass Electrolysis ~70% efficiency –~1700mol H 2 and 850mol LOX –~3500kg H 2 and 27000kg LOX