Author Topic: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)  (Read 28487 times)

Offline maint1234

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #220 on: 04/03/2018 11:21 AM »
How reliable and up to date are these satellite tracking sites like n2yo ?
Till today morning n2yo was showing GSAT-6A  satellite period as 740 min and now its showing 1207 mins ?
Also showing a perigee of 25985 km .
Maybe it updates the figures late. ISRO had claimed that the 2nd boosting was normal , so verifies their claim.

Offline Jajar

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #221 on: 04/03/2018 01:47 PM »
I fear the satellite is lost for good... nothing came out today as I understand that MCF Hassan was supposed to get in touch with it today.... but it seems nothing happened... :(

Offline deruch

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #222 on: 04/03/2018 05:42 PM »
www.n2yo.com has the current parameters as:  25,987.6km x 36,374.7km x 3.3deg  (epoch from 2018-04-03; 18093.22549230)

Assuming that contact is not reestablished, how much of a hazard would the sat pose to GEO sats?  Is the lower perigee and the 3+ degree inclination enough to avoid being a significant danger?
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline Jajar

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #223 on: 04/05/2018 08:41 PM »
So it seems that they are still going ahead with next PSLV launch on April 12th. I reckon that they should suspend ALL future missions, till they really find out what went wrong with Gsat-6a and also with the PSLV mission last August...

Offline ZachS09

Why would ISRO delay future missions if the satellite suffered a failure and not the launch vehicle itself?

I can understand the stand-down due to the fairing separation failure, which they found the cause for, but standing down due to a satellite failure makes no sense to me.
"Liftoff of Falcon 9: the world's first reflight of an orbital-class rocket."

Offline vineethgk

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #225 on: 04/06/2018 02:50 AM »
Why would ISRO delay future missions if the satellite suffered a failure and not the launch vehicle itself?

I can understand the stand-down due to the fairing separation failure, which they found the cause for, but standing down due to a satellite failure makes no sense to me.
Because they build those satellites too, not just the rocket! ;)

They haven't yet figured out yet what went wrong with GSAT-6A even though the launch itself was 'textbook'. They say it could be a power failure that knocked out its communication systems. It could be due to some faulty component, a faulty design or some sort of human error during assembly that wasn't caught during testing. Or perhaps the satellite suffered a slight damage of some kind (vibration?) during ascent or separation that caused the fault later on after orbital firing. If it is the result of a faulty component or a faulty bus design they need to make sure that other upcoming satellites that use the same are unaffected. However, this is all speculative until they publish their findings.

But it is worth noting that they haven't delayed the PSLV C41/IRNSS-1I launch scheduled for April 12 as that satellite uses a different bus.
« Last Edit: 04/06/2018 03:05 AM by vineethgk »

Offline maint1234

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #226 on: 04/06/2018 02:10 PM »
Why would ISRO delay future missions if the satellite suffered a failure and not the launch vehicle itself?

I can understand the stand-down due to the fairing separation failure, which they found the cause for, but standing down due to a satellite failure makes no sense to me.
Because they build those satellites too, not just the rocket! ;)

They haven't yet figured out yet what went wrong with GSAT-6A even though the launch itself was 'textbook'. They say it could be a power failure that knocked out its communication systems. It could be due to some faulty component, a faulty design or some sort of human error during assembly that wasn't caught during testing. Or perhaps the satellite suffered a slight damage of some kind (vibration?) during ascent or separation that caused the fault later on after orbital firing. If it is the result of a faulty component or a faulty bus design they need to make sure that other upcoming satellites that use the same are unaffected. However, this is all speculative until they publish their findings.

But it is worth noting that they haven't delayed the PSLV C41/IRNSS-1I launch scheduled for April 12 as that satellite uses a different bus.

I will start the ball rolling.
What were the changes in this launch and satellite as compared to previous launches ?
1. A upgraded vikas engine , could result in higher vibrations and cause a short circuit.
2. A very large unfurlable antenna . Overloaded the power supply. But this unfurling would take place  at GEO ? , so might be unrelated.
3. Locally mfd li-ion battery , even experienced manufacturers face problems in batteries. Did GSAT 6A have local batteries ?
4. Conspiracy theory - stuxnet or variant. This theory was floated in 2010 when a indian satellite lost power in most of its transponders. Not as improbable as it sounds.

Offline seshagirib

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #227 on: 04/06/2018 03:18 PM »
^space debris hit , could also account for sudden loss of the satellite.

Offline vineethgk

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #228 on: 04/06/2018 05:40 PM »
^space debris hit , could also account for sudden loss of the satellite.
In this case contact was lost with the satellite after it had done its second orbital firing and attained a near-GEO orbital altitude with a perigee of around 25000 km. Certainly not impossible, but not very sure of the probability of a hit from space debris or micro-meteoroids in that region.

