NASA boffins are chuffed as ninepence this week to announce that they have discovered unmistakable signs of a crashed spacecraft far away from the Apollo landing sites on the far side of the Moon.
Now you see my ejecta, now you don't
The boffins believe that the wrecked craft was the Lunar Atmosphere and Dust Environment Explorer (LADEE), sent into orbit around the moon after taking off from Earth in September 2013. As you might expect, LADEE was intended to settle an acrimonious debate among scientists as to whether lunar dust is, or is not, lofted up high above the surface into space.
As it turns out, it isn't: and with this discovery, LADEE's work was largely done. The space probe was sent on a final gradual plunge down towards the lunar surface, carefully aimed so as not to inadvertently crash into one of the historic Apollo landing sites where men once walked.
We are told:
LADEE's engines fired April 11, 2014, to perform a final orbital maintenance maneuver and adjust to guarantee it would impact on the farside of the moon and away from the Apollo landing sites. Over a seven-day period, LADEE's orbit decreased and the spacecraft orbited very low to the surface and close to the walls of lunar craters and mountain ridges to give the team a chance to collect valuable science data. Finally, LADEE impacted the eastern rim of Sundman V crater on April 18.
As the Sundman crater lies just over the rim of the moon as seen from Earth, it wasn't possible to spy the impact site of the LADEE directly from Earth. However our old friend the Lunar Reconnaissance Orbiter (LRO), recently given a two year life extension by NASA, was able to find it from overhead.
LRO boffins tell us:
The impact site is about half a mile (780 meters) from the crater rim with an altitude of about 8,497 feet (2,590 meters) and was only about two tenths of a mile (300 meters) north of the location mission controllers predicted based on tracking data.
The impact crater is small, less than ten feet (three meters) in diameter, barely resolvable by the LROC NAC. The crater is small because the spacecraft - compared to most celestial impacts - was not traveling very fast, approximately 3,800 miles per hour (1,699 meters per second) and had a low mass and a low density. The size of the impact crater made it hard to identify among the myriad of small fresh craters on the lunar surface. Images acquired of the impact region before the impact, were compared with images obtained after the impact to identify the crater.
"As it turns there were several small surface changes found in the predicted area of the impact, the biggest and most distinctive was within 968 feet (295 meters) of the spot estimated by the LADEE operations team," gushes LRO bigcheese Mark Robinson. "What fun!"
Just so. There's more on the LADEE moon rim prang spot from the LRO team here. ®