NASA Selects Apollo-Era Heat Shield

NASA plans to dust off Apollo-era heat shield technology for the next spacecraft it hopes to send to the moon.

The agency announced today it had selected a system for its Orion crew exploration vehicle that protected Apollo capsules, called the Avocat ablator system. The material was no longer in production before more than three years of tests began for Orion.

The Government Accountability Office last year cited heat shield challenges as one of several potential risks to developing a replacement for the space shuttle by NASA's targeted 2015 timeline. Read the report here.

"There is currently no industry capability for producing a thermal protection system of the size required by the Orion," the report says. "Furthermore, heat shield design features required by the Orion, namely the size, have never been proven and must be developed."

Orion is intended to return astronauts to the moon by 2020.

Click "Read more..." to read NASA's press release.

NASA SELECTS MATERIAL FOR ORION SPACECRAFT HEAT SHIELD

HOUSTON -- NASA has chosen the material for a heat shield that will
protect a new generation of space explorers when they return from the
moon. After extensive study, NASA has selected the Avcoat ablator
system for the Orion crew module.

Orion is part of the Constellation Program that is developing the country's next-generation spacecraft system for human exploration of
the moon and further destinations in the solar system. The Orion crew
module, which will launch atop an Ares I rocket, is targeted to begin
carrying astronauts to the International Space Station in 2015 and to
the moon in 2020.

Orion will face extreme conditions during its voyage to the moon and
on the journey home. On the blistering return through Earth's
atmosphere, the module will encounter temperatures as high as 5,000
degrees Fahrenheit. Heating rates may be up to five times more
extreme than rates for missions returning from the International
Space Station. Orion's heat shield, the dish-shaped thermal
protection system at the base of the spacecraft, will endure the most
heat and will erode, or "ablate," in a controlled fashion,
transporting heat away from the crew module during its descent
through the atmosphere.

To protect the spacecraft and its crew from such severe conditions,
the Orion Project Office at NASA's Johnson Space Center in Houston
identified a team to develop the thermal protection system, or TPS,
heat shield. For more than three years, NASA's Orion Thermal
Protection System Advanced Development Project considered eight
different candidate materials, including the two final candidates,
Avcoat and Phenolic Impregnated Carbon Ablator, or PICA, both of
which have proven successful in previous space missions.

Avcoat was used for the Apollo capsule heat shield and on select
regions of the space shuttle orbiter in its earliest flights. It was
put back into production for the study. It is made of silica fibers
with an epoxy-novalic resin filled in a fiberglass-phenolic honeycomb
and is manufactured directly onto the heat shield substructure and
attached as a unit to the crew module during spacecraft assembly.
PICA, which is manufactured in blocks and attached to the vehicle
after fabrication, was used on Stardust, NASA's first robotic space
mission dedicated solely to exploring a comet, and the first sample
return mission since Apollo.

"NASA made a significant technology development effort, conducted
thousands of tests, and tapped into the facilities, talents and
resources across the agency to understand how these materials would
perform on Orion's five-meter wide heat shield," said James Reuther,
the project manager of the study at NASA's Ames Research Center at
Moffett Field, Calif. "We manufactured full-scale demonstrations to
prove they could be efficiently and reliably produced for Orion."

Ames led the study in cooperation with experts from across the agency.
Engineers performed rigorous thermal, structural and environmental
testing on both candidate materials. The team then compared the
materials based on mass, thermal and structural performance, life
cycle costs, manufacturability, reliability and certification
challenges. NASA, working with Orion prime contractor Lockheed
Martin, recommended Avcoat as the more robust, reliable and mature
system.

"The biggest challenge with Avcoat has been reviving the technology to
manufacture the material such that its performance is similar to what
was demonstrated during the Apollo missions," said John Kowal,
Orion's thermal protection system manager at Johnson. "Once that had
been accomplished, the system evaluations clearly indicated that
Avcoat was the preferred system."

In partnership with the material subcontractor, Textron Defense
Systems of Wilmington, Mass., Lockheed Martin will continue
development of the material for Orion. While Avcoat was selected as
the better of the two candidates, more research is needed to
integrate it completely into Orion's design.

IMAGE NOTE: Click to enlarge the June 2006 artist's rendering of a concept crew exploration vehicle's (CEV) re-entry to Earth's atmosphere. (Depicts obsolete configuration.) NASA's Constellation Program is plans to return humans to the moon by 2020. Credit: NASA