Chandrayan-2 Mission

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VikramA
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Re: Chandrayan-2 Mission

Postby VikramA » 08 Sep 2019 22:02

rumors on twitter that lander is intact but almost upside down

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Re: Chandrayan-2 Mission

Postby UlanBatori » 08 Sep 2019 22:22

Gagan wrote:A word about the TV transmission of ISRO launches and possible measures to improve it. I have repeated some things ad-nauseam multiple times in the past.
1. Doordarshan as an socialist era TV broadcaster is poorly motivated to do 21st century transmission. Period.
{agree. Putting a dead image there with a countdown clock, for hours before the lander window, shows a work ethic that stinks. And then their transmission went kaput.}
ISRO has to surge forward, and shed this 70s and 80s mindset and we have to have a more scientifically oriented, modern, high-tech TV coverage.

Gaganji: ISRO IS waaaaaaaaaay ahead of the rest. The PR is worth $$$BB in the effect that it has on people both in India and in the rest of the world. The images of real human emotions. The video of the ice-cool My-Job-Is-2b-like-a-duck Dr. Sivan wiping his spectacles and bawling on the shoulder of the Prime Minister is probably a Huge moment in history. No Bollywood tear-jerker director could have scripted that. I think that did more for India's Image as all the expensive PR campaigns combined.

Broadcasting the faces of the children - and of the Rocket Scientists as they monitored their baby - was truly world-beating. Point to another Space Agency where you find such diversity, such color, such humanity. The nerd wimmen were seen to be just as fashionable and sociable - and smart (!!!) as the "coolest" fashion models. Those red-and white Ashoka-Chakra ear-studs flush with the ear: Sheer class!! OK, except for Mandira Bedi :mrgreen: Those people came across as real smart people.

That probably did more for "wimmens in STEM" than any $$B guvrmand program ever.

I think NASA would have given $20B for such citizen interest and involvement, and such imagery. All Space Agencies struggle mightily with the problem of how to "sell" their budget to the voters. Americans and Russians are probably sick and tired of watching government babus and bhabis cavorting in gorilla suits in microgravity. Its worse than attending a pissicks lecture for 1.5 hours.

The other stuff, sad to say, only we geeks care about. Broadcasting the trajectory live is about as useful as using all the screens in the Rajdhani Express to broadcast the speed and gradient, instead of movies.
They could have a well-announced website where the geek data fills the screen. But prime-time TV? Indians have it down cold. World-leaders.
Last edited by UlanBatori on 08 Sep 2019 22:31, edited 3 times in total.

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Re: Chandrayan-2 Mission

Postby UlanBatori » 08 Sep 2019 22:23

Regarding ISRO's present habit of going all-out on these missions:
Fly High and Proud
And if you should fall...
Remember...
You Almost Had It All!!

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Re: Chandrayan-2 Mission

Postby Indranil » 08 Sep 2019 22:27

VikramA wrote:rumors on twitter that lander is intact but almost upside down

Very unlikely.

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Re: Chandrayan-2 Mission

Postby SaiK » 08 Sep 2019 22:34

100 m/ sec 2.1km to go.. fast braking period.. nothing heard.

That is pretty fast to land w/ balloons(if) and cushions.

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Re: Chandrayan-2 Mission

Postby Dasari » 08 Sep 2019 23:18

SaiK wrote:100 m/ sec 2.1km to go.. fast braking period.. nothing heard.

That is pretty fast to land w/ balloons(if) and cushions.


I thought 59.8 m/sec. But it is very fast. Even if it is free fall from there the terminal velocity at impact would be like sqrt ( 2100*2*1.62 + 59.8**2) = 102m/sec or 360km/hr. On the other hand, it is not free fall. It appears that the thrusters are adding to the speed instead of reducing it due to craft disorientation.

The fact that they used thermal imaging to locate, but 0.30m resolution optical camera could not picture it tells us that it is disintegrated into pieces and may be buried under the dust.

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Re: Chandrayan-2 Mission

Postby Suresh S » 08 Sep 2019 23:25

I totally agree with the mongolian in his above post. he got it absolutely right. That picture of the prime minister and Dr sivan crying is one for the ages . No shame in admitting I cried with them. We are emotional people only , what to do sir. I am not against sophisticated presentation but what we have as Indians, as mongolian put it better than me is precious, we must appreciate it. Those pictures from ISRO during the final stages were sheer gold, unadulterated Indianness, nothing on earth can beat that. Emotions can be a hindrance but without emotions we are no better than a stone . Emotions are what makes us human.

