130 likes | 318 Views
Lunar Descent Trajectory. February 19 th , 2009. Descent Trajectory. Steering Program Descent times >1000s, working on better model Gimbaled Engine No savings until arbitrary payload case. Useful Numbers/Recommendations.
E N D
Lunar Descent Trajectory February 19th, 2009 [John Aitchison] [Mission Ops]
Descent Trajectory [John Aitchison] [Mission Ops] • Steering Program • Descent times >1000s, working on better model • Gimbaled Engine • No savings until arbitrary payload case
Useful Numbers/Recommendations [John Aitchison] [Mission Ops] • 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
Assumptions on First Slide [John Aitchison] [Mission Ops] • 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
Updated Lunar Descent Masses [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]
Landed Mass vs. Prop Mass (cont.) [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]
Descent EOM’s [John Aitchison] [Mission Ops]