Chandrayan-2 Mission

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Ashokk
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Re: Chandrayan-2 Mission

Postby Ashokk » 08 Sep 2019 00:16

Gagan wrote:Guys is this confirmed?

https://twitter.com/vasudevan49/status/ ... 3610146816
Vasudevan Iyengar wrote:Latest update:
Lander found 500m away from the actual landing spot. But almost upside down. Seen from OHRC image and it is intact!
Trying to send commands from Bangalore control center...

On the DSN website right now one of the antennas in Madrid is sending data to the Chandrayaan-2 lander (CH2L) at 11kW :eek:
Last edited by Ashokk on 08 Sep 2019 00:21, edited 2 times in total.

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Re: Chandrayan-2 Mission

Postby sudarshan » 08 Sep 2019 00:16

disha wrote:Sudharshan'ji craft was definitely *not* tumbling during the rough descent phase. That went flawless.

I think the cutover from rough descent to smooth landing was not even. What could be the reasons?

We need to break down into sequences the smooth landing phase and maybe given public information try to localize the issues.


Oh I wasn't saying it was tumbling, I was just addressing the speculation on this thread by others, that of the four retro-rockets, one might have underperformed, causing the remaining three to overcompensate and making the craft tumble. I was saying that the Doppler plot seems to rule out that possibility.

I agree, the craft doesn't seem to have tumbled during rough descent. Something happened during the transition to fine braking.

BTW, yesterday, on the live streaming site, the caption kept saying (annoyingly) "fine breaking" and I was like "don't jinx it, you morons." Then, after the gloom started, the caption was updated to "fine braking" and I thought "too late, you morons."

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Re: Chandrayan-2 Mission

Postby sudarshan » 08 Sep 2019 00:24

Ashokk wrote:On the DSN website right now one of the antennas in Madrid is sending data to the Chandrayaan-2 lander (CH2L) at 11kW :eek:


Sending data? You mean it's working?

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Re: Chandrayan-2 Mission

Postby Ashokk » 08 Sep 2019 00:26

sudarshan wrote:Sending data? You mean it's working?

Probably trying to contact it at high power. Vikram's antenna is probably not pointed in the right direction or might even be damaged. We will have to wait until ISRO releases information.

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Re: Chandrayan-2 Mission

Postby Gagan » 08 Sep 2019 00:30

Maybe they can fire the rockets to straighten and stand it up!

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Re: Chandrayan-2 Mission

Postby disha » 08 Sep 2019 00:33

^Picklu Saar. Vishnu Som and Ballava Pagla, same-same - no difference.

Your statement here:
Vishnu Som, Shiv Aroor - all get our goat at the first disagreement with majority view. Pallava is getting it now
is absolutely wrong and untrue.

I would just recommend reading posts above yours to understand what got our "goats".

This is the last from me on this thread on this topic.

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Re: Chandrayan-2 Mission

Postby disha » 08 Sep 2019 00:33

Gagan wrote:Maybe they can fire the rockets to straighten and stand it up!


Communication loss. Once they establish communication, they can do something about it.

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Re: Chandrayan-2 Mission

Postby g.sarkar » 08 Sep 2019 00:46

https://www.opindia.com/2019/09/chandra ... ills-over/
Chandrayaan 2: As the nation rallies behind ISRO, and prays for Vikram lander, ‘liberal’ hate spills over
OPINDIA STAFF, SEPTEMBER 7, 2019
As the entire nation stood with ISRO to experience a spectacular journey of India’s first attempt to land at the lunar south pole, some petty individuals displayed their sheer negativity and arrogance over social media.
The long night and the next morning also showed that some individuals exist only to mock and pull others down at the very first opportunity.
Some people are so consumed with their hatred for PM Modi that for them, the hopes and efforts of a nation and the hard work of scientists involved do not hold any value at all. All they care about is exploiting every opportunity to criticise one man who they hate just because their political opinions do not match with his.
......
Gautam

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Re: Chandrayan-2 Mission

Postby Bart S » 08 Sep 2019 00:49

Gagan wrote:No
Pallav Bagla needs to pay for his arrogance
He should be shadow banned by ISRO and GoI for an extended period

Even when he was "doing so much for Indian science" he was slyly asking single digit IQ marxist type questions, like how do you justify a space program when India is so poor, and asking the DAE chief if the S1 reactor was designed and built in India.

