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SpaceX Pressure Hammers Stuck Valves; Dragon's ISS Mission Back On Track
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.
wonder if boeing will offer to help.
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!
Seastead this.
Please Please Please don't have a commercial spaceflight disaster this soon. I want to GTFO(ff) of this planet before I die. That sure as hell won't happen as long as we have nothing but NASA crippled by the same useless monkeys in charge who can't even balance the budget.
Shit, even bugs can balance a budget (ie, ants storing food for the winter). Our leaders can't pull off a feat mere bugs can do.
Go Elon! Make those valves your bitch, dude!
Nope. If he's going to make commercial space a reality, I'm all for hearing more from him.
Personally, no. SpaceX and Tesla are both high in the running for "coolest company" in my book. The fact that the same guy is behind them both makes me think it's not just luck. (It would be so tempting to troll Apple at this point, but I think I'll just stop here).
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.
I don't know the details of this system, but pressurisation valves probably open once and... that's it. Typically you want the thruster tanks unpressurised until orbit and pressurised from there until the end of the mission.
The good news is that, because they'll get the Dragon back, they should be able to dismantle the thrusters on Earth and find out why they didn't work properly.
I'd say down-voted due to armchair quarterbacking regarding the level of risk involved in continuing the mission and the excessively snide conclusion. I'm sure SpaceX engineers are far more knowledgeable of the risk factors than any of us meat blobs sitting in our chairs at home reading slashdot are. And as far as pressure hammer is concerned, I would guess (and call it what it is, nothing more than a guess), that they actually had some level of control of the amount of pressure they drove into the system, vs. a random water hammer in a set of pipes that occurs in a home or building.
I'd say down voted because people here haven't a clue about how NASA deals with things concerning the ISS. If you believe they have given any sort of green light on docking then you are greatly mistaken. $20B+ dollars, 10+ years making, and no room for error they will take no chances over a little more than half a ton of cargo. I've been in meetings and seen them pontificate of completely benign things for a week. They take nothing more seriously than the safe being of the ISS. I'm not saying they won't give it a go, but I would be shocked if they have already given SpaceX the go ahead. Not saying they aren't planning, but I will say there are a lot of people who have some decisions to make and they wo't be done lightly.
Nah, even if the mission fails, Musk will show graphs and logs explaining that the valves never actually malfunctioned... ...
(Just Kidding, I am actually on Tesla's side on the test drive debacle)
No sig for the moment.
He is not Job's figure, he is not making expensive toys, he is actually someone struggling to improve mankind. One of the few and against all odds.
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 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.
You do not have a moral or legal right to do absolutely anything you want.
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 and this link, 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.
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.
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.
Science & open-source build trust from peer review. Learn systems you can trust.
Slashdot is brimming with ULA and NASA partisans who will trash talk and outright lie about SpaceX at every opportunity. Given the utter failure of the SLS program to produce any hardware at all, and given the utter failure of the (illegal monopoly) ULA to compete with a price an order of magnitude lower than theirs, it's not surprising.
You are hearing the whines of failure trying to make themselves feel better. They will be forever bitter about SpaceX when they lose their jobs due to SpaceX successes.
I'd say down voted because people here haven't a clue about how NASA deals with things concerning the ISS. If you believe they have given any sort of green light on docking then you are greatly mistaken. $20B+ dollars, 10+ years making, and no room for error they will take no chances over a little more than half a ton of cargo. I've been in meetings and seen them pontificate of completely benign things for a week. They take nothing more seriously than the safe being of the ISS. I'm not saying they won't give it a go, but I would be shocked if they have already given SpaceX the go ahead. Not saying they aren't planning, but I will say there are a lot of people who have some decisions to make and they wo't be done lightly.
Yeah, it's actually more like $100-200 billions depending on how you count, or about the cost of ten to twenty Large Hadron Colliders. And there are six people on board who would have to try to make an emergency escape if something went terribly wrong, so I would imagine everyone involved takes it rather seriously, including SpaceX. SpaceX would become pariahs in the space industry if their hardware did major damage to the ISS or if someone died.
Could you imaging the CEO of Northrop Grumman or Lockheed being able to talk about the engineering issues at this level of detail? Or even the head of NASA? This is why I bought TSLA stock.
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.
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.
"So long and thanks for all the fish."
a lot of cushy jobs and contracts are gonna be lost due to SpaceX's super low cost launches. I'm surprised there isn't a bigger effort to discredit them and spread FUD, a la Edison electrocuting elephants with AC power.
The problem is with what you are using the valves for. Holding back dangerous things like Hydrogen and hypergols require very low leak rates when closed. You don't want to work around these things if they have a potential to leak. If you worked around the Space Shuttle on every RCS (Hypergol Thruster) nozzle there was a cover that had a desiccant pack that would absorb any leaks and turn color to indicate a leak. It's a giant pain in the ass to work with this stuff.
When you make valves that can close this tight they sometimes get stuck. Also with spaceflight you need to optimize mass so you can't put a huge valve on everything or it will add up quickly. One thing some satellites do is use a pyrotechnic burst disk right off the tank. This was it stays perfectly sealed until you blow the disk. This is a problem with reusable crafts because you would have to replace them every flight.
I love Jesus, except for his foreign policy.
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.