Lunar Surface Access Module
Encyclopedia
| Artist impression of the crewed version of Altair on the surface of the moon |
|
|---|---|
| Description | |
| Role: | Lunar landing |
| Crew: | 4 |
| Dimensions | |
| Height: | 9.7 m (31.8 ft) |
| Diameter: | 7.5 m (24.6 ft) |
| Landing gear span: | 14.8 m (48.6 ft) |
| Volume: | 31.8 m³ (1,123 cu ft) |
| Masses | |
| Ascent module: | 10809 kg (23,829.8 lb) |
| Descent module: | 35055 kg (77,283 lb) |
| Total: | 45864 kg (101,112.8 lb) |
| Rocket engines | |
| RCS | 445 N (100 lbf) |
| Ascent Propulsion System (LOX/LH2) RL-10 derivative x 1: |
44.5 kN (4.5 LTf) |
| Descent Propulsion System (LOX/LH2) RL-10 derivative x 4: |
66.7 kN (6.7 LTf) |
| Performance | |
| Endurance: | 7 days (Sortie missions) Up to 210 days (Outpost missions) |
| Payload (cargo mode): | 14,500 kg |
| Aposelene: | |
| Periselene: | Surface |
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The Altair spacecraft, previously known as the Lunar Surface Access Module or LSAM, was the planned lander spacecraft
Lander (spacecraft)
A lander is a spacecraft which descends toward and comes to rest on the surface of an astronomical body. For bodies with atmospheres, the landing is called atmospheric reentry and the lander descends as a re-entry vehicle...
component of NASA's
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
cancelled Project Constellation
Project Constellation
Constellation Program is a human spaceflight program within NASA, the space agency of the United States. The stated goals of the program were to gain significant experience in operating away from Earth's environment, develop technologies needed for opening the space frontier, and conduct...
. Astronaut
Astronaut
An astronaut or cosmonaut is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft....
s would have used the spacecraft for landings on the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
, which had been intended to begin around 2019. Altair spacecraft had been planned to be used both for lunar sortie
Lunar sortie
A lunar sortie is a human spaceflight mission to the Moon. In contrast with lunar outpost missions, lunar sorties will be of relatively brief duration.- NASA sorties :...
and lunar outpost
Lunar outpost (NASA)
A lunar outpost was an element of the George W. Bush era Vision for Space Exploration, which has been replaced with President Barack Obama's space policy. The outpost would have been an inhabited facility on the surface of the Moon. At the time it was proposed, NASA was to construct the outpost...
missions. On February 1, 2010, U.S. President Barack Obama
Barack Obama
Barack Hussein Obama II is the 44th and current President of the United States. He is the first African American to hold the office. Obama previously served as a United States Senator from Illinois, from January 2005 until he resigned following his victory in the 2008 presidential election.Born in...
announced a proposal to cancel the Constellation program, to be replaced with a re-scoped program, effective with the U.S. 2011 fiscal year budget.
Name
On December 13, 2007, NASA's Lunar Surface Access Module was retitled "Altair", after the 12th brightest star in the northern hemisphere's night sky, Altair in the constellation AquilaAquila (constellation)
Aquila is a stellar constellation. Its name is Latin for 'eagle' and it is commonly represented as such. In mythology, Aquila was owned by the Roman god Jupiter and performed many tasks for him....
. In Latin, "aquila" means "eagle
Eagle
Eagles are members of the bird family Accipitridae, and belong to several genera which are not necessarily closely related to each other. Most of the more than 60 species occur in Eurasia and Africa. Outside this area, just two species can be found in the United States and Canada, nine more in...
", providing a connection to the first crewed lunar landing, Apollo 11
Apollo 11
In early 1969, Bill Anders accepted a job with the National Space Council effective in August 1969 and announced his retirement as an astronaut. At that point Ken Mattingly was moved from the support crew into parallel training with Anders as backup Command Module Pilot in case Apollo 11 was...
's Eagle; the name Altair itself is a Latinization of the Arabic
Arabic language
Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...
al-ṭā'ir, meaning "the Eagle," "the Bird," or "the Flyer."
