19 thoughts on “Bon Voyage, Discovery”

  1. Did not look like a foam strike to me– whatever it was (at the 4:42 point in the launch video) looked rather sturdy and metallic; it didn’t disintegrate upon hitting the bottom of the orbiter (hard!) but just bounced off and continued on down the hull. Can’t tell from the video whether it left any damage on the tiles– too much glare on the bottom of the ship. Anyway, it looks rather scary to me.

  2. Looking at it again, it looks like a chunk of whatever insulation that covers the bottom of the long, orange tube running along the bottom of the ET. There are TWO impacts against the bottom of the shittle, and the first impact DEFINITELY leaves a chip on the tile– you can see a very slight difference in the appearence of the tile before and after the strike. YIKES!

  3. The object looks more like a metal sheet than foam insulation. It definitely impacts the orbiter twice. Its a good thing they’re going to the ISS.

  4. I’m hoping that the thinner atmosphere significantly reduced the force of the strike. That and this piece wasn’t the size of a suitcase like the Columbia strike.

    Can’t be certain but it almost looks like you can see the puff of gas as the water ice sublimates and blows away. Makes me think they should have always kept making the tank white to reduce the radiant heating from The Sun.

  5. This doesn’t look significant to me. The debris was pretty close to the camera (in other words, it looked pretty small) and it didn’t leave much of a mark on the Shuttle. Before Columbia, I seem to recall that debris sometimes cut grooves down a good portion of the shuttle’s underbelly. Now there might be some damage on the leading edges of the wings, that would be significantly more dangerous, but as of now, I think they’re probably in good shape.

  6. Seems to me the orbiter was in near vacuum at the time and the delta v of the object in relationship to the vehicle was pretty low.

  7. I second what Cecil pointed out; the dynamic pressure was quite low at that point in the trajectory. We’ll see what the inspection finds.

  8. I read the launch thread at NASASpaceflight.com and the consensus is that it happened at a high enough altitude that it probably isn’t a problem.

    I guess we’ll find out when it gets to the ISS and the underside can be photographed.

  9. I think the relevant factor is the acceleration of the stack, not air pressure or lack of it. Imagine a mass let loose at the top of the ET while boosting, the posterior part of the orbiter could be unlucky enough to accelerate into it.

    Let’s hope the energy of the collision was low and the angle of incidence great.


  10. It seems quite clear that there were TWO strikes. At about the 4:42 point in the launch video on Youtube, a big chunk of foam (or whatever type of insulation is used in this area) basically explodes off long pipe running along the underside of the ET and strikes the underside of the orbiter at right about the point where the forward ET struts are attached– it then bounces off and hits the orbiter again about halfway down before disappearing in the ship’s wake. That first impact is definitely pretty hard. On another board, one poster theorized that a bubble of air was trapped under the insulation at that point and, when the atmospheric pressure outside dropped to zero, the bubble expanded until it violently blew the chunk of insulation away. Sounds plausible to me. The first impact looks very hard, but if the insulation didn’t have much mass, it may not have done any damage. We’ll see.

  11. Orbiter tiles were probably not damaged much if any. Biggest question now is what caused this. I don’t recall a loss this large off the LH2 flange, and the shape is odd, so the issue now is (hopefully to be answered by the post-sep photos of the ET from the Orbiter umbilical well camera): Did cracked Intertank stringer ends cause this foam event? If yes, that’s not good given the final approved flight rationale and waiver used to get STS-133 with ET-137 off the ground.

  12. NASA seems to think it’s foam, but without any dynamic pressure to “accelerate” it (with respect to the orbiter), it was more like a wiffle ball than the Mach 4+ cannon shot that struck Columbia’s RCC.

    This was the first Shuttle launch I’ve seen live. Awesome, in a somewhat different way from the Saturn V.

  13. Fred K, the reason air pressure matters is that if a piece of foam is liberated at lower altitudes / higher pressure the foam will be decelerated rapidly by the drag and if it strikes the orbiter the delta v between the two will be much greater than if the foam came off in near vacuum and maintained the velocity it had at the time of departure and the acceleration of the vehicle alone after the foam liberates isn’t enough to create the sort of delta v required to cause damage. Or at least that is what I’ve gathered from post Columbia studies/reports.

  14. Cecil, thanks for the explanation.

    This particular piece of debris seemed to “blast” off of the ET, and bounce off the shuttle. It’s trajectory clearly wasn’t simple freefalling arc nevertheless its interesting to note these numbers.

    Simple free falling object calculation:
    Assume a 30 m/s2 acceleration, and 1 sec time
    A mass will have 30 m/s velocity (70mph) and travel about 15 meters
    This seems to match the end of the video pretty well.

    The CAIB website isn’t responding, so I can’t compare that with the speed of the destructive Columbia debris

  15. Release was at 3:53 into flight. It’s foam. Good pics will probably get shown at today’s press conference. Any damage will be found tomorrow.

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