Follow Slashdot stories on Twitter

 



Forgot your password?
typodupeerror
Space

SpaceX Landing Attempt Video Released 248

An anonymous reader writes: Last week, SpaceX attempted to land a Falcon 9 rocket on an autonomous ocean platform after successfully launching supplies to the ISS. It didn't work, but Elon Musk said they were close. Now, an amazing video has been recovered from an onboard camera, and it shows just how close it was. You can see the rocket hitting the platform while descending at an angle, then breaking up. Musk said a few days ago that not only do they know what the problem was, but they've already solved it. The rocket's guiding fins require hydraulic fluid to operate. They had enough fluid to operate for 4 minutes, but ran out just prior to landing. Their next launch already carries 50% more hydraulic fluid, so it shouldn't be an issue next time.
This discussion has been archived. No new comments can be posted.

SpaceX Landing Attempt Video Released

Comments Filter:
  • Wait a minute (Score:5, Insightful)

    by Immerman ( 2627577 ) on Friday January 16, 2015 @03:02PM (#48832535)

    It suddenly occurred to me that I've never heard of a hydraulic system "using up" its fluid before. Anyone know anything about how/why the rocket is different?

    • Re:Wait a minute (Score:4, Informative)

      by Shatrat ( 855151 ) on Friday January 16, 2015 @03:05PM (#48832593)

      Maybe they save weight by not providing a return line?

      • Maybe they were using it as fuel.

        Something isn't adding up here, but it wouldn't have surprised me of the obfuscation filter otherwise known as the media has garbled the message.

        • Re: (Score:3, Interesting)

          by Anonymous Coward

          Others are posting about an open system. Besides the loss of the hydraulic fluid which would lighten the load you should also consider that to make a closed loop system it would add mass in the parts and tubes which would be required to contain and create the closed loop.

      • Re:Wait a minute (Score:5, Informative)

        by Anonymous Coward on Friday January 16, 2015 @03:11PM (#48832665)

        Maybe they save weight by not providing a return line?

        And pumps and motors.

        All they need is a pressure tank.

        • by v1 ( 525388 )

          but that means you have to carry more fluid. Unless there's very little fluid normally needed, I don't see how ditching the pumps and motors saved enough weight to put enough additional fluid in the reservoir to matter. I see two lines on a weight graph, a horizontal one for the closed-loop, and a curved line representing the open-loop. At some point these lines cross, and the open-loop becomes a worse option. I'm just surprised that point isn't way earlier for them.

          • by smaddox ( 928261 )

            An open system is also a whole lot simpler. Weight is very important, but so is reliability. If a pump fails (keep in mind the extreme environment), you lose the stage. Increasing the reservoir size is much simpler and more reliable.

    • Re:Wait a minute (Score:4, Interesting)

      by scarpa ( 105251 ) on Friday January 16, 2015 @03:07PM (#48832615) Homepage

      It's an open loop system, presumably to save mass.

    • Re:Wait a minute (Score:5, Informative)

      by infogulch ( 1838658 ) on Friday January 16, 2015 @03:07PM (#48832617)
      His tweet reply [twitter.com] to this question answers:

      @alankerlin Hydraulics are usually closed, but that adds mass vs short acting open systems. F9 fins only work for 4 mins. We were ~10% off.

      • by OzPeter ( 195038 ) on Friday January 16, 2015 @03:21PM (#48832815)

        he tweeted [twitter.com]

        Next rocket landing on drone ship in 2 to 3 weeks w way more hydraulic fluid. At least it shd explode for a diff reason.

      • Re: (Score:3, Interesting)

        by LWATCDR ( 28044 )

        I wonder if they are using a pressurized accumulator for the fins instead of a pump. Still a bit odd since the air flow that close to landing should have been next to zero and one would assume that they still had thrust vectoring on the main engine.

        • Maybe the main-engine vectoring used hydraulic actuators? Internal verniers, nozzle steering, engine steering... something has to push it around, and why would you have two actuation systems? If you're too mass-cheap for a closed-loop hydraulics, a complete independent actuator system for thrust steering seems like a bad bargain.

          • I see later down in this discussion that the engine steering is done with pressurized fuel, which is presumably then dumped into the exhaust stream to burn. And the other actuators are too far from there to make it practical to extend the fuel-based hydraulic system to them.