These mediawalas are freeloading smart-arses. They hoity-toitily arrive with a camera and a mike and put our scientists and military officers under a third degree type interrogation, and being sarcastic all the time. They have no business behaving in such a manner.
Need to be made an example of !!!


Not Bagla (or just him anyway), as he is just a pawn. NDTV must lose their access.

BTW, check out this first hand account of Bagla's past antics:
https://twitter.com/ByRakeshSimha/statu ... 3353994241

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Re: Chandrayan-2 Mission

Postby UlanBatori » 08 Sep 2019 00:52

But almost upside down. Seen from OHRC image and it is intact!


Reminds me of the old Ireland (British-Occupied) joke:
Man comes into a pub, orders a beer, drinks it and says:
BTW, I say, what-what, could some of you blokes come with me and help retrieve my friend who fell into the bog?
Oh, really, how deep is he?
"Up to his ankles".
Then what's the problem?
"He fell head first".

If it impacted "nearly upside down", it is probably finished. I would not have put crucial components next to the legs or the musharraf, reasoning that if the legs crumpled, or came down on 4 sides of a sharp pointy rock, :shock: I still want them to survive. There is a reason why human brains are up there, not down there. The components up above like antenna, are probably not designed for impact.

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Re: Chandrayan-2 Mission

Postby Picklu » 08 Sep 2019 00:57

disha wrote:^Picklu Saar. Vishnu Som and Ballava Pagla, same-same - no difference.

Your statement here:
Vishnu Som, Shiv Aroor - all get our goat at the first disagreement with majority view. Pallava is getting it now
is absolutely wrong and untrue.

I would just recommend reading posts above yours to understand what got our "goats".

This is the last from me on this thread on this topic.


Disha Sir, Even I am saying Vishnu Som and Pallava Bagla are same, they are NOT SJha. My point is they are NOT Ajay Suklaw either.

Hitting Vishnu or Pallava or Shiv Aroor hard on SM for a behavioral mistake is fine to teach them a lesson for life, particularly if the mistake arises from entitlement and ego. What I do not agree is the demand for censor or sack. That I reserve for moral and ethical issues; in our treatment we need to differentiate between these 2 category of crimes.

Btw, I am not alone in this thought process, even many sensible RW tweeps think so

https://twitter.com/sushantsareen/statu ... 63521?s=20
Don’t be silly. @pallavabagla made a terrible & stupid mistake. He was rightly criticised, given a dressing down, shown his place & given a lesson of a lifetime to not act as an entitled ass (a common problem among journos). He has apologised & shown his contrition. Let’s move on.

https://twitter.com/ARanganathan72/stat ... 48800?s=20
Have to say, this wonderfully refreshing, and a first for anyone associated with your channel.
Everyone makes mistakes. Hardly anyone apologises for them. Kudos.

And needless to say, I am ok for any hit on rNDTV in general.

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Re: Chandrayan-2 Mission

Postby UlanBatori » 08 Sep 2019 00:58

The papparazzi are not seeking the really important news: How many deaths in PORK/Peshawar/LaHore from AK-47 bullets nearing apogee? There must have been quite a few fired into the sky this morning in celebrations.

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Re: Chandrayan-2 Mission

Postby Mort Walker » 08 Sep 2019 01:12

Had cameras sent back even a few low resolution photos when changing from rough to fine braking would have been really useful right now.

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Re: Chandrayan-2 Mission

Postby sudarshan » 08 Sep 2019 01:14

UB ji, the craft need not have impacted on its head. It could have rolled that way later. We'll see, there's still hope.

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Re: Chandrayan-2 Mission

Postby UlanBatori » 08 Sep 2019 01:14

^^ HOPE so!!! What they seem to be saying is (I hope) that its not in many pieces strewn over an area. Boxes stressed for launch may survive. IIRC NASA criterion for any experiment (microgravity flight not necessarily space launch) was "should not break and produce splinters in 9G impact".
Last edited by UlanBatori on 08 Sep 2019 01:17, edited 1 time in total.

