Chandrayan-2 Mission

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Re: Chandrayan-2 Mission

Postby Arjun » 09 Sep 2019 07:59

Arjun wrote:CY2 is supposed to overfly the same spot in 3 days from Saturday which would be before LRO I guess...and it has better cameras from what I understand

On the other hand LRO is 50 km orbit and CY2 100km, so LRO might still have an advantage in spotting the wreckage..

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Re: Chandrayan-2 Mission

Postby Mort Walker » 09 Sep 2019 08:14

CY2 orbiter has a resolution of 30 cm and LRO at closest has a resolution of 50 cm. The Apollo landing sites were imaged with LRO's best resolution. CY2 has more capability including a dual frequency Synthetic Aperture Radar (SAR). LRO has lunar neutron detection looking for water ice. CY2 will use an imaging spectrometer.

I don't think we will get much more info about Vikram from LRO, only independent confirmation of the location.

I doubt any communications will be established. Best to go whatever telemetry data is available and imaging from CY2 for failure analysis. Next time build a couple of landers on earth with a gimbaled jet engine to simulate "flight" characteristics. That or work on 3-axis stabilization of spacecraft and test in low earth orbit. The time has come to move on to CY3 for the moon.

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Re: Chandrayan-2 Mission

Postby Amber G. » 09 Sep 2019 08:30

Mort Walker wrote:

I don't think we will get much more info about Vikram from LRO, only independent confirmation of the location.

.

Every little bit helps!! And will be looked on. Obviously it's not a simple case of "resolving" power or any one simple thing. Even different orientation and perspective from one is looking help.

Another important thing, it is near morning so there will be long shadows. So a vertical something which can not be seen, may give information by it's shadow. As I said, no reason to look around corners, let us get all the data.

What we know:
- Vikram has been located on the surface.
- It's hard landing.
- Damage, we do not know - some parts may still be working. Antennas and system are powerful enough that we may still be able to contact it. Solar panels may work (if there is right orientation) . Anyway, per ISRO all effort will be done for next 14 days. Let us wait.

One of the aspect, not appreciated by many, is Vikram is automated system.. Many critical systems are self-contained (inertial navigation and control is state of the art). This means, even if communication failed, other systems may work.

From what I know about Vikram's antenna, I will *not* be surprised that it may give us more data.. but let us wait. In few days we will know one way or the other.
The Chandrayaan-2s Vikram module has been located on the Lunar surface and it must have been a hard-landing, ISRO chairman K Sivan said on Sunday, in an admission that the planned soft-landing wasn't successful.

"Yes, we have located the lander on the Lunar surface. It must have been a hard-landing," Sivan told PTI.

He said that it was located by on-board cameras of the Chandrayaan-2 orbiter. Asked if the lander was damaged during the hard-landing, he said: "That we do not know."

Sivan said efforts to establish contact with the lander were continuing...

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Re: Chandrayan-2 Mission

Postby Mort Walker » 09 Sep 2019 08:51

^^^CY2 did thermal imaging of Vikram and probably using its other sensors as well. True - looking at Vikram from a different orientation will help, but if it came down at over 100 m/s, there maybe little hope. If the communications don't work, the other critical systems are of little use until someone can physically get to Vikram.

Besides the various DSN on earth, I would assume CY2 orbiter is also trying to ping Vikram every time it comes around.

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Re: Chandrayan-2 Mission

Postby Gautam_2 » 09 Sep 2019 09:11

Thermal Imaging camera is not present on CY2. Media did not verify claims and just ran with it.

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Re: Chandrayan-2 Mission

Postby Barath » 09 Sep 2019 10:04

sanjaykumar wrote:I don’t think the weeping was because of a technical failure. The tears came when approached by the prime minister. Dr Sivan seemed to feel he had let down the prime minister, and through him the Indian people.


The tears came after the prime minister's speech. A mix of emotions likely.

