Chandrayan-2 Mission

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Indranil
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Re: Chandrayan-2 Mission

Postby Indranil » 15 Jul 2019 01:48

There is no question in my mind regarding that. This is why I like rocket science. It's complex if you don't want to get into the math. But if you do, and if you are working with a rocket whose baseline is well established, things are pretty deterministic.

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Re: Chandrayan-2 Mission

Postby juvva » 15 Jul 2019 01:49

Another factor may be the visibility of the s/c to byalalu at perigee for orbit boosting burns.

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Re: Chandrayan-2 Mission

Postby A Nandy » 15 Jul 2019 01:51

Launch seems go as of now!

https://twitter.com/isro
Filling of Liquid Hydrogen in Cryogenic stage of #GSLVMkIII-M1 completed.

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Re: Chandrayan-2 Mission

Postby SriKumar » 15 Jul 2019 02:20

krishGo wrote: ISRO set a launch window of 9-16 July. If for a minor reason like weather, a delay, then
If the launch is postponed to a much later date (say a week or so), the propellants will be emptied and the vehicle will be moved back into the Vehicle Assembly building.

They payload with its shroud will also be seperated and then reassembled closer to launch.
Why is the payload removed and reassembled? Is it to drain out the (hydrazine?) propellent in the payload? Something else? Re-charge batteries?

juvva- I recall for the mangalyaan missions ISRO had 2 ships with communication (and command?) facility stationed in Pacific and Indian oceans. In fact, I recall the launch date was moved since one of the boats had a delay in getting to its spot. Seems like no such boats this time and all commands will go out from Bylalu?

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Re: Chandrayan-2 Mission

Postby Saral » 15 Jul 2019 02:29

Countdown on hold due to "glitch"
Possible scrub of launch rumored.

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Re: Chandrayan-2 Mission

Postby Kakarat » 15 Jul 2019 02:35

Clear sky in chennai

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Re: Chandrayan-2 Mission

Postby Gagan » 15 Jul 2019 02:44

"Technical Hold"
Cryo fuel filling must have been completed by now...
7000 people in the launch gallery

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Re: Chandrayan-2 Mission

Postby krishGo » 15 Jul 2019 02:45

Gagan wrote:"Technical Hold"
Cryo fuel filling must have been completed by now...
7000 people in the launch gallery


News channels reporting scrub.

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Re: Chandrayan-2 Mission

Postby SwamyG » 15 Jul 2019 02:49

Awaiting official word now....

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Re: Chandrayan-2 Mission

Postby Mort Walker » 15 Jul 2019 02:50

Rumours are that there may be an issue with stage 3.

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Re: Chandrayan-2 Mission

Postby krishGo » 15 Jul 2019 02:53

SriKumar wrote: Why is the payload removed and reassembled? Is it to drain out the (hydrazine?) propellent in the payload? Something else? Re-charge batteries?


Well, we should remember that staellites are made to operate in vacuum. If the next launch date is too far away, then to preserve some of the sensitive equipment in the payloads, they are moved back to clean rooms till closer to launch. The hypergolic fuel in the satellite itself is not the biggest concern since they are designed to hold them for large amounts of time over the lifetime of the satellite.
Last edited by krishGo on 15 Jul 2019 02:54, edited 1 time in total.

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Re: Chandrayan-2 Mission

Postby Vivek K » 15 Jul 2019 02:53

PTI reporting that ISRO called off launch and will not be able to make this launch window- technical glitch

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Re: Chandrayan-2 Mission

Postby SwamyG » 15 Jul 2019 02:53

Launch called off for now. Will be rescheduled later. The launch window will not be met.

@isro
A technical snag was observed in launch vehicle system at T-56 minute. As a measure of abundant precaution, #Chandrayaan2 launch has been called off for today. Revised launch date will be announced later.
Last edited by SwamyG on 15 Jul 2019 02:54, edited 1 time in total.

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Re: Chandrayan-2 Mission

Postby KJo » 15 Jul 2019 02:53

Called off according to Republic

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Re: Chandrayan-2 Mission

Postby prasannasimha » 15 Jul 2019 02:55

Confirmed . New launch date will be announced.

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Re: Chandrayan-2 Mission

Postby Gagan » 15 Jul 2019 02:57

DDM making a fish market and shouting and screaming while ISRO officials give a news brief
:evil:

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Re: Chandrayan-2 Mission

Postby krishGo » 15 Jul 2019 03:01

krishGo wrote:
Mort Walker wrote:ISRO set a launch window of 9-16 July. If for a minor reason like weather, a delay, then they can still launch in the next day or so. If there is a technical problem, then another date will have to selected.

It’s more important to get this right rather than rushing.


It is also interesting as to what happens when launches are scrubbed.

If the launch is moved to the next day, the propellants on the cryogenic stage and the hyperbolic core stage have to be emptied. They will need to be refueled again before launch. The vehicle stays on the launch pad.

