Washington, Dec 16 (): NASA’s twin lunar-orbiting GRAIL spacecraft are getting ready to crash into the Moon’s surface as a final send-off.
Ebb and Flow, the two space probes of the Gravity Recovery and Interior Laboratory (GRAIL) mission probes, are being sent intentionally into the lunar surface as their low orbit and low fuel levels prohibit further scientific operations.
These two space probes will make suicidal falls on Dec 17. The first impact will come 40 seconds past 5:38 p.m. Eastern Standard Time when Ebb slams into a mountain near the Moon’s north pole at 3,760 miles per hour. The second, from Ebb’s twin, Flow, will come 20 seconds later.
The site is located near a crater named Goldschmidt and this site is selected to avoid the chance of hitting any of the Apollo or other lunar relics and the impacts are not expected to be visible from Earth since the action will happen on the dark side of the Moon.
The probes have been flying around the moon since January 1, 2012 starting with an average altitude of 55km above the surface of the Moon, during their prime mission from March through May and then sinking to around 23km for a closer look in August for an extended mission. At some points they were flying just a few miles above the moon’s tallest mountains.
Previous unmanned trips to the moon have studied its lumpy gravitational field, but Ebb and Flow are the first ones dedicated to this goal. Since their entry into the orbit, the formation-flying spacecraft have peered past the craggy surface into the interior.
The mission has already provided astronomers with key data concerning the surface of the moon and its evolution. The duo’s successful primary mission yielded the highest-resolution gravity field map of any celestial body. Future gravity field models developed from data collected during the extended mission will be of even higher resolution.
Finally, the crash landing, which will conclude the year-long mission, could also yield valuable data for scientists here on Earth.
Ebb and Flow will not be the first craft to crash into the moon. NASA’s GRAIL mission web page says 12 U.S., Soviet and Japanese spacecraft crashed into the moon’s surface between 1959 and 1993.