Own disappointment, feeling of letting down the country/PM, the prime minister's support to him and his team, and the praise, lack of sleep from the previous night - it would have emotionally wrung him out.

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Re: Chandrayan-2 Mission

Postby Bibhas » 09 Sep 2019 10:26

Gautam_2 wrote:Thermal Imaging camera is not present on CY2. Media did not verify claims and just ran with it.


Could possibly the Imaging IR Spectrometer (IIRS) onboard the orbiter, which is capable of Hyperspectral Imaging be used to take image of Vikram in IR region?

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Re: Chandrayan-2 Mission

Postby juvva » 09 Sep 2019 10:31

Gautam_2 wrote:Thermal Imaging camera is not present on CY2. Media did not verify claims and just ran with it.

Yes. Unless they repurposed the "Imaging IR spectrometer" .......

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Re: Chandrayan-2 Mission

Postby Arjun » 09 Sep 2019 10:36

We know the landing site but as Vikram deviated from the pattern the last minute during the final descent, we have to look in an area of 10 x 10 km area from three payloads SAR, IR spectrometer and camera


https://timesofindia.indiatimes.com/india/orbiter-will-have-a-lifespan-of-7-5-years-its-possible-to-find-vikram-lander-from-orbiter-isro-chief/articleshow/71028078.cms

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Re: Chandrayan-2 Mission

Postby chetak » 09 Sep 2019 11:00

Barath wrote:
sanjaykumar wrote:I don’t think the weeping was because of a technical failure. The tears came when approached by the prime minister. Dr Sivan seemed to feel he had let down the prime minister, and through him the Indian people.


The tears came after the prime minister's speech. A mix of emotions likely.

Own disappointment, feeling of letting down the country/PM, the prime minister's support to him and his team, and the praise, lack of sleep from the previous night - it would have emotionally wrung him out.


judging from the extreme smell of burning hair in the usual dark and dingy commie/naxal/commie infested outposts on the extremity of social media, the entire imagery of the PM consoling the ISRO head is a kodak moment par excellence and is priceless in terms of PR for showcasing and promoting India's sophisticated high tech capabilities.

It also humanizes the entire space program and exposes the human side of the PM seldom shown on TV which bigotedly insists on depicting Modi as a control freak running a "facist" and anti minority govt.

whereas the only thing going for the mafia family is the PR disaster of a wooden faced geriatric con man in a turban who spews venom on Modi when commanded to do so.

BTW, shouldn't nehru been taking the blame, seeing as to how the family has earlier shamelessly claimed credit for establishing ISRO and gifting the space program to the nation :mrgreen:

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Re: Chandrayan-2 Mission

Postby chetak » 09 Sep 2019 11:32

NDTV journalist who insulted ISRO scientist found selling ISRO images on Getty, social media users question whether it’s allowed.

NDTV journalist Pallava Bagla has uploaded hundreds of images on commercial photography site Getty, which are available for sale



The NDTV journalist has uploaded hundreds of images on commercial photography site Getty, which are available for sale. Many of such images are from ISRO premises, showing individual scientists, including chairman Dr Kailasavadivoo Sivan, and various satellites and other scientific instruments being developed and assembled at ISRO. Most of such images are priced at ₹23,000, or similar amounts.

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Re: Chandrayan-2 Mission

Postby Philip » 09 Sep 2019 11:39

Look, Nehru kicked the bucket 55 years ago! One can't blame past leaders ad nauseum for problems today. All our past leaders had flaws .Look at Mrs.G.Brilliantly dismemberd Pak." Durga's gift to India" said ABV. But she imposed the emergency and let her spolit brat Sanjay G. run amok.

However, elements of the press today indulge in mere sensationalism. There is little sober, seasoned debate.I watch Rajya Sabha TV and Doordarshan more these days than the mainstream channels each tryinv to out boast each other as being the only one, the first one, to break wind....sorry break news about some really unimportant matter.Pathetic.

