This press release tells us that the Apache Point Observatory is now getting laser ranges to the newly recovered Lunokhod 1. The reflected signal is twice as strong as that from Lunokhod 2 and this new target means there are now five functioning reflectors on the moon.

Steve M

Huh. Very cool! Score another victory for LRO!

Kind of amazing that they've been trying for almost 40 years to get a laser reflection off of it, yet the reflector was apparently very well-oriented with respect to the Earth. Of course, they did state the detection levels in terms of photons returned, and snagging 2000 is seemingly remarkable performance; the SNR for this sort of thing must be quite low indeed.

There's a preprint of a paper summarizing the first four months of ranging to Lunokhod 1 that has been submitted to Icarus : "Laser Ranging to the Lost Lunokhod 1 Reflector" at arxiv.org. The authors find Lunokhod 1 to be "especially valuable for science because it is closer to the Moon’s limb than any of the other reflectors and, unlike the Lunokhod 2 reflector, we find that it is usable during the lunar day."

Steve M