Heat Shield Installed on First Orion Spacecraft

Inside the Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, technicians dressed in clean-room suits install a back shell tile panel onto the Orion crew module. (Credit:  NASA/Dimitri Gerondidakis)
Inside the Operations and Checkout Building high bay at NASA’s Kennedy Space Center in Florida, technicians dressed in clean-room suits install a back shell tile panel onto the Orion crew module. (Credit:NASA/Dimitri Gerondidakis)

KENNEDY SPACE CENTER, Fla. (NASA PR) — The heat shield on NASA’s Orion spacecraft gets all the glory when it comes to protecting the spacecraft from the intense temperature of reentry. Although the blunt, ablative shield will see the highest temperatures – up to 4,000 degrees Fahrenheit on its first flight this December – the rest of the spacecraft is hardly left in the cold.

Engineers and technicians at NASA’s Kennedy Space Center have finished installing the cone-shaped back shell of Orion’s crew module – the protective cover on the sides that make up Orion’s upside down cone shape. It’s made up of 970 black tiles that should look very familiar – the same tiles protected the belly of the space shuttles as they returned from space.

But the space shuttles traveled at 17,000 miles per hour, while Orion will be coming in at 20,000 miles per hour on this first flight test. The faster a spacecraft travels through Earth’s atmosphere, the more heat it generates. So even though the hottest the space shuttle tiles got was about 2,300 degrees Fahrenheit, the Orion back shell could get up to 3,150 degrees, despite being in a cooler area of the vehicle.

And heat isn’t the only concern. While in space, Orion will be vulnerable to the regular onslaught of micrometeoroid orbital debris. Although micrometeoroid orbital debris is too tiny to track, and therefore avoid, it can do immense damage to a spacecraft – for instance, it could punch through a back shell tile. Below the tiles, the vehicle’s structure doesn’t often get hotter than about 300 degrees Fahrenheit, but if debris breeched the tile, the heat surrounding the vehicle during reentry could creep into the hole it created, possibly damaging the vehicle.

Two one-inch-wide holes have been drilled into tiles on Orion’s back shell to simulate micrometeoroid orbital debris damage . Sensors on the vehicle will record how high temperatures climb inside the hole during Orion’s return through Earth’s atmosphere following its first flight in December. (Credit:  NASA)
Two one-inch-wide holes have been drilled into tiles on Orion’s back shell to simulate micrometeoroid orbital debris damage . Sensors on the vehicle will record how high temperatures climb inside the hole during Orion’s return through Earth’s atmosphere following its first flight in December. (Credit:
NASA)

Debris damage can be repaired in space with techniques pioneered after the space shuttle Columbia accident. A good deal of information was gathered then on what amount of damage warranted a repair. But the heating environment Orion will experience is different than the shuttle’s was, and the old models don’t apply.

Engineers will begin verifying new models when Orion returns from its first flight test this December. Before installing the back shell, engineers purposely drilled long, skinny holes into two tiles to mimic damage from a micrometeoroid hit. Each 1 inch wide, one of the holes is 1.4 inches deep and the other is 1 inch deep. The two tiles with these mock micrometeoroid hits are 1.47 inches thick and are located on the opposite side of the back shell from Orion’s windows and reaction control system jets.

“We want to know how much of the hot gas gets into the bottom of those cavities,” said Joseph Olejniczak, manager of Orion aerosciences. “We have models that estimate how hot it will get to make sure it’s safe to fly, but with the data we’ll gather from these tiles actually coming back through Earth’s atmosphere, we’ll make new models with higher accuracy.”

A better understanding of the heating environment for damage on Orion’s heat shield will inform future decisions about what kind of damage may require a repair in space.

  • Hug Doug

    i hadn’t heard about the simulated micrometeorite damage before! very interesting! it looks like all the parts are coming together for Orion

  • Stuart

    Tiles again?

  • Jonathan A. Goff

    Doug,
    One of the applications we had been looking at for our deployable robotic arms was being able to do inspection and repair of backshell TPS tiles. Actually that was the initial application that got us thinking of doing multi-jointed STEM arms in the first place.

    ~Jon

  • Hug Doug

    using Shuttle tiles on the backshell was part of the design from the beginning, since it has to handle higher temperatures on re-entry.

