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Chandrayaan-3 Soft-landing [video]

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Re: Chandrayaan-3 Soft-landing [video]

#461

Post by soligern »

rhuru wrote: post #372

This is a big achievement for India. Not just in space exploration point of view but the side effects of such projects are more interesting. Dozens of major private companies focused on making this success making various spare parts including steel cranes by Tata steel, special alloys of Mishra Dhatu Nigam (The Alloy Company), wings by L&T Aero etc. etc. I know some people here and they were so proud and focused on "…

There are some very interesting, and arguably more challenging missions coming up including a Venus orbiter, manned space flight and a Martian lander. This should really help solidify the manufacturing space around this.

Re: Chandrayaan-3 Soft-landing [video]

#463

Post by rdevsrex »

Trias11 wrote: post #203
The_Colonel wrote: post #71

Earlier quoted context omitted.

Besides what others said, it gets extra spice from the fact Russia failed to do the same just days ago.

Agree. The quicker russians will get rid of putin infestation the sooner this disgrace will end.

Lots of people could say the same about Biden or _____ leader.

Re: Chandrayaan-3 Soft-landing [video]

#464

Post by lioeters »

georgeecollins wrote: post #309
pyeri wrote: post #242

Earlier quoted context omitted.

On the other hand, political speeches on such occasions go down as most remembered historically. The infamous quote "One small step for man, one giant leap for mankind." was obviously said by some politician! (or at least with non-technical motives)

I think it is a sign of habitual cynicism that you assume "One small step for man, one giant leap for mankind." was said by a politician. I think people feel like they are defending themselves from being manipulated by not accepting anything on its face as sincere. Sometimes a pipe is just a pipe.

I think the saying goes, sometimes a cigar is just a cigar. And knowing Freud, you know it's not just a cigar.

Re: Chandrayaan-3 Soft-landing [video]

#466

Post by morepork »

m0llusk wrote: post #86
jvm___ wrote: post #12

Scott Manly has a video on why he thinks the last one failed. It sounds like their landing software didn't have "oh crap, we're way off course, just land wherever". It only had the happy path of "fly to here and land", so when it switched to the landing phase it tried valiently (including flying upside down) to try to fly back to the landing zone, but the landing zone was much further than fuel supplies allowed. Hope…

If anything they seem to have overcorrected for this. This landing path stopped with a near hover at around 800m, then a prolonged hover at 150m while the lander scoped the situation, then an extremely slow descent that allowed for corrections the whole way down. Very impressive.

If they have the fuel available, may as well be very conservative. Either burn the fuel on descent or have it sit in the tank forever on the lunar surface.

Re: Chandrayaan-3 Soft-landing [video]

#467

Post by RheingoldRiver »

abhayhegde wrote: post #360

Especially impressive when taken into account that ISRO couldn't achieve the soft-landing with Chandrayaan-2 four years ago. One of the big things they changed with this lander compared to Chandrayaan-2 was to increase the landing zone from 500mx500m to 4000mx4000m and adding more sensors and cameras to help the computer find a good landing site. For those who didn't watch live, there was another hover phase (0 m/s d…

> was to increase the landing zone from 500mx500m to 4000mx4000m

Can you elaborate on this? Presumably it could land...anywhere on the moon, so what exactly does it mean to increase the landing zone? What determines where it can or can't land?

Re: Chandrayaan-3 Soft-landing [video]

#468

Post by pests »

RheingoldRiver wrote: post #467
abhayhegde wrote: post #360

Especially impressive when taken into account that ISRO couldn't achieve the soft-landing with Chandrayaan-2 four years ago. One of the big things they changed with this lander compared to Chandrayaan-2 was to increase the landing zone from 500mx500m to 4000mx4000m and adding more sensors and cameras to help the computer find a good landing site. For those who didn't watch live, there was another hover phase (0 m/s d…

> was to increase the landing zone from 500mx500m to 4000mx4000m Can you elaborate on this? Presumably it could land...anywhere on the moon, so what exactly does it mean to increase the landing zone? What determines where it can or can't land?

There is a target area we want to land in order to investigate certain terrain or other POI's near the target.

It obviously can't land on mountains and certain rocky or steep terrain. They know its limitations. These limitations determine where it can or can't land.

During target selection they will find an adaquet place on the surface that meets the criteria.

By increasing from 500m^2 to 4000m^2 they need to find a larger area that meets those same needs.

This also helps during the actual landing. It can aim anywhere inside that 4000m^2 area instead of being limited to just a 500m^2 area.

Re: Chandrayaan-3 Soft-landing [video]

#469

Post by ansible »

rst wrote: post #453
ansible wrote: post #152

Earlier quoted context omitted.

Yes, it was a very conservative landing trajectory. But it is very, very difficult to get a hoverslam right the first time, or the second, or the third... I did like seeing the live images captured during descent, I also hope those get made into a video and posted online. Looking forward to the rover deployment too.

This doesn't seem to have been a hoverslam, though -- the probe was hovering at, I think, 150 meters for quite some time, and then maintained a steady and slow rate of descent while still under power.

Yes, Chandrayaan-3 definitely did not performance a hoverslam, the landing was much more conservative than that. With a hoverslam, everything has to go exactly right. A valve that is slightly sticky can be enough to wreak everything.

Re: Chandrayaan-3 Soft-landing [video]

#470

Post by RheingoldRiver »

pests wrote: post #468
RheingoldRiver wrote: post #467

Earlier quoted context omitted.

> was to increase the landing zone from 500mx500m to 4000mx4000m Can you elaborate on this? Presumably it could land...anywhere on the moon, so what exactly does it mean to increase the landing zone? What determines where it can or can't land?

There is a target area we want to land in order to investigate certain terrain or other POI's near the target. It obviously can't land on mountains and certain rocky or steep terrain. They know its limitations. These limitations determine where it can or can't land. During target selection they will find an adaquet place on the surface that meets the criteria. By increasing from 500m^2 to 4000m^2 they need to find a…

oh I see, so it's not that they picked the same center and said "oh btw now you can land in a larger circle around it" but rather they picked a different site altogether? that makes a lot more sense, thanks
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