Topics: Space Exploration - 1.1.3 NASA Constellation Program

1.1.3 NASA Constellation Program


Constellation Program (abbreviated CxP) is a human spaceflight program within NASA, the space agency of the United States. The stated goals of the program are: gaining significant experience in operating away from Earth's environment; developing technologies needed for opening the space frontier; and conducting fundamental science.



Constellation was developed through the Exploration Systems Architecture Study, which determined how NASA would pursue the goals laid out in the Vision for Space Exploration and the NASA Authorization Act of 2005. On February 1, 2010, President Barack Obama announced a proposal to cancel the program effective with the U.S. 2011 fiscal year budget, but later announced changes to the proposal in a major space policy speech at Kennedy Space Center on April 15, 2010, which includes reviving the Orion capsule for use as a rescue spacecraft at the International Space Station.



Part of the Constellation program involves the development of spacecraft and booster vehicles to replace the Space Shuttle and send astronauts to the Moon and possibly to Mars as well. NASA has already begun the process of designing two boosters, the Ares I and Ares V. Ares I would have the sole function of launching mission crews into orbit, while Ares V would be used to launch other hardware for use on missions requiring a heavier lift capacity than the Ares I booster. In addition to these two boosters, NASA is designing a set of other spacecraft for use during Constellation. These include the Orion crew capsule, the Earth Departure Stage and the Altair lunar lander.



Spacecraft

Orion

Orion is being designed as the crew compartment for the Constellation program and Earth orbit missions. Lockheed Martin was selected as the prime contractor to build Orion on August 31, 2006, and Boeing was selected to build the primary heat shield for the Orion crew exploration vehicle on September 15, 2006. NASA is currently planning on developing different Orion capsules tailored for specific missions. The Block I Orion is to be used for International Space Station crew rotation and resupply and other Earth orbit missions, while the Block II and III variants would be designed for deep-space exploration.



Orion consists of three main parts: a Crew Module (CM) similar to the Apollo Command Module but capable of holding four to six crew members; a cylindrical Service Module (SM) containing the primary propulsion systems and consumable supplies; and the Launch Abort System (LAS) which provides capability for the astronauts and Crew Module to escape from the launch vehicle should problems arise during launch ascent. The Orion Crew Module is designed to be reusable for up to 10 flights, allowing NASA to construct a fleet of Orion crew modules.



Altair

Altair (formerly known as the Lunar Surface Access Module, LSAM) would be the main transport vehicle for lunar-bound astronauts. The Altair design is much larger than the Apollo Lunar Module(LM), with almost 5 times the volume, occupying a total of 1,120 cubic feet (32 m3) compared with the Apollo lander's 235 cubic feet (6.7 m3). It stands 32 feet (9.8 m) tall and spans 49 feet (15 m) wide from landing gear tip to tip.



Like its Apollo LM predecessor, Altair consists of two parts: an ascent stage which houses the four-person crew; and a descent stage which has the landing legs, the majority of the crew's consumables (oxygen and water), and scientific equipment. Unlike the Apollo LM, Altair would touch down in the lunar polar regions favored by NASA for future lunar base construction. Altair, like the LM, is not reflyable; the ascent stage would be discarded after use.



The Altair descent stage is to be powered by four RL-10 rocket engines that are currently used for the Centaur upper stage used on the Atlas V rocket. Unlike the current RL-10 engines in use, the newer RL-10s would be able to throttle down to as low as 10% rated thrust (the current specifications allow for 20%), thus allowing the use of Altair for both the lunar orbit insertion (LOI) and landing stages of the lunar mission. The ascent stage is to be powered by a single engine, likely a hypergolic engine similar or identical to the main engine of the Orion CSM, using the descent stage as a launchpad and as a platform for future base construction. There remains a small possibility that the original plan of using LOX/CH4 – fueled engines on board the Block II (lunar) Orion CSM and Altair ascent stage could come to pass; however, this appears very unlikely.



Earth Departure Stage

The Earth Departure Stage (EDS) is the main propulsion system that would send the Ares V Orion/Altair upper stage from low Earth orbit to the Moon. It is the second liquid stage of the Ares V rocket. The Orion spacecraft would launch separately on Ares I, and rendezvous and dock with the Ares V EDS/Altair combination, which would then be configured for the journey to the Moon (known as Earth orbit rendezvous).
1.1.3  NASA Constellation Program
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