Chandrayan-2 Mission

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Re: Chandrayan-2 Mission

Postby Ashokk » 14 Nov 2019 03:34

Chandrayaan-3: Second bid to land on Moon by November 2020
BENGALURU: The Indian Space Research Organisation (Isro), which failed to land a probe on Moon in its first attempt in September 2019 (Chandrayaan-2), has begun work on Chandrayaan-3 with a deadline of November 2020, sources said.
Isro has formed multiple committees — an overall panel and three sub-committees — and held at least four high-level meetings since October. The new mission will include only a lander and rover, as the Chandrayaan-2 orbiter is functioning well. On Tuesday, the overview committee met with the agenda of reviewing the configuration of Chandrayaan-3. It also looked into the recommendations of various sub-committees on propulsion, sensors, overall engineering, navigation and guidance.
Work is in full flow, said a scientist. So far Isro has looked at 10 specific aspects of the mission, including landing site selection, absolute navigation and local navigation. Sources quoted an office order issued on October 5 as having instructed: “It is essential to carry out detailed analysis on the changes for improving the lander system considering the recommendations of both the expert committee (formed to look into Chandrayaan-2) and the recommendations which could not be implemented due to advanced stage of Chandrayaan-2 flight preparation.”
Another scientist said among the top priority for the new mission is “strengthening the legs of the lander”, so that it allows landing even with a high velocity. Sources said that Isro will be building a new lander and a rover. No final decision has been taken on the number of payloads on the lander.
A source said Isro teams are looking at having a detachable module that will carry fuel. “Tentatively called the propulsion module, it will help in taking the landing module — which will have the rover sitting inside the lander — to the lunar orbit,” the source said. In Chandrayaan-2, fuel carried on the orbiter was used for all the manoeuvres performed post launch and until the separation of the landing module. Here, the propulsion module will aid this process. Isro is also looking at reducing the number of manoeuvres around Earth and also during the transit to the lunar orbit. “Instead of six manoeuvres, we may have just three or four,” a source said.

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Re: Chandrayan-2 Mission

Postby Varoon Shekhar » 14 Nov 2019 03:51

^
Excellent news! Nice to see them being so confident and decisive, as well. particularly with regard to the deadline! So no orbiter this time, they will probably attach a LAM to the lander/rover combine, to perform the necessary orbital manoeuvers.

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Re: Chandrayan-2 Mission

Postby Indranil » 14 Nov 2019 04:39

Heartening. This fuel module is an interesting take. What has been revealed is that the lander module was designed to handle a certain amount of deviation. Increasing this tolerance would have increased fuel capacity. So this fuel module is to allow more flexibility.

Will it be launched using GSLV2?

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Re: Chandrayan-2 Mission

Postby arvin » 14 Nov 2019 07:38

Good to see things moving fast. My guess is the new propulsion module would be a bare bones cy2 orbiter structure with only feul and thrusters. Our own fregat space tug. Isro would need to qualify the landing algorithm for re- use before the actual CY 3 mission in 2023 with JAXA.

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Re: Chandrayan-2 Mission

Postby Amber G. » 19 Nov 2019 03:27


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Re: Chandrayan-2 Mission

Postby ashbhee » 19 Nov 2019 04:33

arvin wrote:
ashbhee wrote:I think this is what ISRO should do.
They should not wait for 3 or 4 years to launch Chandrayaan - 3.
Just launch lander only mission, Virkarm - 2. It should be a replica of Vikram - 1 plus any changes that needs to be done for the landing mechanism.
Since it is a repeat mission, it can be done quickly and cheaply. Since it is much lighter mission it can be launched using PSLV or even the new SSLV.


PSLV fourth stage PS4 can only deliver till parking orbit. It is restartable, but wont have the feul for the 5 gravity assist maneovres to send the lander only config to moon capture orbit. Something like fregat would be required which we dont have.
Chandra yaan 2 was a closely coupled design in which lander piggy backed on the orbiter.
Lander only has feul to do the coarse and fine breaking after its drop from 100 km orbit.


