National Technical Reports Library

The National Technical Information Service acquires, indexes, abstracts, and archives the largest collection of U.S. government-sponsored technical reports in existence. The NTRL offers online, free and open access to these authenticated government technical reports. Technical reports and documents in its repository may be available online for free either from the issuing federal agency, the U.S. Government Publishing Office’s Federal Digital System website, or through search engines.

Details

Lunar Ascent and Rendezvous Trajectory Design.

N20080009584

Publication Date	2008
Personal Author	Sostaric, R. R.; Merriam, R. S.
Page Count	23
Abstract	The 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.
Keywords	Lunar trajectories Ascent trajectories Rendezvous trajectories Lunar module Position(Location) Lunar orbits Lunar surface Targets Thrust-weight ratio Descent
Source Agency	National Aeronautics and Space Administration
Corporate Authors	NASA Johnson Space Center; NASA Johnson Space Center; American Astronautical Society
Supplemental Notes	Text in English. Presented at 31st Annual AAS Guidance and Control Conference, Breckenridge, Co, United States, 1-6 Feb. 2008. Publicly available Unlimited. CASI.
Document Type	Conference Proceedings
NTIS Issue Number	200814

Lunar Ascent and Rendezvous Trajectory Design.

Lunar Ascent and Rendezvous Trajectory Design.
N20080009584

Publication Date	2008
Personal Author	Sostaric, R. R.; Merriam, R. S.
Page Count	23
Abstract	The 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.
Keywords	Lunar trajectories Ascent trajectories Rendezvous trajectories Lunar module Position(Location) Lunar orbits Lunar surface Targets Thrust-weight ratio Descent
Source Agency	National Aeronautics and Space Administration
Corporate Authors	NASA Johnson Space Center; NASA Johnson Space Center; American Astronautical Society
Supplemental Notes	Text in English. Presented at 31st Annual AAS Guidance and Control Conference, Breckenridge, Co, United States, 1-6 Feb. 2008. Publicly available Unlimited. CASI.
Document Type	Conference Proceedings
NTIS Issue Number	200814