Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site petrus.UUCP Path: utzoo!watmath!clyde!burl!ulysses!ucbvax!decvax!bellcore!petrus!karn From: karn@petrus.UUCP (Phil R. Karn) Newsgroups: net.space Subject: Re: communications satellite insurance rates Message-ID: <563@petrus.UUCP> Date: Tue, 17-Sep-85 23:47:17 EDT Article-I.D.: petrus.563 Posted: Tue Sep 17 23:47:17 1985 Date-Received: Fri, 20-Sep-85 04:48:17 EDT References: <536@petrus.UUCP> <528@riccb.UUCP> <539@petrus.UUCP> <530@riccb.UUCP> Organization: Bell Communications Research, Inc Lines: 45 > Right, but the vast majority of failures to get satellites on station are > due to a problem while the payload is still within the launcher. True. What do you consider to be the "launcher"? Does this include problems with the AKMs? My point was just that you should compare apples with apples by considering the PAMs to be part of the "shuttle launcher" when comparing it to Ariane. > Only to a limit. There are a lot of satellites that simply cannot be lifted > (to GEO transfer orbit) by Ariane, Delta, Atlas, or even Titan because of > their maximum capacity. But since you were probably intending this to apply > strictly to communications satellites (of which the HS-376 type is typical) > this point is moot. F'rinstance? Both Shuttle and Ariane (with its "SYLDA" - SYsteme Lancement Duel Ariane) are usually flown these days with multiple payloads. Very few communications satellites require (or can afford!) the full capacity of either a Shuttle or Ariane. > You don't need it when you're safely tucked away in the womb of the shuttle > cargo bay. Ariane can do no such thing because it does not provide as > "friendly" an environment as the shuttle does. Not quite. Read some of the back issues of AW&ST regarding the hassles SBS went through as the pioneer Shuttle customer. A major problem was the nasty thermal environment in the cargo bay. A payload like a communications satellite can withstand only brief periods (minutes to hours) in continuous shadow or sunlight. Beyond that, you start melting solar arrays or freezing batteries. The "baby buggy" shade now used with all HS-376-class payloads was the result. It has to be opened for the bay doors to close (i.e., during launch), but then it has to be closed quickly after achieving orbit in order to protect the payload. As you know, this was a problem on the last flight with the Australian satellite and it had to be deployed early. My question is, why can't they just plan to deploy satellites early in the first place and get it over with? Once a satellite like the HS-376 is spun up and deployed (with the proper attitude) it is quite able to take care of itself. Ariane gets you spun up and deployed at the proper attitude (e.g., normal to the sun line) within 15 minutes of leaving the pad, and by then the satellite temperature has hardly had a chance to change much from the nice 20C given it by the ground purge system. (more to follow) Phil Brought to you by Super Global Mega Corp .com