Chandrayan-2 Mission

KJo · Post by **KJo** » 07 Sep 2019 03:32

So what is next? Would this mission be abandoned and would they have to start a new one or is this salvageable?

Gagan · Post by **Gagan** » 07 Sep 2019 03:32

SaiK wrote:Typo. Sorry

Too big a mistake...
Can't be forgiven onlee...

Amber G. · Post by **Amber G.** » 07 Sep 2019 03:33

Just a reminder to all here: that on its way to put this lander down on the moon, India did put its second space craft on the orbit of the moon. Chandrayaan-2 will be doing science for next year or longer. (Lander would have lasted about 2 weeks only).

Mort Walker · Post by **Mort Walker** » 07 Sep 2019 03:33

Budget has to be sanctioned for a Chandrayaan 3. That should be a question for the government.

Dasari · Post by **Dasari** » 07 Sep 2019 03:34

Vikram cannot communicate to ground station. It can only talk to Orbiter. If the Orbiter is on the other end, can Vikram communicate to it? Don't we need to wait for it circle back.

Gagan · Post by **Gagan** » 07 Sep 2019 03:34

KJo wrote:So what is next? Would this mission be abandoned and would they have to start a new one or is this salvageable?

The orbiter mission is on for atleast one year.
They will complete that detailed 3D map of the Moon, that was interrupted when Chandrayaan 1 stopped functioning.
India should have the MOST high resolution image + 3D map of the moon by the time this mission ends

Gagan · Post by **Gagan** » 07 Sep 2019 03:36

Dasari wrote:Vikram cannot communicate to ground station. It can only talk to Orbiter. If the Orbiter is on the other end, can Vikram communicate to it? Don't we need to wait for it circle back.

It can communicate directly
Pragyan rover, can only communicate with Vikram Lander, which communicates with the Deep Space Network

abhijitm · Post by **abhijitm** » 07 Sep 2019 03:36

If ISRO has backup rover and lander then we can attempt one more in near future.

ISRO has landed another made in India unit on moon. Congrats. Keep going. You never walk alone.

Indranil · Post by **Indranil** » 07 Sep 2019 03:36

shaun wrote:Why communication went off at 2.1 km altitude ?? An explosion ??

Loss of attitude control is the most probable cause.

Dilbu · Post by **Dilbu** » 07 Sep 2019 03:37

Is Vikram able to communicate with the orbiter? Does that mean that the lander is still intact?

Kakarat · Post by **Kakarat** » 07 Sep 2019 03:37

If it is confirmed failure then I think ISRO should go for a Lander + Rover only mission with a Vikram-R modified accordingly with in the next year

Gagan · Post by **Gagan** » 07 Sep 2019 03:38

The camera on the Orbiter looks HUGE !!!!
It is like a mini hubble telescope no?
If it is Hi-Res enough, it can see ALL the moon missions.

The only hitch is that the Vikram Landing site have sunlight for pictures to be available !

SaiK · Post by **SaiK** » 07 Sep 2019 03:38

MCDC/ test test test.. landing on Earth as many times with actual test vehicle. Not scaled down versions.

Just saying. It is expensive

SaiK · Post by **SaiK** » 07 Sep 2019 03:40

Dilbu wrote:Is Vikram able to communicate with the orbiter? Does that mean that the lander is still intact?

It depends on what it communicated. Health check should reveal.

Gagan · Post by **Gagan** » 07 Sep 2019 03:40

Kakarat wrote:If it is confirmed failure then I think ISRO should go for a Lander + Rover only mission with a Vikram-R modified accordingly with in the next year

If there is no orbiter, then they can land a much bigger lander, with way more equipment on it.
Maybe they can have the Rover go back and forth between the lander, charge, stay warm, transmit its data, then go out again once the sun rises

abhijitm · Post by **abhijitm** » 07 Sep 2019 03:41

SaiK wrote:MCDC/ test test test.. landing on Earth as many times with actual test vehicle. Not scaled down versions.

Just saying. It is expensive

Space is hard and unforgiving. I hope if ISRO needs money then it will be made available.

shaun · Post by **shaun** » 07 Sep 2019 03:45

This is Mission Control Centre. #VikramLander descent was as planned and normal performance was observed up to an altitude of 2.1 km. Subsequently, communication from Lander to the ground stations was lost. Data is being analyzed.
#ISRO

shaun · Post by **shaun** » 07 Sep 2019 03:45

They haven't mentioned yet that the lander crashed !!

Mort Walker · Post by **Mort Walker** » 07 Sep 2019 03:46

SaiK wrote:MCDC/ test test test.. landing on Earth as many times with actual test vehicle. Not scaled down versions.

Just saying. It is expensive

Moon’s gravity is 1/6 of the earth, then there is no atmosphere as it is a virtual vacuum. No way to test for that on earth. However, it seems ISRO has not mastered 3-axis stabilization control under the influence of less gravity. To do this experiments may have to be carried out in orbit.

Mort Walker · Post by **Mort Walker** » 07 Sep 2019 03:47

shaun wrote:They haven't mentioned yet that the lander crashed !!

It was coming down faster than 200 kmph. Vikram is in pieces.

shaun · Post by **shaun** » 07 Sep 2019 03:48

We still don't know what happened after 2.1 km , with no communication from the lander

hgupta · Post by **hgupta** » 07 Sep 2019 03:48

To fail is to succeed.

I thank the fine folks at ISRO to dare and dream and persist in the face of failure. The entire nation is with you, ISRO. We are rooting for you folks to try again!!

