It was the episode about the moon landings were faked/conspiracies, I think it aired Labor Day weekend in the US. She was the final segment, the astronomer who shoots a laser at the moon. As it happens, she's doing one of those runs 1am Friday morning.

They taped it in January, unfortunately I had to be in Phoenix that day and couldn't go to the observatory. The funny thing was that they were testing their cold weather gear (which was all crap) as they went from New Mexico to Alaska to film that special. Dunno why it took so long to air.

I got a Mythbusters t-shirt out of it, they have an autographed poster at the observatory.