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Re: Chandrayan-2 Mission

Postby madhu » 09 Sep 2019 12:44

he obstacles on the lunar surface may have been stopping the lander Vikram from receiving signals, Chandrayaan-1 Director Mylswamy Annadurai said on Sunday.
"As we have located the lander on the lunar surface, we now have to establish contact with it. The place, where the lander alighted is expected to be not conducive enough for the lander to soft-land. There may be some obstacles, which could have been stopping us from establishing the connection," Mr Annadurai said.

https://www.ndtv.com/india-news/vikram- ... si-2097729

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Re: Chandrayan-2 Mission

Postby nits » 09 Sep 2019 12:47

madhu wrote:
he obstacles on the lunar surface may have been stopping the lander Vikram from receiving signals, Chandrayaan-1 Director Mylswamy Annadurai said on Sunday.
"As we have located the lander on the lunar surface, we now have to establish contact with it. The place, where the lander alighted is expected to be not conducive enough for the lander to soft-land. There may be some obstacles, which could have been stopping us from establishing the connection," Mr Annadurai said.

https://www.ndtv.com/india-news/vikram- ... si-2097729


gurus - what is meaning of this 2 sentence which looks a bit contradictory

"we now have to establish contact with it"

And

"which could have been stopping us from establishing the connection,"

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Re: Chandrayan-2 Mission

Postby chetak » 09 Sep 2019 13:10

Philip wrote:Look, Nehru kicked the bucket 55 years ago! One can't blame past leaders ad nauseum for problems today. All our past leaders had flaws .Look at Mrs.G.Brilliantly dismemberd Pak." Durga's gift to India" said ABV. But she imposed the emergency and let her spolit brat Sanjay G. run amok.

However, elements of the press today indulge in mere sensationalism. There is little sober, seasoned debate.I watch Rajya Sabha TV and Doordarshan more these days than the mainstream channels each tryinv to out boast each other as being the only one, the first one, to break wind....sorry break news about some really unimportant matter.Pathetic.


it was sarcasm.

if past leaders can be "credited" today for gifting the country something as though it was their father's property and us serfs should be ever grateful, then let them also be responsible when things don't go too well.

this particular gent has much to be responsible for and all of it is not to the good when seen in the harsh light of present day reality

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Re: Chandrayan-2 Mission

Postby chetak » 09 Sep 2019 13:12

twitter


Getty Images must be complimented for their due diligence. Very well explained here, through a flow-chart. The photos of ISRO scientists taken by Bagla CANNOT be sold.



Image

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Re: Chandrayan-2 Mission

Postby UlanBatori » 09 Sep 2019 13:12

chetak wrote:The tears came after the prime minister's speech. A mix of emotions likely.
Own disappointment, feeling of letting down the country/PM, the prime minister's support to him and his team, and the praise, lack of sleep from the previous night - it would have emotionally wrung him out.
judging from the extreme smell of burning hair in the usual dark and dingy commie/naxal/commie infested outposts on the extremity of social media, the entire imagery of the PM consoling the ISRO head is a kodak moment par excellence and is priceless in terms of PR for showcasing and promoting India's sophisticated high tech capabilities.
It also humanizes the entire space program and exposes the human side of the PM seldom shown on TV..

I was thinking about what exactly was so awesome about the imagery, and then in the clarity of 3AM it hit me. The PM of course had said it with his usual fast thinking and razor-sharp observation (at 2AM!!!), in his speech, and that is what opened the floodgates of emotion.
I was watching your faces, and it was so clear that you care so much about the Nation


