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More analysis of @Philae2014 telemetry indicates harpoons did not fire as 1st thought Ouch, seems like it didn't land? https://twitter.com/esaoperations/sta

by sktrdie 12y ago

More analysis of @Philae2014 telemetry indicates harpoons did not fire as 1st thought Ouch, seems like it didn't land? https://twitter.com/esaoperations/status/532575061543485440 https://twitter.com/esaoperations/status/532575061543485440 edit - the landing is confirmed, however the harpoons did not fire: https://twitter.com/ESA_Rosetta/status/532579871202238464 https://twitter.com/ESA_Rosetta/status/532579871202238464

masklinn 12y ago
It did land, here's the next tweet: > It looks like @Philae2014 made a fairly gentle touch down on #67P based on amount of landing gear damping #CometLanding but the harpoons may have failed to fire.
- sktrdie 12y ago
  Ah my bad. Nonetheless it seems like harpoons did not fire. Tweet from just 30 secs ago: https://twitter.com/ESA_Rosetta/status/532579871202238464 https://twitter.com/ESA_Rosetta/status/532579871202238464 Can it stay on the surface without the harpoons?
  - 32faction 12y ago
    > Can it stay on the surface without the harpoons? technically yes. Philae has harpoons along with foot screws to secure it to the comet, but if harpoons are super glue, foot screws are tape.
- easytiger 12y ago
  Why does it need to anchor itself? It's not like it will blow away?
  - jarin 12y ago
    It could actually, since there's already outgassing on the comet.
  - robin_reala 12y ago
    Newton’s Second (edit: Third) Law. It wants to extend a drill bit into the surface.
    - 3rd3 12y ago
      Third?
      - robin_reala 12y ago
        …oops (apropos username)
  - ctdonath 12y ago
    Gravity there is so low that something like a light push may be enough to launch. If anything used to examine the surface makes contact and presses (drill, digger), good-bye lander. Firing the harpoon would also be enough to launch, but at least the hook would grab the surface and pull the lander back down, giving enough pull to drill viable long-term anchors.
    - mVChr 12y ago
      Are there any forces in effect as it gets closer and swings around the sun that might cause it to separate from the comet if there is no further attachment by then?
      - JoeAltmaier 12y ago
        Absolutely! If its attached, its via surface ice. That ice will all melt on close approach to the sun. At some point the probe will drift away.
        mVChr 12y ago
        Of course, I should have deduced that. Is the harpoon expected to go deep enough to prevent this from happening?
  - humanfromearth 12y ago
    It will dig into the surface anyway so it will anchor itself even without the harpoon, if it's on the surface of course. See this video that explains how Philae foots work: https://www.youtube.com/watch?v=-77-Z_DHTlY#t=84 https://www.youtube.com/watch?v=-77-Z_DHTlY#t=84 ESA says it landed gently on the surface: https://twitter.com/esaoperations/status/532575615527170048 https://twitter.com/esaoperations/status/532575615527170048
- 32faction 12y ago
  land =/= secure. those harpoons are what is supposed to anchor Philae to the comet. the problem is the reaction thruster, the thruster that counteracts the force generated by the harpoon shot, (to satisfy Newton's 3rd law) is faulty. So they're hoping that when they reshoot the harpoon, the foot screws will be anchored enough to hold it in place. If not, theyre hoping that Philae won't launch too far off the surface so that they can just "reel" Philae back in.
  - masklinn 12y ago
    > land =/= secure. And I replied to a comment which said "land".
bd 12y ago
Emily Lakdawalla tweets from the control center: Ulamec: signal kept coming and going "but we always got it back." Possibly indicates unstable, or tilted. Ulamec confirms the harpoons did NOT fire. There is much they currently do not know. Ulamec: a central rod was pushed into lander 4 cm by landing. Indicates soft rather than hard surface (rod would've pushed more into lander) Just had a chat with Mark McCaughrean and I feel a bit calmer.... McCaughrean: @Philae2014 is down on the surface of the comet and it is transmitting signals. Science instruments are getting data. Yes, McCaughrean confirmed this. RT @JPMajor: @elakdawalla So the ice screws on the lander's feet have at least dug in I assume? https://twitter.com/elakdawalla/status/532578862086250497 https://twitter.com/elakdawalla/status/532578862086250497 ------------------------------------------ And overview of the German DLR stream's briefing (via reddit live stream): Good news: --- Touchdown, all the signals that trigger on touchdown worked. --- Still communication, which means the lander did not tilt or topple. Bad news: --- ADS thruster did not fire, that is the issue was already known beforehand. --- The anchors did not fire, this confusion was due to the rewind motors for the anchors going into action, but the harpoon wasn't actually fired. --- Team doesn't know if it rebounded or not / if it's on the surface. Thus they don't dare issuing a re-firing signal for the harpoons, because they don't know in what position the lander is. Current Situation: --- The arm that damped the landing force only moved very little, which indicates a very soft surface. Which might mean if it rebound the rebound was very soft as well and in this case might settle down again. --- On board computer is waiting for new commands. --- There will be more telemetry in 30 minutes, but contact lost in 120 minutes, so the final verdict could be known only tomorrow. http://www.reddit.com/live/tw0cnch7nxjx/ http://www.reddit.com/live/tw0cnch7nxjx/
- JoblessWonder 12y ago
  Man, measuring how far a rod moves into the lander to gauge depth/surface tension/type? So simple and smart.
  - thisjepisje 12y ago
    It's a robot prodding his finger in the ground :D

by sktrdie 12y ago

masklinn 12y ago

It did land, here's the next tweet: > It looks like @Philae2014 made a fairly gentle touch down on #67P based on amount of landing gear damping #CometLanding but the harpoons may have failed to fire.