            Weird set of engineering compromises, but they make sense. Too bad about underestimating the capacity needed for the upper hydraulic reserve.

            • by LWATCDR ( 28044 )

              Using fuel for hydraulics is standard practice for rocket and jet engines. It is really a given. Using a pressurized total loss hydraulic system for the fins is... an interesting system.

              • by phayes ( 202222 )

                Boosters don't need hydraulics just for the engines, they are also needed to assist in stage separation -- at the opposite side of the booster and at a moment when the engines are off & the RP-1 system is no longer actively being pressurised so they almost always use a separate system using a pressurised tank of fluid. When the need for a hydraulic system for fin actuators on descent was discovered (again, when the engine is mostly off & at the opposite side of the booster) it was logical to use it.

        • by robbak ( 775424 ) on Saturday January 17, 2015 @08:59AM (#48838201) Homepage

          Elon stated while being questioned last week that the steering fins went hard-over (which means they were driven to their maximum angle) when the fluid ran out. With the fins pushing the rocket over, it didn't have much hope of landing. And, yes, a pressurized accumulator is the most likely design of this system.

          /u/DixieAlpha over at reddit programmed a Kerbal Space Program model to try to land with grid fins fixed at 30 degrees. The results were scarily similar to this landing. [reddit.com]

    • Re:Wait a minute (Score:5, Insightful)

      by pushing-robot ( 1037830 ) on Friday January 16, 2015 @03:12PM (#48832691)

      Less complexity, less weight (and gets lighter as you use it). No pumps, no power source for pumps, no return lines, just a pressurized tank and a few valves.

      Of course, you have to know how much you'll need before the flight, and the longer you'll need it the lesser the savings over a traditional system.

    • Re: (Score:2, Informative)

      by Anonymous Coward

      It is lighter and more simple to use up (to expel it when it has done its work) any hydraulic fluid than it is to have a scavenger system. While this would be a problem on your car if each time you pushed the break cylinders it squirt out the fluid after it had actuated the break on a rocket it saves on over all weight and complexity just to have "enough" fluid to do the job

    • Re:Wait a minute (Score:5, Informative)

      by patniemeyer ( 444913 ) <pat@pat.net> on Friday January 16, 2015 @03:20PM (#48832797) Homepage

      In a normal hydraulic system there is a pump that re-pressurizes and returns the hydraulic fluid to a reservoir. To save weight and complexity here since the hydraulics are only used for a few minutes they instead use an "open" hydraulic system in which the pressure comes from a tank of compressed gas and the hydraulic fluid is expelled or burned up as it is used. (The fluid goes one way - out - as it is used).

      After the pressurized gas or fluid was used up they no longer had control over the fins.

      • by Webmoth ( 75878 )

        Everyone is assuming that the spent fluid is being dumped overboard. Do we know that to be the case?

        It's only necessary to expel the spent fluid externally if you want to reduce overall rocket mass while doing so. If that's not necessary, you can still use an open loop system but have a recovery tank to receive the spent fluid, thereby preventing environmental contamination. That's really the only reason to contain it; the cost of lost spent fluid is probably minimal.

        • Re:Wait a minute (Score:4, Informative)

          by hackertourist ( 2202674 ) <[ln.tensmx] [ta] [tsiruotrekcah]> on Friday January 16, 2015 @04:23PM (#48833571)

          The main hydraulic system on the F9 (for gimbaling the engine nozzles) uses RP-1 (i.e. rocket fuel) as its hydraulic fluid. Spent fluid from that system goes into the fuel tank.
          The fins are driven by a separate system at the top of the stage, if they pumped the spent RP-1 overboard you'd have flammable liquids running down the stage, I'm pretty sure they don't want to do that. Returning the RP-1 to the fuel tank is unlikely (needs an insulated pipe around the outside, next to the cold LOX tank). So probably a separate waste tank near the fins.

    • I was about to ask the same, a bit more poorly worded perhaps :D

  • Seems to me that I would save that for emergencies. Use the high speed descent to pressurize air for controlling.

    Just saying...

    • by Anrego ( 830717 ) *

      I would assume for the same reason they are using an open system rather than a closed system: to save weight and complexity.