To put it in UBCN terminological exactitude: you were watching a whole army of SARKARI employees - and not Army either. A bunch of nerds too. And, hey! They CARE! They care enough to pray as the critical moment approached, and cry when things go wrong. It is not
Lunch ke baad aana
. Not "Come back tomaarrow onlee, Aphsar has gone to attend marriage of Minister's nephew's chamcha's flunky's daaghtar".
You were not watching a prepared script, when watching these people. And these were only Mission Control - imagine the thousands behind them, the technicians, the designers, the testers, the programmers, the facility cleaners, the accountants, the Oracle Operators, the CAD people, the Purchasing people...
And these people were not praying about the prospect of getting a 1-crore Match Bonus for scoring a goal or winning a sports match. They were worried about the nation's investment. Their team. Your tax money. So if I get a jaab in this organization, I get to work with such people? AND do fun stuff? And get PAID for that?
Aerospace at its finest. And they weren't even trying to kill humans or "watch the buildings fall".
A billion people lived those minutes and seconds along with those people. And it wasn't a movie.
Of course for some of us, watching a green video monitor with square numbers rolling by, plus a couple of jiggly graphs, is our idea of Heaven. But not all are like us. The rest is all in our imagination. Fortunately :mrgreen:

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Re: Chandrayan-2 Mission

Postby UlanBatori » 09 Sep 2019 13:21

[quote="chetak"]twitter
[quote]Getty Images must be complimented for their due diligence. Very well explained here, through a flow-chart. The photos of ISRO scientists taken by Bagla CANNOT be sold.
ppl, this is Karma. Pagala has now two more oiseaules solidly painted themselves into his corner: Always-Happy Smoke, and Prannoy Roy speaking for NDTV.
All should be dumped in the pakistan as a set. Clearly NDTV as an organization is part of this scam. "Flee-File zone" as the PeeEllAy might say.

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Re: Chandrayan-2 Mission

Postby arshyam » 09 Sep 2019 14:13

Looks like news channels are picking this up:

Chandrayaan 2’s Vikram Lander found in “a single piece” and in a “tilted position”: ISRO officials - Times Now

Bengaluru: Not losing hope, the Indian Space Research Organisation continued to make all-out efforts to establish link with Chandrayaan-2's 'Vikram' lander, now lying on the lunar surface after a hard-landing. Vikram, with rover 'Pragyan' housed inside it, hit the lunar surface after communication with the ground-stations was lost during its final descent, just 2.1 km above the lunar surface, in the early hours of Saturday.

"It had a hard-landing very close to the planned (touch-down) site as per the images sent by the on-board camera of the orbiter. The lander is there as a single piece, not broken into pieces. It's in a tilted position," an ISRO official associated with the mission claimed on Monday.

"We are making all-out efforts to see whether communication can be re-established with the lander," the official said.

"An ISRO team is the on the job at ISROTelemetry, Tracking and Command Network (ISTRAC) here."
Chandrayaan-2 comprises an orbiter, lander (Vikram) and rover (Pragyan).

The mission life of the lander and rover is one Lunar day, which is equal to 14 earth days. ISRO Chairman K Sivan had said on Saturday that the space agency would try to restore link with the lander for 14 days, and reiterated the resolve on Sunday after the orbiter's camera spotted it on the Lunar surface.

An ISRO official said: "Unless and until everything is intact (lander), it's very difficult (to re-establish contact). Chances are less. Only if it had soft-landing, and if all systems functioned, then only communication can be restored. Things are bleak as of now."

"I will rate it (restoring link) as good," another senior official of the space agency said, raising hope that lander springing to life again is not ruled out.

"But there are limitations. We have experience of recovering spacecraft (which had lost contact) in geostationary orbit. But here (in the case of Vikram), that kind of operational flexibility is not there. Already it's lying on the surface of the Moon, and we cannot reorient it. Vital thing is antennas will have to pointed towards the ground station or the orbiter. Such operation is extremely difficult. At the same time, chances are good and we will have to keep our fingers crossed," the official said.

The official said the lander generating power is not an issue, as it has "solar panels all around it" and it also has "internal batteries" which "are not used much." Vikram carried three payloads Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere (RAMBHA), Chandra's Surface Thermo-physical Experiment (ChaSTE) and Instrument for Lunar Seismic Activity (ILSA).

