← Back to context

Comment by bsilvereagle

6 days ago

> “Our test facilities can’t reach the combination of heat flux, pressure, shear stresses, etc., that an actual reentering spacecraft does. We’re always having to wait for the flight test to get the final certification that our system is good to go.”—Jeremy VanderKam, deputy manager for Orion’s heat shield, speaking in 2022

This is a strange claim, considering NASA used to have 2 facilities that were capable of this - one at Johnson and one at Ames. They were consolidated (https://ntrs.nasa.gov/api/citations/20160001258/downloads/20...) but it seems like the Arc Jet Complex at Ames is still operational https://www.nasa.gov/ames/arcjet-complex/

17 comments

bsilvereagle

Reply
idlewords  6 days ago

The Orion heat shield is sixteen feet across. NASA's test facilities can only test small material samples in these facilities, not capture how the entire heat shield will behave.

  • sillysaurusx  6 days ago

    How does SpaceX test it? Have they needed to solve this problem?

    • SyzygyRhythm  6 days ago

      There were 19 successful unmanned Dragon 1 missions before Crew Dragon, and an unmanned Crew Dragon mission before the first crewed one (actually two missions, but one didn't reenter from orbit). The heat shield material and design was essentially the same and so there was a great deal of flight heritage.

      3 replies →

    • hvb2  6 days ago

      By having a much higher launch cadence and then analyzing the flight hardware afterwards.

      Also, they don't have anything human rated going beyond LEO. Coming back from the moon means you're going significantly faster and thus need a better heat shield

      1 reply →

    • idlewords  6 days ago

      They do iterative flight testing. Starship is I believe on its twelfth flight test; the first one was in 2023.

    • swiftcoder  6 days ago

      SpaceX has a reusable launch vehicle, so they could afford to fly a whole mess of unmanned flights before they stuck a human in there

    • jccooper  5 days ago

      Crew Dragon flew an automated demo flight before flying with crew. It was proceeded by 20 flights of Dragon 1 over 10 years.

      Starship's heatshield has already been tested full-up half a dozen times. Many changes have been made as a result.