NASA's Apollo lunar module ascent engine roars again

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An Apollo lunar module ascent engine has been test fired after being in storage for decades to help technology development for NASA's new Moon programme Constellation.

Fired on the auxiliary propulsion system testbed at White Sands Test Facility three times over 25 and 26 June for undisclosed durations, the Pratt & Whitney Rocketdyne RS-18 used liquid oxygen and liquid methane. For Apollo the engine used hypergolic propellants, but NASA wants to switch to cryogenic fuels for an estimated mass saving of 910kg (2,000lb) for its new Altair lunar lander.

nasa apollo lunar lander rs-18 ascent stage engine fired in june
©NASA

 Above: Camera 3 at the auxiliary propulsion system testbed at the White Sands Test Facility captures an image of one of the engine firings
The last time a lunar ascent engine was test fired was 36 years ago. Speaking at the American Institute of Aeronautics and Astronautics' Joint Propulsion Conference in Hartford, Connecticut, ascent engine test team member John Melcher declined to say how long the firings lasted. He said: "If the test is less than 1s the data can have too many errors."

He added that future firings could last for 5s and that there is resistance within NASA against using cryogenics as they do not ignite on contact while hypergolics do, making ignition simple. Ignition pyrotechnics for cryogenic propellants were tested in the third quarter of 2007. Altair is planned to fly to the Moon by 2020 carrying up to four astronauts for a lunar surface mission lasting a week or more.