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Re: Chandrayan-2 Mission

Postby ArjunPandit » 09 Sep 2019 14:35

I am refreshing this thread in the hope of a good news ..i know odds are stacked against it ....but still hope refuses to die

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Re: Chandrayan-2 Mission

Postby chola » 09 Sep 2019 14:37

^^^ Wow! If we can connect to the lander again and maybe get Pragyan out it will be an even better story.

Has anyone else ever did this for a moon mission? We would be the first, I think.

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Re: Chandrayan-2 Mission

Postby srin » 09 Sep 2019 14:47

Looking at the Vikram photos, I think it has a directional antenna on top for communications with orbiter and earth. Not sure if they also have a low-gain omni-directional antenna too as a backup.

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Re: Chandrayan-2 Mission

Postby ArjunPandit » 09 Sep 2019 14:52

On second thoughts if true, this is serious nokia level manufacturing..to sustain that level of crash

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Re: Chandrayan-2 Mission

Postby chetak » 09 Sep 2019 15:16

srin wrote:Looking at the Vikram photos, I think it has a directional antenna on top for communications with orbiter and earth. Not sure if they also have a low-gain omni-directional antenna too as a backup.



surely the designers would not have reduced all communications to a single point of failure antenna without some built in redundancy.

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Re: Chandrayan-2 Mission

Postby nits » 09 Sep 2019 15:31

ArjunPandit wrote:On second thoughts if true, this is serious nokia level manufacturing..to sustain that level of crash


speculating that lander actually did not lost trajectory from 2 KM as shown and it could be more of connection lost issue... surviving 2 km crash and still intact is not feasible IMHO. Also it will matter that what about internals of lander - are all parts etc intact or damaged

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Re: Chandrayan-2 Mission

Postby SSSalvi » 09 Sep 2019 15:37

General public have seen the tearful faces in this WA ,Twitter,FB age so drawing conclusions about why those tears? Are they croc tears? .. etc.

Were there no tears in the absence of these media hypes? Does not one weep when his project fails? Do people not cry when years of mehnat goes waste in a fraction of a second? Did people not cry then?

There have been comments on why did He cry?
I doubt if it is for all those new high fly things like : I betrayed the nation? I betrayed my PM,. ... and so on.
It is a simple human emotion.

That way I still wonder why someone has not called ISRO , a deshdrohi.. read the first sentence on ISRO website about CH2 timeline.. in fact while sanctioning the CH2 project in 2008 the blue turban must have added curse to dilboo this project.
His curse could could not however affect the Mars Probe launched before the today's pure sarkar.

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Re: Chandrayan-2 Mission

Postby A Deshmukh » 09 Sep 2019 16:44

Philip wrote: .Look at Mrs.G.Brilliantly dismemberd Pak." Durga's gift to India" said ABV.

Fakes News of the day. ABV himself confirmed on TV that he never compared Indira with Durga as mentioned in the newspaper headlines.

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Re: Chandrayan-2 Mission

Postby ArunK » 09 Sep 2019 16:47

nits wrote:
ArjunPandit wrote:On second thoughts if true, this is serious nokia level manufacturing..to sustain that level of crash


speculating that lander actually did not lost trajectory from 2 KM as shown and it could be more of connection lost issue... surviving 2 km crash and still intact is not feasible IMHO. Also it will matter that what about internals of lander - are all parts etc intact or damaged


Please remember that Moon's gravity is 16% of earth's gravity. Acceleration due to Gravity is 1.62 m/sec^2

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Re: Chandrayan-2 Mission

Postby Dileep » 09 Sep 2019 16:57

Haridas wrote:
ramana wrote:UB, They are using hypergolic liquid fuel and can be precisely metered by a valve. I think the current draw is monitored to give status.
But recall it takes > 2 minutes for signals to go back and forth

Control software shouldnt use fuel consumption based thust estimation, but by directly measuring actual thrust using strain gauges. A seperation control loop to translate commanded thrust profile to actual by controlling fuel flow rate. My two naya paisa.


