Re: Debris Hits on Endeavour

Philip Chien (kc4yer@amsat.org)
Tue, 22 Dec 1998 16:58:04 -0500

>>    This is from KSC's landing report...
><snip>
>>Preliminary reports reveal that the orbiter is in
>>good shape post flight.  Endeavour's lower surface sustained 70 total
>>debris hits with 21 of those being 1-inch or larger.

Earl Needham, KD5XB    mailto:KD5XB@AMSAT.ORG
>
>	Just what would the orbiter hit?  Other than various small pieces
>of the
>STS itself?  Meteorites?  Debris from earlier/other missions?  Nails on the
>road?  <G>

Based on the phrase "lower surface" I would surmise that this is in
reference to pieces of the external tank insulation coming off and hitting
the tiles during ascent.  There was a change to how the SOFI (Spray On Foam
Insulation) is applied and more dings on the tiles have been noticed.  As
part of the analysis a video camera was mounted on a solid rocket booster
on the STS-95 shuttle flight to collect data from that area.

Other possible sources for the damage include debris on the runway (not a
significant source of damage since the runway is actually vacuumed shortly
before each landing), ice from the External Tank, and micrometeoroids and
debris in orbit.



Mike DiMuzio <mdimuzio@cisnet.com> said:

>	Mainly space junk, althoug there might be some from meteorites.
>A previous shuttle mission came close to losing a window from a piece of
>space debris, although I can't remember which.

No where close!  This is a rather unusual case where something have been
*heavily* over exagerated - and at the same time understated.

No debris has ever come close to damaging the outer 'thermal pane' on any
of the shuttle's exposed windows - tabloid press reports to the contrary.
The thermal pane is only required to protect the shuttle during ascent and
is redundant on-orbit and during reentry.  So even if the thermal pane was
damaged enough to lose pressure it wouldn't require an early return for the
shuttle.

On the other hand, the thermal panes do get nicked on a fairly regular
basis, averaging about one per mission.  And to prevent a small crack from
becoming a bigger problem in the future they're replaced as necessary,
entailing both time and expense.



Philip Chien, KC4YER
Earth News
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