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ISS Space Technology

SpaceX Dragon Launches Successfully, But No Rocket Recovery 117

Posted by Soulskill from the trying-difficult-things dept.
New submitter monkeyzoo writes: SpaceX has successfully launched a Falcon 9 rocket carrying a SpaceX Dragon spacecraft en route to the International Space Station with supplies (including an Italian espresso machine). This was also the second attempt to land the launch rocket on a barge, but that was not successful. Elon Musk tweeted that the rocket landed on the recovery ship but too hard to be reused. Video of the launch is available on the SpaceX webcast page.
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SpaceX Dragon Launches Successfully, But No Rocket Recovery More

SpaceX Dragon Launches Successfully, But No Rocket Recovery

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  • Landed OK but tipped over (Score:5, Informative)

    by Bruce Perens ( 3872 ) <bruce@perens.com> on Tuesday April 14, 2015 @04:25PM (#49474005) Homepage Journal

    Musk tweeted here [twitter.com] that the rocket landed fine but there was residual lateral velocity that tipped it over after landing. The photos on that tweet are worth looking at.

    Obviously, now they have to work on fine positioning with elimination of lateral velocity before it comes down on the barge. Not an easy problem, especially given that the first stage doesn't have much Delta-V in its cold gas reaction control thrusters and does most of its positioning with the grid fins and the engine. Which means using more fuel. Hopefully there's enough, or room for building up the RCS.

    • OK, this might be crazy, but another alternative would be to move the barge. It's got big thrusters now, I think 1000 HP on each corner.

      • They should land it in a net or something that springs up around it to catch it.

        • Well, that might be better than ULA's plan to have the engine detach, fly under its own hang-glider, and then be snagged in flight by a helicopter. :-)

          Catching it in a net might not compensate for lateral Gs and torque on the rocket, which is a big empty tank at that point and could crumple. But maybe...

          • You know, they don't necessarily *need* to save the tank in order to save most of the cost. I bet the engines are both the most expensive and the heaviest parts, and they're at the bottom. If the stage doesn't actually hit so hard that the legs crumple and the engines contact the platform/ground, having the first stage tip over *might* still allow recovery of at least some of the octaweb. Maybe not the ones on the side that it landed on after tipping, but there's lots of engines on those stages, and I'd be shocked if they're less than 5% of the total launch cost each (the first stage, with nine engines, is about 70% of the total cost in total and there isn't a lot more to it than engines, fuel tanks, and the landing systems). Re-using even one of those would be a tremendous profit.

            Obviously, it's best if they can recover and reuse literally the entire stage, just rebuild the stack, fill 'er up, and launch again. I'm pretty damn sure they'll get there eventually, too. In the meantime... here's hoping the stage left enough intact components on the barge to examine and possibly even reuse some pieces of a previous rocket. That would still be a momentous achievement.

            • It's not clear yet whether the rocket remained on the barge after tipping.

              Sure, it would be nice to get at least partial recovery. But they seem so close to full recovery of a full first stage.

        • Yeah; it seems to me like the solution would be to catch the rocket with a tethering mechanism, and then absorb the lateral thrust with the barge itself.

          But I think what they're attempting to do here is minimize the complexity/parts of the situation, and solve the problem in logic as much as they can -- because that logic can be reused in every navigation system they develop. The last test showed that sometimes you do need more parts (or in that case, fluid), but this time it was a combination of the hardw

        • Re: Landed OK but tipped over (Score:1)

          by Anonymous Coward

          A huge baseball glove! Tis the season.

        • Re: (Score:2)

          by Megane ( 129182 )
          The main problem with that is that the walls are relatively very thin. Imagine something the size of a paper towel roll, but made of one thickness of aluminum foil, and some rocks at one end to represent the weight of the engines and remaining fuel. Now drop it from the roof of a building and try to catch it with a net. It's not going to be very round after you do that.

      • I think the ultimate goal is to delete the barge and land on land - they're using the barge because they can put it somewhere uniquely devoid of anything that anyone cares about.

        It takes far bigger thrusters to move the whole planet underneath the descending rocket...

        • It takes far bigger thrusters to move the whole planet underneath the descending rocket...

          You have a point. But you wouldn't really have to move the whole planet. Just an object large enough to land upon. Like the barge in a harbor, arbitrarily close to land.

          Of course, this is only worth exploring if there just isn't enough room to further stabilize the rocket during the close approach.

          • Re: (Score:2)

            by Adriax ( 746043 )

            I would assume they can fix the lateral velocity.
            If it can land but fall over then it's going quite slowly laterally. Any real residual motion and it would have been reported bouncing/somersaulting off.

            I'm sure worst case scenario is they invent the batarrang and launch 3-4 stabilizing tie down cables when it lands.

