Copper Heaters Improve Fuel Tank Safety on NASA's Return to Flight Mission

July 27, 2005


NEW YORK, NY— Copper's superior heat-transfer properties are essential to new heating systems that replaced foam insulation in key areas on the Space Shuttle Discovery, which successfully launched into orbit on Tuesday, July 26.

"NASA's use of copper for Discovery's thermal protection system is a weighty accomplishment for the 10,000-year-old metal," says Ken Geremia, Communications Manager for the Copper Development Association (CDA). "Copper is essential to so many industries including plumbing, communications and energy, but high-profile applications like this are certainly very exciting."

The redesigned external fuel tank, or ET, now uses four small heaters to protect a critical section where a suitcase-size chunk of foam fell during the Space Shuttle Columbia launch in 2003, leading to the disaster that killed all seven crewmembers. Foam also broke off from this area, known as the bipod fittings, during an earlier shuttle mission but did not have serious consequences.

It is routine procedure for NASA to spray the entire ET with insulating foam prior to a shuttle launch. This is done to keep the tank's super-cold cargo - 526,126 gallons of liquid propellant used to fire the shuttle's three main engines - in a liquid state and to prevent icing. Frozen condensation on the external fuel tank is a risk because it, like the insulation, could break away during lift-off and damage the shuttle's heat-deflecting ceramic tile exterior.

For its "Return to Flight" mission, the first space shuttle voyage since the Columbia tragedy, NASA engineers replaced foam on the bipod fittings with four 300-watt cartridge heaters (including two back-up heaters). These heaters are situated on top of copper plates and are installed under the bipod fittings, eliminating the need for foam insulation.

After extensive testing in wind, vibration, structural, and thermal trials, the bipod heaters are being retrofitted to shuttle fuel tanks for all future space missions. NASA will continue to spray foam on non-critical areas of the fuel tank for future shuttle launches.

Copper Heating Belts

Copper is also being used for a belt-like heater for the uppermost bellows (a flexible joint) of the Liquid Oxygen Feedline, located on the exterior fuel tank. This section needs extra protection because it is positioned above the shuttle, and frozen debris falling from it would likely strike the ship. The bellows heater consists of two copper-nickel metal strips about 53 inches long and one-half inch wide.

The external fuel tank is the largest piece of equipment on the shuttle, standing 15 stories high and weighing over 1.5 million pounds when filled. When the shuttle reaches its optimal velocity, the ET (like the two rocket boosters that fire the ship into orbit) is jettisoned and falls back to earth.

Editor's Note: For more information and to download high-resolution images, please visit July 2005 Issue of Discover Copper.