Nine Months of Testing Proves Integrity of Tank Manufacturing Process, Boosts Confidence in Using Composite Fuel Tanks for Reusable Space Transportation Systems

Engineers
from Northrop Grumman Corporation (NYSE: NOC) and NASA’s
Marshall Space Flight Center, Huntsville, Ala., have proven
that a new type of cryogenic fuel tank made from composite
materials has the structural integrity to withstand the
mechanical and thermal stresses associated with repeated
fueling and simulated launch cycles.

The nine-month, 40-cycle series of tests, concluded Aug.
9, is part of Northrop Grumman’s ongoing partnership with
NASA to help mature space technologies required to develop
safe, affordable and reusable space transportation systems.
The test program began in November 2003.

“These tests prove that it’s possible to build a lightweight
fuel tank that’s not only a safe, reliable container for
liquid hydrogen,” said Drew Smith, NASA’s cryotanks project
leader, “but also a durable, reusable component that can
also help us reduce the costs associated with acquiring
and operating a reusable launch vehicle.” Composite cryogenic
fuel tanks also offer a 10 to 25 percent weight savings
over conventional aluminum fuel tanks, he added, which could
enable larger payloads in the future.

Liquid hydrogen is an essential but highly volatile fuel
used in the combustion process that propels rockets. It
must be stored and used at -423 degrees Fahrenheit, a temperature
that causes most materials to become quite brittle. Liquid
hydrogen also has an extremely fine molecular structure,
which allows it to seep through the tiniest of holes.

The composite tank used for the tests was a 6-foot-diameter,
15-foot-long tank produced by Northrop Grumman as part of
NASA’s Next Generation Launch Technology program. The tank
was fabricated and cryo-structurally tested at the agency’s
Marshall Space Flight Center.

“Each cycle in our test program consisted of filling the
tank with liquid hydrogen, pressurizing to an internal pressure
of 113 pounds per square inch, then subjecting it an axial
load to simulate the stresses experienced by a rocket during
launch,” explained Tod Palm, Northrop Grumman’s cryogenic
tank project leader. “Nine months and 40 cycles of testing
and monitoring the composite test tank for leaks has given
us the confidence that this type of cryogenic fuel tank
can be safely and repeatedly launched, recovered and reused
for next-generation space missions.” An axial load is applied
along the vertical axis of the launch vehicle.

Much of the team’s success in the test program, added Palm,
can be attributed to key technical advances made by Northrop
Grumman and NASA in designing and constructing the composite
tank. The tank is approximately one quarter of the projected
size (27.5 feet in diameter x 80 feet long) of a fuel tank
envisioned for some reusable launch vehicle concepts.

The composite tank technology demonstrated has potential
applications not only as cryogenic fuel tanks for Earth-launched
space vehicles, but also as on-orbit storage of cryogenic
fuels such as liquid hydrogen or liquid oxygen. This orbiting
“fuel depot” would be used to fuel space vehicles traveling
from low-Earth orbit to the moon, Mars or beyond.

Northrop Grumman’s work for NASA on the cryogenic fuel tanks
was done as part of a three-year series of Next Generation
Launch Technology contract options that began in June 2001.
The contracts, collectively worth approximately $30 million,
included work on permeation-resistant composite cryotanks,
development and refinement of new manufacturing processes
that will allow the company to build large composite tanks
without an autoclave; and design and engineering development
of conformal fuel tanks appropriate for use on a single-stage-to-orbit
vehicle.

Lessons learned from these contracts are expected to help
NASA continue to mature technologies needed to develop and
launch space systems envisioned under Project Constellation,
a core part of the Vision for Space Exploration.

Northrop Grumman Integrated Systems is a premier aerospace
and defense systems integration organization. Headquartered
in El Segundo, Calif., it designs, develops, produces and
supports integrated systems and subsystems optimized for
use on networks. For its government and civil customers
worldwide, Integrated Systems delivers best-value solutions,
products and services that support military and homeland
defense missions in the areas of intelligence, surveillance
and reconnaissance; space access; battle management command
and control; and integrated strike warfare.

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Contact:

Brooks McKinney
Northrop Grumman Integrated Systems
(310) 331-6610
brooks.mckinney@ngc.com

Tory Neiwert
NASA MSFC
(256) 544-3938
tory.a.neiwert@nasa.com