Go to link this link and let it down load then start watching the video at 21minutes into the NASA video. You see things passing behind the tether, since they pass behind the tether they can not be ice crystals. The camera if I remember right is 75 miles away makings some of these things enormously huge. http://video.google.com/videoplay?docid=-9080369676973948865&q=ufo
They look like dropa stones that were found in a cave on the borders of China and Tibet which is interesting read in of itself.