The huge, orange External Tank (ET) that will help launch
Space Shuttle Discovery on its next mission isn’t glitzy like
the crystal New Year’s ball in Times Square. But its journey
from NASA’s Michoud Assembly Facility marks something special
for 2005: the Year of Return to Flight.
The tank, designated ET-120, rolled out on its transporter and
was loaded onto a covered barge today at Michoud, in New
Orleans, for shipment to NASA’s Kennedy Space Center, Fla. The
barge will take four to five days to travel from the
Mississippi River-Gulf of Mexico Outlet to Florida’s Banana
River, which flows into the Atlantic Ocean. Shipping the tank
is an important milestone, particularly for the NASA team that
spent 23 months working on modifications to make it safer.
“Our team of contractors and civil servants has worked hard
developing, testing and implementing improvements that will
reduce the risk to the orbiter during liftoff and ascent,” said
Sandy Coleman, manager of the External Tank Project, an element
of the Space Shuttle Propulsion Office at NASA’s Marshall Space
Flight Center in Huntsville, Ala. “This will be the safest,
most reliable tank NASA has ever produced.”
During a launch, the ET delivers 535,000 gallons of liquid
hydrogen and oxygen propellants to the three main engines,
which power the Shuttle to orbit. It 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.
Modifications to the tank address the Columbia Accident
Investigation Board’s recommendation to reduce the risk to the
Shuttle from falling debris during ascent.
During Columbia’s launch in January 2003, insulating foam from
the bipod area, near the front of the craft where the ET
attaches to the orbiter, fell off the and damaged the left
wing.
ET-120 incorporates several safety improvements, including an
improved bipod fitting that connects it to the orbiter; a video
camera mounted on the liquid oxygen feed line to document
liftoff; reversed bolts on the flange of the tank’s mid-section
and a new spraying procedure for the thermal protection
required there; a redesign of three bellows on the liquid
oxygen feed line, the 70-foot pipe feeding liquid oxygen to the
main engine; and a more defined spray procedure on the
longeron, a structural support for the tank’s aft, orbiter
attachment struts.
“Clearly, the modifications to the External Tank are at the
heart of our Return to Flight work,” said Michael Kostelnik,
deputy associate administrator for the International Space
Station and Space Shuttle Programs. “Seeing this tank begin its
journey to the Kennedy Space Center, where it will be prepared
for launch, makes it clear how far we’ve come in making the
Shuttle a safer spacecraft for our astronauts,” he said.
The ET is the largest element of the Shuttle system, which also
includes the orbiter, main engines and Solid Rocket Boosters.
It measures 27.6 feet wide and 154 feet tall. Despite the
tank’s size, the aluminum skin covering it is only one-eighth-
inch thick in most areas. Yet, it still withstands more than
6.5 million pounds of thrust during liftoff and ascent. The
tank is the only Shuttle component that cannot be reused.
A seven-member Discovery crew will fly the Return to Flight
mission, designated STS-114, to the International Space
Station. The major mission objectives are testing and
evaluating new procedures for flight safety. Returning the
Shuttle to flight is the first step in the Vision for Space
Exploration, which calls for a stepping stone strategy of human
and robotic missions to achieve new exploration goals. The
Shuttle will be used to complete assembly of the International
Space Station. The Station is a vital research platform for
human endurance in space and a test bed for technologies and
techniques that will enable longer journeys to the moon, Mars
and beyond.
The Space Shuttle Propulsion Office at Marshall manages the
tank project. Lockheed Martin Space Systems Co., in New
Orleans, is the primary contractor.
For photos, fact sheets and information about Return to Flight
operations, visit:
