Jan 14 2009
From The Space Library
NASA announced the successful conclusion of the third round of testing of the Common Extensible Cryogenic Engine (CECE) technology, intended to return astronauts to the lunar surface safely. Pratt & Whitney Rocketdyne in West Palm Beach, Florida, had conducted the tests to gather data on the concept engine. Engineers had designed the CECE with the flexibility to reduce thrust from 100 percent to 10 percent, allowing a spacecraft to land gently on the lunar surface. The test set a record, with the engine successfully throttled to 104 percent of its potential and then reduced to 8 percent. A careful assessment of test results from the first two rounds of testing had shown pressure oscillations in the engine at lower throttle levels, known as “chugging.” The vibrations from the chugging could potentially resonate with the structure of the rocket, causing problems for the lander and the crew. However, in the third round of testing, engineers successfully eliminated engine chugging. To achieve this, they controlled the flow of liquid hydrogen and liquid oxygen to the combustion chamber, using a new injector design and propellant feed system that carefully managed the pressure, temperature, and flow of propellants.
NASA, “NASA Tests Engine Technology for Landing Astronauts on the Moon,” news release 09-005, 14 January 2009, http://www.nasa.gov/home/hqnews/2009/jan/HQ_09-005_Cryo_engine_test.html (accessed 14 January 2011).
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