The RS-18 is a reconfigured version of the

Rocketdyne Rocketdyne is an American rocket engine design and production company headquartered in Canoga Park, California, Canoga Park, in the western San Fernando Valley of suburban Los Angeles, California, Los Angeles, in southern California. Rocketdyne ...

Lunar Module Ascent Engine (LMAE), modified to burn

liquid oxygen Liquid oxygen, sometimes abbreviated as LOX or LOXygen, is a clear cyan liquid form of dioxygen . It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an application which is ongoing. Physical ...

(LOX) and liquid methane (CH₄) for NASA's Exploration Systems Architecture Study (ESAS) engine testing in 2008.

Development

The 2005 NASA Exploration Systems Architecture Study (ESAS), part of the 2004 Vision for Space Exploration, recommended that the crew exploration vehicle (CEV) lunar surface access module (LSAM) ascent stage propulsion and service module propulsion systems employ a pressure-fed LOX/liquid methane (CH₄) engine. "Green" propellants, such as LOX and liquid methane, offer savings in both performance and safety over equivalently sized hypergolic propulsion systems in spacecraft applications such as ascent engines or service module engines. The mass savings over monomethyl hydrazine (MMH) and nitrogen tetroxide (N₂O₄) were around 1,000 - 2,000 lb (450 – 910 kg) for the LSAM ascent module, which was larger than the current design. The thrust levels identified in ESAS were 5,000 - 10,000 lbf (22 - 44 kN) for the ascent engine. To remove key technology risks in the decision for hypergolic or LOX/Methane, the Propulsion and Cryogenics Advanced Development (PCAD) project is being conducted within NASA, led by the Glenn Research Center, for 5,500 lbf (24,500 N) ascent engine technology.

Progress

The RS-18 rocket engine was tested using LOX and liquid methane under simulated altitude conditions at NASA Johnson Space Center White Sands Test Facility (WSTF). This project is part of NASA's Propulsion and Cryogenics Advanced Development (PCAD) project. Altitude simulation was achieved using the WSTF Large Altitude Simulation System, which provided altitude conditions equivalent up to —122,000 ft (~ 37 km). The RS-18 gas spark-torch igniters were designed and supplied by Pratt and Whitney Rocketdyne as part of the LOX/Methane RS-18 test program. Pyrotechnic ignition was not attempted on the RS-18, but was subsequently successfully demonstrated as part of the 2009 Armadillo Aerospace IPP engine testing. The RS-18 engine was not selected for the

Constellation program The Constellation program (abbreviated CxP) was a crewed spaceflight program developed by NASA, the space agency of the United States, from 2005 to 2009. The major goals of the program were "completion of the International Space Station" and a " ...

, and that NASA program was eventually cancelled on February 1, 2010.

References

{{Include-NASA Rocket engines using methane propellant Rocketdyne engines Rocket engines using the pressure-fed cycle Rocket engines of the United States