techpubs@PRC.Unisys.COM (Technical Pub. Vince Short) (09/18/90)
In the STS-41 press kit, we find that:
". . . After being deployed from Discovery . . . a two-stage Inertial
Upper Stage and a single-stage Payload Assist Module will boost Ulysses
on a trajectory that will take it to Jupiter in 16 months. . . ."
This is a direct transfer orbit to Jupiter.
My question: if this can be done for Ulysses (direct transfer orbit
to Jupiter), why couldn't it have been done for Gallileo which
was sent to Jupiter via a complex Venus-Earth-Earth gravity assist orbit.
Gallileo was launched via Atlantis during mission STS-34 in October 1989.
However, it only used an Inertial Upper Stage (IUS) without the "assist"
of a Payload Assist Module (PAM) after the IUS burns.
Why no PAM on Gallileo? Is Gallileo so much heavier than Ulysses? Anyone
have any numbers (masses, delta v's, etc) for the craft and their orbits?
Was there just no way to attach a PAM between the IUS and Gallileo?
Or what?
Joseph M. Fedock
Technical Publications
Unisys Corporation
DS/EISG/VFL
Paoli, PA 19301
(215) 648-2495
techpubs@burdvax.PRC.Unisys.COM clj@ksr.com (Chris Jones) (09/18/90)
In article <15004@burdvax.PRC.Unisys.COM>, techpubs@PRC (Technical Pub. Vince Short) writes: >In the STS-41 press kit, we find that: > >". . . After being deployed from Discovery . . . a two-stage Inertial >Upper Stage and a single-stage Payload Assist Module will boost Ulysses >on a trajectory that will take it to Jupiter in 16 months. . . ." > >This is a direct transfer orbit to Jupiter. > >My question: if this can be done for Ulysses (direct transfer orbit >to Jupiter), why couldn't it have been done for Gallileo which >was sent to Jupiter via a complex Venus-Earth-Earth gravity assist orbit. > >Gallileo was launched via Atlantis during mission STS-34 in October 1989. >However, it only used an Inertial Upper Stage (IUS) without the "assist" >of a Payload Assist Module (PAM) after the IUS burns. > >Why no PAM on Gallileo? Is Gallileo so much heavier than Ulysses? Anyone >have any numbers (masses, delta v's, etc) for the craft and their orbits? >Was there just no way to attach a PAM between the IUS and Gallileo? >Or what? The mass is the thing. Galileo is "so much heavier than Ulysses", so you've got to take the gnergy from wherever you can get it. Galileo has had a convoluted history, involving almost every permutation of being two spacecraft or one, launched from either the shuttle or some other (unmanned) booster, involving the Shuttle-Centaur or not. Once it was decided to fly it all together (orbiter and descent package) on the Shuttle-Centaur, its configuration was pretty well fixed. Post Challenger, Centaur in the cargo bay was thought to be a bad idea, so it was launched by an IUS, and it's going to take this complicated trajectory to get Galileo to Jupiter, only 9 or 10 years late (but still ahead of anything comparable). -- Chris Jones clj@ksr.com {world,uunet,harvard}!ksr!clj
henry@zoo.toronto.edu (Henry Spencer) (09/18/90)
In article <15004@burdvax.PRC.Unisys.COM> techpubs@PRC.Unisys.COM (Technical Pub. Vince Short) writes: >My question: if this can be done for Ulysses (direct transfer orbit >to Jupiter), why couldn't it have been done for Gallileo... >... Is Gallileo so much heavier than Ulysses? Yes. Ulysses is tiny by comparison. The first two Shuttle/Centaur launches were originally going to carry (a) Galileo and (b) a *pair* of Ulysses-class probes, back in the days before the US reneged on its "commitment" to the International Solar Polar Mission. -- TCP/IP: handling tomorrow's loads today| Henry Spencer at U of Toronto Zoology OSI: handling yesterday's loads someday| henry@zoo.toronto.edu utzoo!henry
aoab314@ut-emx (Srinivas Bettadpur) (09/18/90)
In article <15004@burdvax.PRC.Unisys.COM> techpubs@PRC.Unisys.COM (Technical Pub. Vince Short) writes: > >My question: if this can be done for Ulysses (direct transfer orbit >to Jupiter), why couldn't it have been done for Gallileo which >was sent to Jupiter via a complex Venus-Earth-Earth gravity assist orbit. >Why no PAM on Gallileo? I am told that this is because Galileo is intended to orbit Jupiter, and hence must carry retro-rockets, whereas Ulysses is a Jupiter flyby only. Shuttle weight constraints were the reason for the complicated flight geometry for the former. Srinivas