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Parachute Problems Plague NASA's Flying Saucer

Posted by samzenpus on from the that-didn't-go-as-plan dept.

An anonymous reader writes: NASA's test of a Mars landing system came to a end Monday when the saucer-shaped vehicle's parachute tore away after partly unfurling high over the Pacific Ocean. NASA says they will provide more details at a news conference Tuesday. Another parachute failed during a similar test of a new Mars spacecraft last year. "This is exactly why we do tests like this," NASA engineer and LDSD mission commentator Dan Coatta said after the test. "When we're actually ready to send spacecraft to Mars, we know that they are going to work when that big mission is on the line."

41 comments

  1. I know a lot of this is cutting edge... by Viol8 · · Score: 2

    ... but the parachute? Really? If you know the speed and the density of the atmosphere you're going to deploy it in then the rest is basic physics and engineering. Just make sure you make the damn thing strong enough!

    1. Re:I know a lot of this is cutting edge... by g0tai · · Score: 1

      It's not the first time they've had problems with chutes either, however this is the biggest one they've done so far, and things don't always scale up (you need thicker fabric, etc to handle larger stresses)

      From the limited video footage, the chute looked to be already torn at deployment, so it may have been doomed to fail well before it opened (though NASA have had tearing problems before, one wonders if they had built anything in to mitigate that known risk into the design)

      (*i am not an expert, just an average thickie)

    2. Re:I know a lot of this is cutting edge... by peragrin · · Score: 1

      a lot of parachute issues are deployment problems at speed/ heat.

      Take a spacecraft which is flying at thousands of MPH toward the ground, burning at 2000 degrees, and then deploy a soft fabric.

      If you don't unfold it perfectly you lose everything. if one strand of folding rope is out of place you lose everything. The amount of engineering going into just the folding of a parachute would surprise you.

      --
      i thought once I was found, but it was only a dream.
    3. Re:I know a lot of this is cutting edge... by jellomizer · · Score: 1

      The idea is to make such a parachute optimal for the device it wants to land. To bulky it become more expensive to deploy, as well unlike earth Mars has a thinner atmosphere so it will need more surface area. So the engineering spec would to make it bigger and smaller at the same time.

      --
      If something is so important that you feel the need to post it on the internet... It probably isn't that important.
    4. Re:I know a lot of this is cutting edge... by Anonymous Coward · · Score: 0

      We need to make it bigger and smaller at the same time. Management requests are like that here too.

    5. Re:I know a lot of this is cutting edge... by Anonymous Coward · · Score: 0

      Supersonic parachute.

    6. Re:I know a lot of this is cutting edge... by pz · · Score: 5, Informative

      ... but the parachute? Really? If you know the speed and the density of the atmosphere you're going to deploy it in then the rest is basic physics and engineering. Just make sure you make the damn thing strong enough!

      You would think so, yes, except that no one has developed a parachute precisely (or even remotely) like this one before: it's the biggest super-sonic parachute ever (the ring portion of the 'chute deploys at over Mach 4 ... normal aerodynamics don't work there), AND, it has to be light enough to meet mission parameters for weight budget. While you might think it's basic physics, the empirical details are a bear to get right.

      It's not just that this is, in fact, rocket science, but really, really hard, cutting-edge rocket science.

      Having watched the NASA-released video, the failure mode appeared to be very different from the first test. The first test suffered from imperfect deployment that resulted in uneven loading and thus failure of the main 'chute. The droge (the first little 'chute) went out perfectly, but the main parasol failed to open. The second test failed more quickly, without even partial deployment of the main 'chute, as if it was immediately ripped apart. Watch the videos, they're fascinating!

      --

      Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.
    7. Re:I know a lot of this is cutting edge... by Anonymous Coward · · Score: 0

      If you know the speed and the density of the atmosphere you're going to deploy it in then the rest is basic physics and engineering. Just make sure you make the damn thing strong enough!

      Turns out that that isn't so basic at all, as the crew of any sailing ship can tell you, and when you're deploying something tens or hundreds of millions of miles away, you don't get second chances like you would on earth with a competent sail master.

      But hey, go ahead and pretend if you like, it's not your money on the line.