I would imagine the control relationship between the valve control and the thrust generated would be very complex and non linear in "gain" and "time delay". It is impossible to characterize it all "in vacuum" under "lunar gravity" at the 'full range of '0 to 100% thrust'. The feedback loop can do only so much, right? By "overperformance" should mean the "gain" was high, ie more thrust generated for certain valve opening. The result of higher gain is almost always 'oscillation' or 'saturation'.

That should be what happened.

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Re: Chandrayan-2 Mission

Postby Primus » 09 Sep 2019 17:23

chetak wrote:twitter


Getty Images must be complimented for their due diligence. Very well explained here, through a flow-chart. The photos of ISRO scientists taken by Bagla CANNOT be sold.





This is standard protocol for any photograph. If it clearly identifies an individual and is not taken as a part of a 'crowd scene' in public space, it cannot be 'sold'. With some restrictions it may be used for 'editorial purpose' but again only if it is taken in a public location. Every photographer needs to get a 'model release' from the person in the photograph, even if it is a street urchin in a poor country that the Western tourists are so fond of photographing (that's another pet peeve of mine).

This Pagla fellow needs to be prosecuted, nothing less will suffice.

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Re: Chandrayan-2 Mission

Postby Rsatchi » 09 Sep 2019 17:34

Not just this chap
But what about the other 'Fat Conductor' from next door who was trolling viciously following loss of contact from C-2.

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Re: Chandrayan-2 Mission

Postby Rsatchi » 09 Sep 2019 17:36

Should he not be taken to the cleaners for his lack of basic science/maths/English competency.

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Re: Chandrayan-2 Mission

Postby UlanBatori » 09 Sep 2019 17:59

speculating that lander actually did not lost trajectory from 2 KM as shown and it could be more of connection lost issue... surviving 2 km crash and still intact is not feasible IMHO. Also it will matter that what about internals of lander - are all parts etc intact or damaged

If u look at the Armstrong lander test video again: When Armstrong ejected, that may have blown off one side of it (I don't see how they built an ejectable canopy into that but that was very good thinking!)
But the rest of the lander shot off to the far background, and fell down. The crash crumpled the thing and it exploded in flames.

Neither happened with Vikram. Hypergolic propellant is something which ignites without much prodding, and there must be some left, so why did it not explode into flames if it suffered that much damage? OTOH, how would one see a fire in Space? there is no buoyancy to send up smoke signals. This is why the initial report of "detected on thermal imager" was VERY bad news, unless it was dark and cold enough to detect the warm nozzles (which is good news that it was too dark to see by optical cameras, means sun is not up yet). But now BRF says there was no thermal imager so I don't know. In that case there was enough light to see using optics, which is **NOT** so good news.

OTOH if there WAS a fire, the thermal image should have been EZ to detect even from Earth. 2000K against a 200K background? If u can pick up stars u can pick that up.

************

Remember that the Apollo lunar lander was human-rated to carry 3 suited astronauts. Given the presence of the ejection seat, it can't have been the full final design, but the craft was probably stronger than Vikram since it had to carry at least one human. The ejection height was below 500 meters, hain? The acceleration down was no doubt higher than that above the Moon.

My point is that the drop from there shattered and crumpled the lander, you can see it happening before the dust and flames take over.
So I think the Vikram actually did "land". Maybe on a tilted surface? Why?

See my arguments from the above. I don't like them.
Known:
1) It came down within 500m, maybe much closer, of the intended site.
2) It started "Naaarmal" at 2.1km when it still had significant horizontal speed.
3) It ended up well within 500m of intended target (would be interesting to know whether it was further out or fell short)
4) It DID NOT free-fall from any significant altitude (Armstrong video and structural strength argument)
5) It CANNOT have had much horizontal speed at touchdown. (Ditto)

IOW, you have to wonder whether there were multiple failures.
Rest is all speculation based on the above facts and inferences from the Armstrong Human-Rated Lander video of 1968.