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Re: Chandrayan-2 Mission

Postby Sridhar » 08 Sep 2019 23:30

Gagan wrote:A word about the TV transmission of ISRO launches and possible measures to improve it. I have repeated some things ad-nauseam multiple times in the past.
1. Doordarshan as an socialist era TV broadcaster is poorly motivated to do 21st century transmission. Period.

2. A high quality transmission will need a lot of money in the form of a fleet of dedicated cameras on the ground, in the air, on the rocket launcher or the lander, gyro stabilization, special telescopes. All will need to be imported. The broadcaster will have to give out a contract to develop software to allow on-screen telemetry, and develop VERY high quality animation, that is synced to telemetry.
3. VERY close coordination with ISRO - which is itself a government organization with at least some ethos that remain in bygone era. ISRO seems to be struggling between the demands for secrecy, and log-kya-kahenge syndrome. I suggest that they explode forward with confidence. I for one love them, warts and all, and expect nothing more than NAAAARMAL PARFAARMANCE from them !!!
4. ISRO will have to install cameras on all launchers, at multiple places, which they already do, but will have to dedicate a lot of band width to the transmission. Further they will perhaps have to deploy a parallel system to collect audio-visual data and re-transmit to the TV broadcaster.
5. ISRO and India will have to deploy special ships in the IOR, or use french islands in southern IOR, or further equip our station in Antarctica for this

One reason why all this isn't happening is the expense. I don't agree that this expense is unjustifiable. It is of primary importance now.
In fact there is now a VERY NOTICEABLE difference between ISRO launch transmission and what other space powers are doing. And ISRO and India comes across as uncaring and callous.

I urge ISRO to do their OWN transmission using Antrix corporation. Transmission should be purely scientific, with no room for sycophancy. There is NO NEED TO SHOW THE ISRO CHIEF, the PM or other dignitaries, or the gathered children. There IS NO NEED TO SHOW PEOPLE APPLAUDING, while cutting away from improtant scientific data being displayed. Comparable commentary done by videshis talks about rate of fuel burn, they descrbe how the launcher is rotating by X degrees along it axis to orient itself, they talk about stage separation in huge detail. They describe the events surrounding the pre-launch in much more detail. All these are done by people who are fluent in conversation.

We need a Harsha Bhogle for ISRO launch commentary. Not a cricketer himself, but very knowledgeable never the less, and able to give very detailed information and engross people with his speech.

Telemetery HAS TO BE ON SCREEN !!!! We as fans of ISRO's work, like to analyze in detail every step of the way. But have to rely on miserly snippets of information released by a media shy ISRO. ISRO has a lot of room to improve in media management. Do they or Antrix have a dedicated media manager? One can't send a senior scientist to tackle the media -that is not right. It is akin to sending someone unprepared in war into battle with a pack of hungry wolves, who's primary purpose to take one improper word and sensationalize it!

ISRO has to surge forward, and shed this 70s and 80s mindset and we have to have a more scientifically oriented, modern, high-tech TV coverage.


And for the nth time, this is ISRO’s feed - Doordarshan merely telecasts it. The cameras are ISRO’s, the commentators are theirs and those deciding which camera to switch to are ISRO’s. Doordarshan may not be stellar but they would do better than this (e.g. their coverage of the main national events like Republic Day and Beating Retreat have gone up significantly at least in the technical department. Maybe Doordarshan’s cameras (to make sure that there are no security issues involved) coupled with younger ISRO talent for the commentary or an outside space journalist (there is a small new generation of journalists following in the footsteps of the Hindu/Frontline crew but more polished).

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Re: Chandrayan-2 Mission

Postby arvin » 08 Sep 2019 23:41

Gagan wrote:ISRO can release more detailed telemetery data and timelines in its website if it is OK with the powers that be.

What happened to the lander? We know that the Moon's environment is super hostile. Did that environment have a role to play in the lander's failure?
Did one of the 800KN engines under perform? Was there a software glitch?