If the launch is postponed to a much later date (say a week or so), the propellants will be emptied and the vehicle will be moved back into the Vehicle Assembly building. They payload with its shroud will also be seperated and then reassembled closer to launch.


Reiterating what happens now..

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Re: Chandrayan-2 Mission

Postby Mort Walker » 15 Jul 2019 03:05

No worries. This is a complicated mission and India is doing this for its own capabilities and science. To frame it as a space race with China or other countries would be a misnomer.

Yes, the liquid propellants would have to be unloaded and re-loaded later. Some of these could be corrosive to pumps and hoses, so there is that concern.

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Re: Chandrayan-2 Mission

Postby Gagan » 15 Jul 2019 03:06

Hopefully the next launch time will be during daytime
There is a silver lining everywhere :)

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Re: Chandrayan-2 Mission

Postby Katare » 15 Jul 2019 03:06

Indranil wrote:
Amber G. wrote:
If only it was that easy.... :)..

Hope people don't mind stating some obvious things and some physics :).. But these things need a very precise "mooharat". The starting point (Sriharikota) is fixed. The end point is fixed (except for a few hundred meters to be chosen later). The time to land is also fixed (beginning of the solar day on moon so that you have full day -14 earth days for solar panels to work) . It may seem there are choices later to adjust but to
arrive at the fixed landing site with the right time and have right lighting conditions for the descent the journey must be planned to meet constraints this mission planning, primarily in the form of trajectory shaping and the limitation of launch opportunities, known as launch windows.

Here are some general important understandings. (I am just speaking from physics point of view about a few important things - there is much more in actual planning)

Trajectory geometry constraints and spacecraft performance capabilities combined to limit the possibilities.

So let us look closely at the trajectory characteristics. ( An understanding of the interrelation of operational constraints and trajectory shaping is essential to understand to give some idea how much work has gone through by our scientists). Let us take each phase:

Launch phase:
Daily window which had a duration of a few hours during a given 24 hour period.
Monthly window which consisted of a few days during a given month or lunar cycle.

- Factors are Range Safety (Direction chosen from the launch sites is limited and thus the time window)
-Booster Performance- (One wastes too much fuel if the optimum time is delayed)
- Insertion Tracking- - ( operational requirement to track the space vehicle for at least 3 minutes after earth orbit insertion in order to make a GO / NO-GO for orbit decision - this should be reachable from the tracking station)

There are similar restraints for
- Earth parking orbit phase

- Trans lunar injection

- Trans lunar coast phase

- Lunar orbit phase
ityadi ityadi ..so each thing has to be planned in advance very carefully..
Hope this helps.

I was about to write something similar. The target point in space and time is fixed. The path to that point is fixed, the speeds along that point is fixed, so launch time is also pretty "fixed".

But then I held back because I am pretty sure that ISRO (and any other space agency) has planned for contingencies. For example, one of the orbit raising maneuvers on MoM did not work perfectly and they had to adjust. With MoM they had higher flexibility because they had to synchronize only with Mars orbit around the sun and not its night and day. I do not know how much flexibility ISRO has with Chandrayaan 2. I mean if one of the earth bound or moon bound orbit adjusting maneuvers goes wrong, will ISRO still land on the same lunar day (sacrificing daytime spent on moon) or will it wait for the next dawn?


You are smart saar!!!
Mars orbital mechanics 101 won’t apply to moon. Earth gets a clear shot at the moon every 24 hours and a satellite can easily chase or slowdown to catch-up the moon. All maneuvers, slowing or accelerating, require energy so optimization for lowest possible maneuvering is important. What is it that they can’t wait for couple of hours for sunrise? Unlike Mars’s 20 months moon comes back at the same spot every 15 days.

Not a big deal just curious what is so important that usually SRDE Isro has chosen to a tfta night launch. Curiosity comes from the fact that I don’t remember ISRO ever launching a rocket at the night time before?

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Re: Chandrayan-2 Mission

Postby Kakarat » 15 Jul 2019 03:11

https://twitter.com/isro/status/1150512237045379072
A technical snag was observed in launch vehicle system at T-56 minute. As a measure of abundant precaution, #Chandrayaan2 launch has been called off for today. Revised launch date will be announced later.


The next attempt would only be in the next window at the earliest
When is the next window?

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Re: Chandrayan-2 Mission

Postby krishGo » 15 Jul 2019 03:13

Katare wrote:Not a big deal just curious what is so important that usually SRDE Isro has chosen to a tfta night launch. Curiosity comes from the fact that I don’t remember ISRO ever launching a rocket at the night time before?


There have been several launches by ISRO in the night. I believe one of the recent PSLV launches was in the night.

