From: utzoo!decvax!harpo!eagle!karn
Newsgroups: net.columbia
Title: Re: fuel tank color query
Article-I.D.: eagle.614
Posted: Wed Nov 10 21:47:11 1982
Received: Fri Nov 12 06:52:33 1982
References: ecn-pa.629

The external fuel tank is covered with insulation to protect the tank
during ascent and to protect the cryogenic fuels.  This insulation
accounts for the color of the tank.

On the first two missions, the insulation was painted white; all later
tanks do away with the paint, saving weight.

Phil Karn