Lander may have still been swinging. As Dileep says, large oscillations as the controller tried to compensate for an input much larger than its design. Not successful in fully damping the oscillation before touchdown. The thrusts to try and counter the oscillation, caused significant drift from the target zone, which also implies significant sideways speed as it tried to compensate.


So it was still aiming for the target: did not abort that and try moving to the secondary target? This is what bothers me. There was at least one more failure on-board after 2.1 km (maybe happened before).

I would have told the software that
eeph u r close to ground, IMPERATIVE to zero out sideways speed, forget target-center ambitions. X meters miss distance is perfectly fine, but Y > X not good within the following arcs...


It touched down, not fully on legs, or yes, but still with significant tilt and sideward speed due to swing. Or came down on a steep slope. Crumpled one or more legs.

Also, it does not appear to be sending out comms though it was supposed to have significant internal power and smarts to use the external power from the solar panels facing outward. How directional is the backup antenna (if any?) Maybe they decided that if Orientation not within 20 degrees, mission is kaput so no need for omni antenna?

But I have a more optimistic thought on the omni antenna. The reason to use a high-gain antenna is to minimize power required, at the edges of the Lunar Day, maybe last well into the night - and just MAYBE survive till dawn, which would imply a very long surface life.

The same low power put into an omni-directional antenna (huge solid angle!) would generate a far too weak signal - at dawn or dusk.

Remember that the Sun is always very low on the horizon at the South Pole even if one were on a flat surface (no hilltop landing attempted, presumably) So solar power right now may be very weak, which is another reason why cameras on Orbiter are having difficulty seeing the situation during the brief pass(es).

Perhaps as solar day progresses, Earth-based telescopes can resolve much better pictures, and maybe guide Orbiter to get better photos. And the generated power may get to the point where its calls can be picked up. When that happens, a SIT-REP may come out, and all functioning systems can report in. Possibility of re-orienting the directional antenna can be explored. MAYBE, just MAYBE, retracting the remaining legs and firing a thruster (I don't want to be the one that has to authorize that..) just right, could convince it to right itself and sit on its nozzles. Then the door ramp can be opened and Pragyan can roll out, maybe for the 6 days remaining. TOTAL scientific mission success, at that point, though the chemistry experiment raises my concerns about test tubes, burettes and pipettes... Hint: they make even Antarctic explorers carry those ancient things, don't they?

The lunar whatzit experiment and the seismograph (which must already have one good data set in it from the "landing") will work. 2 out of 3 ain't bad.

So! No reason to give up hope. The above may explain all the statements from ISRO.
- It is not coming upright even if thrusters can be commanded, because one or more legs are crumpled. Any such attempt will lead to more damage.
- It is difficult to contact, and not contacted so far.
- There is reason for hope, since The Day Is Still Young.

Given the above, even if contacted, it seems extremely unlikely that the Ambassador Mark 2019 Bullockless Cart can roll out. Getting that particular door open would be a miracle, getting the ramp to tilt down and provide a good angle to the ground is even more unlikely: the rover may roll over if it rolls down the ramp in that case.

BUT.... miracles do happen.

And then we can debate what was the second- and maybe third - failure that occurred. The first alone should ***NOT** have caused the bad landing.

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Re: Chandrayan-2 Mission

Postby Singha » 09 Sep 2019 18:24

>> next time build a couple of landers on earth with a gimbaled jet engine to simulate "flight" characteristics.
neil armstrong ejected from one these .... but just look at the seasoned hands on engineering skills to get this done and working. startup mode work.