    8. Re:I know a lot of this is cutting edge... by Anonymous Coward · · Score: 0

      That's what she said!

    9. Re:I know a lot of this is cutting edge... by Eloking · · Score: 1

      a lot of parachute issues are deployment problems at speed/ heat.

      Take a spacecraft which is flying at thousands of MPH toward the ground, burning at 2000 degrees, and then deploy a soft fabric.

      If you don't unfold it perfectly you lose everything. if one strand of folding rope is out of place you lose everything. The amount of engineering going into just the folding of a parachute would surprise you.

      Yeah, about this...

      Why is it so hard to develop a control unit to unfold the parachute? I know it's been used thousand time with success already but is there no other way than blowing up the cover and throwing that big ball of parachute and hoping it will unfold perfectly? (Yes, I know it's more controlled than that, but you get my point)

      --
      Elok
    10. Re:I know a lot of this is cutting edge... by Anonymous Coward · · Score: 0

      It's not a parachute in the classic sense - it's more like an enormous airbag around the perimeter of the craft designed to help high-altitude aerobraking. Lots of problems to solve.

    11. Re:I know a lot of this is cutting edge... by Ashenkase · · Score: 1

      It's not a parachute in the classic sense - it's more like an enormous airbag around the perimeter of the craft designed to help high-altitude aerobraking. Lots of problems to solve.

      The SIAD or "airbag" has worked flawlessly the last two tests. The parachutes are the systems that have been failing... 0 for 2. If the 3rd test produces the same result with the chute then maybe the team should switch focus and bump up the specs on the SIAD and concentrate on retro rocket landings.

    12. Re:I know a lot of this is cutting edge... by Anonymous Coward · · Score: 1

      Having watched the NASA-released video, the failure mode appeared to be very different from the first test. The first test suffered from imperfect deployment that resulted in uneven loading and thus failure of the main 'chute. The droge (the first little 'chute) went out perfectly, but the main parasol failed to open. The second test failed more quickly, without even partial deployment of the main 'chute, as if it was immediately ripped apart. Watch the videos, they're fascinating!

      2014 high-res video (around 1:20):
      https://www.youtube.com/watch?...
      2015, low-res video (around 4:00):
      https://www.youtube.com/watch?...

      I don't know how you can see much from the second video, as NASA has not released anything high-res yet.
      could be the same problem as before, the feed is way too low-res to understand what went wrong.

    13. Re:I know a lot of this is cutting edge... by Anonymous Coward · · Score: 0

      Why not just go Space X style and just try to land it with rockets? It seems like there are a lot more ways a parachute could fail, but hey, I'm not a rocket scientist.

    14. Re:I know a lot of this is cutting edge... by pz · · Score: 2

      I don't know how you can see much from the second video, as NASA has not released anything high-res yet.
      could be the same problem as before, the feed is way too low-res to understand what went wrong.

      Thanks for the links. I had another look and you may be right -- it may be the same failure mode. In fact, it might be that the most recent 'chute actually lasted longer than the first one.

      --

      Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.
    15. Re:I know a lot of this is cutting edge... by NicknameUnavailable · · Score: 1

      Think of it more in an evolutionary sense than a purely design/engineering one. People tend to suck at design/engineering (that is, there are a lot of failures along the way to success.) Traditionally parachute design has revolved around folding patterns and things of that nature because we didn't have automated means to unfurl a parachute (most are still hand-folded) - you don't just go from hand-folding and relying on folding patterns to an automated deployment mechanism - even with an automated deployment mechanism you are going to have variations from one implementation to the next due to differences in materials (two blocks of aluminum are not created equal - there is variation even in the best-made materials that might cause slightly different flexing and load tolerances.) The leap from hand-folded parachutes to an automated system is practically equivalent to a gliding lizard's wing flaps to a bird's tail feathers - it's a pretty extreme difference even if the two serve similar purposes.

    16. Re:I know a lot of this is cutting edge... by LeadSongDog · · Score: 2

      ... If you know the speed and the density of the atmosphere you're going to deploy it in ...

