[MLUG - DISCUSSION] shuttle theories

[Mike Miller <EMAIL:PROTECTED>]

Here are excerpts from two new articles about the Columbia disaster.
It's encouraging to see that there were warning signs (because it implies
that similar future disasters might be avoidable).  It's discouraging to
see that nobody heeded the warnings!  --Mike


NASA WAS TOLD IN 1990 ABOUT VULNERABLE TILES
from The New York Times

The space agency was warned in 1990 that the protective tiles around the
shuttle's wheel wells were particularly vulnerable to damage and failure,
inviting catastrophe because those tiles protect both fuel tanks and the
shuttle's hydraulic system.

The study, conducted by experts at Stanford University and Carnegie Mellon
and financed by NASA, also identified ice that builds up on the supercold
external fuel tank as a major source of debris that could fall on the tiles
and trigger a cascade of failures that could doom the spacecraft.

These two observations fit the leading theory emerging as investigators try
to discover what destroyed the shuttle Columbia. If this theory is correct,
it would mean that accidents involving two vulnerable areas — the foam and
the tiles — combined to destroy the craft.

NASA officials said yesterday that they still believed that the object that
hit the underside of the wing on takeoff was foam insulation, but there is
growing speculation that it may have been mixed with ice. Video images
taken about 80 seconds into the flight show the object to be white or
light — the insulation itself is bright orange — fueling speculation that
NASA engineers may have seriously underestimated its weight when they
concluded that a blow from a block of rigid foam would pose no safety
hazard to the orbiter. The insulation is applied as a shaving cream-like
foam, but turns hard as a brick.
<http://www.nytimes.com/2003/02/05/national/05FOAM.html>


FOAM WAS LARGEST PIECE TO HIT A SHUTTLE
from The Washington Post

The chunk of insulating foam that broke free from shuttle Columbia's
external fuel tank Jan. 16 was the biggest piece of debris ever to hit a
shuttle during launch, and only two previous launches have encountered even
moderately large impacts from the tough insulating material, a NASA
official said yesterday.

That suggests that NASA engineers had little practical experience to rely
upon as they weighed the potential importance of the event -- and as they
made their decision, days later, to write off the collision as probably no
threat to the shuttle's safety.

The new detail about foam debris impact described by Michael Kostelnik, a
NASA deputy associate administrator, was one of several pieces of new
information to shed light yesterday on the frustrating level of uncertainty
that engineers had to work with as they decided whether to ignore the
incident or perhaps design a radical plan to bring the crew home safely.

Among the uncertainties were the potential effects of the debris not only
on the shuttle's ceramic tiles -- the major focus of NASA's attention --
but also on the reinforced carbon leading edges of the shuttle's left wing,
which are stronger than the tiles in some respects but have their own
vulnerabilities.
<http://www.washingtonpost.com/wp-dyn/articles/A26683-2003Feb4.html>

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