When I said, "Just launch lander only mission, Virkarm - 2", I did not mean just send the lander without a navigation module to reach moon.
It looks like ISRO is thinking the same lines.
https://timesofindia.indiatimes.com/ind ... 047390.cms

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Re: Chandrayan-2 Mission

Postby ramana » 21 Nov 2019 04:13

So how does this happen?
The control system expected the lander to be at higher speed for start of fine braking?

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Re: Chandrayan-2 Mission

Postby Gerard » 21 Nov 2019 07:14


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Re: Chandrayan-2 Mission

Postby disha » 21 Nov 2019 10:08

From TOI.

It appears that the reduction in velocity during the fine descent period was higher than the designed parameters. This might have thrown the software into tizzy and hence the crash landing.

My speculation, the lander has to go from point A to point B, but the braking is higher and the software realizes that it can only go to say A.5. Now it cannot add thrust! But it is designed to go to point B. And the software goes into an irrecoverable loop where all it has control on is varying braking thrust when it actually needs a 'boosting' thrust!

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Re: Chandrayan-2 Mission

Postby Indranil » 22 Nov 2019 01:15

disha wrote:It appears that the reduction in velocity during the fine descent period was higher than the designed parameters. This might have thrown the software into tizzy and hence the crash landing.

Yes, S. Somanath had hinted at this in the podcast I had linked before. It was not a bug or glitch. The parameters of the craft were outside the design parameters of the software. He had said that the spacecraft is designed for tolerances around ideal values. Tolerances can be increased, but that comes at the price of added fuel.

He had said that there is no reason to not make the whole report public as soon as it is ready. Let's see.

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Re: Chandrayan-2 Mission

Postby disha » 22 Nov 2019 01:38

Indranil wrote:Yes, S. Somanath had hinted at this in the podcast I had linked before. It was not a bug or glitch. The parameters of the craft were outside the design parameters of the software. He had said that the spacecraft is designed for tolerances around ideal values. Tolerances can be increased, but that comes at the price of added fuel.

He had said that there is no reason to not make the whole report public as soon as it is ready. Let's see.


I do not think I ever said it as a software bug or a glitch. My first post on this subject did say that the control software might have been presented parameters out of its design bounds. My thinking at that time was Vikram could not get a lock on the safe spot to land and that might have presented unbound parameters.

Now we know that the more than anticipated reduction in fine descent created this situation. And throwing software in tizzy is what I mean by control laws not able to gain control over the situation due to out-of-control events. :)

IMPORTANT: What Vikram attempted was far far far more complex than landing a craft in a region which is as smooth as a baby's bottom (comparatively and figuratively).

I am also *not* in favor of revealing the whole report in public. First of all the DDMs will not understand a difference between control and law and go into #Blow2ISRO mode. Second it will reveal the antecedents of the software. Since what is the difference between landing Vikram on a remote spot and a 'dharmo' on another remote spot? Other than former being more complicated.

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Re: Chandrayan-2 Mission

Postby disha » 22 Nov 2019 01:42

somdev wrote:The control software is most probably written in ADA. In ADA operations may be implemented as subprograms using conventional sequential control structures. Unless there was something fundamentally wrong in logic the Ada execution is mostly flawless.


It has nothing to do with Ada or even anything fundamentally wrong.

Think of it as this way, the control law needs to supply more fuel to the thrusters so that it can add more thrust to reach point B instead of point A.5. However there is not enough fuel in the craft! So what can it more do? And this is just one of the parameter we are speculating on. In reality, Vikram had to deal with 100s of parameters in realtime.

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Re: Chandrayan-2 Mission

Postby Indranil » 22 Nov 2019 01:49

Disha,

I understood what you said. I am supporting you. :D

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Re: Chandrayan-2 Mission

Postby chetak » 24 Nov 2019 10:32

Finally, an official response on how #Chandrayaan2 lander #Vikram lost control. See attachments: Left: My story that "extra brakes may have sent it out of control", Right: Govt reply in Lok Sabha saying the same.