      Nontrivial. Requires the ability to forecast high altitude Martian weather years in advance. So far, we can barely manage a few days in advance for Earth weather. Then there's that minor detail of wanting some flexibility to adjust the atmospheric attack angle in case the arrival date isn't quite what was originally intended. No it isn't rocket science. It's way harder.

      --
      Oh, I'm sorry sir, I thought you were referring to me, Mr. Wensleydale.
    17. Re:I know a lot of this is cutting edge... by avandesande · · Score: 1

      The weight of the motors and fuel has to be subtracted from you payload. The cost in weight for parachutes is much less.

      --
      love is just extroverted narcissism
    18. Re:I know a lot of this is cutting edge... by TWX · · Score: 1

      Chute probably wasn't actually torn, it was designed to provide a specific amount of drag at a very high speed through a thin atmosphere, so it had a pattern of holes and solid panels with that intent in mind. Could be something as simple as the direction of the weave in the fabric didn't behave as expected, or the stresses were higher than expected in critical points where the reinforcing webbing attached to the main fabric. I'm no expert on parachutes, but some fabrics will tear in specific ways, and it could well be that this fabric did much the same.

      --
      Do not look into laser with remaining eye.
    19. Re:I know a lot of this is cutting edge... by Anonymous Coward · · Score: 0

      Gee whiz!! Why didn't all those PhD's think of that?

      Your, sir are an above average Slashdotter!!

    20. Re:I know a lot of this is cutting edge... by gstoddart · · Score: 1

      The test off the Hawaiian island of Kauai was investigating technology designed to slow down a large landing vehicle falling through the atmosphere at supersonic speeds.

      Another giant parachute also failed to inflate during a similar NASA test of new Mars spacecraft technology last year. One of the main goals this year was to test the redesigned parachute.

      Oh, I don't know ... solving specific engineering for a specific task is always going to involve new stuff.

      I'm sure this is way more complicated than "basic physics and engineering", despite the arm-chair "gee, that sounds easy" crap we usually see here on Slashdot.

      --
      Lost at C:>. Found at C.
    21. Re:I know a lot of this is cutting edge... by Anonymous Coward · · Score: 0

      Part of basic engineering is testing your prototype to make sure that your basic physics didn't sphere-off any cows, which is precisely what they did here.

    22. Re:I know a lot of this is cutting edge... by braindrainbahrain · · Score: 3, Interesting
      FAA Licensed Parachute Rigger here ("License to kill", lol).

      Parachutes don't just unfold, they actually deploy in a very controlled fashion. All it takes is something to initiate the sequence. In human parachutes, a pilot chute is released, which pulls out a deployment bag. The bag in turn does not open until suspension lines are stretched, and once the canopy is released from the bag, it inflates due to the difference in static air pressure within. vs dynamic air pressure outside (Bernoulli's principle). There are further mechanisms to slow down deployment in order to control the deceleration and opening shock (important for human well being). Problems occur if things happen out of sequence, or if the parachute is structurally unsound.

      I can't speak for the system NASA is using, but I expect there already is a unit to "unfold" the parachute, and it is all part of the parachute system already.

    23. Re:I know a lot of this is cutting edge... by cyn1c77 · · Score: 1

      It's not the first time they've had problems with chutes either, however this is the biggest one they've done so far, and things don't always scale up (you need thicker fabric, etc to handle larger stresses)

      From the limited video footage, the chute looked to be already torn at deployment, so it may have been doomed to fail well before it opened (though NASA have had tearing problems before, one wonders if they had built anything in to mitigate that known risk into the design)

      (*i am not an expert, just an average thickie)

      The parent is right. A supersonic parachute deployment will require modeling the fluid (air) and the chute's structural mechanical response in a coupled fashion. This would push current computational limits. The fact that they modeling materials whose dynamic response is poorly studied (fabric) makes it all that much harder from an engineering perspective.

      Realistically, some computational modeling might get you in the right ballpark, depending on the quality of the modeler and model, but you're going to need to do a whole lot of validation testing. The three tests that NASA has schedule for the project appear insufficient, especially since it appears that their design and modeling approach is not predictive. (Sorry NASA, but it's true on this one!)

