Slashdot Mirror

← Back to Stories (view on slashdot.org)

Philae May Have Grazed Crater Rim

Posted by Soulskill on from the move-fast-and-break-things dept.

An anonymous reader writes: The European Space Agency is gradually sorting through the data collected during the brief window Philae was alive and transmitting on the surface of a comet. Analysis of that data has provided another interesting clue about what happened to the probe as it bounced across the comet's surface. According to results from the on-board magnetometer, immediately after the first touchdown, the lander's spin rate increased somewhat. It continued to spin for about 36 minutes until another event dramatically changed its spin rate. This suggests it collided with something, because there was no corresponding vertical deceleration to indicate it had landed once more. Scientists think Philae likely grazed the rim of a crater with one of its landing legs. 65 minutes later, it landed again, and bounced to its final resting place just a few minutes later. The ESA's article has some interesting graphs showing how the data changed as the lander progressed through these different events.

7 of 48 comments (clear)

  1. Almost made it ... by gstoddart · · Score: 5, Insightful

    You know, as much as a lot of people are looking at this as a failure, I look at this as a reminder of just how damned difficult this kind of stuff is.

    What was it? Ten years in transit, several slingshots around planets to build up speed, deep hibernation for something like two years, waking up, finding where it is in space, find the damned comet, get close to it, and the launch the landing bits and pray that it works because it's all automated.

    It really really sucks that this didn't play out as everyone hoped.

    But it's mind boggling how many things went utterly right before one thing went wrong.

    My mind boggles over the sheer amount of engineering on this which actually worked, and the massive number of things which are lurking to go wrong.

    It's hard to even think of an analogy for this ... jumping out of a plane without a parachute and landing in a moving convertible which someone told you 10 years would be passing through the middle of Kansas somewhere around noon ... while blindfolded, knitting a sweater,assembling a piano, and juggling sharks. :-P

    And, that might not even come close.

    --
    Lost at C:>. Found at C.
    1. Re:Almost made it ... by paskie · · Score: 4, Insightful

      I don't know why are people looking at it as failure. We got plenty of data, we even got the very important chemical analysis data in the last session. It would have been great if it worked further, just as it was awesome that the Mars rover worked much longer than their projected mission lifetime was. But if that did not work out, we still got a lot of value out of this, so I don't follow why should it be a failure.

      --
      It's not the fall that kills you. It's the sudden stop at the end. -Douglas Adams
    2. Re:Almost made it ... by osu-neko · · Score: 3, Informative

      The mission did not succeed in most of its stated objectives. By definition that makes it a failure.

      It's not a complete failure, and we can learn from what failed to attempt to design future missions to avoid these particular failure modes, and we can even celebrate the successes that we did get from the mission, but we cannot truly call the mission as a whole a success.

      The mission did not fail in most of its stated objectives. By definition that makes it a success.

      It's not a complete success, and we can learn from what failed to attempt to design future missions to avoid these particular failure modes, and while we can lament the failures that did occur, we cannot truly call the mission as a whole a failure.

      --
      "Convictions are more dangerous enemies of truth than lies."
    3. Re:Almost made it ... by Anonymous Coward · · Score: 5, Funny

      Yeah, that whole fly around the solar system in hibernate mode for ten years, slingshotting half a dozen times off planetary flybys, matching speed and rendezvousing and soft landing on a comet... Complete failure that. They should just go back to posting on Slashdot or something else they're good at.

    4. Re:Almost made it ... by gstoddart · · Score: 4, Interesting

      The mission did not succeed in most of its stated objectives. By definition that makes it a failure.

      Well, think of it as being two distinct phases.

      First, you rendezvouz with the comet. That's an extraordinary feat, and worked brilliantly. It represents several firsts, because matching speed with a comet and being in the same place it's supposed to be in 10 years? That's pretty damned hard to do.

      Second you fire the lander portion at the comet and hope it sticks. And it has to stick to an object you aren't 100% sure of its shape, rate of spin, and composition. And it has to do it by itself because of the communication delay.

      Which seems kind of like trying to tell a blind person when to cross the street based on your out-dated video view of the street, and no idea what the future traffic is going to be.

      The part that failed was the "OK, you're mostly kinda pointing across the busy highway ... now start running when you get this and let us know when you get to the other side".

      And in an interview I heard with one of the project members before the final landing ... they knew damned well that was kind of a high risk thing, and was being done completely blind.

      So, the huge task of making rendezvous was pretty much textbook.

      The blindfolded-on-a-moving-train "Annie Oakley" sharp shooting bit? Surprisingly, quite difficult.

      --
      Lost at C:>. Found at C.
  2. First post to mention RTG from ignorant position! by jareth-0205 · · Score: 3, Insightful

    Just because you know someone's going to bring it up again for no apparent reason with armchair justification. Thought I'd get it out of the way...

  3. Re:First post to mention RTG from ignorant positio by RobinH · · Score: 3, Insightful

    Yes, now that they've read "The Martian" and played some Kerbal Space Program, they're now experts at interplanetary travel.

    --
    "I have never let my schooling interfere with my education." - Mark Twain