Read Full Report Here:

Extra braking caused Vikram to deviate: Govt in LS


Image


Image

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Re: Chandrayan-2 Mission

Postby chetak » 24 Nov 2019 10:42

Chandrayaan-3 plans indicate failures in Chandrayaan-2


Chandrayaan-3 plans indicate failures in Chandrayaan-2

Chethan Kumar
Nov 19, 2019,

The Vikram lander made an unsuccessful effort to soft-land on the lunar surface

BENGALURU: The changes the Indian Space Research Organisation (Isro) is making in the proposed Chandrayaan-3 mission are indicative of the things that may have gone wrong with Chandrayaan-2 that failed to soft-land a probe on Moon in September 2019.

From a new guidance algorithm to improved communication systems on the lander, the overview committee that met last Tuesday (November 12) has pointed to multiple recommendations made by the failure analysis committee (FAC) looking into Chandrayaan-2 failure.

As part of the final discussions at the meeting the committee accepted the “Propulsion+Landing Module” configuration for Chandrayaan-3, and said: “Guidance algorithm to be finalised considering all recommendations of FAC and also after detailed simulations.”

The TOI was the first to report that Chandrayaan-3 mission is likely to have this — lander & rover (landing module) and propulsion module— configuration on November 14.

Software & Algorithm Glitch?

Sources indicated that one of the main reasons that the FAC found for Chandrayaan-2’s failure in soft-landing Vikram (the lander) was a glitch in the software and the algorithm that saw the lander lose orientation just metres away from the lunar surface. They said that the velocity of the lander was higher than expected and that it may have had attitude errors.

The overview committee, last week noted: “...Also, after detailed simulations LDV (laser doppler velocity) sensor for the direct measurement of velocities (all three axes) must be incorporated.

“The LDV sensor was developed even for Chandrayaan-2, but since it did not perform well in ground tests, it was not included,” a source said.

LDV sensors will be useful as they will help directly measure the velocity from the height of about 20km, sources added and said Bengaluru-based LEOS lab under Isro has developed the sensor.

Direct Velocity Measurement

Among other things, Isro is looking to improve the data transfer capability on the lander for the new mission, which will help transfer lunar surface images from the lander imager camera right from the beginning of the powered descent — likely to be from about 30km from the lunar surface.

“The camera was taking images even on Chandrayaan-2, but we didn’t have the capability to transfer real time, this time, the committee feels that we need this to get the right orientation,” another source said.

The committee has noted: “...Data rate, telemetry and orientation to be appropriately arrived at based on the descent trajectory.”

Power & Communication

Also, Chandrayaan-3 is expected to have solar cells on four sides of the lander— its predecessor had it only on three sides— to improve performance.

“Feasibility of populating solar cells on the fourth side vertical panel where Rover is accommodated to be studied to avoid power issues if landing happens with large attitude error resulting in absence of Sun in the plane,” the committee has said.

The panel, which will meet again later this year, has also tasked sub-committees to look at establishing margins for different touchdown conditions. “Strengthening of lander legs to be considered… power and communication between lander and ground to be ensured post landing irrespective of lander orientation,” the panel has noted.

Sources added that this may mean that the space agency will add more antennas on the lander to keep communication alive even if the lander does not land on the legs.

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Re: Chandrayan-2 Mission

Postby Vayutuvan » 25 Nov 2019 00:26

Indranil wrote:The parameters of the craft were outside the design parameters of the software. He had said that the spacecraft is designed for tolerances around ideal values. Tolerances can be increased, but that comes at the price of added fuel.


I said this almost immediately after the hard landing.

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Re: Chandrayan-2 Mission

Postby Gerard » 03 Dec 2019 06:24


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Re: Chandrayan-2 Mission

Postby SaiK » 03 Dec 2019 06:56

I don't want C3 going to launch pad, w/ complete testing on Earth.

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Re: Chandrayan-2 Mission

Postby NRao » 03 Dec 2019 11:06

NASA Finds India’s Vikram Moon Lander Crash Site, With Amateur’s Help

NASA has found pieces of Vikram, a small spacecraft that India attempted to land on the moon in September. They did it with the help of an engineer from India who scoured the lunar surface in his spare time.