I am suspecting software glitch. The rough braking was a success with no issue with the 4 x 800N thrusters. Guessing here , then the thrusters at sides 2 and 4 could be shut and on sides 1 and 3 were adjusted to point legs from horizontal to facing downwards. i.e 90 degree clockwise turn.
As per report today, one of the thrusters over fired
so legs would be at anything beyond 90 degree turn.
So why did the attitude control system fire it for longer than needed. Wasnt there a pure hardware only feedback mechanism to detect a vertical legs down, antenna up positon.

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Re: Chandrayan-2 Mission

Postby Prasad » 09 Sep 2019 00:00

Unfortunately I agree with the yak-herder. Despite the sheer rage that the commentators induce each time they yack on over the multiple callouts during a launch or a landing, the lay person (who is in the majority) needs the commentator to explain wth is going on. Would it be nicer to have a separate webfeed with much reduced commentary and greater telemetry+imagery? Yeah. Are we going to get it? Probably not. Would be nice though, to get it later if possible. Shouldn't take much time to edit out a video with just mission control audio and on-screen data and limited commentary though.

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Re: Chandrayan-2 Mission

Postby sanjaykumar » 09 Sep 2019 00:11

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.

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Re: Chandrayan-2 Mission

Postby Mort Walker » 09 Sep 2019 00:13

We don't know if it was a software error or a combination of hardware and software. I would speculate the software is fine, but there simply wasn't enough altitude to recover from an error in roll or pitch.

The below video about the Apollo 11 Lunar Module testing on earth. A jet engine below counter act the weight on earth for the moon. It was tested 20 times and the 21st time it malfunctioned. Armstrong ejected.

https://www.youtube.com/watch?v=dNlZXso0-I4&t=68s

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Re: Chandrayan-2 Mission

Postby ArjunPandit » 09 Sep 2019 00:21

^^mort sir copie d and shared on twitter...are you on twitter..can add you for the credit...

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Re: Chandrayan-2 Mission

Postby Mort Walker » 09 Sep 2019 00:27

I am not on twitter or facebook. I only do BRF. It need not be credited as it is already there for the world to see.
What is amazing is this was done in 1968, where computer controls were no where near as sophisticated. Only a great pilot could do this who had nerves of steel.

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Re: Chandrayan-2 Mission

Postby UlanBatori » 09 Sep 2019 01:00

Mort Walker wrote:The below video about the Apollo 11 Lunar Module testing on earth. A jet engine below counter act the weight on earth for the moon. It was tested 20 times and the 21st time it malfunctioned. Armstrong ejected.
https://www.youtube.com/watch?v=dNlZXso0-I4&t=68s

Wow!

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Re: Chandrayan-2 Mission

Postby UlanBatori » 09 Sep 2019 01:03

The below video about the Apollo 11 Lunar Module testing on earth. A jet engine below counter act the weight on earth for the moon. It was tested 20 times and the 21st time it malfunctioned. Armstrong ejected.


WOW!

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Re: Chandrayan-2 Mission

Postby chetak » 09 Sep 2019 01:55

Prasad wrote:Unfortunately I agree with the yak-herder. Despite the sheer rage that the commentators induce each time they yack on over the multiple callouts during a launch or a landing, the lay person (who is in the majority) needs the commentator to explain wth is going on. Would it be nicer to have a separate webfeed with much reduced commentary and greater telemetry+imagery? Yeah. Are we going to get it? Probably not. Would be nice though, to get it later if possible. Shouldn't take much time to edit out a video with just mission control audio and on-screen data and limited commentary though.



It is mandatory to record each activity separately so that a complete record of all related activities is available.

ATC recorders for example record on multiple tracks with time stamp so that any analysis, if required later, for any purpose, can be extracted as it is already coordinated, synchronized and appears on a common timeline. FDRs and CVRs on aircraft also do this.

Let us be charitable and concede that the recorders used by ISRO are way more sophisticated and are capable of recording everything of interest on multiple tracks.

Any telemetry data stream from the vehicle, audio or video of all microphones/cameras and all command signals up or down linked right from the commencement of the prelaunch sequence would be captured and backed up on multiple storage devices.

some guy on youtube, using the available open source videos has already separated some of the telemetry from the imagery.

ISRO may or may not choose to release some of the data it has into the public domain.

