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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Altair (spacecraft) | 2/2 | https://en.wikipedia.org/wiki/Altair_(spacecraft) | reference | science, encyclopedia | 2026-05-05T12:41:46.351134+00:00 | kb-cron |
Altair intended to utilize current cryogenic technologies for the descent stages and hypergolic technologies for the ascent stage. The Apollo LM, as advanced in both computer and engineering technology in its day, used hypergolic fuels in both of its stages, chemicals that combust on contact with each other, requiring no ignition mechanism and allowing an indefinite storage period. Both the cryogenic and hypergolic systems, like that of the Apollo LM, would be force-fed using high-pressure helium, eliminating the need for the turbopumps utilized in most rocket engines. Mission requirements obliged the vehicle to be able to descend from an equatorial or high-inclination lunar orbit to a polar landing site, along with bringing it and the Orion spacecraft into lunar orbit, as the Orion spacecraft's onboard Aerojet AJ-10 rocket engine and the amount of fuel it carried would have been insufficient to brake the Orion/Altair stack into lunar orbit (also necessary if flown without Orion for cargo-only missions). The new lander would have been powered by a modified RL-10 engine (currently in use on the upper stage of the Delta IV rocket and Centaur upper stage of the Atlas V rocket), burning liquid hydrogen (LH2) and liquid oxygen (LOX) for the descent phase. A single AJ-10 rocket engine, like that on the Orion, was intended to power the ascent stage. Originally, NASA wanted to power the ascent stage using LOX and liquid methane (LCH4) engines, RS-18, as future missions to Mars would require the astronauts to live on the planet. The Sabatier Reactor could be used to convert the carbon dioxide (CO2) found on Mars into methane, using either found or transported hydrogen, a catalyst, and a source of heat. Cost overruns and immature LOX/LCH4 rocket technology forced NASA to stick with cryogenic and hypergolic systems, although later variants of Altair were meant to serve as testbeds for methane rockets and Sabatier reactors after a permanent lunar base was established.
== On-orbit assembly == Because of the spacecraft's size and weight, Altair, and its associated Earth Departure Stage, would have been launched into a low-Earth orbit (LEO) using the super heavy-lift Ares V launch vehicle, followed by a separate launch of an Orion spacecraft lifted by an Ares I. After rendezvous and docking with Altair in LEO, the crew would have then configured the Orion/Altair for the journey to the Moon.
== Offices and development == The development of Altair was managed by the Constellation Lunar Lander Project Office at Johnson Space Center (JSC). JSC worked directly with Apollo astronauts, various industry suppliers and universities to develop the architecture for Altair. In conjunction with early development a mockup or testbed was to have been developed at JSC to study/develop specialized subsystems and other design considerations. Northrop Grumman, which built the Apollo Lunar Module, was contracted to help the project office develop the system concept.
== See also == List of crewed lunar lander designs
== References == This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.
== External links ==
Altair Lunar Lander Fact Sheet Space Review Globalsecurity Propulsion and Cryogenic Advanced Development for Altair