The SpaceX Press Conference

Elon is saying that the mission was completely successful, but they lost the first stage. First relight to gentle the entry was successful, but the second one to come into the ocean resulted in an exceedance of attitude control authority for roll. Centrifuged propellant shut down engine prematurely. But they’re getting all the pieces, so they’ll be able to figure out how to fix for next time.

[Update a few minutes later]

First and second stage engines performed better than predicted. Pad also worked well.

[Update a few minutes later]

Second stage shut down prematurely, but didn’t affect mission, apparently. They know why and will fix for next flight. Next two flights won’t attempt first-stage recovery, in order to maximize payload for customers. [All via @Jeff_Foust]

Next recovery attempt will be on CRS-3. Vehicle may also have landing legs (implies attempt at flyback to land, not ocean — today’s flight must have inspired confidence).

[Update a while later]

I mistyped above. The second stage didn’t shut down prematurely, it had a problem with restart. But I think it was just a test of the vehicle, and didn’t affect the primary mission.

12 thoughts on “The SpaceX Press Conference”

  1. Second stage shut down prematurely

    I thought the problem with the second stage was at relight. Before the webcast ended, they said the orbit was good.

  2. Actual recovery of the first stage would have been a surprise. Seems they have enough data to work out the kinks so perhaps the next attempt will come even closer.

    I’ve read elsewhere that it looks like rolling of the rocket on the decent caused enough centripetal force that the fuel was drawn away from the pump inlets causing the engine to shut down early. If so, this doesn’t sound like a terrible problem to overcome — either mitigate the rolling or change how fuel is drawn into the pumps during decent. Structural failure due to stresses during decent would be a lot more concerning, but it appears the first stage actually survived reentry which is very exciting.

    1. Some commenters at NSF.com pointed out that the landing legs could help mitigate the roll, like a figure skater extending her arms.

      It sounds to me like the first stage did very well indeed.

      1. I wonder if the rotation is induced on purpose to stabilize the booster during decent. It makes sense that they would given the booster coming down tail first doesn’t seem to be the most aerodynamically stable thing.

        1. Given that most of the mass is probably in the rocket engines / mounting HW / etc., it may actually be statically stable. I doubt that they want to get it rolling anywhere near fast enough to spin stabilize though; de-rolling it to establish closed-loop thrust vector control would be nontrivial. I would also be surprised if there’s enough change to the angular momentum with the landing legs extended to make much difference in the roll stability.

          The great benefit of TVC is that you have shitloads of control power independent of dynamic pressure; should be fairly easy to stabilize the booster in pitch.

    2. If the single engine burn is just to decelerate from terminal velocity, that’s very little delta-V and a correspondingly short burn for a hoverslam (ok, hoversplash) landing. I suspect it got pretty close to the water before it spun out. Musk has said he will release video footage later in the week, which should show one way or the other.

  3. Another clue. On the main page you have the update and a slightly more detailed first paragraph, but in the response page the post just says:

    Elon is saying that the mission was completely successful, but they lost the first stage. First relight to gentle the entry was successful, but the second one to come into the ocean resulted in an exceedance of attitude control authority.

    Refreshing produces it consistently. Hrm…

    Anyway, I think a separate RCS system, perhaps using draco thrusters, might be warranted.

  4. Rand, I hope you’ll give Orbital Sciences a nod. It aggravates me their Cygnus delivery to the I.S.S. is getting a fraction of the publicity that SpaceX Dragon enjoyed.

    1. I did follow the Orbital launch and docking and congratulate them, but Antares depends on Russian hardware. Falcon doesn’t. SpaceX is aiming for Mars so I cheer each little stop on that path more than I cheer Orbital who lacks either the vision or the hubris (depending on your point of view) to claim that.

    2. I’ve watched both Antares launches, and got up early on Sunday to watch the capture and berthing. (I also got up early a week ago, only to find that the rendezvous had been cancelled.) So I support Orbital. I’m also excited to see Wallops Island finally becoming a serious spaceport after all these years. It’s only 160 miles away from me. I can’t watch launches from Cape Canaveral or Vandenberg, but I did go outside and see the Minotaur V launch a few weeks ago. That was fun. I tried looking for Antares, but its launch azimuth is in the opposite direction from me and I didn’t have a flat enough horizon to see the contrail.

      But Fritz also has a point. Orbital wants to resupply the ISS, which is fine, but SpaceX is developing reusable rockets, a manned spacecraft, and wants to colonize Mars, which are inherently more exciting. Resupplying the ISS is just a steppingstone for SpaceX.

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