  • James

    Can’t the Dragon take higher temps? Its supposed to be able to do moon and mars return.

  • Vladislaw

    “Dragon’s PICA-X heat shield protected the spacecraft during reentry from temperatures reaching more than 3,000 degrees F. SpaceX worked closely with NASA to develop PICA-X, a SpaceX variant of NASA’s Phenolic Impregnated Carbon Ablator (PICA) heat shield.

    SpaceX chose PICA for its proven ability. In January 2006, NASA’s Stardust sample capsule returned using a PICA heat shield and set the record for the fastest reentry speed of a spacecraft into Earth’s atmosphere — experiencing speeds of 28,900 miles per hour.

    NASA made its expertise and specialized facilities available to SpaceX as the company designed, developed and qualified the 3.6 meter PICA-X shield it in less than 4 years at a fraction of the cost NASA had budgeted for the effort. The result is the most advanced heat shield ever to fly. It can potentially be used hundreds of times for Earth orbit reentry with only minor degradation each time — as proven on this flight — and can even withstand the much higher heat of a moon or Mars velocity reentry.”

    http://www.spacex.com/news/2013/04/04/pica-heat-shield

  • Robert Gishubl
  • BeanCounterFromDownUnder

    IIRC SpaceX is continuing development of it’s PICA-X for next version of V2.
    Cheers.

  • BeanCounterFromDownUnder

    All this time and billions of dollars and they’re still testing heatshields and only really have a mockup for their first flight. Not only that but all Orion vehicles are one-offs. Such waste is inexcusable 🙁
    Cheers

  • disqusser10157

    Would the arm be mounted on the Crew Module, or the Service Module?

  • Jonathan A. Goff

    Disquesser,
    We never got past the proposal stage on the Orion “compactly stowable robotic manipulator” project, but notionally had planned on it being mounted on the Service Module, at least on the way up. Depending on the dimensions we ended up with, it might be possible to make a version that could restow itself somewhere near the entry hatch on the capsule to enable recovery/reuse. But our baseline plan was an expendable arm that would mount on the SM.

    ~Jon

  • disqusser10157

    Interesting. I have often looked at missions proposed for the Orion (both by NASA and by random people online) and thought “too bad we don’t have a robot arm to help with that”. For all the money they’ve spent on the Orion, it often really does seem like little more than a scaled-up Apollo.

  • windbourne

    Personally, I think the arm would be better attached to a BA-330 unit, combined with a tug.

  • disqusser10157

    I’m a big fan of space tugs, but NASA lost interest in them as it became apparent how expensive the Shuttle was going to be to build and operate.

  • windbourne

    The shuttle was an everything to everybody, which made it a disaster.
    But, a simple BA tug used in space would be very useful with the ability to move from station to station, or perhaps even to say the Hubble.

  • Hug Doug

    I’ve never seen any report quantitatively state that SpaceX’s PICA-X heat shield can handle higher temperature loads than NASA’s AVCOAT.

    There are a lot of people floating around the internet saying that the Orion heat shield can’t handle the forces it would be subjected to from a Mars return, but I’ve never seen that claim substantiated.

    In any case, this article is specifically about the heat load on the backshell – and I have no idea what temperatures SpaceX’s backshell is able to handle.

  • Hug Doug

    i think this would be more accurately described as an Engineering Test Article than a mockup. it’s wired up with a lot of sensors and some test equipment that a flight Orion won’t have, but otherwise they are the same.

    i’m given to understand that this same test vehicle will be reused for Orion’s in-flight abort testing.

  • Vladislaw

    ooohh … well then .. these prices are a bargin.

  • Vladislaw

    Didn’t the Canadians propose something like this for an Orion so they could grab the JWST and do repairs?

  • Hug Doug

    I wouldn’t say that lol

  • BeanCounterFromDownUnder

    Yeah ok I was being a bit sarky.
    Cheers.

  • BeanCounterFromDownUnder

    I believe that in Garrett’s recent session, he referred to a proprietory SpaceX material for their ‘backshell’ protection but he didn’t mention specific temperature limits. I would expect them to match them to the PICA-X material so that if PICA-X can withstand say 3500 degrees F, then whatever is expected for the backshell is matched accordingly.
    But sorry, no details.
    Cheers