LCROSS Mission on Track Despite Propellant Binge

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A navigation glitch that caused NASA’s Lunar Crater Observation and Sensing Satellite (LCROSS) to consume more than half of its propellent over the weekend should not prevent the novel spacecraft from crashing into the Moon this October as planned.

Designed by Redondo Beach, Calif.-based Northrop Grumman Aerospace Systems, the $80 million LCROSS was launched June 18 with NASA’s Lunar Reconnaissance Orbiter atop an Atlas 5 rocket. The spacecraft’s primary mission is to search for water on the Moon by transmitting data and images of debris plumes that will occur when the spacecraft’s spent upper-stage Centaur rocket crashes into the lunar surface Oct. 9.

NASA officials say the LCROSS mission remains on track, despite the anomaly discovered Aug. 22 by NASA’s mission operations team at Ames Research Center in Mountain View, Calif.

“[LCROSS] does have enough fuel to complete its mission,” NASA spokesman Grey Huataluoma said Aug. 26.

According to spacecraft data, a problem with the probe’s inertial reference unit, a sensor used for attitude control and vehicle orientation, caused the spacecraft’s thruster to fire excessively, draining an estimated 100 kilograms to 140 kilograms of onboard propellant, according to Northrop Grumman spokeswoman Sally Koris.

Since then the operations team at NASA Ames took steps to restart the spacecraft’s inertial reference unit and reduce fuel consumption to a nominal level. Procedures also were implemented to minimize the possibility of another anomaly occurring while the spacecraft is out of contact with the ground. Since the restart, the inertial sensor has not experienced any additional problems, according to information available on NASA’s LCROSS Web site.

The team is continuing to investigate the root cause of the problem with LCROSS manufacturers, but mission managers are optimistic that the probe will reach its planned impact at the lunar south pole, currently set for 7:30 a.m. EDT Oct. 9. The impact is expected to create a plume of debris that will expose any water ice, hydrocarbons or organics to sunlight, at which point they will vaporize, breaking down into basic components that can be monitored by the LCROSS spacecraft before it, too, crashes into the lunar surface.

The debris cloud also is expected to be visible from Earth by amateur astronomers with telescopes as small as 25.4 centimeters to 30.5 centimeters in diameter.