NASA Ames Research Center, Moffett Field, CA
NASA Marshall Space Flight Center, Huntsville, AL
NASA Thermal Materials Test May Revolutionize Spacecraft Design
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 NASAs Ames Research Center, in the heart of Californias 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, tomorrows 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 NASAs 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: http://amesnews.arc.nasa.gov/releases/2000/animation/reeentry%20vehicle00/reentry.html
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, NASAs lead center for space transportation systems development.
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