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Re: Chandrayan-2 Mission

Postby Haridas » 08 Sep 2019 01:15

sudarshan wrote:Well then now is the chance, right? The "Ghastly Trolls" should now dig up old footage of the Bagla's antics and put it up for all to see how much he has "done for ISRO."

That Doppler curve shows steady deceleration during the rough braking phase. If the craft were tumbling then, the deceleration would have been erratic (since the direction of rocket acceleration would be unsteady), and would have showed in the Doppler plot. Then the rough braking ends, and unfortunately, the comms fail within a second of that point. For that one second, though, the plot seems steady. So no change in velocity of craft for that one second from 2:19 to 2:20?

Seeing the doppler shifted data radio spectrum, told the story of wobbling last seconds of flight. The minute oscillation in observed doppler shift corresonding to net delta velocity component (radial to radio receiver); the spatial non-omni directional antenna pattern appearing as changed signal intensity as the craft lost 3 axis stability.

IMHO is no doubt it was prime-mover problem and not control system problem.

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Re: Chandrayan-2 Mission

Postby Gagan » 08 Sep 2019 01:19

Hmmm
One wonders what happens when those AK-47 bullets come back to their perigee...
Any abduls there will meet their 72

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Re: Chandrayan-2 Mission

Postby UlanBatori » 08 Sep 2019 01:20

Too lazy to check: what thrusters were used for the rough, and what for the fine?

BTW,
1) Images and sample aalysis data from the rover were the culmination of the scientific objectives. Probably not going to happen. So was the whole project a loss? ABSOLUTELY NOT.

2) This was -what? second flight of the GSLV-3? In most Space Agencies this would have been a trial flight with dummy payload. If the launch survived, 90% success. Injection to GTO, 110%.

3) In addition, they went ahead with a massively complex lunar mission. Entering lunar orbit: check.
4) Separation of lander module from orbiter: check
5) Lander managed to aim correctly for landing point: check
6) Successful flight at like 100 miles above lunar surface: check (huge gravity fluctuation issues IIRC; whatever predictive algorithm and compensator they had, worked perfectly! )
7) "Coarse" braking: successful first attempt!!! (check!!)
8) Telemetry worked up to end of coarse braking, 2.1 km from landing point, very low altitude. CHECK!!
9) Getting PM in and out of Mission Control for 2AM event: CHECK!
10) Slapping down and de-briefing NDTV: CHECK!

ISRO are being too hard on themselves. They just completed the equivalent of 3 major missions with perfect success.
Minor issue identified with the motor for the lander. who cares about images from a hot abrasive airless desert that makes KSA look like a paradise anyway? I already posted he realities about the two "Major Aims" of going to the lunar south pole: ice molecules and He-3 atoms. (yawn!!)
Last edited by UlanBatori on 08 Sep 2019 01:30, edited 1 time in total.

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Re: Chandrayan-2 Mission

Postby Gagan » 08 Sep 2019 01:24

Weren't the Apollo Landers beaming back live movies back to earth no?
The whole of the US was watching Neil Armstrong land on the moon on their version of Doordarshan, LIVE.

ISRO doesn't deploy enough bandwidth to beaming back a live stream for its rocket launches even.
Time they really upped their game on this media management front.

ISRO and India need to shed this fascination with cheapest, most cost effective, for the benefit of the poor and needy BS ASAP !!!
ISRO needs to invest in providing live video feeds from space crafts, launchers. ISRO needs to hire and deploy ships in southern Indian ocean, or lease downlinks from the French or whoever and make it possible onlee.

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Re: Chandrayan-2 Mission

Postby Haridas » 08 Sep 2019 01:27

Bart S wrote:
Gagan wrote:No
Pallav Bagla needs to pay for his arrogance
He should be shadow banned by ISRO and GoI for an extended period

Even when he was "doing so much for Indian science" he was slyly asking single digit IQ marxist type questions, like how do you justify a space program when India is so poor, and asking the DAE chief if the S1 reactor was designed and built in India.

These mediawalas are freeloading smart-arses. They hoity-toitily arrive with a camera and a mike and put our scientists and military officers under a third degree type interrogation, and being sarcastic all the time. They have no business behaving in such a manner.
Need to be made an example of !!!


Not Bagla (or just him anyway), as he is just a pawn. NDTV must lose their access.