Mort Walker · Post by **Mort Walker** » 07 Sep 2019 03:50

Chandrayaan 3 is the need now. The PM should have said he will try for that.

shaun · Post by **shaun** » 07 Sep 2019 03:53

It seems we have a precedent

Surveyor 4 was the fourth lunar lander in the American uncrewed Surveyor program sent to explore the surface of the Moon. This spacecraft crashed after an otherwise flawless mission; telemetry contact was lost 2.5 minutes before touchdown.

SaiK · Post by **SaiK** » 07 Sep 2019 03:54

Indranil · Post by **Indranil** » 07 Sep 2019 03:55

Mort Walker wrote:
SaiK wrote:MCDC/ test test test.. landing on Earth as many times with actual test vehicle. Not scaled down versions.

Just saying. It is expensive
Moon’s gravity is 1/6 of the earth, then there is no atmosphere as it is a virtual vacuum. No way to test for that on earth. However, it seems ISRO has not mastered 3-axis stabilization control under the influence of less gravity. To do this experiments may have to be carried out in orbit.

Why not? You just need something which exerts a vertical upward force of 5/6 times that of weight of the lander. For example, in a tethered experiment, you can use a helium balloon.

IndraD · Post by **IndraD** » 07 Sep 2019 03:56

Sources confirm that up to 2.1 km all was fine. Soon rotation rates increased and the engine thrust went up to 100% in place of around 70%. The velocity too shot up indicating tumbling & crashing. At this stage, the telemetry link was lost. https://twitter.com/writetake/status/11 ... 28256?s=20

Bart S · Post by **Bart S** » 07 Sep 2019 03:57

hgupta wrote:To fail is to succeed.

I thank the fine folks at ISRO to dare and dream and persist in the face of failure. The entire nation is with you, ISRO. We are rooting for you folks to try again!!

I have not failed. I've just found 10,000 ways that won't work.

Thomas A. Edison

The real success of the mission is in the awareness and spark that it will kindle in a million young minds who will build the future iteration of ISRO and India. It has already succeeded in that.

Najunamar · Post by **Najunamar** » 07 Sep 2019 03:57

Does this mean, we'll get the data already transmitted to the orbiter as well as pics in approx 2 hrs when the lander is also in line with the earth? Perhaps from other telemetry stations?

Najunamar · Post by **Najunamar** » 07 Sep 2019 03:58

Sorry meant orbiter...

Gagan · Post by **Gagan** » 07 Sep 2019 03:59

The final moments of Vikram Lander:

The graph deviates at 2:17 seconds. At 2:42, Vikram is nearly inverted !!! It recovers, then over corrects !!!
It tumbled at the critical juncture when soft landing phase was started. This indicates perhaps that one engine shut off later than the other, causing an imbalance.

Mort Walker · Post by **Mort Walker** » 07 Sep 2019 03:59

What causes engine throttling at 100%. The control logic was probably fine, but hardware was not.

vnms · Post by **vnms** » 07 Sep 2019 03:59

Najunamar wrote:Does this mean, we'll get the data already transmitted to the orbiter as well as pics in approx 2 hrs when the lander is also in line with the earth? Perhaps from other telemetry stations?

ISRO already has the pics.

Remember, the orbits were adjusted to have the orbiter be insight of the lander to observe the landing.

Gagan · Post by **Gagan** » 07 Sep 2019 04:00

See from 2:42 till 2:59 ...

Amber G. · Post by **Amber G.** » 07 Sep 2019 04:00

Trusting my eyesight and memory, the last I saw the telemetry data from the screen :

Horizontal velocity 48.1 m/s
Vertical velocity 59.8 m/s
Downrange distance: 1.09 km
Earth communication: OFF

vnms · Post by **vnms** » 07 Sep 2019 04:01

Amber G. wrote:Trusting my eyesight and memory, the last I saw the telemetry data from the screen :

Horizontal velocity 48.1 m/s
Vertical velocity 59.8 m/s
Downrange distance: 1.09 km
Earth communication: OFF

That's exactly what I recollect.

Gagan · Post by **Gagan** » 07 Sep 2019 04:03

If it was inverted or horizontal, and its engines burning, that will cause deviation from the flight path laterally, which possibly seems to have happened.
Also descent velocity which was coming down, will start to now increase

Mort Walker · Post by **Mort Walker** » 07 Sep 2019 04:04

Indranil wrote:
Mort Walker wrote:
Moon’s gravity is 1/6 of the earth, then there is no atmosphere as it is a virtual vacuum. No way to test for that on earth. However, it seems ISRO has not mastered 3-axis stabilization control under the influence of less gravity. To do this experiments may have to be carried out in orbit.
Why not? You just need something which exerts a vertical upward force of 5/6 times that of weight of the lander. For example, in a tethered experiment, you can use a helium balloon.

The balloon will exert a vertical force which is not at the center of mass of the lander.

Amber G. · Post by **Amber G.** » 07 Sep 2019 04:05

Indranil wrote:
Mort Walker wrote:
Moon’s gravity is 1/6 of the earth, then there is no atmosphere as it is a virtual vacuum. No way to test for that on earth. However, it seems ISRO has not mastered 3-axis stabilization control under the influence of less gravity. To do this experiments may have to be carried out in orbit.
Why not? You just need something which exerts a vertical upward force of 5/6 times that of weight of the lander. For example, in a tethered experiment, you can use a helium balloon.

Helium balloons will not work in vacuum as the way you think.. it will only increase the weight of the lander (+ mass of helium)..

(There is NO practical way we know to simulate low gravity except going in earth's orbit (or vomit-comet type rides which are essentially the same).
(Swimming is water may make you feel "weightless" but it is not exactly what you need to simulate zero g, for obvious reasons)

Mort Walker · Post by **Mort Walker** » 07 Sep 2019 04:08

^^^He's talking about doing it on earth. Then there is the question of wind too.