Boeing completes prototype heat shield for NASA's Orion spacecraft

Boeing said today it had completed a developmental heat shield designed to protect future NASA astronauts from extreme heat during re-entry into Earth's atmosphere following lunar and low-Earth orbit missions.

Specifically this shield is targeted for use on NASA's Orion Crew Exploration Vehicle (CEV) which is the space agency's planned mission to send human explorers back to the moon, and then onward to Mars and other destinations in the solar system.

According to NASA, Orion will be similar in shape to the Apollo spacecraft, but significantly larger. The Apollo-style heat shield is the best understood shape for re-entering Earth's atmosphere, especially when returning directly from the moon. Orion will be 16.5 feet in diameter and weigh 25 tons. Inside, it will have more than two-and-a-half times the volume of an Apollo capsule. The larger size will allow Orion to accommodate four crew members on missions to the moon, and six on missions to the International Space Station or Mars-bound spacecraft. Orion is scheduled to fly its first missions to the space station by 2014 and carry out its first flight to the moon by 2020.

NASA says Orion will enter Earth's atmosphere at 6.8 miles per second, generating surface temperatures equivalent to more than 4,800 degrees Fahrenheit - about five-times the amount of heat the space shuttle's heat shield endures, NASA said. The Frisbee-shaped heat shield is manufactured in one piece. It will be attached to the base of the Orion's cone-shaped crew capsule and must protect the capsule during both low-Earth-orbit returns and very fast moon-mission re-entries into Earth's atmosphere, when it carries astronauts back home.

Boeing's Thermal Protection System (TPS) Manufacturing Demonstration Unit (MDU) is fabricated from Phenolic Impregnated Carbon Ablator (PICA) material. The material is lightweight and has an efficient rate of burn, known as ablative. Such materials actually burn to deflect heat off the surface. Fiber Materials, of Biddeford, Maine, produces the material under a contract to Boeing. PICA is being considered for Orion's heat shield due to its proven performance on NASA's Stardust spacecraft heat shield. Each piece is significantly larger than typical space shuttle tiles, greatly reducing parts count and complexity, Boeing said. Boeing is continuing its work with NASA Ames to develop the flight heat shield design in support of Orion's TPS preliminary design review in early 2008. Final work is expected to be completed by 2009.

NASA researchers have also been working on new circuit chips that can take the heat of a blast furnace and keep on performing. Silicon Carbide (SiC) chips can operate in 600 degrees Celsius or 1,112 degrees Fahrenheit where conventional silicon-based electronics - limited to about 350 C - would fail.In the past, integrated circuit chips could not withstand more than a few hours of high temperatures before degrading or failing. This chip exceeded 1,700 hours of continuous operation at 500 degrees Celsius - a breakthrough that represents a 100-fold increase in what has previously been achieved, NASA said.

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