Ann Hutchison

NASA Ames Research Center, Moffett Field, CA

(Phone: 650/604-3039)

June Malone

NASA Marshall Space Flight Center, Huntsville, AL

(Phone: 256/544-0034)


NASA plans a rigorous flight test tomorrow of thermal protection materials
that may radically change the design and performance of future aerospace
vehicles. They also may overturn an age-old tenet of aerodynamics: that
only blunt-body aerospace vehicles can survive the searing temperatures
created as the vehicles tear through the atmosphere.

At about 4:00 a.m. PDT, a U.S. Air Force Minuteman III missile carrying an
Mk 12A reentry vehicle (RV) is set to blast off from Vandenberg Air Force
Base near Lompoc, CA. The RV is equipped with four 5.1-inch-long strakes,
or sharp leading edges. Each contains three materials known as Ultra High
Temperature Ceramics (UHTCs), which are designed to prevent spacecraft from
burning up during reentry into Earth’s atmosphere.

“We believe these materials may lead to a radical new concept in aerospace
vehicle design and performance — the use of sharp leading edges on
hypersonic vehicles,” said Joan Salute, project manager for the mission at
NASA’s Ames Research Center, in the heart of California’s Silicon Valley.
“The potential increase in spacecraft maneuverability is like going from a
semi-trailer to a Ferrari.” Salute said the material showed exceptional
performance during its first flight test in 1997 and during tests in Ames’
arcjet facilities.

Sharp leading edges offer several advantages over the blunt-body design
currently in use. They could allow a space shuttle or crew return vehicle
to maneuver in space more like an airplane and potentially allow astronauts
to return to Earth from anywhere on orbit. They also might eliminate the
electromagnetic interference that causes the communications blackouts that
plague reentering blunt-body space vehicles. Reducing the amount of drag
could lead to a reduction in propulsion requirements. In addition,
planetary probes could make use of sharp-body technology for aerobraking
and to maximize their maneuvering capability.

“Our goal is ultimately to transfer this technology to the aerospace
industry for use in next-generation reentry vehicles,” said Jeff Bull,
chief engineer for the project at Ames. “Based on input from the industry,
tomorrow’s test will incorporate a more realistic representation of a
leading edge that may be used on a reusable launch vehicle.”

“Sharp leading edge technology is one of several technologies NASA is
developing to help achieve its aerospace goals,” said Michael Phipps,
project manager of the Pathfinder Experiments Project at NASA’s Marshall
Space Flight Center, Huntsville, AL. Phipps cited several areas that may
benefit from this new technology, including increased safety and
reliability of aerospace vehicles. The technology also may reduce the cost
of putting payloads into space, from thousands of dollars per pound to a
few hundred dollars per pound in the long term, making access to space more
affordable to a variety of markets.

Once it reaches an altitude of about 400 nautical miles, the RV will be
released, returning through Earth’s atmosphere at blistering speed. It
will be slowed by a parachute and land in a lagoon at the Kwajalein missile
range in the Pacific Ocean. Sensors in the strakes will measure how closely
performance matches pre-flight calculations, and at what temperature the
materials begin to melt.

One pair of strakes will be retracted just before reaching temperatures
high enough to cause the material to begin ablating, or burning off. The
other pair will retract shortly after ablation begins, at a temperature of
nearly 5,100 degrees Fahrenheit. NASA engineers expect to collect data
throughout the 23-minute flight, up to the moment of splashdown. The
reentry vehicle will be recovered from the lagoon floor for post-flight
analysis. Animation of the entry and recovery of the RV is available at
the following URL:

This research is part of the SHARP (Slender Hypervelocity Aerothermodynamic
Research Probes) program, a joint effort among NASA, Sandia National
Laboratories and the U.S. Air Force. It is funded by the Pathfinder
Program at Marshall Space Flight Center, NASA’s lead center for space
transportation systems development.