The tests by Pratt and Whitney Rocketdyne in West Palm Beach, Florida, helped gather data on this concept engine that might play a role in the next stage of human exploration of the moon.
The goal of a lunar lander descent engine is to slow the vehicle so astronauts can land safely.
Known as the Common Extensible Cryogenic Engine, or CECE, the engine is deep-throttling one, which means it has the flexibility to reduce thrust from 100 percent down to 10 percent, allowing a spacecraft to gently land on the lunar surface.
The 13,800-pound thrust engine uses extremely cold liquid oxygen and liquid hydrogen as propellants. During the test, the engine was successfully throttled from a high of a 104 percent of the engine"s potential down to eight percent, a record for an engine of this type.
A cryogenic engine is needed to provide high performance and put more payload on the surface of the moon. The CECE demonstrator has evaluated two engine configurations during three rounds of hot-fire testing.
“The first test series in 2006 was a challenge but showed promise," said Tony Kim, Deep Throttling Engine project manager at NASA"s Marshall Space Flight Center, Huntsville, Alabama.
“Testing in 2007 provided an in-depth examination of low-power-level throttling and engine performance characteristics. This third cycle we actively addressed and found solutions to the challenges we faced," he added.
The team carefully assessed test results that showed pressure oscillations in the engine at lower throttle levels called “chugging." The latest engine configuration incorporates a new injector design and propellant feed system that carefully manages the pressure, temperature and flow of propellants.
“The technology developed from this effort will help engineers successfully design future cryogenic engines to meet the throttling requirements of the Constellation Program"s Altair lunar lander," Kim said.&13;