Vikram was part of India’s Chandrayaan-2 mission to the moon, which launched in July. If the spacecraft had reached the surface in one piece on Sept. 7, India would have been only the fourth country to successfully put a lander on the moon. But less than two miles above the surface, Vikram veered from the planned descent trajectory and fell out of radio contact.

India’s space agency said the next day that it had located the lander. But it never published any images of the hard landing site taken by the mission’s accompanying orbiter, which remains in operation and is carrying out a scientific mission that will last for years.

A NASA spacecraft, the Lunar Reconnaissance Orbiter, has passed over the mission’s intended landing site, on a high plain near the south pole, several times since September. But initial analyses of the images did not reveal an obvious impact scar comparable to the Beresheet lander launched by Israel this year, which crashed in April. NASA scientists noted that the spacecraft might have been hidden in the shadows.

A lot of people were looking, including Shanmuga Subramanian, an Indian computer programmer and mechanical engineer.

“The crash landing of Vikram rekindled an interest in the moon not only for me and others also,” he wrote in an email. “I think even if Vikram had landed and sent some images, we would have never had such interest. For the first few days I was scanning the images randomly and there were lot of false positives.”

After reviewing the last known velocity and position of Vikram, Mr. Shanmuga shifted where he was looking. He noticed a white speck on the lunar surface that was about two-thirds of a mile from where Vikram was supposed to have set down. That speck was not visible in an earlier image. He wondered if the crash might have buried the lander in the lunar soil.

Mr. Shanmuga reported what he had found to NASA and scientists working with the Lunar Reconnaissance Orbiter’s camera, who confirmed his finding and scoured the surrounding area. Comparing images taken before Vikram’s landing attempt and those taken on Nov. 11, they were able to identify the impact point about 2,500 feet to the southeast of the planned touchdown site, and a spray of debris emanating outward.

The pieces of debris were not much bigger than the minimum of what the camera could make out. The resolution of the camera was about 1.3 meters per pixel; the three largest pieces of debris were about two pixels by two pixels in size and cast a one-pixel shadow, NASA said.

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Re: Chandrayan-2 Mission

Postby sanjaykumar » 03 Dec 2019 11:10

Actually the Indian found Vikram with nasa’s help. That should be obvious.

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Re: Chandrayan-2 Mission

Postby sanjaykumar » 03 Dec 2019 11:11

Even to the NYT.

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Re: Chandrayan-2 Mission

Postby Gautam_2 » 03 Dec 2019 11:36

desi found lander and informed nasa which promptly took credit, didn't even mention him. just need white man's approval.

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Re: Chandrayan-2 Mission

Postby naruto » 03 Dec 2019 14:33

^^^, their website does credit him.

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Re: Chandrayan-2 Mission

Postby arshyam » 03 Dec 2019 17:02

Gautam_2 wrote:desi found lander and informed nasa which promptly took credit, didn't even mention him. just need white man's approval.

They did credit him. What's with the unnecessary butthurt?


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Re: Chandrayan-2 Mission

Postby lakshmanM » 03 Dec 2019 18:23

ISRO ignored him, NASA replied. Shouldn't people be more worried about that?

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Re: Chandrayan-2 Mission

Postby Zynda » 03 Dec 2019 19:41

I could not see any references to him contacting ISRO for them to ignore him. It seems like since he used LRO images to track lander, he thought it was better to contact NASA and they could take it further from there.

Speculation Alert: It is possible ISRO would have spotted the exact location of crashed lander. There were some comments here on BRF by a couple of knowledgeable members about ISRO not being comfortable with releasing images as it would give out some details about sensitive issues like our surveillance imagery capabilities.

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Re: Chandrayan-2 Mission

Postby Vivek K » 03 Dec 2019 21:25

Was there no protection around the rover that was housed inside the lander? Was ISRO trying to communicate with the Rover to try to wake it up? Can the orbiter talk directly to the Rover without the lander?