      Also, I'm not a space nutter, but this stuff impresses the hell out of me. That looked damn close.

    • So, instead of taking a larger reservoir of hydraulic fluid you recommend they install a secondary pneumatic control system as well, along with an efficiency leeching ramscoop for collecting compressed air? Sounds like a good way to simultaneously increase complexity and reduce payload to me.

    • Seems to me that I would save that for emergencies. Use the high speed descent to pressurize air for controlling.

      Just saying...

      Due to the fact that they've only got 4 mins of fluid, I'd say they're already doing that. It's for the low-speed descent to the capture pad that the fluid is needed. Obviously, they cut their margins a bit too close, and so now will be increasing the fluid instead of decreasing the control time. I'm sure they've run the numbers to see if the other way was more viable, as they want as little extra mass as possible.

    • by OzPeter ( 195038 ) on Friday January 16, 2015 @03:15PM (#48832735)

      Seems to me that I would save that for emergencies. Use the high speed descent to pressurize air for controlling.

      While IANARE, The problem with pressurized air as a control mechanism is that it is elastic/compressible (while hydraulic fluid is basically non-elastic/non-compressible). Which means that if you use air your control is basically going to suck big donkey's balls as your control vanes will bounce around in the airstream as the air in the control system acts like a big spring. Thus degrading the landing accuracy of your rocket.

      On the other hand hydraulic fluid being stiff means that when you send the control vane to a position it stays there, and the only thing that moves it is a leak or destruction of the vane. Note that they will be some bounce in a hydraulic system, but nowhere near as much as in an air based system.

      Now as to the hydraulic fluid in this case being used up, I am guessing that they considered the mass imposed by a collection system and decided, "fuck it, it's too much mass to recycle it, we're just going to dump that shit overboard".

    • Don't tell us, tell them!

      http://www.spacex.com/careers/... [spacex.com]

  • by pushing-robot ( 1037830 ) on Friday January 16, 2015 @03:03PM (#48832543)

    Looks like most of my Kerbal Space Program landings.

    • by Loki_1929 ( 550940 ) on Friday January 16, 2015 @03:59PM (#48833293) Journal

      Based on my experience in Kerbal, they're 95% of where they need to be. They've done the really hard stuff (controlled burns to bring the craft down at the right spot, slowing the descent at the right time without running out of fuel, etc) successfully. Properly orienting the rocket should be relatively easy assuming that the systems responsible for that haven't run out of fuel. The fact that the engine was able to get it that close without the fins working speaks volumes for how well the thing is operating.

      Even if something else goes wrong the next time or two, they'll have a successful landing shortly. The simple fact that it hit the platform ought to be enough to let them start trying on land after another one or two similar attempts. As failures go, this was extremely successful.

      • by dkman ( 863999 )
        I'm kind of wondering if they could put some arms on the platform to reach out and grab it at that point. I had wondered how they intend to "manage" it once it does land. A big pole on a boat is one wave away from falling over, so they have to have some plan to "strap it down". If they had 4 claws come up from each corner to stabilize it they may have been able to recover from this landing.

        Then your complex part is terrestrial, where it's not offsetting potential payload and easier to maintain.

        I know i
    • More like BBQ Kibbles & Bits landings.
  • by catchblue22 ( 1004569 ) on Friday January 16, 2015 @03:11PM (#48832677) Homepage

    This was the first time SpaceX had flown the new grid fin control system on a real first stage under real conditions. They did not know exactly how well the grid fins would behave. As it turned out, the grid fins had to move more than they expected during the descent (or the forces were larger than they expected), so they ran out of hydraulic fluid 30 seconds before landing. This is similar to an airplane losing control of its elevator just before landing. The fact that the rocket reached the barge and that its vertical speed was reasonably slow (certainly not 100m/s) indicates the resiliency of their systems. They are putting 50% more fluid into the system, so this shouldn't happen next time.

    I think this video is epically cool. I can watch it again and again. Simply awesome.

    • by Anrego ( 830717 ) *

      Indeed. I'm not a space nutter, but this impresses the hell out of me. With a problem this hard, the fact that they are down to minor mistakes like this and not major fundamental issues is awesome.