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Re: Chandrayan-2 Mission

Postby SaiK » 09 Sep 2019 03:58

Dasari wrote:
SaiK wrote:100 m/ sec 2.1km to go.. fast braking period.. nothing heard.

That is pretty fast to land w/ balloons(if) and cushions.


I thought 59.8 m/sec. But it is very fast. Even if it is free fall from there the terminal velocity at impact would be like sqrt ( 2100*2*1.62 + 59.8**2) = 102m/sec or 360km/hr. On the other hand, it is not free fall. It appears that the thrusters are adding to the speed instead of reducing it due to craft disorientation.

The fact that they used thermal imaging to locate, but 0.30m resolution optical camera could not picture it tells us that it is disintegrated into pieces and may be buried under the dust.


let's take that vertical velocity.

100 m/s at 2.1 km alt [where did I get this? I thought I saw this in one of the post or video]
59.8 m/s at 1.09 km alt
viewtopic.php?f=3&t=7725&start=1240#p2378402

What would be the impact speed at ground zero? [assuming something went wrong that maintained this deceleration rate]

PS:
hv,vv,dr [I guess the decent started at -35km down range or altitude?]
386m/s, 74.0m/s, 30.7 km
293m/s, 73.3m/s, 19.1km
268m/s, 72m/s, 16.5 km
100 m/s at 2.1km <------ I don't know where I got this.
48.1m/s, 59m/s, 1.09 km

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Re: Chandrayan-2 Mission

Postby UlanBatori » 09 Sep 2019 04:35

For all we know, Godzilla-ul-Lunari came up from the Ocean of Storms, reached up and swatted Vikram at 2.1km.

But I have a different question. What is the tradition at EyeEssArrOw when the error is found, and traced to someone's Oracle Operation? Seems like there is supposed to be a chain of Reviews and Testing and Re-Reviews and Re-Re-Reviews and 6-Sigma and 9-Sigma. And several levels of oversight. A long Chain of Command facing execution?

As I have heard the tradition at the vaunted JayPeeEll is very simple: Mission fails: Principal Investigator fired. I once knew someone who had been PI on 7 missions. Or maybe 8 but the 8th was the one that didn't work. Seemed like a very long life under those rules.
Same presumably in the Navy. Ship gets hit by wayward Iraqi Exocet, commander of the USS Start was court-martialed, probably dismissed. Maybe not sent to jail or executed, I don't know.

Right now the error is blamed on "overperformance" of one of the coarse braking motors, as I read it. Fits with the overall theme of the GeeEssEllVee overperforming, leading to fuel savings for the Orbiter leading to 7-fold increase in orbiter lifetime.

But what is "overperformance" when you are braking? If you aim for Mars and end up at Juipter that is not overperformance, it is gross failure. Were they using SOLID rockets for the braking phase, to not be able to meter it precisely?

The scenes of consolation etc were very touching, but it can't be very different in any operation where one error kills 10 years of work of 5000 people. Not to mention H&D. Space is a harsh and unforgiving environment with lots of Gravity and many Space Agency Suits are exactly suited to that.

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Re: Chandrayan-2 Mission

Postby SaiK » 09 Sep 2019 04:40

naasika jay pee yell investments and funding programs are way way big, and can't be compared at all.. we go by meager budget onree saar. they can afford hirree&phyrre. naasikaas invest like 100 times more for the same...so accept a phyrr

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Re: Chandrayan-2 Mission

Postby Amber G. » 09 Sep 2019 04:48

Dasari wrote:

... Even if it is free fall from there the terminal velocity at impact would be like sqrt ( 2100*2*1.62 + 59.8**2) = 102m/sec or 360km/hr. On the other hand, it is not free fall.....


FWIW, Slight OT but since many are calculating it, some basic physics: That way to calculate terminal velocity is (V^2=V_0^2+2gs) is correct ( I used: Horizontal velocity 48.1 m/s - Vertical velocity 59.8 m/s Downrange distance: 1.09 km )
Horizontal Velocity will not change, vertical component is given by formula above.
BTW - A trick, if you are interested in magnitude of the final velocity (and not direction) the formula V^2 = V_0^2+2gs) will work for *any* kind of "free fall" - no matter what kind of path it follows.. (You can use this for a fraction-less roller coster -- the speed depends only on height). (Easy way to derive it is to think energy remaining constant , and KE is (1/2) m v^2 and difference in PE is (mgh) and you get the formula gs = (1/2) (V^2-V_0^2) ityadi,

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Re: Chandrayan-2 Mission

Postby Amber G. » 09 Sep 2019 04:55

Meanwhile we can always calculate and animate: LRO_NASA's orbits over Sept and Oct looks like passes over where Vikam may have landed intact or not..