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Re: Chandrayan-2 Mission

Postby ArjunPandit » 03 Dec 2019 21:30

lakshmanM wrote:ISRO ignored him, NASA replied. Shouldn't people be more worried about that?

although he did the right thing. but couldnt he publish his findings independently....we also have to factor in that US organizations have much larger budgets and much bigger size....most importantly they are more open and confident about themselves..in india there's always a fear...many times while dealing with some economics time series about India v/s US i have got response from FRB, BLS folks.. and no response from GoI sites contact us and some universities...i wont say chalta hai ..but may be a fear ..why/what is the person tryng to do...
BTW..remember i was saying on this thread that we can identify using the images..and people mentioned that resolution would be low for any meaningful analysis...a good learning for me at least

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Re: Chandrayan-2 Mission

Postby JayS » 03 Dec 2019 23:28

Zynda wrote:I could not see any references to him contacting ISRO for them to ignore him. It seems like since he used LRO images to track lander, he thought it was better to contact NASA and they could take it further from there.

Speculation Alert: It is possible ISRO would have spotted the exact location of crashed lander. There were some comments here on BRF by a couple of knowledgeable members about ISRO not being comfortable with releasing images as it would give out some details about sensitive issues like our surveillance imagery capabilities.

That sounds like a lot of BS. The images can easily be downgraded to hide real capability. That's a trivial job.


NASA releasing high-quality imagery for crowd-sourced search on them for something of interest is nothing new. I remember to have seen a documentary about the mission they sent to collect asteroid dust. They released very high-resolution images of the dust catching gel slices, so people could locate tiny dust particles in them.

Also, I don't understand, why should that guy have contacted ISRO on it first and not NASA..? Its NASA data he was working on and NASA was the authority to cross verify and confirm. He didn't get there in single attempt, so there was no point in going gaga over it unless NASA has cross-verified. What would ISRO do in this loop..?

Has ISRO released the trajectory data, whatever they had, which could have helped the searchers narrow down...?? I have not seen any mention of it. So asking.

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Re: Chandrayan-2 Mission

Postby Indranil » 04 Dec 2019 01:17

Gautam_2 wrote:desi found lander and informed nasa which promptly took credit, didn't even mention him. just need white man's approval.

This is hardly the case. NASA gave him full credit for the discovery. Then they described what they did to identify the rest of the debris.

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Re: Chandrayan-2 Mission

Postby Amber G. » 04 Dec 2019 07:28

Gautam_2 wrote:desi found lander and informed nasa which promptly took credit, didn't even mention him. just need white man's approval.


Actually Shanmuga Subramanian got pretty nice credit.. *many* *many* were looking for before/after images.. if you see my older posts it clearly shows the magnitude of the task - (it is like finding 1 rupee coin size thing from a a distance a plane/drone flying 1000 meters above the ground in a large 1kmx1km size land littered with rocks in not the ideal lighting. As said before, we had to wait as people were examining millions of before/after images.

One good thing about LRO (LROC) are all the images are available to public (and ISRO) so everyone can help. That is really a nice thing about this project from Nasa.

CY2's's orbit is closer so it has/will have much higher resolution pictures and since now we know the location it will be easy to confirm.

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Re: Chandrayan-2 Mission

Postby Amber G. » 04 Dec 2019 07:32

lakshmanM wrote:ISRO ignored him, NASA replied. Shouldn't people be more worried about that?

Sorry but this is kind of silly - "ISRO ignored" part .. NASA's LRO's pictures are in public domain so everyone can look.. more eyes there are easier to see/compare those millions of pictures to see a pixel size difference. (BTW *many* were looking and are happy that someone eventually found it).

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Re: Chandrayan-2 Mission

Postby Amber G. » 04 Dec 2019 07:47

Vivek K wrote:Was there no protection around the rover that was housed inside the lander? Was ISRO trying to communicate with the Rover to try to wake it up? Can the orbiter talk directly to the Rover without the lander?

No practical "protection" would have likely helped since the impact velocity was *very* high. (See my earlier posts in September time frame - the velocity of impact is about 75 m/s (260 Km/Hr).) ISRO (and other radio telescopes around the world) were looking any transmission fo lander/rover. ISRO was trying to "wakeup" lander. Orbiter does *not* remain in contact with rover/lander all the time - Earth based radio-telescopes do. Rover can "talk" primary with lander only. Orbiter, of course goes in and out in the communication range of the lander/rover.

