The RS-18 is a reconfigured version of the

Rocketdyne Rocketdyne was 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. The Rocke ...

Lunar Module Ascent Engine (LMAE), modified to burn

liquid oxygen Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an applica ...

(LOX) and liquid methane (CH₄) for NASA's

Exploration Systems Architecture Study The Exploration Systems Architecture Study (ESAS) is the official title of a large-scale, system level study released by the National Aeronautics and Space Administration (NASA) in November 2005 of his goal of returning astronauts to the Moon and ...

(ESAS) engine testing in 2008.

Development

The 2005 NASA Exploration Systems Architecture Study (ESAS), part of the 2004

Vision for Space Exploration Vision, Visions, or The Vision may refer to: Perception Optical perception * Visual perception, the sense of sight * Visual system, the physical mechanism of eyesight * Computer vision, a field dealing with how computers can be made to gain und ...

, recommended that the crew exploration vehicle (CEV)

lunar surface access module The Altair spacecraft, previously known as the Lunar Surface Access Module or LSAM, was the planned lander spacecraft component of NASA's cancelled Constellation program. Astronauts would have used the spacecraft for landings on the Moon, wh ...

(LSAM) ascent stage propulsion and service module propulsion systems employ a pressure-fed LOX/liquid methane (CH₄) engine. "Green" propellants, such as

LOX Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an appli ...

and

liquid methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...

, 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