For Lunar Reconnaissance Orbiter (LRO), the lunar eclipse on June 15, 2011 is likely to be the longest and darkest of its life. This matters because LRO relies on sunlight to power its systems and instruments. Although it spends half of every orbit on the night side of the Moon, each night side pass lasts only an hour. For the June 15 eclipse, LRO will be in the dark for more than twice as long.
During a previous total eclipse, LRO hibernated, turning off all of its instruments to conserve its battery power until the Moon emerged from the Earth's shadow. For the June 15 event, LRO will leave on the Diviner Lunar Radiometry Experiment. Diviner will measure the cooling of the Moon's surface during the eclipse. This unique temperature record is expected to reveal information about the roughness and composition of the swath of lunar surface visible to Diviner's sensors during the eclipse.
The visualization archived on this page shows LRO flying over the lunar surface during the darkest part of the eclipse, with Diviner measuring temperatures along a swath about 3.5 kilometers wide. LRO will pass this part of the surface again during the eclipse, and it will tilt a bit so that Diviner can point at the same strip of lunar surface. The difference between the two temperature readings gives the rate of cooling at each point along the swath.
Other visualizations in this series depict the view of the eclipse