NASA Says It's 'Certain' Of Cause In Columbia Tragedy
More than a year after
the space shuttle Columbia disintegrated 60,000 feet above Texas
and Louisiana, NASA now says it knows "for certain" what caused the
accident. Fixing that problem, along with one recently discovered,
means NASA will delay the next shuttle launch until at least March,
In a scenario rarely modeled before Columbia -- and exhaustively
simulated since -- NASA's associate administrator for space flight,
Bill Readdy, says air or nitrogen, liquified by the cryogenics that
super-cooled the external tank, seeped into tiny cracks in the
foam. As the spacecraft rose into the Florida skies on January
16th, 2003, that liquified air returned to a gaseous state and
expanded. A chunk of insulating foam the size of a suitcase
departed the tank. It didn't just slide off, as NASA thought it did
based on past experience. The pressure of the expanding gas between
the tank and the insulation blew it off "with considerable
The foam then did something that blatantly defied the design of
the huge, orange external fuel tank. Instead of slipping away from
the orbiter, it slammed into Columbia's left wing with enough force
to punch a hole in it. It was that puncture which allowed
super-heated gasses to breach the shuttle's heat shielding and led
to Columbia's destruction on February 1st, 2003. The tragedy
claimed the lives of all seven astronauts on board.
A New Problem
As they go over the remaining three space shuttles with all but
a microscope, NASA has discovered a much newer problem: the rudder
speed brake assembly on Discovery. Minor corrosion was found on the
In addition, a gear installed when a backup assembly was last
rebuilt had been installed backwards. Now, NASA is removing the
actuators on Discovery, Atlantis and Endeavour.
Atlantis had been scheduled to initiate the shuttles' return to
flight sometime between September and November. But now that NASA
has decided to redesign the external fuel tanks and pull the speed
brake assemblies, that deadline just didn't seem realistic.
"We said, 'Stop. Let's go ahead and extend the schedule, and
let's figure out what the right way is to go about" meeting the
recommendations of the Columbia accident investigators, NASA
Administrator Sean O'Keefe said. "We're not going to be driven by
the calendar. This is going to be a milestone-driven event."
Readdy (right) said the
fuel tank redesign would incorporate a new method of applying
insulating foam, one that would hopefully eliminate air pockets
between the tank and the insulation. Hopefully, that will help fix
the problem that led to Columbia's fiery demise.
NASA last month decided to change the fundamental mission of the
remaining shuttle fleet, devoting it entirely to completion of the
International Space Station. It'll work like this: One shuttle will
fly to the station. It will be completely inspected during the
flight and while docked at the station. Another shuttle will be
standing by in case a problem is found in orbit. While it won't
necessarily be on the launch pad, Readdy says it will be ready to
go within 90 days of a launch decision. That's typically how long
the station's food and atmosphere can last with the usual crew of
three and up to seven shuttle astronauts on board. In an extreme
situation, Readdy says, a rescue shuttle could fly in as little as
That would mark the first time since Skylab that NASA kept a
spacecraft at the ready for rescue missions.
The solution wouldn't have worked in Columbia's case. America's
oldest flying shuttle was too heavy to make it to the space
station. It lacked the necessary fuel. But the newer shuttles are
all capable of an ISS rendezvous.
Inspection work on Discovery is moving along more quickly than
on its sister ships. Because of that, NASA has decided to make it
the spacecraft which will initiate the return to flight on STS-114.
Atlantis had been on deck before that decision was made. It will
now serve as the backup spacecraft for the first Discovery mission,
more than a year from now.