      That said, this could be tested at smaller sizes and then scaled up using an analytical approach. The scaling isn't always going to be linear, however and it will require experts to identify the relevant and dominate dimensionless groups to correctly scale things. I'd recommend that they scale things down, schedule a whole lot of sub-scale tests in their supersonic wind tunnel (which you can instrument more substantially), and only field full-scale tests once they have good sub-scale predictive performance at a variety of different sub-scales, including predicting chute failure. In today's levels of high oversight on each full-scale test, they really can't afford to fail twice... especially if you can't cough up a lot of videos of subscale testing working perfectly. Frankly, if this was a for-profit company, the team would already be shitcanned based on their response to the failure: "... take a look at the high-resolution video that we’re going to get back, along with the rest of our data, to make a determination about what is going to happen." (If "high-resolution video" is the best diagnostic that you have, you're screwed. Hopefully there are strain gauges and accelerometers on each load bearing component so that you can actually conlcusively figure out what failed and why.)

    24. Re:I know a lot of this is cutting edge... by painandgreed · · Score: 1

      ... but the parachute? Really? If you know the speed and the density of the atmosphere you're going to deploy it in then the rest is basic physics and engineering. Just make sure you make the damn thing strong enough!

      Ya, but in theory, theory and practice are the same, but in practice, they are not.

  2. Still better than when... by vikingpower · · Score: 1

    ... a flying saucer problem plagues your parachute.

    --
    Religous speak to God. Insane are spoken to by God. When all shut up, one can finally hear Shostakovich in peace
  3. Not for long... by xxxJonBoyxxx · · Score: 2

    >> Parachute problems plague flying saucer

    Not for long. The ground problem soon became a bigger issue.

  4. The important part by TheDarkMaster · · Score: 1

    The LDSD intself worked?

    --
    Religion: The greatest weapon of mass destruction of all time
  5. vueja de by meglon · · Score: 2

    This article is a reprint of an article in 1946 (Earth time frame) on the planet Remulak, followed by a large in-depth thread about New Mexico's climate (planet Earth, Sol system) during the summer months (Earth time frame).

    --
    Fascism: An authoritarian and nationalistic right-wing system of government and social organization. See also: NAZI's
  6. Video by pantaril · · Score: 4, Informative

    https://www.youtube.com/watch?...
    You can see the parachute deployment and tear-down at 5:40

  7. how many successful deployments needed? by Anonymous Coward · · Score: 1

    Because if you're sending an extremely expensive rover to another planet and depending on this thing, I think you don't want to fail several times, finally tweak enough to achieve one success, and say, "done!".

    Was that one success just a fluke? One chance in 20 where everything went just so? I think you'd want a higher confidence answer than that.

  8. LDSD by KlomDark · · Score: 1

    I once saw a flying saucer on a parachute after taking some LDSD, so getting a kick out of this...

  9. Plague? Is this the Daily Mail? by eepok · · Score: 1

    Really, though. From what I can read in the article (which may be limited because I was no reading major), "A parachute failed during a NASA test of new technology for landing larger spacecraft..." and "Another giant parachute also failed to inflate during a similar NASA test of new Mars spacecraft technology last year."

    Two data points does not a plague make.

  10. Who's gonna be the first by Anonymous Coward · · Score: 0

    asshole to regurgitate that there's really not much science in rocket-science, like it was a true statement?

    1. Re:Who's gonna be the first by Anonymous Coward · · Score: 0

      On the contrary, rocket science is roughly 53.8% science, 46.2% rocket.

    2. Re:Who's gonna be the first by oobayly · · Score: 1

      Huh? The GP said the exact opposite.

  11. If you aren't failing... by Anonymous Coward · · Score: 0

    ...you aren't learning (right?)

  12. Seen this before by Tablizer · · Score: 1

    Seems the Roswell aliens had the same problem.

    --
    Table-ized A.I.
  13. Work Fail? by Anonymous Coward · · Score: 0

    "When we're actually ready to send spacecraft to Mars, we know that they are going to work when that big mission is on the line." -- Actually, we know that sending it to mars in its current form will Fail - so we know it will fail today, and until it works (which could be thousands of years from now) - we won't be going to Mars. Give us more funding.