Bharat Rakshak Forum Announcement

Hello Everyone,

A warm welcome back to the Bharat Rakshak Forum.

Important Notice: Due to a corruption in the BR forum database we regret to announce that data records relating to some of our registered users have been lost. We estimate approx. 500 user details are deleted.

To ease the process of recreating the user IDs we request members that have previously posted on the BR forums to recognise and identify their posts, once the posts are identified please contact the BRF moderator team by emailing BRF Mod Team with your post details.

The mod team will be able to update your username, email etc. so that the user history can be maintained.

Unfortunately for members that have never posted or have had all their posts deleted i.e. users that have 0 posts, we will be unable to recreate your account hence we request that you re-register again.

We apologise for any inconvenience caused and thank you for your understanding.

Regards,
Seetal

Indian Space Programme Discussion - Sept 2016

The Military Issues & History Forum is a venue to discuss issues relating to the military aspects of the Indian Armed Forces, whether the past, present or future. We request members to kindly stay within the mandate of this forum and keep their exchanges of views, on a civilised level, however vehemently any disagreement may be felt. All feedback regarding forum usage may be sent to the moderators using the Feedback Form or by clicking the Report Post Icon in any objectionable post for proper action. Please note that the views expressed by the Members and Moderators on these discussion boards are that of the individuals only and do not reflect the official policy or view of the Bharat-Rakshak.com Website. Copyright Violation is strictly prohibited and may result in revocation of your posting rights - please read the FAQ for full details. Users must also abide by the Forum Guidelines at all times.
Singha
BRF Oldie
Posts: 61959
Joined: 13 Aug 2004 19:42
Location: the grasshopper lies heavy

Re: Indian Space Programme Discussion - Sept 2016

Postby Singha » 01 Apr 2018 22:40

Do sats have a internal ac to control temperature?

Do li ion batts derate at low temp like lead acid car batts do?

disha
BR Mainsite Crew
Posts: 6279
Joined: 03 Dec 2006 04:17
Location: gaganaviharin

Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 01 Apr 2018 22:41

^Satellite power issues are actually normal. Power management within the confines of the package and in the harsh environment of space creates its own set of challenges.

ISRO's I3K bus had its power challenges (for example the W2M satellite https://www.space.com/6365-newly-launched-satellite-fails-space.html)

From the publicly available sources., ISRO lost contact with the satellite. There is hope that if it re-acquires contact with the satellite, it can possibly use backup pathways to get its satellite going.

---

To the query on solar panel deployment., the latest launches immediately deploy their solar arrays so that they have reliable power for post-launch maneuvers. This is not a solar panel deployment issue.

The large unfurlable antenna was supposed to be deployed once the sat reached its designated slot. The comm loss is not due to that.

Most likely the comm systems might have seen a power surge and the comm system with the ground track might itself have failed. Once ISRO makes formal announcements, then only we will know further.

It is sad and unfortunate, but such mishaps happen. Indians should get used to this kind of setbacks and take it on the chin and move forward since ISRO is pushing the limits further and further.

Expect lot of hand-wringing and rona-dhona from the usual chateratis like this one https://thewire.in/space/the-problems-with-measuring-isros-economic-impact.

Ignore such chateratis.

disha
BR Mainsite Crew
Posts: 6279
Joined: 03 Dec 2006 04:17
Location: gaganaviharin

Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 01 Apr 2018 22:49

Singha wrote:Do sats have a internal ac to control temperature?

Do li ion batts derate at low temp like lead acid car batts do?


No to both for satellites. Since there is no "air" to "condition" in space for satellites.

Thermal heat management in satellites is a science in itself. Satellites have both active and passive thermal management systems, some explained here https://en.wikipedia.org/wiki/Spacecraft_thermal_control

Since sat power buses are growing in sizes and capacity while the sat size itself is shrinking, power management and thermal management is challenging. Thermal management challenges did the chandrayaan in for example. While W2M had issues due to power management.

ISRO's own sat buses are going from DC Power 3KW to 6KW to 12KW (https://en.wikipedia.org/wiki/Spacecraf ... al_control)., and ISROs I2K bus has been very reliable.

Given that any glitch due to power is highly unlikely.

More likely will be the comm systems link with the ground stations. Or the circuit managing the comm systems link with the ground station.

PS: Li-ion batteries do derate, but they have thermal management (kept warm and insulated) in satellites for such batteries.

chetak
BRF Oldie
Posts: 16542
Joined: 16 May 2008 12:00

Re: Indian Space Programme Discussion - Sept 2016

Postby chetak » 01 Apr 2018 23:01

disha wrote:
Singha wrote:Do sats have a internal ac to control temperature?

Do li ion batts derate at low temp like lead acid car batts do?


No to both for satellites. Since there is no "air" to "condition" in space for satellites.

Thermal heat management in satellites is a science in itself. Satellites have both active and passive thermal management systems, some explained here https://en.wikipedia.org/wiki/Spacecraft_thermal_control

Since sat power buses are growing in sizes and capacity while the sat size itself is shrinking, power management and thermal management is challenging. Thermal management challenges did the chandrayaan in for example. While W2M had issues due to power management.

ISRO's own sat buses are going from DC Power 3KW to 6KW to 12KW (https://en.wikipedia.org/wiki/Spacecraf ... al_control)., and ISROs I2K bus has been very reliable.

Given that any glitch due to power is highly unlikely.

More likely will be the comm systems link with the ground stations. Or the circuit managing the comm systems link with the ground station.

PS: Li-ion batteries do derate, but they have thermal management (kept warm and insulated) in satellites for such batteries.


There may not be the possibility of a single point failure, no??

Not after so many successful and reliable birds in space.

Some sort of catastrophic failure, taking out multiple or redundant systems??