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Re: Chandrayan-2 Mission

Postby Singha » 09 Sep 2019 18:25

need hands on physical product like above to test 100s of times .... cant depend on AI and sw simulations ... boo woo

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Re: Chandrayan-2 Mission

Postby Mort Walker » 09 Sep 2019 18:37

UB,

1. Apollo LM was meant to carry 2 persons not 3. The 3rd person stayed in orbit around the moon in the return vehicle.
2. CY2 orbiter most likely used its spectrometer to get the thermal imaging. I believe ISRO reports more than the press.
3. Vikram is intact, but may be on its side. All we know is orientation is wrong and maybe the initial tweet about it being upside down is correct.
4. As AmberG pointed out, LRO has a different orientation to get another image of Vikram.
5. Since ground DSN is unable to communicate, ISRO will probably try to communicate via CY2 orbiter and maybe LRO. They may be able to establish comms at higher frequencies that would be attenuated through the earth’s atmosphere. CY2 orbiter has an X band SAR. Don’t know if Vikram has any X band receivers.

All hope isn’t lost, but it doesn’t look good either. As the lunar day progresses, perhaps better imaging will reveal more.

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Re: Chandrayan-2 Mission

Postby Mort Walker » 09 Sep 2019 18:43

Singha wrote:need hands on physical product like above to test 100s of times .... cant depend on AI and sw simulations ... boo woo


All it takes is money, but lesson learned. As ISRO could build something just like this instead of using balloons.

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Re: Chandrayan-2 Mission

Postby JayS » 09 Sep 2019 19:03

Dileep wrote:
Haridas wrote:Control software shouldnt use fuel consumption based thust estimation, but by directly measuring actual thrust using strain gauges. A seperation control loop to translate commanded thrust profile to actual by controlling fuel flow rate. My two naya paisa.


I would imagine the control relationship between the valve control and the thrust generated would be very complex and non linear in "gain" and "time delay". It is impossible to characterize it all "in vacuum" under "lunar gravity" at the 'full range of '0 to 100% thrust'. The feedback loop can do only so much, right? By "overperformance" should mean the "gain" was high, ie more thrust generated for certain valve opening. The result of higher gain is almost always 'oscillation' or 'saturation'.

That should be what happened.


A liquid fuel thruster should not have very complex valve opening to thrust function, for hypergolic fuels, I'd imagine. And by now ISRO must be having tons of data to correlate performance of nozzles in tests in their test cells vs performance in vacuum. (would gravity matter for thrust?? :?: How?? ) Are they using a new rocket motors with new fuel and/or architecture..?? I'd expect them using proven rocket motors for this application.

It makes sense that there was higher gain than expected which could have pushed the control system in self induced oscillations. And perhaps there was not enough time available to recover there after.

I read somewhere that only two thrusters were used for fine braking out of four. Is that correct info..?? I don't know what was the geometric config of the thrusters, but it sound odd to use two thrusters. If this is correct, I am perplexed why ISRO used this kind of setup. I frankly don't think this is correct.

PS: I checked the thruster location from pictures published by ISRO - they basically are placed in the centre of all four sides of Vikram, forming a square among themselves.

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Re: Chandrayan-2 Mission

Postby madhu » 09 Sep 2019 19:26

If we assume that the lander’s fine breaking had worked as intended and stoped at first point (500m above the surface) and waited for input to land from ISRO which did not obviously did not come as it had lost connectivity the final impact velocity will be around 40m/s (V^2 = 0^2+2*g*h)
I think this is a almost 10 times the designed for which is around 4m/s as per india today article.
How much can we expect out of it be intact?

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Re: Chandrayan-2 Mission

Postby chetak » 09 Sep 2019 19:28

Mort Walker wrote:
Singha wrote:need hands on physical product like above to test 100s of times .... cant depend on AI and sw simulations ... boo woo


All it takes is money, but lesson learned. As ISRO could build something just like this instead of using balloons.


are you suggesting that ISRO has done all this without any physical tests of some sort.


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