Re: [dsat] OT: STS-107 Abort to ISS Possible?

From: Markus Mehring (
Date: Tue Feb 04 2003 - 21:54:51 EST

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    On Wed, 05 Feb 2003 02:07:14 +0000, you (Curt Porter
    <>) wrote:
    >   I am still wondering about the possibility of an escape to ISS.
    >Yes, the orbits are significantly different.
    And that's an understatement. "Totally different" is more like it.
    >But, while NASA says
    >that Columbia was too heavy to reach ISS, this is based on getting
    >there and back to Earth again, and in a short time frame. This is
    >also based on staying within NASA's very conservative safety and
    >performance parameters.
    The primary reason for this, above anything else, is weight (and thus
    propellant consumption). Columbia was the heaviest of the Shuttles. Lots of
    old and unused instrumentation and wiring from the days of testing and
    flight proofing (some of which had been removed in the last maintenance
    downtime period preceding last year's STS-109, the HST servicing mission),
    less weight-aware construction and design than the newer Shuttles, also due
    to older technology. The younger Shuttles (Discovery, Atlantis, especially
    Endeavour, which -as the Challenger replacement- is the youngest in the
    fleet) are far lighter than Columbia was, since they could have been
    constructed with more experience in Shuttle operations at hand. This weight
    penalty resulted in Columbia being unable to deliver the really heavy ISS
    components. It could reach the ISS (it was scheduled for an ISS flight
    later this year), but only with a lighter payload for the station. Bear in
    mind that some of the latest ISS missions with the younger and lighter
    Shuttles launched the heaviest payloads ever flown, well on the edge of
    their payload capabilities. This is why Columbia had mostly been assigned
    to non-ISS flights such as HST servicing and Spacehab missions.
    >  If, flight day one, it was decided that Columbia was mortally damaged,
    Not to forget that Launch Day +1 was the first day the ET debris issue
    surfaced, during the standard post-launch film review. It then took more
    than a week to analyse the issue properly and come to a conclusion.
    >then standard flight safety margins are no longer useful. Making the
    >most economical use of propellant, using time windows when the orbits
    >were advantageous, using even preturbations from Sun and Moon, all would
    >take time, but they would have two weeks or more to do it.
    I very much doubt that would have worked. Altering the orbit so heavily
    would have been an extremely big deal, this really is a severe propellant
    issue to start with. If someone wants to do the number crunching, although
    the question is of course academic now...
    >ISS has some manoeuvering ability also, would this not help?
    Unsignificantly, if at all. The ISS isn't exactly mobile, it's mostly a
    "station" in the sense of the word. That is, stationary and
    station-keeping. Not surprisingly, considering what a massive object it is
    by now.
    CU!	Markus
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