    • by Bo'Bob'O ( 95398 )

      Interesting that despite running out of fluid 30 seconds before the crash. It still landed in nearly the exact center of the platform. Is it just that it dosn't take much maneuvering even to cover that distance? Or was the platform moving to 'catch' it I wonder?

  • by Forgefather ( 3768925 ) on Friday January 16, 2015 @03:13PM (#48832707)

    What gets me most about this is the nonchalant attitude.

    "yea we blew up the rocket and the barge, but no biggie. We'll do better next time"

    I think that is why nerds get so exited over SpaceX. That attitude of not letting fear of failure dictate future actions.

    • by Hotawa Hawk-eye ( 976755 ) on Friday January 16, 2015 @03:24PM (#48832855)

      To be fair, the pictures I've seen of the barge indicate it came through mostly unscathed. So they only blew up the rocket. :)

      • So they only blew up the rocket.

        Hey, their competitors would have just thrown it away anyway...

      • I just got a look at the vine b/c the site is blocked at my work. My thoughts are:
        It was much closer than I thought, and that must be one tough barge.

      • by Bo'Bob'O ( 95398 )

        It looks like they lost a hydraulic pump for one of their thrusters from the photos I've seen. So not quite unscathed, that was probably tens of thousands of dollars of damage, but that's chump change if they can make it work.

    • by Anrego ( 830717 ) *

      Gotta agree.

      Business in general has become very risk adverse with a few exceptions (spacex and google being the big ones). Many of us feel constrained in this environment where everything we do has to mostly work or we won't get a second change or an opportunity to improve it. Everything has become about risk management and ROI and soul crushing metrics. It's very refreshing to see this kind of apparent "lets just do something we know probably won't work the first time, and keep doing it until it does" atti

    • by Kjella ( 173770 )

      Well, they usually just let it fall in the ocean so I don't quite see the big risk they're taking here. The rocket will be FUBAR anyway, the barge is basically a bulk metal piece and I assume that if they were looking at a high speed impact they would have fired the engines to avoid significantly damaging/sinking the barge. The money is spend on all the R&D on engine control, fins, legs and whatnot. They got nothing to lose in the actual landing attempt, basically they get a free shot with every rocket

    • by Bo'Bob'O ( 95398 )

      They don't have stock-holders or congressmen holding the purse strings to try and impress. They don't need to downplay or spin the outcome of a test flight because everyone involved knows that a good testing program will have some failures. And in fact finding new failure modes in early testing is better then not finding them at all.

      So while to SpaceX this was a useful test; their stocks would be falling right now, sending bean counters into a panic were they publicly traded.

  • Fix slashdot! (Score:5, Informative)

    by Carewolf ( 581105 ) on Friday January 16, 2015 @03:19PM (#48832793) Homepage

    WTF is going on with the left margin. God damn it, it is broken in every single browser. Are they crapping on classic slashdot to punish us for beta not working?

  • no more RUDs, then? (Score:5, Informative)

    by ihtoit ( 3393327 ) on Friday January 16, 2015 @03:23PM (#48832839)

    To borrow from the KSP forum, that's "Rapid Unscheduled Disassembly". Or, "explosions", to the uninitiated.

  • Well Done, SpaceX (Score:5, Insightful)

    by Anonymous Coward on Friday January 16, 2015 @03:37PM (#48833021)

    This was the first Falcon 9v1.1 flight [1] with gridfins and [2] sent to land on a teeny tiny little platform at sea (a MUCH smaller target than an aircraft carrier, while descending from MUCH higher than any carrier pilot and having no wings and only VERY limited fuel and throttle-range for lift and control)

    It was an excellent display of competence that puts Boeing and Lockheed-Martin to shame; both mega-corps have been sucking billions from the government nipple for many decades without ever once even TRYING to make such an improvement for which they certainly had the expertise and resources. These giant aerospace companies were born as innovative entrepreneurial entities that invested in technological advances and experiments to advance "the state of the art" in order to win their share of the free market.... but after the deaths of their founders they got hired-gun CEOs and moved to a model of only innovating when they could get the government to give them billions of dollars to do it. With many decades of "cost-plus" contracts (where the government pays "whatever it costs, PLUS some percent as profit") the big bloated defense contractors have had no incentive to innovate (ABSOLUTELY ZERO incentive to reduce costs) and have become lazy. SpaceX and more more like it are needed to drive the big old firms into either returning to efficiency and innovation, or bankruptcy.

