Philae May Have Grazed Crater Rim 48
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.
Almost made it ... (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.
Re:Almost made it ... (Score:5, 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.
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And Philae is not done yet either... It is still on the comet - it's just that the batteries ran down because there is insufficient sunlight to charge them... As this comet inevitably re-approaches the sun on its orbit and the solar panels can begin charging the batteries again, Philae will come to life and pick up where it left off...
This mission is not over...
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Do you have any links discussing this more in depth? I took a look at http://en.wikipedia.org/wiki/P... [wikipedia.org] and that one is pretty brief and it's not remotely clear if it succeeded at these or not.
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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.
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Also, most expensive rimjob ever.
Re:Almost made it ... (Score:5, Funny)
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Of course it bounced, it's in microgavity (about 10ug as I recall). And every one of those bounces was far softer than any landing Apollo has ever seen. When you're talking about rendezvousing with an orbital object, a non-soft landing typically involve a hell of a lot more *CRUNCH*, and probably quite a bit of *BOOM*.
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The point is that the systems designed to stop it from bouncing failed for some reason. They wanted it to be in sunlight to collect solar power. They didn't achieve that.
They are really rocket scientist heroes in my opinion, but I'm sure they are kicking themselves nonetheless. Some of these guys have spent 20 years on the project. They deserve a bigger payoff.
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Hey, they managed to accomplish almost all their primary goals - that's a pretty big payoff for attempting something nobody has ever tried before. It's a shame that the long-term secondary goals didn't pan out as hoped, but those are kind of the "we were extra-super-awesome and lucky" prize.
Re:Almost made it ... (Score:5, Interesting)
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.
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In retrospect, jet planes and predicting the invention of the tank would've helped the Germans win WW1.
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Not to mention that we still have a functioning comet orbiter still sending back data. I'd call the mission a success and look forward to the next comet landing attempt where we can learn from this one to avoid what happened with Philae.
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But it's mind boggling how many things went utterly right before one thing went wrong.
Yes, it's time to talk about what we can do to prevent another #shirtstorm. It doesn't matter how "right" the science is if scientists themselves can't police their own.
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Re: Almost made it ... (Score:2)
Philadelphia did return a significant amount of data. It even drilled I to the surface, though I don't know whether the unanchored proble could actually pierce the surface.
Re: Almost made it ... (Score:2)
'Philae'. That's what I get from posting on iOS.
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Not to meniion how many things were not just right, but unknown when we started. Could we harpoon a comet? We didn't know, so let's try it! Could we screw into a comet? Again, we don't know it's true composition, but let's throw it in because what the hell.
There were plenty of unknowns in this mission so even though it didn't go 100%, we still learned a ton. And
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People are looking at it as a huge success. I'm completely confused as to who views this as anything but. About 80% of things intended to be done with this entire operation have been done.
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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
It's a car analogy... so it'll do! ;)
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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.
Sadly, I recall that the devices that were on the lander that should have arrested its bounce both failed (the rocket, and the harpoons). So, there 'was' a failure. The mission, though, got lots of data, so it can't be seen a complete failure. It is amazing, awe inspiring, and wonderful. Just not as wonderful as it would have been if the lander had stuck to the first landing place, and been around to witness the out gassing.
First post to mention RTG from ignorant position! (Score:4, 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...
Re:First post to mention RTG from ignorant positio (Score:4, Insightful)
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In some cases it's political. In this case it was weight.
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That excludes more than you know. Many elements are slightly radioactive.
For example, lead is approximately 1,4% lead-204. If you really want to work without radioactive isotopes you gotta spin up the centrifuges.
And you gotta have deep pockets.
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Actually, the ESA is developing RTGs based on americium-241 rather than plutonium.
http://www.lpi.usra.edu/meetings/nets2012/pdf/3043.pdf
KSP (Score:1)
It's beginning to sound more and more like a perfect landing in Kerbal Space Program.
Impressive (Score:2)
So, in a word, we have actually rimmed a comet?