Spaceflight

NASA is investigating the use of Space Shuttle tile material for the Block 1A Crew Exploration Vehicle (CEV) in case an ablative thermal protection system (TPS) is not ready by the 2012 deadline for the transport of crew to the International Space Station.

NASA’s Ames Research Center in California is spearheading CEV TPS research, but the Houston, Texas-based Johnson Space Center published its own solicitation in January. It says Johnson intends to buy Shuttle tile material for the CEV, and says “to survive low Earth orbit re-entry a human-rated ceramic tile is required”.

“This is a belt and braces approach to make sure we have a back-up in case there is a problem with the lunar return advanced TPS. It doesn’t change the plan. It’s still expected to be ablative,” says Johnson. An Ames request for quotation in September asked vendors to propose ablative materials that can cope with heat flux up to 1,000W/cm². The alternate TPS would need to endure a heat flux of up to 200W/cm², but Shuttle tiles only endure 50W/cm².

The CEV design continues to evolve. NASA has dropped plans for liquid oxygen/methane propulsion, saying it offers no near-term benefit for lunar missions. As a result, the agency is now looking at a 5m (16ft)-diameter CEV, instead of the 5.5m originally specified.