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Re: Chandrayan-2 Mission

Postby Amber G. » 04 Dec 2019 08:47

ArjunPandit wrote:
lakshmanM wrote:ISRO ignored him, NASA replied. Shouldn't people be more worried about that?

although he did the right thing. but couldnt he publish his findings independently....we also have to factor in that US organizations have much larger budgets and much bigger size....most importantly they are more open and confident about themselves..in india there's always a fear...many times while dealing with some economics time series about India v/s US i have got response from FRB, BLS folks.. and no response from GoI sites contact us and some universities...i wont say chalta hai ..but may be a fear ..why/what is the person tryng to do...
BTW..remember i was saying on this thread that we can identify using the images..and people mentioned that resolution would be low for any meaningful analysis...a good learning for me at least

Few comments:
1 - This was by a joint effort - NASA's LRO/LROC's images are in public domain and thousands of people use it -- many were looking for Vikram. There were *many* reports/joint-efforts - people finding something "intersting" and other better experts looking it, verifying and confirming it.. slow process. These images were from October 15 flyby , and as I posted then it was likely to take months to go through all the millions of the images .
2 - It is quite *hard* to "identify" using images - very hard, difference is literally pixels - you can't really resolve it to see anything other than seeing a dot which was not there before.
3 - See <this> to see before/after images. Gives some idea why not everyone was able to see it right away.

Now perhaps one can see CY2's high resolution camera to see more details since we know the actual location now.

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Re: Chandrayan-2 Mission

Postby disha » 04 Dec 2019 12:19

lakshmanM wrote:ISRO ignored him, NASA replied. Shouldn't people be more worried about that?


Wrong speculation. Nothing of the above sort should be speculated.

Others have already pointed out, but to reiterate:

1. NASA publishes its moon data. Just like ISRO publishes its Mars photos.
2. Shanmugam was keenly interested and worked hard and reported his findings to NASA to x-verify (since it is NASA data to begin with)
3. NASA confirmed and released the right image with appropriate tags (debris/impact points etc)
4. NASA gave Shanumgan credit

ISRO can now look at that area with its C-2 Orbiter and refine Vikram's hard landing further.

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Re: Chandrayan-2 Mission

Postby Manish_P » 04 Dec 2019 15:04

Now?

They have said that earlier clearly

Link - https://www.isro.gov.in/updates-archivals

They didn't share the images (of the lander?). Has NASA?

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Re: Chandrayan-2 Mission

Postby Gerard » 05 Dec 2019 07:48

Image
Image


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Re: Chandrayan-2 Mission

Postby Amber G. » 02 Aug 2020 08:45

1 Year update:

Gerard wrote:Vikram Lander Found


Update from Shanmuga Subramanian (The person in above news) on twitter: Chandrayaan2's Pragyan "ROVER" intact on Moon's surface & has rolled out few metres from the skeleton Vikram lander whose payloads got disintegrated due to rough landing .. More details in tweets <click>

1.Debris I found was of Langumir probe from the Vikram lander
2. Debris NASA found might be from other payloads, antenna, retro braking engines, solar panels on side etc.,
3. Rover has rolled out from lander & has actually travelled few metres from the surface
South Pole region is not always well lit and the lander was in a shallow depth of 2 ms from the surface so it was not visible in Nov 11th's NASA flyby due to different angle of incidence & would be difficult for anyone to find it unless the sun is directly above the surface
Since sun is never directly above moon's surface in that region, it would have been so difficult, the above image was taken on Jan4th, 2020 | The 1st image I tweeted is enlarged version of the below image


The person has communicated to ISRO - Have not seen official response.

Here are a few pictures from above:
Image
Image
Image

------*** ----

Meanwhile, In March of this year, there was supposed to be major publication/ data release for CY-2 but got delayed by Covid. Apart from obvious disappointment of Pragyan, it seems that all other aspects of CY2 are providing awesome data and people are happy

They (ISRO) say that major release of data / report etc will be done in October this year.
Last edited by Amber G. on 02 Aug 2020 09:56, edited 2 times in total.


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