  • It seems SpaceX is relying on a trial-and-error strategy during the development of the soft landing capability of their booster much more than they (or others in the industry) do for other components or capabilities of space launch or other aeronautical systems. I don't see (unmanned) rockets or drones being developed in this fashion. Even large rockets that can achieve orbit will normally be modeled, simulated and tested component-wise to the point that they will usually work at the first or second attempt
    • SpaceX has modeled the hell out of it. It's just really really hard. Honestly, I'd rather they fail in spectacular fashion and explore all the dark corners of their design before they stick people on the top of it. What's great about this is it's all gravy at this point. Once they work all the kinks out, it's going to eviscerate the competition when it comes to cost to orbit per ton. I can only imagine every other commercial launch company must look at SpaceX with a mix of horror and amazement.
    • Re:trial and error (Score:5, Informative)

      by bledri ( 1283728 ) on Friday January 16, 2015 @06:51PM (#48835065)

      It seems SpaceX is relying on a trial-and-error strategy during the development of the soft landing capability of their booster much more than they (or others in the industry) do for other components or capabilities of space launch or other aeronautical systems. I don't see (unmanned) rockets or drones being developed in this fashion. Even large rockets that can achieve orbit will normally be modeled, simulated and tested component-wise to the point that they will usually work at the first or second attempt when the entire system is integrated and tested for the first time. So why is this so different here? Is it just cheaper? Or is it actually that much harder to make the rocket land softly on its own exhaust jet than to make it go into orbit?

      It's important to remember that the primary mission was a complete success. The Dragon delivered the cargo to the ISS and is awaiting trash and cargo to return to Earth. This was a post mission experiment meant to collect data. It's very common to completely loose a rocket in the early flights, but that's not what happened here.

      SpaceX does what's called LEAN development, which is basically like agile software development. Really all development is incremental, the difference with lean/agile is you admit that instead of pretending that you can design the perfect solution from the start. SpaceX has a huge computer cluster and they model the hell out of everything they do. Then they try it to see how it works in the real world, measure the results and make improvements. The experiments are always done after stage separation in a way that collects important data without putting the mission as risk. You can call that trial and error, but that does the process a disservice.

      There have been experimental rockets and landers that land vertically, most notably the DCX. But no one has reentered a first stage of an actual in service rocket, the previous vehicles have always been test platforms and never accelerating to launch vehicle velocities nor going to launch vehicle altitudes. NASA has flown aircraft to collect data from earlier SpaceX missions because no one else has EVER controlled a first stage's return to earth. (Shuttle SRBs were not controlled, just big steel tubes falling from lower and slower than the F9.) The first stage is a long cylinder with blunt ends and it reenters the atmosphere at hypersonic velocities. On top of that, it's a super light weight and fragile airframe. Just getting the thing down to terminal velocity in one piece is a big deal.

      The LEAN development model is less expensive than the classic approach. It's also faster and yields really good results. You learn about problems sooner and don't bake them too deeply into your design. Look at it this way, the closest competitor to SpaceX in developing a reusable VTVL rocket is Blue Origin, started by Jeff Bezos. Blue Origin started with more money than SpaceX and before SpaceX. SpaceX is delivering cargo to the ISS, and about to test the Dragon V2 abort system in preparation of flying astronauts in 2017. They are also self funding the development of a much bigger reusable rocket (slightly bigger than the Saturn V). They are doing all of this while providing the least expensive launch prices in the world. Less expensive than Russia. Meanwhile Blue Origin hasn't even reached orbit. They aren't even trying to reach orbit, they are still developing a suborbital rocket, even though they have a number of experienced engineers that worked on the DCX. Oh, to be fair, Blue Origin is developing an engine for use by ULA (and Blue Origin) and doing some work on a man rated capsule. But nothing is anywhere close to flying.

  • by xeno ( 2667 ) on Friday January 16, 2015 @04:28PM (#48833629)

    Hey, as these things go, this was a very very good failure. Consider that we've just progressed from the old reality's typical "the vehicle will splash down somewhere in this 500-square-mile area of the ocean," to Spacex's new reality of "we accurately flew down to a 0.0018-square-mile platform, and borked the touchdown on this first try."