Prior to the announcement of the "Altair" name, reports had suggested other names had been considered by NASA, but Altair won in a vote by the design team over Pegasus
Pegasus
Pegasus is one of the best known fantastical as well as mythological creatures in Greek mythology. He is a winged divine horse, usually white in color. He was sired by Poseidon, in his role as horse-god, and foaled by the Gorgon Medusa. He was the brother of Chrysaor, born at a single birthing...
.
Description
NASA developed only conceptual designs for Altair. No Altair spacecraft were built — plans called for a first landing on the Moon in 2018.Like the Apollo Lunar Module
Apollo Lunar Module
The Apollo Lunar Module was the lander portion of the Apollo spacecraft built for the US Apollo program by Grumman to carry a crew of two from lunar orbit to the surface and back...
(LM), Altair was envisioned as having two stages
Multistage rocket
A multistage rocket is a rocket that usestwo or more stages, each of which contains its own engines and propellant. A tandem or serial stage is mounted on top of another stage; a parallel stage is attached alongside another stage. The result is effectively two or more rockets stacked on top of or...
. The descent stage would have housed the majority of the fuel, power supplies, and breathing oxygen for the crew. The ascent stage would house the astronauts, life-support equipment, and fuel for the ascent stage motor and steering rockets. Like the Apollo LM, the Altair's crew cabin was based on that of a cylinder. Initially a horizontal cylinder, like that of the LM (despite the "boxy" appearance on the outside), current blueprints and computer simulations show the use of a vertical cylinder. Unlike its two-man Apollo ancestor, Altair was designed to carry the entire four person crew to the surface, while the temporarily unoccupied Orion
Orion (spacecraft)
Orion is a spacecraft designed by Lockheed Martin for NASA, the space agency of the United States. Orion development began in 2005 as part of the Constellation program, where Orion would fulfill the function of a Crew Exploration Vehicle....
crew module remains in lunar orbit.
Altair was intended to be capable of operating away from Earth (in space and on the lunar surface) for up to 210 Earth days. Altair will also be capable of flying unmanned missions, as had been proposed with LM Truck concept during the Apollo Applications Program
Apollo Applications program
The Apollo Applications Program was established by NASA headquarters in 1968 to develop science-based manned space missions using surplus material from the Apollo program...
. Mission planners would have been able to choose among three distinct mission modes for Altair:
- Crewed sortie mode
- Crewed outpost mode (with no airlock)
- Uncrewed cargo mode, capable of transporting up to 15 metric tons to the lunar surface
Altair, like the LM, was planned to have two hatches; one on top for docking and internal transfer between Altair and Orion, and a main hatch for accessing the lunar surface. Unlike the Apollo LM, Altair had an airlock similar to those on the Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
and the International Space Station
International Space Station
The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...
between the cabin and main hatch. The airlock allowed the astronauts to don and doff their spacesuits without tracking potentially hazardous moon dust into the main cabin and allowed the vehicle to retain its internal pressure. Unlike the Apollo LM, in which the entire cabin was depressurized during extra-vehicular activity
Extra-vehicular activity
Extra-vehicular activity is work done by an astronaut away from the Earth, and outside of a spacecraft. The term most commonly applies to an EVA made outside a craft orbiting Earth , but also applies to an EVA made on the surface of the Moon...
, the airlock would have allowed a crew member with a malfunctioning spacesuit to quickly return to the Altair spacecraft without having to terminate the entire EVA, and allowed the landing party to complete most of their tasks during their 7-day lunar stay. Also, the airlock would have remained as part of the Altair's descent stage, allowing NASA to utilize the airlock as a component of the Lunar Outpost.
Because the Ares V
Ares V
The Ares V was the planned cargo launch component of the Constellation program, which was to have replaced the Space Shuttle after its retirement in 2011. Ares V was also planned to carry supplies for a human presence on Mars...
payload shroud was planned to have a diameter of 33 feet (10.1 m) and height of 49 feet (14.9 m) (including landing gear), the landers were designed to retract so as to fit within the Ares V's payload shroud.
The spacecraft would also have included an improved miniature camping-style toilet, similar to the unit now used on the ISS and the Russian Soyuz spacecraft
Soyuz spacecraft
Soyuz , Union) is a series of spacecraft initially designed for the Soviet space programme by the Korolyov Design Bureau in the 1960s, and still in service today...