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Re: Chandrayan-2 Mission

Postby Mort Walker » 15 Jul 2019 03:17

Dates of Moon Perigee (closest to Chennai, India)

Jan 22 1:29 am 357,342 km 222,042 mi
Feb 19 2:32 pm 356,761 km 221,681 mi
Mar 20 1:17 am 359,377 km 223,306 mi
Apr 17 3:34 am 364,205 km 226,306 mi
May 14 3:22 am 369,009 km 229,291 mi
Jun 8 4:45 am 368,504 km 228,978 mi
Jul 5 10:30 am 363,726 km 226,009 mi
Aug 2 12:41 pm 359,398 km 223,319 mi
Aug 30 9:23 pm 357,176 km 221,939 mi
Sep 28 7:54 am 357,802 km 222,328 mi
Oct 26 4:08 pm 361,311 km 224,508 mi
Nov 23 1:10 pm 366,716 km 227,867 mi
Dec 19 1:55 am 370,265 km 230,072 mi

In a worst case scenario - ISRO may want to do another launch of the GSLV-MkIII. GSAT-20 is scheduled for Sep. 2019. That launch may go ahead and Chandrayaan-2 would be in October at the earliest.

In a best case scenario - Around Republic Day 2019, ~August 15th.

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Re: Chandrayan-2 Mission

Postby krishGo » 15 Jul 2019 03:19

Kakarat wrote:https://twitter.com/isro/status/1150512237045379072
A technical snag was observed in launch vehicle system at T-56 minute. As a measure of abundant precaution, #Chandrayaan2 launch has been called off for today. Revised launch date will be announced later.


The next attempt would only be in the next window at the earliest
When is the next window?


Depends on a lot of variables. It can be as soon as the day after tomorrow or a fortnight to a month from now (in the worst case maybe some months). The seriousness of the snag, its cause, the need to stick to the original landing schedule, the amount of flexibility in the orbital raising manoeuvres (they will have some buffer there) ityadi.
Last edited by krishGo on 15 Jul 2019 03:22, edited 1 time in total.

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Re: Chandrayan-2 Mission

Postby KJo » 15 Jul 2019 03:20

My friend in the press tells me that the talk is that there as a leak in the cryogenic engine.

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Re: Chandrayan-2 Mission

Postby Kakarat » 15 Jul 2019 03:23

krishGo wrote:
Kakarat wrote:https://twitter.com/isro/status/1150512237045379072


The next attempt would only be in the next window at the earliest
When is the next window?


Depends on a lot of variables. It can be as soon as the day after tomorrow or a fortnight to a month from now. The seriousness of the snag, its cause, the need to stick to the original landing schedule, the amount of flexibility in the orbital raising manoeuvres (they will have some buffer there) ityadi.


I dont think ISRO will take any chances as both Chandrayaan 2 and GSLV MKIII M1 are important milestones, so they will completely analyse the issue before attempting to launch again

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Re: Chandrayan-2 Mission

Postby Mort Walker » 15 Jul 2019 03:24

My guess is that it will be October at the earliest if it is indeed a leak in the cryogenic engine.

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Re: Chandrayan-2 Mission

Postby Mort Walker » 15 Jul 2019 03:26

The technical snag was noticed when the cryogenic fuel was being loaded. The vehicle would need to be approached to assess the problem. The fuel loaded in the rocket would first have to be emptied, and then the rocket would have to be studied for further investigation. According to an Isro source, the whole process would take at least 10 days. The new schedule would likely be disclosed only after that.


The question is, what was the leak rate? Was it in one of the lines or a pump?

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Re: Chandrayan-2 Mission

Postby Katare » 15 Jul 2019 03:43

krishGo wrote:
Katare wrote:Not a big deal just curious what is so important that usually SRDE Isro has chosen to a tfta night launch. Curiosity comes from the fact that I don’t remember ISRO ever launching a rocket at the night time before?


There have been several launches by ISRO in the night. I believe one of the recent PSLV launches was in the night.

If you could post a source, it would be very helpful

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Re: Chandrayan-2 Mission

Postby Amber G. » 15 Jul 2019 03:50

Katare wrote:
Mars orbital mechanics 101 won’t apply to moon. Earth gets a clear shot at the moon every 24 hours and a satellite can easily chase or slowdown to catch-up the moon. All maneuvers, slowing or accelerating, require energy so optimization for lowest possible maneuvering is important. What is it that they can’t wait for couple of hours for sunrise? Unlike Mars’s 20 months moon comes back at the same spot every 15 days.

Not a big deal just curious what is so important that usually SRDE Isro has chosen to a tfta night launch. Curiosity comes from the fact that I don’t remember ISRO ever launching a rocket at the night time before?


