In an attempt to prevent future accidents, NASA is using a heated copper plate to replace some of the foam insulation that protects the space shuttle's fuel tanks from freezing.
The agency has been concerned about chunks of foam damaging the shuttle ever since the shuttle Columbia disintegrated during re-entry Feb. 1, 2003, killing all seven astronauts on board. NASA believes the accident was caused by a foam bipod ramp that peeled off during the strain of launch. The loose foam hit the left wing of the orbiter and ripped a hole in it, so the shuttle could not withstand the pressure of re-entry.
Polyurethane foam has been used since the beginning of the space shuttle program to insulate the fuel tanks. Ice can build up while the shuttle sits on the launch pad filled with extremely cold liquid hydrogen fuel.
The loss of foam during flight has been a problem for decades, NASA officials said, but its importance was only realized after the Columbia disaster. The wedge-shaped foam structures can do a lot of damage with the speed of launch and space travel, despite being only 30 inches long, 14 inches wide and 12 inches tall.
The foam is being replaced by four rod heaters placed below each of the three bipod fittings in a copper plate. The bipods connect the orbiter to the external fuel tank.
``You've got to heat the bipod to keep away ice,'' said June Malone, spokeswoman for the George C. Marshall Space Flight Center in Huntsville, Ala. ``We've eliminated the foam, but still met the requirements.''
Flight center researchers believe the process of applying the foam caused defects, not the foam itself.
``We've changed the manually applied foam in a number of ways,'' Malone said. ``We've got two people watching the sprays; we've changed the timing of the sprays.''
The first fuel tank fitted with the new electric heaters is expected to be delivered to the Kennedy Space Center in Cape Canaveral, Fla., by October 2004, and NASA officials are optimistic about a March flight.