, a food warmer to eliminate the "cold soup" menu used during Apollo missions, a laser-guided distance measurement system (with radar backup), using data acquired by advanced unmanned lunar orbiting spacecraft, and new "glass cockpit
Glass cockpit
A glass cockpit is an aircraft cockpit that features electronic instrument displays, typically large LCD screens, as opposed to the traditional style of analog dials and gauges...
" and Boeing 787
Boeing 787
The Boeing 787 Dreamliner is a long-range, mid-size wide-body, twin-engine jet airliner developed by Boeing Commercial Airplanes. It seats 210 to 290 passengers, depending on the variant. Boeing states that it is the company's most fuel-efficient airliner and the world's first major airliner to use...
-based computer system identical to that on the Orion spacecraft.
Engines
Altair intended to utilize current cryogenicCryogenic fuel
Cryogenic fuels are fuels that require storage at extremely low temperatures in order to maintain them in a liquid state. Cryogenic fuels most often constitute liquefied gases such as liquid hydrogen....
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, will be force-fed using high-pressure helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
, eliminating the need for malfunction-prone pumps utilized in most rocket technology.
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
Aerojet
Aerojet is an American rocket and missile propulsion manufacturer based primarily in Rancho Cordova, California with divisions in Redmond, Washington, Orange, Gainesville and Camden, Arkansas. Aerojet is owned by GenCorp. They are the only US propulsion company that provides both solid rocket...
AJ-10 rocket engine and the amount of fuel it carries are insufficient to brake the Orion/Altair stack into lunar orbit (also crucial if it is flown unmanned without an Orion crew). The new lander would have been powered by a modified RL-10
RL-10
The RL10 was USA's first liquid hydrogen fueled rocket engine. An updated version is used in several current launch vehicles. Six RL10 engines were used in the S-IV second stage of the Saturn I rocket. One or two RL10 engines are used in the Centaur upper stages of Atlas and Titan rockets...
engine (currently in use on the upper stage of the Delta IV rocket
Delta IV rocket
Delta IV is an active expendable launch system in the Delta rocket family. Delta IV uses rockets designed by Boeing's Integrated Defense Systems division and built in the United Launch Alliance facility in Decatur, Alabama. Final assembly is completed at the launch site by ULA...
and Centaur upper stage of the Atlas V
Atlas V
Atlas V is an active expendable launch system in the Atlas rocket family. Atlas V was formerly operated by Lockheed Martin, and is now operated by the Lockheed Martin-Boeing joint venture United Launch Alliance...
rocket), burning liquid hydrogen
Liquid hydrogen
Liquid hydrogen is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.To exist as a liquid, H2 must be pressurized above and cooled below hydrogen's Critical point. However, for hydrogen to be in a full liquid state without boiling off, it needs to be...
(LH2) and liquid oxygen
Liquid oxygen
Liquid oxygen — abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries — is one of the physical forms of elemental oxygen.-Physical properties:...
(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
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...
(LCH4), as future missions to Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
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 have forced NASA to stick with cryogenic and hypergolic systems for the near future, although later variants of Altair were meant to serve as testbeds for methane rockets and Sabatier reactors after a permanent lunar base is established.
On-orbit assembly
Because of the spacecraft's size and weight, Altair, and its associated Earth Departure StageEarth Departure Stage
The Ares V Earth Departure Stage was a rocket stage which NASA planned to design at its Marshall Space Flight Center in Huntsville, Alabama as part of Project Constellation...
, would have been launched into a low-Earth orbit (LEO) using the heavy-lift Ares V
Ares V
The Ares V was the planned cargo launch component of the Constellation program, which was to have replaced the Space Shuttle after its retirement in 2011. Ares V was also planned to carry supplies for a human presence on Mars...
launch vehicle, followed by a separate launch of an Orion spacecraft lifted by an Ares I
Ares I
Ares I was the crew launch vehicle that was being developed by NASA as part of the Constellation Program. The name "Ares" refers to the Greek deity Ares, who is identified with the Roman god Mars...
. 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 would have been 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 GrummanNorthrop Grumman
Northrop Grumman Corporation is an American global aerospace and defense technology company formed by the 1994 purchase of Grumman by Northrop. The company was the fourth-largest defense contractor in the world as of 2010, and the largest builder of naval vessels. Northrop Grumman employs over...
, which built the Apollo Lunar Module, was contracted to help the project office develop the system concept.