BTW, check out this first hand account of Bagla's past antics:
https://twitter.com/ByRakeshSimha/statu ... 3353994241



Not just permanent ban from meeting or entering ISRO, but also HAL, BDL, DRDO and All military establishments. Shame on his father, mother & teachers.


https://twitter.com/HaridasKukkur/statu ... 10560?s=19

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Re: Chandrayan-2 Mission

Postby sudarshan » 08 Sep 2019 01:36

Gagan ji, the stream of Neil Armstrong was black and white.

Haridas wrote:Seeing the doppler shifted data radio spectrum, told the story of wobbling last seconds of flight. The minute oscillation in observed doppler shift corresonding to net delta velocity component (radial to radio receiver); the spatial non-omni directional antenna pattern appearing as changed signal intensity as the craft lost 3 axis stability.

IMHO is no doubt it was prime-mover problem and not control system problem.


You're looking at the signal intensity, I guess? The slope of the Doppler plot seems to indicate steady velocity change (steady deceleration). Signal intensity change can also be due to yawing, which can happen if there's some rotation along the vertical axis. That doesn't affect the landing deceleration.

Anyway, all speculation at this point. Will wait for ISRO's analysis.

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Re: Chandrayan-2 Mission

Postby Haridas » 08 Sep 2019 01:42

Gagan wrote:Maybe they can fire the rockets to straighten and stand it up!

I see Incorrigible optimism 8) not grounded in reality.

No signal transmission means irrecoverable.

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Re: Chandrayan-2 Mission

Postby Gagan » 08 Sep 2019 03:25

TFWIW:
What we know about India's failed lunar landing:

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Re: Chandrayan-2 Mission

Postby Gagan » 08 Sep 2019 03:40

DD interview with Dr K Sivan

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Re: Chandrayan-2 Mission

Postby SaiK » 08 Sep 2019 03:43

"We thought one of the thrusters may have underperformed," said an Isro scientist. "But after some preliminary analysis, it looks like a thruster overperformed."

https://timesofindia.indiatimes.com/ind ... 030431.cms

Officially, Isro maintained that data was still being analysed. However, a scientist told TOI, Every failure is a lesson to perfection."Vikram's legs were to be horizontal during the roughbraking and had to be rotated by 90 degrees to bring them vertical to the landing surface before fine-braking. At this point, the thrust might have been more than optimal, impacting the lander's orientation. It's like a car losing direction due to sudden braking at high speed. When Vikram went silent, Isro mission control searched for links from Nasa's deep space network centre in Madrid and the Indian station in Mauritius, but to no avail.

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Re: Chandrayan-2 Mission

Postby Arjun » 08 Sep 2019 06:21

Gagan wrote:TFWIW:
What we know about India's failed lunar landing:

Good point made that out of the entire 'live telecast' only about two minutes was on the actual telemetry data and the rest of the time was focused on the 'people at mission control'....terrible when compared to even the data made available by Beresheet. So you may not have live camera feed - but at least focus on the telemetry data ! That's what a live telecast of moon landing is supposed to be all about

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Re: Chandrayan-2 Mission

Postby SSridhar » 08 Sep 2019 07:14

Arjun wrote:Good point made that out of the entire 'live telecast' only about two minutes was on the actual telemetry data and the rest of the time was focused on the 'people at mission control'....

Agree. Very irritating.

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Re: Chandrayan-2 Mission

Postby Amber G. » 08 Sep 2019 07:15

Gagan wrote:Weren't the Apollo Landers beaming back live movies back to earth no?
The whole of the US was watching Neil Armstrong land on the moon on their version of Doordarshan, LIVE.

....

I watched that LIVE.. I also have recordings of hours of audio transmission in my archive..
The "Live" part took LOT of effort ... *only* moon walk part after they sat up antena's etc.... VERY grainy B&W transmission (There is a post by Mort Walker.. how they reduced the band width.. NASA used a slow-scan camera optimized for a smaller format, 320 scan lines of data (instead of 525 lines normal us broadcast those days) at 10 frames per second (instead of normal 30) that could be transmitted at just 500 kHz... (in stead of 6Mhz band width of normal TV station in US) ..Check any archive footage on youtube to see what I mean)

(CY2 orbiters bandwidth is about 100x of this)

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Re: Chandrayan-2 Mission

Postby UlanBatori » 08 Sep 2019 07:19

Amazing how they figured out these things in those days. The Fast Fourier Transform had barely been invented. For most people a TV set was a novelty: the preferred format was 16mm film. Presentation slides of the rocket scientists were made on actual glass pieces ( I still have a few, salvaged from a box that they left out to be trashed after my thesis advisor passed away and they cleaned out his office).

