Comments on: A long-lost object on the Moon will help test general relativity

By: David Harris

David Harris — Thu, 29 Apr 2010 22:22:15 +0000

@Peter: That is cool – if you find out more info about that radar corner reflector, let us know. I’m not sure radar would be so useful for this kind of test as the wavelength is probably too long for the precision measurements they are trying to make. But I seem to remember hearing about some other experiments that involved firing radar at the Moon. I’ll try to dig that out.

By: Peter Chivers

Peter Chivers — Thu, 29 Apr 2010 03:49:46 +0000

This is great stuff and well done. I seem to remember that a RADAR three corner reflector was also left on the moon by one of the APOLLO teams! Hence a test in the RF spectrum could be conducted as well.?

By: David Harris

David Harris — Wed, 28 Apr 2010 16:13:53 +0000

Thanks, Joel. The text has been amended above.

By: Joel Raupe

Joel Raupe — Wed, 28 Apr 2010 15:29:47 +0000

It’s not precise to credit the San Diego team with finding Lunokhod 1. That belongs to the Lunar Reconnaissance Orbiter Camera (LROC) at Arizona State University (and NASA/Goddard). Without their precision targeting of the LRO, slewing its narrow angle camera and locating Lunokhod 1, the San Diego team would not have succeeded in tapping a reflection, though this last accomplishment is no mean feat. A pencil-thin laser is a half-mile in width by the time of its return. (The reflection is tallied in individual photons.) 39 years of rigorous searching failed, though the Apache Point (NM) team, taking over from McDonald Observatory in 2005, had high hopes after LRO’s nominal mission began. Their patience paid off. Lunokhod 1 appears to have ended up 1400 meters north of its carrier lander.