There are text books to show why "launch windows" are so important .. has very little to do with 'moon coming to the same position' in obvious sense. IOW if earth was not spinning, and one can select any launch point any time can be chosen. The moon's distance (perigee/apogee) or position is not much of a concern. (One may have to spend more or less fuel but one can manage as the rockets are powerful enough)

The youtube posted before (https://forums.bharat-rakshak.com/viewtopic.php?p=2365616#p2365616 is worth watching .. it explains the critical points quite nicely.

The point is if you want to land at one particular point on the moon your parking orbit on moon has to be well determined (wrt inclination) and since moon spins, timing has to be perfect to start the defend.

Similarly to have first orbit around the earth has to be precise, in inclination and perigee of orbit should be close to opposite side of the location of the moon etc and since earth is spinning and location to launch and monitor are fixed on earth we have to have very short time windows..

Anyway the video mentioned above explains it much better. Hope that is helpful.
Here is that link again https://youtu.be/G8xkYel9p-0

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Re: Chandrayan-2 Mission

Postby g.sarkar » 15 Jul 2019 04:15

https://www.bbc.com/news/world-asia-india-48905147
Chandrayaan-2: India space launch delayed by technical problem
The launch of India's second lunar mission has been halted, less than an hour before the scheduled blast-off, to due to a technical problem, says the Indian Space Research Organisation.
If successful, India will become the fourth country to make a soft landing on the Moon's surface.
Only the US, China and the former Soviet Union have been able to do so.
The $150m mission - Chandrayaan-2 - aims to gather data on water, minerals and rock formations on the Moon.
The Indian-made satellite had been scheduled for launch at 02:51 local time on Monday (21:21 GMT Sunday) from Sriharikota space station on India's eastern coast.But the countdown was halted 56 minutes before the launch time after a "technical snag was observed in launch vehicle system," Isro said. A new launch time will be announced later.The chief of the Indian Space Research Organisation (Isro), K Sivan, said this was "the most complex space mission ever to be undertaken by the agency".
The lander and rover are expected to touch down near the lunar south pole in early September, becoming the first ever spacecraft to land in that region.
.....
Gautam

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Re: Chandrayan-2 Mission

Postby Gagan » 15 Jul 2019 04:22

They will have to take all the cryo fuel out!
Handling that liquid hydrogen is a major pain and dangerous to boot!

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Re: Chandrayan-2 Mission

Postby sivab » 15 Jul 2019 04:56

Mort Walker wrote:
In a best case scenario - Around Republic Day 2019, ~August 15th.

:shock:

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Re: Chandrayan-2 Mission

Postby Mort Walker » 15 Jul 2019 05:38

We really won't know much for at least a week. If the cause of the leak is systemic, then expect further delays including delays to other GSLV-MkIII launches. Personally, I would be happy if it happens sometime in the next 4-5 months before the year is out. Much more important to get this right and not make a Rs. 1000 Crore mistake.

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Re: Chandrayan-2 Mission

Postby sanjaykumar » 15 Jul 2019 06:03

https://www.nytimes.com/2019/07/14/worl ... nding.html

The program is already showing results. This is of utmost importance.

(Professor Hoodbhoy, if you are reading this, perhaps you can compare the curriculum in your part of the world with what inspires these Indian kids).

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Re: Chandrayan-2 Mission

Postby Gagan » 15 Jul 2019 08:13

Underwhelming article as usual from the NYT, very subpar

Bleddy reporterni went to some elite school in india, yapped about how the kids are pumped, threw in the usual leftist-marxist “pooooor peoples, but still wanting ispace programs” crap.
Every word written by these folks and their leftist-marxist chamchas in Indian DDM is to undermine indian achievement and do a passing reference with snide comments thrown in

Total waste of time news article

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Re: Chandrayan-2 Mission

Postby g.sarkar » 15 Jul 2019 08:35

Gaganji,
NYT wrote this article before the delay in the Chandrayaan-II, and in anticipation of its success. It took some time to get the interviews in the Delhi school where the sky is dark from pollution. In my opinion it was written to show India in a negative light as the rest of the world congratulated India on its success. Like OK you succeeded, but you are poor and dirty, remember your place in the world.
Such small pinpricks are common in the western press.
Gautam

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Re: Chandrayan-2 Mission

Postby Singha » 15 Jul 2019 08:58

one of pslv launches was during a heavy rain. these things can work fine in rain.

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Re: Chandrayan-2 Mission

Postby sanjaykumar » 15 Jul 2019 09:31

I think some have missed the point of the NYT posting.

https://www.theguardian.com/science/201 ... erica-moon

Apollo, a stupendous achievement, was done in a nation where perhaps 20% of the population lived in poverty, Detroit was practically razed in some neighbourhoods, the Vietnam war was proving to be deeply unpopular and J Edgar Hoover was equal in his loathing of Martin Luther king and the hippies.

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Re: Chandrayan-2 Mission

Postby CRamS » 15 Jul 2019 10:00

<POOF>
Please stick to the topic.
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