          • Of course, this is only worth exploring if there just isn't enough room to further stabilize the rocket during the close approach.

            why not both? (as they say).

            it would seem that you want extra assurance that things 'work right' when out in extremes (like space or deep sea). why not cover all the bases? work on the precision landing but also allow for 'wiggle room' in the design. the idea of a net catching something is a nice conceptual idea; something that 'gives' or adapts sounds pretty good to me.

            hell,

          • Re: (Score:3)

            by matfud ( 464184 )

            Have you ever tried to move a barge or for that matter any boat rapidly enough to compensate for something the rocket could not? If it is a slight know drift then maybe. Last min rapid changes. Not a chance.

            • I haven't tried to move a boat larger than 35 feet in the water, and that had a lot of inertia. So, I get your point.

              It's got 4000 HP of active stabilization that is supposed to keep it within 3 meters of a point in rough seas. The thrusters are on all 4 corners, and rotate 360 degrees on command. So, I thought maybe that could do it. Maybe not.

              • Re: (Score:3)

                by matfud ( 464184 )

                Station keeping is slightly different.
                The wind and waves may shift the ship but the currents in the water are fairly consistent. The bulk of the ship is in the water and predominately affected by the currents. It takes a while for wind to affect it. and there is little to be done about waves apart from ride over them if small or correct for position afterwards if they are large enough to move the vessel.

            • Re: (Score:2)

              by Rei ( 128717 )

              Don't move the whole boat. Move a steel plate on the deck with hydraulic rams.

              Again, not the best solution. But at least better than moving the whole boat.

              • Re: (Score:2)

                by smaddox ( 928261 )

                Some kind of platform docking mechanism does seem like a reasonable solution. Clearly they're close enough that such an addition should add enough tolerance for a high recovery fraction. However, it also looks like they're close enough that it may just take some more software calibration.

                KISS, as they say (keep it simple, stupid).

          • Re: (Score:2)

            by nadaou ( 535365 )

            > You have a point. But you wouldn't really have to move the whole
            > planet. Just an object large enough to land upon. Like the barge
            > in a harbor, arbitrarily close to land.

            hovercraft!

        • Actually I don't think so. From what I've read, Musk wants to do launches and landings as close to the equator as possible. Needs far less fuel that way.

        • I think the ultimate goal is to delete the barge and land on land - they're using the barge because they can put it somewhere uniquely devoid of anything that anyone cares about.

          I thought they were using the barge because that's where rockets generally end up if you fire them sideways from land - over the ocean.

          • Only if you launch at the coast. If he launches from somewhere like Texas, then there's still plenty of North America to land on.

    • I wonder, supposing it didn't tip over, how much would it cost to refurbish it for another launch. How many parts would you have to replace?

      • I don't know what parts are consumable, but if the second stage is attached with explosive bolts, those would be.

        The ultimate would be to just gas it up and go :-)

        • They use a pneumatic separation system. No consumables, fewer munitions for people to have to work around, greatly reduced mechanical shock during separation, etc.

          The engines can start and restart multiple times, as demonstrated by the hot fire tests and multiple burns during flight. I don't think they use pyro valves or anything of the sort anywhere. There's been talk of refueling on the ASDS and having the stage fly itself back to land, so they're hoping for something very close to gas and go.

          • Thank you. I remember that the sequencing of explosive bolts - all at once instead of one at a time - killed a Soyuz crew.

            Gosh, that video looks so close.

      • That's almost certainly one thing SpaceX was hoping to help determine with this landing. If it'd landed properly, they'd take it apart to see where there was wear and tear, and what needed replacing/fixing (or redesigning) as a result. That'll have to have to wait for the next launch, now, though they may be able to still recover some of the rocket for analysis (it fell over, but I'm assuming it's still physically on the barge).

        • The first one they get back intact is planned to have non-destructive testing and to do demo flights in Texas but not into orbit. The second one they get back intact is supposed to be dismantled.

          We have yet to find out what, if anything, is left of today's stage. It may be that some materials evaluation can take place.

  • I was hoping the rocket would be recovered this time. I'm hoping they will release the video like last time, and we can see what happened. The rocket recovery was the most exciting aspect of this launch. (Apart, of course, from the espresso machine. Ha ha.)

  • It failed less than the first attempt did. I don't like extrapolating from two sample points, but this does suggest improvement. Perhaps attempt three will get it right.

  • They say it is daft him trying to land it on water (Score:5, Funny)

    by HannethCom ( 585323 ) on Tuesday April 14, 2015 @04:46PM (#49474179)
    The first one hit hard and sank into the water.
    The second one touch down fell over and sank into the water.
    I predict the third one will burn down, tip over, then sink into the water.
    But the fourth one, that will stand!
    • Please! This is supposed to be a happy occasion. Let's not bicker and argue about what crashed when.

