by neufer » Wed Sep 03, 2008 4:26 pm
I had mentioned that due to the moon's orbital velocity of ~ 1 km/s
that a lidar beam bouncing off of a lunar retroreflector would be sent
back where it came from
in the moon's frame of reference but not in
the earth's frame of reference such that the center of the return beam
would end up centered 2.5km. east of the lidar observatory.
However, as apparent in
http://apod.nasa.gov/apod/ap080903.html ,
the earth is
also rotating in the same eastward direction as the
moon at about 0.4 km/s such that the center of the return beam
ends up centered only 1.5km. east of the lidar observatory.
Since the return beam is much wider than 1.5km. this is not a problem.
I had mentioned that due to the moon's orbital velocity of ~ 1 km/s
that a lidar beam bouncing off of a lunar retroreflector would be sent
back where it came from [b]in the moon's frame of reference[/b] but not in
the earth's frame of reference such that the center of the return beam
would end up centered 2.5km. east of the lidar observatory.
However, as apparent in http://apod.nasa.gov/apod/ap080903.html ,
the earth is [b]also[/b] rotating in the same eastward direction as the
moon at about 0.4 km/s such that the center of the return beam
ends up centered only 1.5km. east of the lidar observatory.
Since the return beam is much wider than 1.5km. this is not a problem.