sktrdie 12y ago
Ah my bad. Nonetheless it seems like harpoons did not fire. Tweet from just 30 secs ago: https://twitter.com/ESA_Rosetta/status/532579871202238464 https://twitter.com/ESA_Rosetta/status/532579871202238464 Can it stay on the surface without the harpoons?
- 32faction 12y ago
  > Can it stay on the surface without the harpoons? technically yes. Philae has harpoons along with foot screws to secure it to the comet, but if harpoons are super glue, foot screws are tape.
easytiger 12y ago
Why does it need to anchor itself? It's not like it will blow away?
- jarin 12y ago
  It could actually, since there's already outgassing on the comet.
- robin_reala 12y ago
  Newton’s Second (edit: Third) Law. It wants to extend a drill bit into the surface.
  - 3rd3 12y ago
    Third?
    - robin_reala 12y ago
      …oops (apropos username)
- ctdonath 12y ago
  Gravity there is so low that something like a light push may be enough to launch. If anything used to examine the surface makes contact and presses (drill, digger), good-bye lander. Firing the harpoon would also be enough to launch, but at least the hook would grab the surface and pull the lander back down, giving enough pull to drill viable long-term anchors.
  - mVChr 12y ago
    Are there any forces in effect as it gets closer and swings around the sun that might cause it to separate from the comet if there is no further attachment by then?
    - JoeAltmaier 12y ago
      Absolutely! If its attached, its via surface ice. That ice will all melt on close approach to the sun. At some point the probe will drift away.
      - mVChr 12y ago
        Of course, I should have deduced that. Is the harpoon expected to go deep enough to prevent this from happening?
- humanfromearth 12y ago
  It will dig into the surface anyway so it will anchor itself even without the harpoon, if it's on the surface of course. See this video that explains how Philae foots work: https://www.youtube.com/watch?v=-77-Z_DHTlY#t=84 https://www.youtube.com/watch?v=-77-Z_DHTlY#t=84 ESA says it landed gently on the surface: https://twitter.com/esaoperations/status/532575615527170048 https://twitter.com/esaoperations/status/532575615527170048
32faction 12y ago
land =/= secure. those harpoons are what is supposed to anchor Philae to the comet. the problem is the reaction thruster, the thruster that counteracts the force generated by the harpoon shot, (to satisfy Newton's 3rd law) is faulty. So they're hoping that when they reshoot the harpoon, the foot screws will be anchored enough to hold it in place. If not, theyre hoping that Philae won't launch too far off the surface so that they can just "reel" Philae back in.
- masklinn 12y ago
  > land =/= secure. And I replied to a comment which said "land".

bd 12y ago

Emily Lakdawalla tweets from the control center: Ulamec: signal kept coming and going "but we always got it back." Possibly indicates unstable, or tilted. Ulamec confirms the harpoons did NOT fire. There is much they currently do not know. Ulamec: a central rod was pushed into lander 4 cm by landing. Indicates soft rather than hard surface (rod would've pushed more into lander) Just had a chat with Mark McCaughrean and I feel a bit calmer.... McCaughrean: @Philae2014 is down on the surface of the comet and it is transmitting signals. Science instruments are getting data. Yes, McCaughrean confirmed this. RT @JPMajor: @elakdawalla So the ice screws on the lander's feet have at least dug in I assume? https://twitter.com/elakdawalla/status/532578862086250497 https://twitter.com/elakdawalla/status/532578862086250497 ------------------------------------------ And overview of the German DLR stream's briefing (via reddit live stream): Good news: --- Touchdown, all the signals that trigger on touchdown worked. --- Still communication, which means the lander did not tilt or topple. Bad news: --- ADS thruster did not fire, that is the issue was already known beforehand. --- The anchors did not fire, this confusion was due to the rewind motors for the anchors going into action, but the harpoon wasn't actually fired. --- Team doesn't know if it rebounded or not / if it's on the surface. Thus they don't dare issuing a re-firing signal for the harpoons, because they don't know in what position the lander is. Current Situation: --- The arm that damped the landing force only moved very little, which indicates a very soft surface. Which might mean if it rebound the rebound was very soft as well and in this case might settle down again. --- On board computer is waiting for new commands. --- There will be more telemetry in 30 minutes, but contact lost in 120 minutes, so the final verdict could be known only tomorrow. http://www.reddit.com/live/tw0cnch7nxjx/ http://www.reddit.com/live/tw0cnch7nxjx/

JoblessWonder 12y ago
Man, measuring how far a rod moves into the lander to gauge depth/surface tension/type? So simple and smart.
- thisjepisje 12y ago
  It's a robot prodding his finger in the ground :D