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Altair Descent and Ascent Reference Trajectory Design and Initial Dispersion AnalysesThe Altair Lunar Lander is the linchpin in the Constellation Program (CxP) for human return to the Moon. Altair is delivered to low Earth orbit (LEO) by the Ares V heavy lift launch vehicle, and after subsequent docking with Orion in LEO, the Altair/Orion stack is delivered through translunar injection (TLI). The Altair/Orion stack separating from the Earth departure stage (EDS) shortly after TLI and continues the flight to the Moon as a single stack. Altair performs the lunar orbit insertion (LOI) maneuver, targeting a 100-km circular orbit. This orbit will be a polar orbit for missions landing near the lunar South Pole. After spending nearly 24 hours in low lunar orbit (LLO), the lander undocks from Orion and performs a series of small maneuvers to set up for descending to the lunar surface. This descent begins with a small deorbit insertion (DOI) maneuver, putting the lander on an orbit that has a perilune of 15.24 km (50,000 ft), the altitude where the actual powered descent initiation (PDI) commences. At liftoff from Earth, Altair has a mass of 45 metric tons (mt). However after LOI (without Orion attached), the lander mass is slightly less than 33 mt at PDI. The lander currently has a single descent module main engine, with TBD lb(sub f) thrust (TBD N), providing a thrust-to-weight ratio of approximately TBD Earth g's at PDI. LDAC-3 (Lander design and analysis cycle #3) is the most recently closed design sizing and mass properties iteration. Upgrades for loss of crew (LDAC-2) and loss of mission (LDAC-3) have been incorporated into the lander baseline design (and its Master Equipment List). Also, recently, Altair has been working requirements analyses (LRAC-1). All nominal data here are from the LDAC-3 analysis cycle. All dispersions results here are from LRAC-1 analyses.
Document ID
Document Type
Conference Paper
Kos, Larry D. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Polsgrove, Tara T. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Sostaric, Ronald r. (NASA Johnson Space Center Houston, TX, United States)
Braden, Ellen M. (NASA Johnson Space Center Houston, TX, United States)
Sullivan, Jacob J. (NASA Johnson Space Center Houston, TX, United States)
Lee, Thanh T. (NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 25, 2013
Publication Date
August 2, 2010
Subject Category
Launch Vehicles and Launch Operations
Report/Patent Number
Meeting Information
American institute of Aeronautics and Astronautics meeting(Toronto, Ontario)
Distribution Limits
Public Use Permitted.

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