    • Re: (Score:1)

      by Anonymous Coward

      The fourth was the biggest one they built, but it disappeared 24 hours after going online.

  • Unless its absolutely calm, how can you not get lateral motion, maybe shooting nets over top from each corner to secure it? Other suggestion was the 1000hp thrusters on the barge, this would be like balancing a broom handle in your hand, standing on a ball.

    • Eh.. launch vehicles are already an inverted-pendulum problem; I don't think the guidance and navigation would be an issue. I suspect the thrusters, even that size, simply don't have the necessary control authority. Besides, the ultimate goal is landing on land, so you're better off getting the rocket to be able to handle it itself. I'm sure it will be a lot easier to convince the powers that be that they can land on land safely when they can demonstrate doing it on a floating barge a few times.

      • They may need to use a barge to make recovery of the middle 1st stage on the Falcon heavy easier. Since the outer pair of rockets would be jettisons earlier, and return to base, the middle rocket would be much further downrange and returning to land may not be possible.

        • As far as I know, the only purpose of the barge is for technical development; the ultimate goal is return to launch site. I have no citation for this, but my intuition is that he won't try to deal with the Falcon Heavy boosters until the Falcon 9 and Falcon Heavy core are reliably returning to base and possibly even being reused.

          The launch profile shouldn't change all that much for the Falcon Heavy; it's just sending more mass to the places Falcon 9 goes today.

    • Re: (Score:2)

      by gatkinso ( 15975 )

      Ever see that video of drones playing catch with a broomstick?

      https://www.youtube.com/watch?... [youtube.com]

      • Re: (Score:1)

        by jnowlan ( 618290 )

        Amazing. So they could use drones to 'capture' the rocket! In conjunction with parachutes?

        I wonder why they are not using parachutes now? I admit I haven't been following closely.

  • Kudos for Musk (Score:4, Insightful)

    by bughunter ( 10093 ) <.ten.knilhtrae. .ta. .retnuhgub.> on Tuesday April 14, 2015 @04:48PM (#49474191) Journal

    This is an achievement. Take it from an old rocket grognard, a veteran of Amroc, Orbital, and others: just getting this far is an accomplishment.

    And it's smart of Musk to append a test operation onto a paying mission. The launch fee for the ISS delivery offsets a major portion of the cost of the test.

    And in a test sequence, close does count, because all data gathered is useful. And often, data from a failure is more useful than data from a success.

    "Success is a lousy teacher; it seduces smart people into thinking they can't lose." —Bill Gates

    • When it comes to hitting a platform in the middle of the Atlantic ocean with a 15-story building falling from the edge of space, they're basically 2/2.

      The ultimate game of lawn-darts!
      =Smidge=

      • Re: (Score:2)

        by Rob Riggs ( 6418 )

        The ultimate game of lawn-darts!

        Or a nice game of "Global Thermonuclear War".

        • Nuclear weapons are not - and don't need to be - anywhere near as accurate with their targeting.

          They also aren't intended to land.
          =Smidge=

          • Re: (Score:1)

            by Anonymous Coward
            Nuclear weapons are not - and don't need to be - anywhere near as accurate with their targeting.

            Yeah, actually they do because the effects fall off with the square of the distance and they're designed to be used against hardened targets that require a near-direct hit to destroy. Right now, the most accurate of the bunch, the 9K720 Iskander short-range ballistic missile, has a 50% chance (circular error percentage) of putting its warhead within a 7-meter circle surrounding the target from about 300 mile

            • Re: (Score:2)

              by Megane ( 129182 )
              Yes, but they don't have to also be at zero vertical and horizontal velocity when they hit. Both of the past SpaceX landings have landed roughly on target. Their problem has been those velocity vectors in a non-vertical direction.
  • After the last one he said "the next one will also explode, but for a different reason". Dammit, I want explosions!

  • My Dads last job was to track the Shuttles solid fuel boosters and when the parachutes didn't deploy properly, best he could do is mark where they entered the water at.

    • How is that remotely the same thing? The shuttle boosters weren't guided, weren't in powered flight, weren't re-lightable, weren't targeting anywhere terribly specific, weren't trying to make a vertical landing, and were designed for a water landing. None of that applies to the Falcon 9 first stage. Also, the F9 recovery system didn't fail to deploy, it simply didn't fully correct for the rocket's motion. Considering that the booster is basically an inverted pendulum and that there's almost always some late

  • Two attempts and both of them at least hit the barge, even if they can't actually soft land on the barge they're well on their way to proving that they can at least land within a few hundred feet of their target. And if they can do that they probably only need a larger landing area, say a large parking lot, for a successful landing. The tests in Texas have proven that the rockets can have a controlled decent, just a few more kinks to iron out.

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