Poll

How close to the center of the barge will the first stage land?

Failed landing burn, aborted, or other mishap
6 (1.3%)
Landing on water surface at any point from barge
8 (1.8%)
Landing partially or wholly on barge but partial or complete vehicle loss
66 (14.8%)
Landing partially or wholly on barge but not on center, vehicle intact
209 (47%)
Landings on the center of the barge (center of stage inside center circle)
156 (35.1%)

Total Members Voted: 445


Author Topic: Predict accuracy of upcoming DSCOVR Mission attempted barge landing  (Read 23890 times)

Offline SoulWager

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My guesses:
15% hits center of barge and is destroyed.
15% doesn't hit center of barge and is destroyed.
60% hits center of barge and survives.
10% doesn't hit center of barge and survives.

Offline Robert Thompson

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Not center, intact. The triage on CRS5 seemed assured.

Offline wes_wilson

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Had to go with land in center. 

My choice of "Land in center, re-launch two weeks later on inflight Dragon V2 abort test" wasn't listed...  :-\
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Offline robertross

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Had to go with land in center. 

My choice of "Land in center, re-launch two weeks later on inflight Dragon V2 abort test" wasn't listed...  :-\

There were only so many number of options/questions available for the poll
That's the best range I could think of at the time
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Offline Lar

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Actually you can add options. I've made some doozies, with 20 options or more. That's not to say that it's necessarily a good idea to have a lot of options.
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Offline john smith 19

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I went with 3, which is a down grade from the last poll.

If you play by the rules of Baysian statistics then the odds worsen for a failed attempt.  :(

Normal statistics would say it's still 50/50.

Personally I'd like to think they have learned sufficient about oil usage and other issues to bring it down safely.

But I thought that on their first attempt as well.  :(

So the question is have they found all the "unknown unknowns"  this time ?
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Offline mvpel

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I went with 3, which is a down grade from the last poll.

If you play by the rules of Baysian statistics then the odds worsen for a failed attempt.  :(

The trouble with that approach is the occurrence of a failed attempt only gives evidence about the true state of the world at the moment of that failure, and doesn't account for things like, say, adding 50% more hydraulic fluid on the next attempt. In the real world, with clever engineers, the odds improve after a failed attempt. See FTG-06b, for another example.
« Last Edit: 01/17/2015 01:37 PM by mvpel »
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Offline pagheca

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I don't vote on this kind of polls, usually, for personal "statistical" and undisclosable reasons :).

However, let me note that if that Falcon 9 ACS - not taking in account all due differences, of course - was mounted on an ICBM in the future it would be an improvement!
« Last Edit: 01/17/2015 01:48 PM by pagheca »

Offline Rocket Science

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I went with 3.... If they get it on the island, good enough for me at this point! :)
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Offline Mark K

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If you play by the rules of Baysian statistics then the odds worsen for a failed attempt.  :(

Normal statistics would say it's still 50/50.


Ahh... no: Bayes reasoning does not say that. If you are looking at THE SAME probability distribution and you get more information - like a data point on it for failure. then yes, your estimates going forward of what that distribution looks like will change, maybe with a greater failure possibility, maybe not, depending on the prior model. In this case you are looking at a new probability distribution which we know is different -  more fluid, different trajectory, higher starting point, etc., so your estimate will have to add all that in to get your new estimated outcome model. That will be your new "prior". It may very well have a lower possibility of success, but it won't just be because of the previous failure, since a lot more stuff is changing, and you know it is, in the sense that you should be incorporating it into your prior probability model for the new launch.

Pedantic mode off. I do this because I see it this for all kinds of predictive statistics and these  ideas can really lead to funny decision making.



Offline cro-magnon gramps

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I voted #1... because this stage is going into new territory... higher and faster at time of turn around... it just seems to me that the unknowable unknowns increase dramatically, and after the CRS-5 landing attempt, I'm not so positive as I was... I was stuck between #1 and #2, and went the way I did based on Elon's comment that this is trickier... I don't think they will have the same problems as last time, but I am suspicious they will find new reasons for the stage to do a RUD... not that I want it, I would prefer a repeat or better of CRS-5... maybe I would change my mind if it were after 8 pm and the bottle was open :D

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Offline Alkan

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I picked 5. You have to be optimistic. If a malfunction happens, it's bad luck. If it works, I think it's going to be pretty much on target based on how close the last one was after the grid fins ran out of hydraulic fluid. So, I just picked an option under the assumption "it works." And, based on the accuracy of their previous predictions and tendency to under-promise and over-deliver, I think it'll work.

But I'm going to bet that it will be delayed by at least a few days and we won't see it until February.

Offline intrepidpursuit

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I picked 5 because I'm optimistic. Even with the grid fins working against them they looked to be close to dead on with their 45 degree rocket.

A close second to me is 1, because I think there is a high likelihood that they have miscalculated or measured something related to their incredible T>W, 0 speed, 0 altitude final maneuver which has still never really been tried.

The others are distant runners up. SpaceX doesn't seem to do anything halfway. It will either get there or something will go wrong.

Offline AncientU

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If you play by the rules of Baysian statistics then the odds worsen for a failed attempt.  :(

Normal statistics would say it's still 50/50.


Ahh... no: Bayes reasoning does not say that. If you are looking at THE SAME probability distribution and you get more information - like a data point on it for failure. then yes, your estimates going forward of what that distribution looks like will change, maybe with a greater failure possibility, maybe not, depending on the prior model. In this case you are looking at a new probability distribution which we know is different -  more fluid, different trajectory, higher starting point, etc., so your estimate will have to add all that in to get your new estimated outcome model. That will be your new "prior". It may very well have a lower possibility of success, but it won't just be because of the previous failure, since a lot more stuff is changing, and you know it is, in the sense that you should be incorporating it into your prior probability model for the new launch.

Pedantic mode off. I do this because I see it this for all kinds of predictive statistics and these  ideas can really lead to funny decision making.

Also must consider potential failure modes... not the least of which during last attempt was returning to the vicinity of the ASDS in a rather large ocean.  Sticking the landing was relatively minor in comparison. 

Combining success on the former with changes to improve odds of the latter should significantly improve the odds on this attempt.
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Offline ericlopaty

Didn't Elon himself say that it should blow up for a different reason?   ;)

Offline Lar

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He was being a weisenheimer... :)
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Online deruch

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Didn't Elon himself say that it should blow up for a different reason?   ;)

No.  He said that he hoped that if it blew up, it would at least be for a different reason.  ;)

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Offline JamesH

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Also must consider potential failure modes... not the least of which during last attempt was returning to the vicinity of the ASDS in a rather large ocean.  Sticking the landing was relatively minor in comparison. 

I think its the other way round. Getting close to he barge is the 'easy' bit, landing it is the tough bit. They have grid fins and a lot (comparitivly) time to aim and redirect the stage to get it close to the barge. The landing itself is a one off lots of things need to go right at the same time brown trouser moment.

Offline Herb Schaltegger

Didn't Elon himself say that it should blow up for a different reason?   ;)

No.  He said that he hoped that if it blew up, it would at least be for a different reason.  ;)

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Reading - it still IS fundamental. ;)

Quote
Next rocket landing on drone ship in 2 to 3 weeks w way more hydraulic fluid. At least it shd explode for a diff reason.
https://twitter.com/elonmusk/status/556105370054053889
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Offline llanitedave

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Unfortunately, now all the Musk-quote Kremlinologists will be quizzing their crystal balls to come up with reasons for the stage to explode.  If it doesn't explode, Musk risks losing credibility...




"But... it simply HAS to explode!  Elon said it would!"
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