Lunar Descent Trajectory February 19th, 2009 [John Aitchison] [Mission Ops]

[John Aitchison] [Mission Ops] Descent Trajectory Steering Program Descent times >1000s, working on better model Gimbaled Engine No savings until arbitrary payload case [John Aitchison] [Mission Ops]

Useful Numbers/Recommendations 1 additional kg on lunar surface ≈ 2.1 kg additional kg in lunar orbit 2000 km circular lunar parking = add 55kg descent prop mass!! Use EP as long as possible Stay above 20 km until final descent Also: Altitude Sensor System Updates [John Aitchison] [Mission Ops]

Assumptions on First Slide Graph 1 110km, 15km orbit; vertical to horizontal burn; constant 2000 N thrust; constant mdot=.67 kg/s Graph 2 Graph 1 assumptions; 315kg wet mass; worst case mountain scenario Graph 3 Added prop to get to 110km circular; instantaneous deltaV; Hohmann transfers [John Aitchison] [Mission Ops]

Updated Lunar Descent Masses System Subsystem Mass (kg) Power   Batteries 20 Solar Panels 2 Communications CPU 0.57 Camcorder 0.38 Receiver 0.2 Transmitter Antenna 0.1 Propulsion Structure 34.1 Propellant 157.7 Attitude Thrusters 7 2.5 Star Sensor 3.2 Rover 31.5 Frame 30.45 Thermal Control 24.7 Total Dry 156.9 Total Wet 314.6 [John Aitchison] [Mission Ops] 4

Landed Mass vs. Prop Mass -Also basis of EOM code [John Aitchison] [Mission Ops]

Landed Mass vs. Prop Mass (cont.) [John Aitchison] [Mission Ops]

[John Aitchison] [Mission Ops] Landed Mass vs. Prop Mass (cont.) [John Aitchison] [Mission Ops]

[John Aitchison] [Mission Ops] Landed Mass vs. Prop Mass (cont.) [John Aitchison] [Mission Ops]

Effects of Non 110km Circ Orbit [John Aitchison] [Mission Ops]

Effects of Non 110km Circ Orbit (cont.) [John Aitchison] [Mission Ops]

Effects of Non 110km Circ Orbit (cont.) [John Aitchison] [Mission Ops]

[John Aitchison] [Mission Ops] Descent EOM’s [John Aitchison] [Mission Ops]