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Lunar Ascent and Rendezvous Trajectory DesignThe Lunar Lander Ascent Module (LLAM) will leave the lunar surface and actively rendezvous in lunar orbit with the Crew Exploration Vehicle (CEV). For initial LLAM vehicle sizing efforts, a nominal trajectory, along with required delta-V and a few key sensitivities, is very useful. A nominal lunar ascent and rendezvous trajectory is shown, along with rationale and discussion of the trajectory shaping. Also included are ascent delta-V sensitivities to changes in target orbit and design thrust-to-weight of the vehicle. A sample launch window for a particular launch site has been completed and is included. The launch window shows that budgeting enough delta-V for two missed launch opportunities may be reasonable. A comparison between yaw steering and on-orbit plane change maneuvers is included. The comparison shows that for large plane changes, which are potentially necessary for an anytime return from mid-latitude locations, an on-orbit maneuver is much more efficient than ascent yaw steering. For a planned return, small amounts of yaw steering may be necessary during ascent and must be accounted for in the ascent delta-V budget. The delta-V cost of ascent yaw steering is shown, along with sensitivity to launch site latitude. Some discussion of off-nominal scenarios is also included. In particular, in the case of a failed Powered Descent Initiation burn, the requirements for subsequent rendezvous with the Orion vehicle are outlined.
Document ID
20080009584
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Sostaric, Ronald R. (NASA Johnson Space Center Houston, TX, United States)
Merriam, Robert S. (NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 24, 2013
Publication Date
February 6, 2008
Subject Category
Spacecraft Design, Testing And Performance
Report/Patent Number
AAS 08-066
Meeting Information
Meeting: 31st Annual AAS Guidance and Control Conference
Location: Breckenridge, Co
Country: United States
Start Date: February 1, 2008
End Date: February 6, 2008
Sponsors: American Astronautical Society
Funding Number(s)
PROJECT: ALHAT Proj. 079749.01.10
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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