Offline vineethgk

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #229 on: 04/06/2018 05:47 PM »


Why would ISRO delay future missions if the satellite suffered a failure and not the launch vehicle itself?

I can understand the stand-down due to the fairing separation failure, which they found the cause for, but standing down due to a satellite failure makes no sense to me.
Because they build those satellites too, not just the rocket! ;)

They haven't yet figured out yet what went wrong with GSAT-6A even though the launch itself was 'textbook'. They say it could be a power failure that knocked out its communication systems. It could be due to some faulty component, a faulty design or some sort of human error during assembly that wasn't caught during testing. Or perhaps the satellite suffered a slight damage of some kind (vibration?) during ascent or separation that caused the fault later on after orbital firing. If it is the result of a faulty component or a faulty bus design they need to make sure that other upcoming satellites that use the same are unaffected. However, this is all speculative until they publish their findings.

But it is worth noting that they haven't delayed the PSLV C41/IRNSS-1I launch scheduled for April 12 as that satellite uses a different bus.

I will start the ball rolling.
What were the changes in this launch and satellite as compared to previous launches ?
1. A upgraded vikas engine , could result in higher vibrations and cause a short circuit.
2. A very large unfurlable antenna . Overloaded the power supply. But this unfurling would take place  at GEO ? , so might be unrelated.
3. Locally mfd li-ion battery , even experienced manufacturers face problems in batteries. Did GSAT 6A have local batteries ?
4. Conspiracy theory - stuxnet or variant. This theory was floated in 2010 when a indian satellite lost power in most of its transponders. Not as improbable as it sounds.

GSAT-6A was by and large similar to its predecessor GSAT-6 (for which it was supposed to act as a backup and/or a complement) if we go by the info provided by ISRO. If I'm not wrong they have been using indigenous Li-Ion batteries in spacecrafts before without encountering any issue, the novelty this time being its usage in the second stage of the rocket.

Offline vineethgk

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #230 on: 04/07/2018 12:33 AM »
Preliminary analysis indicates no problems with onboard systems of GSAT-6A, spacecraft likely went into safe mode due to an 'external disturbance' says ISRO Chief. Attempts at revival still on.

Quote
ISRO Chairman K Sivan told Express that the ongoing revival of GSAT-6A has nothing to do with future missions and the space agency is geared-up to carry out 10 missions in the next nine months as planned, including Chandrayaan-2. “PSLV-C41, carrying India’s eighth navigation satellite, will be launched on April 12. Losing communication link with GSAT-6A was unfortunate, but our scientists are working round-the-clock to retrieve the satellite and we are still hopeful.

The preliminary analysis shows there is no problem with any of the systems in the satellite and due to some external disturbance, the spacecraft has gone into safe mode. We have a mechanism to re-establish the communication link in such cases and the ISRO is putting its best foot forward. So this will not deter the space agency from going ahead with its future missions,” he asserted.

Source
« Last Edit: 04/07/2018 12:34 AM by vineethgk »

Offline maint1234

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #231 on: 04/07/2018 02:26 AM »
Preliminary analysis indicates no problems with onboard systems of GSAT-6A, spacecraft likely went into safe mode due to an 'external disturbance' says ISRO Chief. Attempts at revival still on.

Quote
ISRO Chairman K Sivan told Express that the ongoing revival of GSAT-6A has nothing to do with future missions and the space agency is geared-up to carry out 10 missions in the next nine months as planned, including Chandrayaan-2. “PSLV-C41, carrying India’s eighth navigation satellite, will be launched on April 12. Losing communication link with GSAT-6A was unfortunate, but our scientists are working round-the-clock to retrieve the satellite and we are still hopeful.

The preliminary analysis shows there is no problem with any of the systems in the satellite and due to some external disturbance, the spacecraft has gone into safe mode. We have a mechanism to re-establish the communication link in such cases and the ISRO is putting its best foot forward. So this will not deter the space agency from going ahead with its future missions,” he asserted.

Source

After the satellite is in GTO , external events are - firing of its engine for orbit change and solar flares .
This is a interesting article i just googled .
http://news.mit.edu/2013/space-weather-effects-on-satellites-0917

ISRO being as cryptic as always.
But for some reason this failure is very  irritating for me as a maintenance person.
Failures in new technologies is acceptable but once different areas in matured systems start failing , alarm bells should start ringing.

Offline Star One

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #232 on: 04/08/2018 06:17 PM »
Preliminary analysis indicates no problems with onboard systems of GSAT-6A, spacecraft likely went into safe mode due to an 'external disturbance' says ISRO Chief. Attempts at revival still on.