    I'll take that kind of progress any day.

  • The first reports I read said the rocket came down to hard and damaged the platform. I thought it landed vertically by coming in too fast and smashing the platform surface. Watching the video, the rocket landed sideways before exploding. Things always goes badly when they go sideways.
  • I personally find this is about as cool as anything I have seen in the last decade. What they are doing requires the very best engineering that mankind currently offers -- I'll take this over building 2000 feet tall buildings, or 50 mile long bridges any day.
  • Remind me again, why doing this crazy rocket landing is better than using a parachute recovery like the shuttle boosters did?

    • The shuttle's Solid Rocket Boosters always had a bunch of salt water damage that had to be cleaned up and refurbished before being reused, and that refurbishment process costs only slightly less than manufacturing from scratch. The Falcon 9 is a liquid fuel rocket, so that same saltwater has even more things it can damage like pipes and pumps. SpaceX is trying to avoid any major saltwater clean-up, yet still have a place to put the rocket down that's unlikely to hurt anyone when the landing still fails ever
    • Re:parachute (Score:4, Informative)

      by xeno ( 2667 ) on Friday January 16, 2015 @05:57PM (#48834575)

      Because parachute recovery is a method of salvage, while "crazy rocket landing" is a method of full reuse without refurbishment.

      Keep in mind that refurbishing the waterlogged shuttle boosters ended up being 3X more costly than original estimates, much of the nozzle apparatus was completely trashed each time, and the whole process took months to turn around a single booster.

      SpaceX is working toward an airplane/airport-style refuel-and-refly-immediately model. That autonomous landing platform is actually a fuel depot, with the eventual intention to refuel first stages and relaunch them immediately for short hops back to a proper launch facility where they can be fitted with a new payload within a day. Crazy? Maybe. Wrong? I don't think so.

    • Re:parachute (Score:5, Informative)

      by bledri ( 1283728 ) on Friday January 16, 2015 @06:02PM (#48834613)

      Remind me again, why doing this crazy rocket landing is better than using a parachute recovery like the shuttle boosters did?

      SpaceX tried parachute recovery with the F9 v1 (the rocket flying now is the v1.1, though really is more like a version 2). After multiple attempts, they could not get the rocket to survive reentry. There are many reasons for this. First of all, the shuttle boasters were big heavy steal tubes. That's fine for a strap on booster, but not so good for the first stage. Rocket stages are very light weight, since the lighter the rocket the more payload it can carry (this is true for boosters too, but it's a different trade off when coupled to a "first stage".) Second the shuttle boosters separated at lower speed and a lower altitude than the first stage of an F9. So you have a much lighter, complex F9 reentering at much higher velocities. Third, the shuttle boosters were more "refurbished" than reused. The goal of SpaceX is to (ultimately) land the first stage and be able to refuel and relaunch it with a minimum of work. Shuttle boosters had to be fished out of the water, disassembled, cleaned, inspected, etc... SpaceX was hoping to use parachutes as a first step, but they always hoped to eventually land the boosters. Their timeline just got accelerated when uncontrolled reentries kept breaking up.

    • One of the biggest reasons is that, in the location this is happening, parachutes means "lands in the ocean" which implies that your rocket is going to get bathed in salt water, probably engines first. I'm sure you could design some sort of a deployable cover to cover the engines (although they're have to be vented of fuel and cooled first) that would prevent salt water from entering, but I doubt that would be less complex than this scheme and it would almost certainly be heavier.

      Finally, remember that one

  • by eexaa ( 1252378 ) on Saturday January 17, 2015 @05:32AM (#48837671) Homepage

    I mean, If it's already slowed down like this, why not just gently land the rocket into the ocean and take it up with some prepared nets/ropes? IMHO it can save a lot of headache from trying to hit a platform this small.

    If the water getting in the rocket is problem, what about a gigantic sheet of plastic on the water surface? (still cheaper and more reliable than hitting the landing pad).

"How many teamsters does it take to screw in a light bulb?" "FIFTEEN!! YOU GOT A PROBLEM WITH THAT?"

Working...