Re: STS-73 'beam' observation

Philip Chien (
Wed, 1 Nov 1995 00:43:32 -0400

>Perhaps you can explain something for me: Using the information from the
>SatPasses Home Page, I watched the Shuttle fly over Fort Lauderdale this
>morning. I noticed what I can only describe as a 'headlight' effect : a
>dim, gray glow that extended in front of the shuttle. I would say that
>it was not quite as long as the sun is wide, if that helps. It widened
>as it got farther away from the shuttle. It had sort of a rounded,
>elongated triangular shape that emanated from the shuttle.
>I have seen the Shuttle and satellites fly over many times, but have
>never seen this before.

It's quite certain, from what you've described, that you're seeing the
results of a waste water dump.  The shuttle generates bunches of water, as
a byproduct of generating power via its fuel cells.  Excess water is dumped
overboard via small nozzles located close to the crew hatch.  The water is
liquid when it's pumped overboard but quickly freezes and sublimates in to
ice crystals.

The ice crystals were almost certainly lit up by the same source of light
as the shuttle - the sun.

Be glad you got to see it.  It's fairly rare for a water dump to occur at a
time when it's so visible from the ground.

Philip Chien, Earth News - space writer and consultant  PCHIEN@IDS.NET
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