Quote
ISRO Chairman K Sivan told Express that the ongoing revival of GSAT-6A has nothing to do with future missions and the space agency is geared-up to carry out 10 missions in the next nine months as planned, including Chandrayaan-2. “PSLV-C41, carrying India’s eighth navigation satellite, will be launched on April 12. Losing communication link with GSAT-6A was unfortunate, but our scientists are working round-the-clock to retrieve the satellite and we are still hopeful.

The preliminary analysis shows there is no problem with any of the systems in the satellite and due to some external disturbance, the spacecraft has gone into safe mode. We have a mechanism to re-establish the communication link in such cases and the ISRO is putting its best foot forward. So this will not deter the space agency from going ahead with its future missions,” he asserted.

Source

After the satellite is in GTO , external events are - firing of its engine for orbit change and solar flares .
This is a interesting article i just googled .
http://news.mit.edu/2013/space-weather-effects-on-satellites-0917

ISRO being as cryptic as always.
But for some reason this failure is very  irritating for me as a maintenance person.
Failures in new technologies is acceptable but once different areas in matured systems start failing , alarm bells should start ringing.

Not if it’s something like a space debris hit or a micro meteoroid strike , that’s just bad luck.

Offline vineethgk

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #233 on: 04/09/2018 12:56 AM »
Solar storms and failure of (indigenous?) Li-Ion batteries being investigated as possible causes for GSAT-6A trouble. Attempts at revival are still on.
Quote
ISRO scientists, on the condition of anonymity, told The New Indian Express that they were relentlessly trying to salvage the satellite, which is still revolving around the earth.“There have been cases where satellites have been salvaged after some time duration, and we hope the same happens with GSAT-6A,” said a senior scientist, who, however, refrained from explaining how much time and whether that was possible with a revolving satellite.

With a 13-hour revolution around the earth, the scientists are getting just one shot every 24 hours to re-establish communication links with GSAT-6A. It is not clear if the scientists will be able to salvage a revolving satellite — in which case, after a period of time, it would be “declared a failure”.ISRO scientists are assessing various reasons for the power system malfunction, but two are mainly being verified — effect of solar storm and the new lithium-ion cells used on board the satellite.
Source

If my memory is correct, they have used the indigenous Li-Ion cells in satellites before, the novelty in this mission being its use in the GS2 stage of the rocket itself.

Aside from that, has there been a powerful enough solar storm of some kind recorded as hitting the earth at the time of GSAT-6A's communication blackout? If so, what are the odd chances that it would affect a particular satellite and not the others?

Offline penguin44

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #234 on: 04/09/2018 06:03 AM »
None. No sunspot activities either as its solar minimum.

Offline vineethgk

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #235 on: 04/10/2018 05:51 PM »
GSAT-6A is being continuously tracked, still hopeful about restoring link says ISRO Chief
Quote
Talking to TOI, Isro chairman Dr K Sivansaid, “With the help of the satellite tracking system and other sources, we now know the exact location of GSAT-6A. Earlier, we were searching in the dark. But now we know the exact position of the satellite and keeping a close watch on its movement round-the-clock.

We are hopeful that at a particular orientation, it will capture the signal from the ground station and communication will be restored. Currently, GSAT-6A is moving in the geo transfer orbit at perigee of around 26,000km and apogee of about 33,000km.”
Quote
 “We expect that the satellite has the power as its solar panels are fully deployed and getting recharged.” 
Quote
On addition of any new safety mechanism in IRNSS-1I to avoid power failure, the chairman said, “Power systems used in GSAT-6A and IRNSS-1I are totally different. The power system being used in IRNSS-1I is very simple and proven as all seven navigation satellites launched earlier are working successfully.”

Offline worldtimedate

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Re: LIVE: GSLV F-08 - GSAT-6A - March 29, 2018 (11:26 UTC)
« Reply #236 on: 04/20/2018 07:30 AM »
Power system failure cost Isro GSAT-6A: VSSC chief

Quote
A failure in the power system could have led to the Indian Space Research Organization (Isro) losing contact with the recently launched GSAT-6A communication satellite, a senior official of the Vikram Sarabhai Space Centre (VSSC) said on Wednesday.

Quote
"We have already analysed and understood what could have gone wrong. The power system comprises the solar panel, battery and circuit. We assume a short has happened in the electrical circuit," VSSC director S Somanath said, adding that the protection circuits might not have become functional on time, leading to the damaging of wires.

Quote
Ruling out a possible sabotage, Somanath said that all systems were tested at various stages. He added that the scientists were still trying to control the satellite.

"We located the satellite immediately after the loss of contact, we are continuing to see the satellite, and we are trying to send some commands. But the satellite is tumbling, and is not under control. We hope that one day it will start receiving commands and we will be able to bring it to a safe mode. In the past, some satellites have responded after months of remaining out of contact," the VSSC director said.

Somanath said based on the GSAT-6A experience, additional precautions were being taken.

worldtimedate [ http://www.world-timedate.com/ ]

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