karn@petrus.UUCP (Phil R. Karn) (03/13/86)
I wonder if anyone else out there was also fascinated by the photo on page 73 of the March 3, 1986 Aviation Week. It shows a group of domestic US communications satellites remaining stationary against a moving background of stars. A friend spoke with the NASA contractor employee who took that picture and learned the following: The picture was taken with an ordinary 35 mm camera, a 200 mm lens, and ASA 1000 color film (presumably Kodak VR-1000). The exposure was 5 minutes (I guessed 4 from the lengths of the star trails and the stated spacing of the satellites). The satellites themselves aren't so dim that lightgathering is much of a problem; apparently the biggest problem is finding a location that is truly free from light pollution. This raises the interesting possibility of amateurs doing a full optical survey of the geostationary orbit, identifying and cataloguing each object. I wonder how bright the various Rhyolite electronic-intelligence satellites and their successors mentioned in The Puzzle Palace are. Considering that they have very large antennas which are probably fairly reflective due to thermal coatings, I suspect they are even easier to see than the Hughes HS-376 class spacecraft shown in Av Week, which are mostly dark solar arrays. The best time to make these photos would be at local midnight, when the lit side of the spacecraft fully faces the earth. Of course, you'd have to avoid the spring and fall eclipse seasons. Phil Karn