Author Topic: ISRO about to attempt moon landing  (Read 347 times)

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Offline chris_leyson

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ISRO about to attempt moon landing
« on: September 06, 2019, 08:05:45 pm »
 

Offline StillTrying

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Re: ISRO about to attempt moon landing
« Reply #1 on: September 06, 2019, 08:54:02 pm »
Crashed.

CML+  That took much longer than I thought it would.
 

Offline chris_leyson

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Re: ISRO about to attempt moon landing
« Reply #2 on: September 06, 2019, 09:44:31 pm »
So close, it's a shame. Because Vikram was spinning at 2km from the surface with a vertical velocity of 60km/s it's end of mission. Hopefully ISRO find some clues from the telemetry. Good luck ISRO  :-+
 

Online CatalinaWOW

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Re: ISRO about to attempt moon landing
« Reply #3 on: September 06, 2019, 09:54:35 pm »
If I interpreted the video correctly it was even closer than that.  ~300 meters and 60 meters/sec descent rate.  Really, really close to pulling it off.  As you say, hopefully the telemetry will let them figure out what went wrong, and then it is up to the budgeteers to arrange another try.
 

Online hamster_nz

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Re: ISRO about to attempt moon landing
« Reply #4 on: September 07, 2019, 12:42:29 am »
Just watched the replay. First guess was one of the final descent engines didn't fire, and the unbalanced thrust sent it spinning rather than breaking.

But the sudden change in trajectory means quite a bit of momentum went somewhere, so it might be more likely that there was some sort of failure that gave it a big kick.

Darm, that was looking really good up till then.
« Last Edit: September 07, 2019, 12:47:36 am by hamster_nz »
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Offline amyk

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Re: ISRO about to attempt moon landing
« Reply #5 on: September 07, 2019, 02:09:08 am »
Ironic how that guy doing the commentary kept praising them for the "ultra low cost" of the mission... I thought it was common knowledge that 10% of the effort gets you 90% of the way, and it's the last 10 or 1% that takes 99% of the effort...? :-//
 

Offline Rerouter

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Re: ISRO about to attempt moon landing
« Reply #6 on: September 07, 2019, 02:28:21 am »
The effort you have to put in is statistics at its most evil,

lets say your efforts amount to a confidence of 50% that everything will go perfectly,
Double your efforts, it gets you to 75%
Triple your efforts, it gets you to 87.5%
Quadruple your efforts, to 93.75%
Quintuple your efforts, to 96.875%

so the closer you want to 100%, the more exponential the amount of effort you need to put in, and anything you can do to increase your confidence per round is much better than just throwing resources at it. So you can get away with low costs, if some really clever people can bump that initial confidence up to say 90%, so by the second round your already at 99%,

again, you never get 100%, no matter how many people or dollars you throw at it, you can only approach it.
 

Online hamster_nz

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Re: ISRO about to attempt moon landing
« Reply #7 on: September 08, 2019, 10:12:25 am »
The video in this tweet syncs up the radio frequency waterfall over the stream:

https://twitter.com/DJSnM/status/1170374542549630976

(is it still a waterfall if it goes sideways :D )

And here is the last 5 minutes

https://twitter.com/cgbassa/status/1170434231622914048

As a sudden change in doppler means a sudden change in speed, so it looks like something dramatic happened.
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