WASHINGTON — NASA and Lockheed Martin Space Systems Company paid tribute to the workforce who built the external tanks for the space shuttle fleet on Thursday at NASA’s Michoud Assembly Facility in New Orleans. ET-138, the last newly manufactured tank to roll out of the assembly building, served as a backdrop for speakers praising the employees.

“This is a bittersweet moment for everyone who’s been part of this great and dedicated NASA and Lockheed Martin external tank production team,” said John Honeycutt, manager of the External Tank Project Office at NASA’s Marshall Space Flight Center in Huntsville, Ala. “ET-138 is the last in a series of tanks that has provided increasingly safer launches of space shuttles.”

Lockheed Martin Space Systems Company of Denver was awarded a contract in 1973 to build the external tanks. Through almost 30 years of shuttle flights, Lockheed Martin workers at Michoud have built and delivered 134 flight tanks to the Space Shuttle Program.

“Today is an emotional one for us,” said Mark Bryant, vice president, Lockheed Martin External Tank Project at Michoud. “We have worked hard to build safe tanks for NASA, and I think this last one can be the safest yet. Yes, we’ve persevered through the challenges of Return to Flight and Katrina. Those events made us stronger, and as a result, we’ve developed better, more efficient ways to build even safer tanks.”

Following the ceremony, a traditional New Orleans brass band and hundreds of handkerchief-waving employees escorted ET-138 on its rollout to Michoud Harbor.

The tank was scheduled to depart after the ceremony aboard the Pegasus barge on a six-day, 900-mile sea journey to NASA’s Kennedy Space Center in Florida. Two tugs will tow Pegasus to the Port of Gulfport where Freedom Star, NASA’s solid rocket booster recovery ship, is waiting to tow the tank to Kennedy.

At Kennedy, ET-138 will be processed for flight, mated with twin solid rocket boosters and attached to space shuttle Endeavour in preparation for the last scheduled orbiter mission. The flight is designated as STS-134 and targeted to launch on Feb. 26, 2011.

The external tank designated ET-122 will be refurbished at Michoud and also shipped to Kennedy in late September. It is assigned to the “launch on need” for STS-134; in the unlikely event a rescue mission is needed. ET-122 was damaged during Hurricane Katrina in August 2005 and is being restored to flight configuration.

During a launch, the external tank delivers 535,000 gallons of hydrogen and oxygen liquid propellants to the three main engines, which power the shuttle to orbit. The tank is covered by polyurethane-like foam, with an average thickness of about one inch. The foam insulates the propellants; keeps ice from forming on the tank’s exterior; and protects its aluminum skin from aerodynamic heat during flight.

The external tank is the largest element of the space shuttle, which also includes the orbiter, main engines and twin solid rocket boosters. It measures 27.6 feet wide and 154 feet tall. Despite the tank’s size, its aluminum skin is only one-eighth-inch thick in most areas. Yet, it withstands more than 7.5 million pounds of thrust during liftoff and ascent. The tank is the only major shuttle component that is not reused.

NASA Television’s daily Video File will include B-roll of the event. For streaming video, schedules and downlink information, visit: http://www.nasa.gov/ntv

For more information about the Space Shuttle Program, visit: http://www.nasa.gov/shuttle

See: NASA’s Last Two Space Shuttle External Tanks Are Being Built at Michoud