LCROSS Looks Back at Earth

On Saturday, Aug. 1, 2009, the LCROSS spacecraft successfully completed its first Earth-look calibration of its science payload. An additional Earth-look and a moon-look are scheduled for the remainder of the cruise phase of the mission.

The purpose of the LCROSS Earth-look was to perform a routine health check on the science instruments, refine camera exposure settings, check instrument pointing alignment, and check radiometric and wavelength calibrations.

From its vantage point of 223,700 miles (360,000 km) from Earth, the LCROSS science team changing exposure and integration settings on the spacecraft’s infrared cameras and spectrometers and performed a crossing pattern, pushing the smaller fields of view of the spectrometers across the Earth’s disk. At this range, the Earth was approximately 2.2 degrees in diameter.

“The Earth-look was very successful,” said Tony Colaprete, LCROSS project scientist. “The instruments are all healthy and the science teams was able to collect additional data that will help refine our calibrations of the instruments.”

During the Earth observations, the spacecraft’s spectrometers were able to detect the signatures of the Earth’s water, ozone, methane, oxygen, carbon dioxide and possibly vegetation.