Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!decvax!harpo!eagle!karn From: karn@eagle.UUCP (Phil Karn) Newsgroups: net.space Subject: Re: sattelites Message-ID: <1047@eagle.UUCP> Date: Thu, 21-Jul-83 06:09:42 EDT Article-I.D.: eagle.1047 Posted: Thu Jul 21 06:09:42 1983 Date-Received: Thu, 21-Jul-83 21:35:37 EDT References: sri-arpa.3180 pur-phy.835 Lines: 21 In the interests of reducing netnews traffic in general and flame reduction in particular, I've worked out the percentage visibility between a shuttle orbiter and a geostationary satellite. Using my orbit program and a bit of geometry, I stepped through a one day period in 10 second steps, counting the number of steps in which the shuttle can see the geostationary satellite. The answer is 54.87%. Assumptions: 1. The shuttle is in a ~300 km, 28.46 deg inclination circular orbit. (Specifically I used STS-7.) 2. Not knowing the final location of TDRS-1, I used SBS-2 which is parked at 97 deg west. The actual position won't matter when averaged over a long interval, since the TDRS will rotate once per day around the shuttle's orbit plane. 3. The earth is perfectly spherical for purposes of visibility. 4. Communications aren't cut off until the earth itself actually blocks the direct line-of-sight path. (I.e., the atmosphere is ignored.) Phil