Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 



Forgot your password?
typodupeerror
ISS NASA Space

SpaceX Pressure Hammers Stuck Valves; Dragon's ISS Mission Back On Track 170

Posted by timothy
from the click-and-clack-the-tappet-brothers dept.
SpaceX's Dragon launch to the ISS earlier today went off smoothly, but the mission encountered trouble shortly after: three sets (of four) of the craft's maneuvering thrusters didn't work. CNET quotes SpaceX founder Elon Musk: "It looks like there was potentially some blockage in the oxidizer pressurization (system). It looks like we've been able to free that blockage, or maybe a stuck valve. We've been able to free that up by cycling the valves, essentially pressure hammering the valves, to get that to loosen. It looks like that's been effective. All the oxidizer tanks are now holding the target pressure on all four (thruster) pods. I'm optimistic we'll be able to bring all four of them up and then we'll work closely with NASA to figure out what the next step is for rendezvousing with space station," and follows up with the good news that "Shortly after the briefing concluded, engineers reported all four sets of thrusters were back on line and that testing was underway to verify the health of the system." Barring further problems, Dragon could reach the ISS as soon as Sunday.
This discussion has been archived. No new comments can be posted.

SpaceX Pressure Hammers Stuck Valves; Dragon's ISS Mission Back On Track

Comments Filter:
  • by Baldrson (78598) * on Friday March 01, 2013 @08:45PM (#43051457) Homepage Journal
    Cryogenic valve failures are problems that seems to put about 50% of private launch service companies under or at least at serious risk from decades ago.

    I'm sure Musk is aware of this but really, it just seems to make sense to find the best cryo valve guy in the world and give him one and only one full time job: Make sure the damn things work!

  • by Alex Vulpes (2836855) on Friday March 01, 2013 @09:08PM (#43051593)
    Oh come on, that's not really fair—I'm pretty sure the whole PayPal mess happened after Musk sold his portion of the company. Also, the guy uses plain English a lot more than technical jargon.
  • by Sarten-X (1102295) on Friday March 01, 2013 @11:26PM (#43052175) Homepage

    I'll bite.

    Making awesome things takes a lot of cooperation. To a certain extent, that cooperation can be bought. Cooperation can be bought more cheaply and more easily, however, if the person being bought is already in favor of the project, and once they're involved, they're far more likely to be passionate about the project's ultimate success, rather than viewing it as yet another boring job in a long career.

    Leaders like Steve Jobs and Elon Musk don't just do the "executive" part of the "Chief Executive Officer" role. They act as figureheads leading an army of supporters who believe in the project and are devoted to it. That fanatical love for the goal [pacifict.com] is seen as crazy by outsiders, but it leads to a quality product in the end - albeit after some major trials and tribulations. A bit of vision, a bit of business, and a bit of distorted reality are the secret ingredients to leadership.

  • by ensignyu (417022) on Friday March 01, 2013 @11:49PM (#43052279)

    It's not accurate to say that the Dragon will be automatically docking with the ISS, since the Dragon doesn't support automated docking yet. Rather, it very slowly approaches the station, holds steady at about 10m, and then the crew (or mission control in Houston) spends hours operating a robotic arm to grab it and bring it in.

    As others have pointed out, NASA has the final say over whether the Dragon can even come within a kilometer of the ISS.

    The initial approach during the COTS-2 demo was 0.24 meters/second according to this link [spaceflight101.com] and this link [wordpress.com], and the final approach from 30m is even slower.

    I'd imagine that the ISS could manage to avoid an object traveling towards it from 30m at roughly the speed of a tortoise, considering that most other dangerous objects in space are traveling much faster.

    That's not to say that the thrusters couldn't misfire at just the wrong moment, but considering the care taken in the approach, it's not like they're just aiming it in the direction of the ISS and hoping for the best. It'd have to be a failure that didn't manifest at all until close to the last second, which would be extraordinarily bad luck.

  • by 0123456 (636235) on Friday March 01, 2013 @11:53PM (#43052297)

    Yes, CRS-1 had an engine failure and couldn't deploy its secondary payload, but the Dragon itself still got to the ISS in good shape.

    Even that is a bit of an exagerration: they could have deployed the secondary payload in approximately the correct orbit, but NASA wouldn't let them because there was a tiny risk of colliding with ISS if they did so.

  • by snadrus (930168) on Saturday March 02, 2013 @12:22AM (#43052421) Homepage Journal

    Doing something at 100x less cost is a big deal. Sure it took political influence to be the NASA's first commercial sale. In the end he even saved taxpayers money, so what's not to like?

    Driving coast-to-coast without using gas is a chicken-and-egg problem. I'm glad to see someone taking-on the stranglehold of world's largest cartel, with some success.

  • by Anonymous Coward on Saturday March 02, 2013 @03:18AM (#43052887)

    Pressure hammer, or water hammer as it is more commonly known, is not a simple pressure transient. It is far more complicated than that and can exceed design tolerances by orders of magnitude. It is a shock-wave traveling at the speed of sound. In power plants, water hammer has destroyed valves, ripped pipes apart, destroyed heat exchangers, etc. The water hammer than you have in your house is occurs at ambient temperatures and pressures, yet it is still able to destroy your piping. When it happens in your body, it rips apart arteries and veins. Consider what happens when it isn't an ambient condition and where there is an enormous pressure difference allowing for phase changes in the liquid. Feel free to do a search and find examples where inches of steel have been shredded by water hammer or where massive heat exchangers have imploded or exploded.

    Sorry, but mentioning a spacecraft that has had a pressure hammer event is as big of a red light as mentioning a ship that has had a flooding event or a nuclear plant that has had a massive radiation release. It doesn't mean that everything is fucked, but is sure could be! Pressure hammer events almost ripped Apollo 13 apart on launch. It is NOT a joke. It is a BFD.

  • by KGIII (973947) on Saturday March 02, 2013 @03:19AM (#43052889) Journal

    I believe it docks in a non-collision course - meaning the CanadArm reaches out and grabs it as it goes by. If the folks on the ISS aren't comfortable then they don't do anything except wave as the module goes past. Short of some sort of absurd fault which fires the thrusters off at the last minute there shouldn't be any major risk with this. People smarter than I did the engineering so I may be missing something.

  • Not so bad (Score:4, Interesting)

    by sjames (1099) on Saturday March 02, 2013 @03:34PM (#43055925) Homepage

    It's a little early for the doom and gloom here. It looks like they got the valves open and the thrusters working. There's no reason to believe the mission can't be completed at this time.

    Yes, it would be better if the valves didn't stick in the first place, and I'm sure they'll look at the problem again, but as problems go in spaceflight, this is just one of a VERY long list of things that have gone wrong that could have been mission ending but turned out OK that have been seen by government and private operations over the years.

Science and religion are in full accord but science and faith are in complete discord.

Working...