It will be day time at the site when this passes over on Sep 17 and Oct 14.. Hope they will be keeping their eyes open. Image

Picture thanks to Sankar Viswanathan (social media)

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Re: Chandrayan-2 Mission

Postby Primus » 09 Sep 2019 05:05

UB is absolutely right in understanding our ethos.

Avengers - End Game was budgeted at $356 million, don't know how much it cost in the end. Chandrayaan-2 cost us only $87 million. Yet, it captured the heartbeat of over a billion human beings and made us proud of our people. It was way more emotional and soul-stirring than anything Hollywood could offer. In terms of keeping the hope alive and the flame burning, it has done way more than any slick and suave television programming could have. The video of Sivan and ModiJi has gone viral and I bet every Indian has seen it. Nothing beats showing your humanity and this has done it more than you could imagine.

Sometimes I feel NaMo is a blessed soul and we should be grateful he is leading the nation. May the Lords protect him.

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Re: Chandrayan-2 Mission

Postby Amber G. » 09 Sep 2019 05:06

Just for record here: Here is Edgar Kaiser's (A radio astronomer) recording of the descent manoeuvre of the Chandrayaan-2 Vikram lander. He lost the signal at 20:19 UTC. Others saw it longer. He was saying that "He was looking/hoping to follow CY2 orbiter.
Image

***
CY2 (orbiter not Vikram) looked healthy even here (later recorded).. 1 Hr 58 Minutes and 30 second was time it took for last orbit.

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Re: Chandrayan-2 Mission

Postby ramana » 09 Sep 2019 05:44

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

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Re: Chandrayan-2 Mission

Postby ramana » 09 Sep 2019 05:46

AmberG, I like that formula a lot. I once used it to estimate resistance of a body through barrier and later fine tuning came up with close number by the analysts.

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Re: Chandrayan-2 Mission

Postby UlanBatori » 09 Sep 2019 06:01

Not 2 minutes, u mean seconds. It's only 400,000km roundtrip, so just couple of seconds. How can performance go so much over with hypergolic unless the valve got stuck open I wonder. Or they hit combustion instability that gave super efficient burn followed by explosion? Maybe the thruster blew up, causing loads far greater than anything that the controller could compensate, the gizmo tumbled and that was that: free fall with random thrust. Much like the Armstrong video. Suddenly I don't feel so bad about our quad-yak-copter that insists on rolling 180 degrees as soon as it is out of ground effect. Some ppl I know are going to be very busy if it was comb. instability. But why so late in the cycle I wonder.

Maybe the lander propulsion is not completely figured out, but was done to meet the schedule? Comb. instability back in the 1980s was reported to happen in say 1 out of 6 afterburners of brand-new F-100 fighter engines. Those also reported "overperformance" due to oscillating combustion before they burned up the AB liner and blew up. Rocket instability was blowing up 1 out of 19 Pershing Missiles on the launch pad. Come to think of it, there have been very few Indian space missions that required metered, continuous thrusters. GEO-sats, yes, but that's just a few short bursts at pretty high power. So maybe there is not enough experience in this area.

Gets back to the policy of "Fly High And Proud" etc. Unfortunate problem with this business of pushing till failure is that it is the 2% of the capability that failed, that is remembered. IMO, the landing and rover parts were just the "cool factor": no one is dying for want of the data on nature of lunar regolith. The utility of that is purely to submit abstracts to conferences in exotic locales.

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Re: Chandrayan-2 Mission

Postby Amber G. » 09 Sep 2019 06:04

Okay to help few folks here: Path of Vikram (about the last position I know in the orbit) CY2 and Nasa's LRO:
( 6th Sep about - 20:00-21:00 UTC)...May be once we get more precise data, would be fun to put some zoom-in's...

Image

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Re: Chandrayan-2 Mission

Postby saip » 09 Sep 2019 06:07

^^^You mean > 2 SECONDS. Even that is too long.

