1. Propulsion – Attitude Control Casey Kirchner
Propellants chosen: MMH + NTO
Good storability for long-term mission
Off-the-shelf hardware for systems
DV requirements
200 m/s tether spin up/down
100 m/s course correction
500 m/s propulsive Martian landing
System integrated into HAB along bottom of vehicle, where tether attaches
Thrusters on bottom of vehicle for Martian descent, clustered around tether
Thrusters on side of vehicle for enroute maneuvers

2. Propulsion – Attitude Control Casey Kirchner
Based on Shuttle RCS parameters, an Isp of 220 s is reasonable
Based on current preliminary numbers, this is not good enough to get the mass fraction within an acceptable limit (Hab ~ 15% prop)
Isp code not integrated with sizing code, so some reworking will get numbers within range
Descent engines will be designed separate from RCS engines and will alter performance predictions
Tankage issues related to propellant acquisition will need to be resolved, but are within the realm of possibility