The Challenger Admission

Restrictions were also imposed by the Air Force, whom NASA got support from to increase their political influence. The shuttle had to conform to the Air Force's size and weight requirements and they wanted the shuttle to be able to carry large satellites that the Air Force needed to launch. A heavier space shuttle than intended had to be designed and this required the shuttle to be positioned alongside the solid rocket boosters instead of above them. Now, the space shuttle risked being caught in the fireball if the rockets exploded during the launch.

Despite the changes that were made, once completed, the space shuttle was deemed a reliable workhorse and a superior way of traveling into space. Perhaps all the praise made NASA overly confident, causing them to dismiss Boisjoly and Thompson's advice the night before the launch. The engineers were involved in a three-way teleconference to alert their managers that launching in cold temperatures could affect the 'O' ring joint seals. The managers of Morton Thiokol, who had manufactured the rockets, decided that the problem wasn't serious enough to cancel the launch. Their multimillion dollar contract was up for renewal and NASA had a tight launch schedule to maintain. The launch had already been delayed and if the shuttle didn't launch by February 1, some of the science experiments and business arrangements regarding the satellite would be jeopardized.

Ice on the launch pad: Temperatures in Florida were exceptionally low on January 28, 1986.

After the Challenger exploded, and the presidential commission investigated the causes of the disaster, it was clear that the wrong decision had been made that night. Many design changes to the shuttle were planned and it was over two years before the U.S. sent another manned flight to space. An escape system was developed for future missions, and the 'O' rings were redesigned. A heated layer was also added to the joints, preventing them from getting too cold, and a third 'O' ring was added.

It was not the last disaster for NASA, but manned space exploration has persisted. In May 2006, space shuttle Discovery is due to launch. But as one engineer explained, keeping the shuttle up and running is like dealing with a patient in intensive care. The days of the space shuttle are numbered, and the remaining fleet will retire in the not too distant future.

For more info:

Challenger STS 51-L Accident
http://www.hq.nasa.gov/office/pao/History/sts51l.html

Space Shuttle Challenger Disaster: A NASA Tragedy
http://space.about.com/cs/challenger/a/challenger.htm

7 Myths About the Challenger Shuttle Disaster
http://www.msnbc.msn.com/id/11031097/