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Re: Chandrayan-2 Mission

Postby SaiK » 08 Sep 2019 07:24

^and they landed on moon with humans.

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Re: Chandrayan-2 Mission

Postby rajsunder » 08 Sep 2019 07:29

Haridas wrote:
Gagan wrote:Maybe they can fire the rockets to straighten and stand it up!

I see Incorrigible optimism 8) not grounded in reality.

No signal transmission means irrecoverable.

Saw some posts on reddit r\space. people were interpreting the radio telescope data as a hard landing and a bounce by the lander.

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Re: Chandrayan-2 Mission

Postby UlanBatori » 08 Sep 2019 07:34

Maybe it landed at 10 m/s as commanded :)

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Re: Chandrayan-2 Mission

Postby SaiK » 08 Sep 2019 07:37

1. did we really lose signal at a low altitude [assuming there is a delta latency between vikram and byalaru receivers, and the received altitude is not an estimate].

2. if not, then loss of signal could be crash landing.

What I don't understand, if there is latency and actual data received, then it is not the second case, but it lost signal at altitude. Doesn't this mean, something happened (jets overheated?) at the stated altitude.

but then, between two feeds (from vikram), say x (milliseconds), the whole event happened. It is likely case then.

may be fine-braking should have happened at a higher altitude / WAG

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Re: Chandrayan-2 Mission

Postby Anujan » 08 Sep 2019 07:41

sudarshan wrote:
Ashokk wrote:On the DSN website right now one of the antennas in Madrid is sending data to the Chandrayaan-2 lander (CH2L) at 11kW :eek:


Sending data? You mean it's working?


It is contacting Chandra X-ray Observatory

https://chandra.harvard.edu/about/

Totally different thing.

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Re: Chandrayan-2 Mission

Postby sudarshan » 08 Sep 2019 07:45

No ji, earlier in the day, I swear, the Madrid CH2L thingy on the site said "Chandrayan 2 Lander." Maybe they switched it to the x-ray observatory now. It seems right now the Goldstone SOHO thingy is trying Chandrayan 2 Lander. Could be that the moon has set in Madrid, maybe?

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Re: Chandrayan-2 Mission

Postby UlanBatori » 08 Sep 2019 07:53

How can earth-based telescopes see the far side of the Moon? Relaying from Chinese satellite?

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Re: Chandrayan-2 Mission

Postby sudarshan » 08 Sep 2019 08:00

The landing spot was on the near side of the moon. Yesterday was ashtami (shukla paksha - waxing phase), so one half of the near side of the moon was visible from the earth. Meaning, the other half of the near side was just starting its lunar day, and would continue to have sunlight for fourteen days (until krishna paksha ashtami). The landing spot was chosen based on this criterion, remember?

So the lander is in the line of sight from earth. And today being navami, the spot is now brightly illuminated by the sun also. Not that this matters to a radio telescope.

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Re: Chandrayan-2 Mission

Postby Primus » 08 Sep 2019 08:03

EswarPrakash wrote:When Rama asked for the moon

I could not stop myself from writing what I felt


Thank you, Eswar Ji. Heartfelt indeed. Echoes what so many of us have been thinking and feeling.

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Re: Chandrayan-2 Mission

Postby sudarshan » 08 Sep 2019 08:31

Hmm, scratch what I said above about near and far side, I might be guilty of spreading disinformatsiya. It seems, looking at crater maps, that the moon's south pole is on the far side as seen from earth? Will check and get back. But then, like UB said, I fail to see how a radio telescope from earth can pick up signals from the moon's far side.

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Re: Chandrayan-2 Mission

Postby Mort Walker » 08 Sep 2019 08:31

UlanBatori wrote:How can earth-based telescopes see the far side of the Moon? Relaying from Chinese satellite?


The Chinese put a relay communications satellite around the moon first.


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