Newsgroups: sci.space.shuttle
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Shuttle Payload Questions
Message-ID: <1989Feb9.022607.2075@utzoo.uucp>
Organization: U of Toronto Zoology
References: <26162@cci632.UUCP>
Date: Thu, 9 Feb 89 02:26:07 GMT

In article <26162@cci632.UUCP> djw@cci632.UUCP (David Wright) writes:
>	Is there a difference between Columbia, Atlantis, and Discovery
>   structural configurations? Is there any reason why Atlantis is usually
>   the orbiter used on DoD missions...

Basically, Columbia is older and is heavier.  A number of improvements
were made to the later orbiters, notably Atlantis and (I think) Discovery.
There is no particular preference for Atlantis for DoD missions, although
Columbia is excluded from most of the weight-critical missions, and DoD
missions tend to be weight-critical.

> ... Also how come Columbia has been in dry
>   dock (is that an applicable term?) for so long? Are they making modif-
>   ications to increase the payload capacity? 

Although some mods are being made, basically Columbia got left behind in
various pieces of updating work because she was a less capable orbiter.
Current plans are to make her the long-duration orbiter, for Spacelab in
particular.

>	I thought Atlantis was the orbiter that was to launch from Vandenburg.

I don't remember which one was scheduled to be first for Vandenberg, but
there was no plan to dedicate specific orbiters to specific launch sites
that I know of.

>   could Columbia be undergoing a complete retrofit to make her compatible
>   with the rest of the fleet? 

I think you'd have to rebuild her completely, at almost the cost of a new
orbiter, to bring her up to the same specs as the newer birds.  It turned
out that a slight relaxation of the initial post-Challenger weight limits
made it possible to fly pretty well all Spacelab missions on Columbia,
which fitted in with the idea of modifying one orbiter for longer stay
time in orbit.
-- 
Allegedly heard aboard Mir: "A |     Henry Spencer at U of Toronto Zoology
toast to comrade Van Allen!!"  | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