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Re: Chandrayan-2 Mission

Postby Amber G. » 09 Sep 2019 06:23

ramana wrote:AmberG, I like that formula a lot. I once used it to estimate resistance of a body through barrier and later fine tuning came up with close number by the analysts.


Thanks. Yes. Actually this very simple formula is one of the best to access damage to collision type events. You don't need velocities vector, care which direction the craft was moving (or even, in some cases, what kind of thrusters were being used etc). All you need to know is the speed and height from the ground.

You find/calculate last known energy (PE + KE) and PE at the ground .. rest of the energy is used in destroying the craft (+ some in throwing the dust/rock cloud + heating up the surface + KE of the exhaust gases if any engine is still working etc). The formula is quite simple as PE for orbits near ground is = mgh and KE = 1/2 mv^2. You find the difference in energy (final V=0, PE=0 etc. This gives the upper limit for collision energy causing harm. Actual damage can be estimated, as first approximation, as fraction and fraction depends on the kind of modeling one does.

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Re: Chandrayan-2 Mission

Postby Vashishtha » 09 Sep 2019 06:51

https://twitter.com/Madrassan_Pinky/status/1170609817850793984?s=09

ISRO sources confirm lander found intact 500m from landing site. Considering it's ABP news, take it with a huge grain of salt until official confirmation.

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Re: Chandrayan-2 Mission

Postby UlanBatori » 09 Sep 2019 07:09

So at what point does one consider the mission successful? If the Lander has suffered minimal damage but cannot communicate, is it accepted to have achieved a Lunar Landing?

See this tweet:
ISRO Official Update @shivraj_Office
Now we are the first country to land on the southern pole of the moon Big Congratulations to team @isro Hope we can communicate Vikram Lander soon @PMOIndia #VikramLanderFound


Dang! They should have put a cellphone inside so it could take and send pictures. That would constitute total success.
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Re: Chandrayan-2 Mission

Postby TandavBrahmand » 09 Sep 2019 07:14

Vashishtha wrote:https://twitter.com/Madrassan_Pinky/status/1170609817850793984?s=09

ISRO sources confirm lander found intact 500m from landing site. Considering it's ABP news, take it with a huge grain of salt until official confirmation.


Don't think it can be "intact" - hard to believe. ISRO has used thermal imaging to spot it. That is the official position AFAIK.

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Re: Chandrayan-2 Mission

Postby UlanBatori » 09 Sep 2019 07:26

What is @shivraj_office? Is it really official ISRO/PMO? Are they declaring that Indian landing at lunar South Pole is claimed? OK, a bit of a hard landing, but..


If the Lander is lying on one side, half the solar panels should see sunlight.... Maybe there will be power?

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Re: Chandrayan-2 Mission

Postby TandavBrahmand » 09 Sep 2019 07:29

The very official update page is here. Not much information since Sep 7th.

https://www.isro.gov.in/update/07-sep-2 ... est-update

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Re: Chandrayan-2 Mission

Postby Amber G. » 09 Sep 2019 07:36

Amber G. wrote:Okay to help few folks here: Path of Vikram (about the last position I know in the orbit) CY2 and Nasa's LRO:
( 6th Sep about - 20:00-21:00 UTC)...May be once we get more precise data, would be fun to put some zoom-in's...

Image


Posting the same orbits from a slightly different perspective.
Image

Green is Nasa-LRO, Yellow CY2 Blue Vikram .. (Vikram's approx position is near the south pole etc)

(Trying to see what are the good times to look for Vikram from these two crafts which has very good cameras)

Arjun
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Re: Chandrayan-2 Mission

Postby Arjun » 09 Sep 2019 07:42

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

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Re: Chandrayan-2 Mission

Postby anupamd » 09 Sep 2019 07:43

Isro has now confirmed its a hard landing ...
https://m.timesofindia.com/india/vikram ... 037009.cms

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Re: Chandrayan-2 Mission

Postby Haridas » 09 Sep 2019 07:46

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.

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Re: Chandrayan-2 Mission

Postby Vashishtha » 09 Sep 2019 07:50

Don't think it can be "intact" - hard to believe. ISRO has used thermal imaging to spot it. That is the official position AFAIK.


Yeah that's why I said to take it with a grain of salt. Slim chance it survived imho


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