🚀 go-pugleaf

In article <725334983@romeo.cs.duke.edu> jwt@duke.cs.duke.edu (Jeffrey W. Tannehill) writes:
>...paint the underside black.  This brought up the question "Why is the
>bottom of the Shuttle black?"  It occurred to us that a black surface might
>absorb a lot more radiation and that in space there might be greater
>exposure to radiation than on earth, so why isn't the whole shuttle white
>or perhaps silver to reflect as much as possible?

As Brian pointed out, the difference in colors reflects differences in
materials resulting from different heat loads during reentry.

A black surface will generally absorb more light and heat, but it will
also radiate heat better.  Choice of materials for spacecraft thermal
control is complex and much depends on detail.  Actually, it probably
*would* be preferable, strictly from a thermal viewpoint, to have the
shuttle belly painted white... but I doubt that paint would survive
reentry on the high-temperature areas.
-- 
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  henry@zoo.toronto.edu  utzoo!henry