Tuesday, August 28, 2007

Teachers in Space

I will never forget the morning I entered my seventh grade science class and our teacher, Mr. Harshfield, quietly played a video recording of that morning's launch of the Space Shuttle Challenger. It was the 28th of January 1986, and 73 seconds after liftoff the classroom fell into a stunned silence as we witnessed the disaster that claimed the lives of seven astronauts, including Christa McAuliffe who would have been the first teacher launched into orbit under a new NASA program. The tragedy was later traced to a design flaw in the "O-ring" seal on one of the solid rocket boosters, leading to a fuel leak which ultimately broke up the entire shuttle.

The dream of sending a teacher safely into space was finally realized last week, when the Space Shuttle Endeavour successfully returned home after 13 days in orbit. Former elementary school teacher Barbara Morgan, who served as NASA's backup astronaut to McAuliffe for the ill-fated Challenger mission in 1986, said "the flight was absolutely wonderful" and "the shuttle program gets an A-plus". There were initially some concerns about the safety of the crew after a small gouge was discovered in the protective heat shield on the underside of the shuttle. The gash was apparently caused by a collision during liftoff with a baseball-sized chunk of insulating foam from the external fuel tank, similar to the damage that caused the Space Shuttle Columbia to disintegrate during re-entry in February 2003, but considerably less severe and in a less vulnerable location on the spacecraft.

Engineers from NASA determined that the risk posed by the gouge was not significant enough to justify an unrehearsed spacewalk to repair the damage from the International Space Station, where the shuttle was docked for most of the mission. Given the tragic potential of the damage, as exemplified by the Columbia disaster, it must have been a difficult decision for the engineers to make and for the astronauts to accept. But knowing the extreme risks of an impromptu spacewalk to the underside of the shuttle -- a procedure that has never been attempted before, and one that would normally require extensive training and practice in enormous dive tanks to simulate the weightless environment -- and considering the unknown effectiveness of the proposed repair work, NASA's decision is understandable.

Thankfully, it all worked out in the end. The space agency is now planning to implement several modifications to the foam-covered fuel tanks to prevent future damage to the shuttle's heat shield. These modifications are expected to be complete in time for the next mission to the International Space Station, in April 2008.