Lunar Surface Access Module
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The Lunar Surface Access Module (LSAM) is the planned American moon landing vehicle that will allow astronauts to land there around 2020 as part of NASA's Project Constellation.
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[edit] Name
It is rumoured that the final name of the LSAM will be "Artemis", after the Greek Moon goddess who was the sister of Apollo, however, no official announcement has been made.[1]
[edit] Description
The LSAM, which is similar in design to (but much larger than) the Apollo Lunar Module (LM), will consist of two stages: a descent stage, which will house the majority of the fuel, power supplies, and breathing oxygen for the crew, and an ascent stage, which will house the astronauts, life-support equipment, and fuel for the ascent stage motor and steering rockets. Like the Apollo LM, the LSAM's crew module is based on a sideways cylinder, but unlike its two-man Apollo ancestor, the LSAM is designed to carry the entire four-man mission crew to the surface while the Orion Spacecraft remains unmanned in lunar orbit. It will also be flown unmanned, similar in the Apollo Applications Program's LM Truck concept, but without having to fly a manned Orion spacecraft out to the Moon.
The LSAM, like the LM, will have two hatches – one located on top for docking and internal transfer between the LSAM and the Orion, and a main hatch for going out to the lunar surface. Unlike the Apollo LM, the LSAM will have an airlock similar to those on the Space Shuttle and International Space Station between the cabin and main hatch. The airlock will allow the astronauts to don and doff their spacesuits without tracking hazardous moon dust into the main cabin, as well as allowing the vehicle to retain its internal pressure – the Apollo LM required the entire cabin to be fully depressurized before a moon walk. The airlock would allow an astronaut with a malfunctioning spacesuit to re-enter the vehicle without the entire crew having to end their moon walk.
The spacecraft will also include a miniature camping-style toilet, similar to the unit now used on the ISS and the Russian Soyuz spacecraft; a food warmer to eliminate the "cold soup" menu used during Apollo missions; a laser-guided distance measurement system (with radar backup); and new "glass cockpit" and Boeing 787-based computer system that will be identical to that used on the Orion spacecraft.
[edit] Engines
It will use current cryogenic fuel technologies for the descent and ascent stages. The Apollo Lunar Module, advanced technology in its day, used hypergolic fuels, chemicals that combust on contact with each other, requiring no ignition mechanism and allowing an indefinite storage period. The cryogenic fuels, like the hypergolic fuels planned for the Orion spacecraft, will be pressure-fed using helium gas, eliminating malfunction-prone pumps.
Mission requirements oblige the vehicle to be able to descend from an equatorial (or high-inclination) lunar orbit to a polar landing site, along with braking it and the Orion spacecraft into lunar orbit, as the Orion spacecraft's onboard Delta II-based engine and the amount of fuel it carries are insufficient to brake the Orion/LSAM stack into lunar orbit (also crucial if it is flown unmanned without an Orion crew). The new lander will be powered by four modified RL-10 engines (currently in use on the Centaur second stage of the Atlas V rocket), burning liquid hydrogen (LH2) and liquid oxygen (LOX) for the descent phase, and using a single RL-10 for the trip back to the CEV.
Originally, NASA wanted to power the ascent stage using LOX and liquid methane (LCH4), 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 and immense amounts of (presumably solar) energy. Cost overruns and immature LOX/LCH4 rocket technology have forced NASA to stick with cryogenic fuel for the near future, although later variants of the LSAM will serve as testbeds for methane rockets and Sabatier reactors after a permanent lunar base is established.
[edit] On-Orbit Assembly
Because of the spacecraft's size and weight, the LSAM, and its associated Earth Departure Stage, will be launched into a Low-Earth Orbit using the 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 the LSAM in LEO, the crew will then configure the Orion/LSAM combination, followed by the firing of the Earth Departure Stage to propel the two spacecraft to the Moon. If an unmanned LSAM is flown, the spacecraft will be checked out after the first EDS firing in LEO (similar to that of the Apollo "Parking Orbit") before the second firing of the EDS propels the unmanned LSAM to the Moon.
[edit] References
2. The latest contractor's design proposals are quite different in configuration from NASA's original designs:
Lockheed-Martin, selected by NASA to develop the LSAM, has released three design proposals: Concept 1: Dual Thrust Axis Lander Concept 2: Retro-Propulsion Lander Concept 3: Single Stage Lander
Link to document with illustrations and detailed explanations of each at: http://www.lockheedmartin.com/data/assets/13350.pdf
[edit] External links
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Main Article: Project Constellation |
| Components: Orion | Ares I | Ares IV | Ares V | Earth Departure Stage | Lunar Surface Access Module | J-2X | RS-68 | |
| Launch Sites: Kennedy Space Center LC-39 | |
| Misc: Vision for Space Exploration | Exploration Systems Architecture Study | Abort Modes | Missions | In-Flight Aborts and Rescue Options | |
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| Orbiters | Apollo Command/Service Module, Soyuz spacecraft/Lunniy Orbitalny Korabl, Orion |  |
| Landers | Apollo Lunar Module, Lunniy Korab, Lunar Surface Access Module | |