Mort Walker
BRF Oldie
Posts: 6735
Joined: 31 May 2004 11:31
Location: The rings around Uranus.

Re: Indian Space Programme Discussion - Sept 2016

Postby Mort Walker » 01 Apr 2018 23:15

Preliminary data shows chances of recovery of GSAT-6A: ISRO

My guess is that a secondary comms link via some other subsytem may be trying to get the primary link back on line. If anything - this is a fantastic learning process which has incredible applications to other weapon system development in terms of reliability. The downside is that it is a $40 million lesson.

Mort Walker
BRF Oldie
Posts: 6735
Joined: 31 May 2004 11:31
Location: The rings around Uranus.

Re: Indian Space Programme Discussion - Sept 2016

Postby Mort Walker » 01 Apr 2018 23:17

chetak wrote:
There may not be the possibility of a single point failure, no??

Not after so many successful and reliable birds in space.

Some sort of catastrophic failure, taking out multiple or redundant systems??


You can build robust redundancy, but it will be at a cost of weight which is precious for space launches.

A Nandy
BR Mainsite Crew
Posts: 128
Joined: 06 Sep 2009 23:39

Re: Indian Space Programme Discussion - Sept 2016

Postby A Nandy » 02 Apr 2018 00:51

http://www.dnaindia.com/india/report-ta ... ce-2598025

In a major development, India-based Neutrino Observatory (INO) project which suffered multiple delays for over a decade, was granted environment clearance by (EC) the Ministry of Environment and Forests on Monday to set up the lab in Tamil Nadu’s Theni district weeks after the recommendation of the Expert Appraisal Committee (EAC) of Infra2.

The INO to be set up in Bodi West Hills on the Tamil Nadu-Kerala border in Theni district is one of the largest basic sciences projects in the country that would primarily study atmospheric neutrinos produced by cosmic rays in a 1,200 meters deep cave under a mountain.

Vips
BRFite
Posts: 650
Joined: 14 Apr 2017 18:23

Re: Indian Space Programme Discussion - Sept 2016

Postby Vips » 02 Apr 2018 02:25

Mort Walker wrote:Preliminary data shows chances of recovery of GSAT-6A: ISRO

My guess is that a secondary comms link via some other subsytem may be trying to get the primary link back on line. If anything - this is a fantastic learning process which has incredible applications to other weapon system development in terms of reliability. The downside is that it is a $40 million lesson.


The monetary loss will be minimal as the satellite will be covered by Insurance.The real down side is the time gap that will be taken to replace the satellite.

Mort Walker
BRF Oldie
Posts: 6735
Joined: 31 May 2004 11:31
Location: The rings around Uranus.

Re: Indian Space Programme Discussion - Sept 2016

Postby Mort Walker » 02 Apr 2018 03:45

The GSAT 6A is a GoI satellite for governmental and national security use. I didn’t think GoI insured non commercial satellites.

The time gap is there, but they’ve already produced one, so producing another wouldn’t take as long even though there may be some long lead time components.

Haridas
BRFite
Posts: 201
Joined: 26 Dec 2017 07:53

Re: Indian Space Programme Discussion - Sept 2016

Postby Haridas » 02 Apr 2018 04:14

^^^^ Military would not allow insurers to do their due diligence review and inspection, so Mil satellite almost always are not insured.

Philip
BRF Oldie
Posts: 18861
Joined: 01 Jan 1970 05:30
Location: India

Re: Indian Space Programme Discussion - Sept 2016

Postby Philip » 02 Apr 2018 05:55

Could this be sabotage? Cannot be ruled out as this was a well- advertised mil. launch.The US never ever give out info about their mil. launches for the same. Our commns. to the sat. could've been hacked at the crucial stage.We should've simply announced another civvy commn-sat with a higher payload.Why advertise to all our foes the details of such a sensitive launch?

disha
BR Mainsite Crew
Posts: 6279
Joined: 03 Dec 2006 04:17
Location: gaganaviharin

Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 02 Apr 2018 09:41

No need to go into CTs. Comm links fail and there might be redundancy built in., ISRO is working on getting its comm link back. I am sure they will pore over the telemetry with a fine comb and tease out all necessary information.

chetak
BRF Oldie
Posts: 16542
Joined: 16 May 2008 12:00

Re: Indian Space Programme Discussion - Sept 2016

Postby chetak » 02 Apr 2018 09:46

Philip wrote:Could this be sabotage? Cannot be ruled out as this was a well- advertised mil. launch.The US never ever give out info about their mil. launches for the same. Our commns. to the sat. could've been hacked at the crucial stage.We should've simply announced another civvy commn-sat with a higher payload.Why advertise to all our foes the details of such a sensitive launch?


The thought had momentarily crossed my mind.

maybe some neighbor, testing a space weapon, which they have "reputedly" developed??

SSridhar
Forum Moderator
Posts: 22431
Joined: 05 May 2001 11:31
Location: Chennai

Re: Indian Space Programme Discussion - Sept 2016

Postby SSridhar » 02 Apr 2018 10:54

In the early part of our space programme, we had several power-related issues. But, later, they seem to have been resolved as we had a large string of successful satellites, barring one or probably two. I do not believe that the Chinese could have targetted a satellite still not in its slot and that too a few minutes after an orbit raise. It is too far fetched.

But, I agree with Philip that we should begin to be more circumspect in future in military launches.

arshyam
BRF Oldie
Posts: 2808
Joined: 11 Aug 2016 06:14

Re: Indian Space Programme Discussion - Sept 2016

Postby arshyam » 02 Apr 2018 11:12

I am asking this after some hesitation - could the failure announcement itself be a false flag? I can't think of any legit reasons for it considering we had announced it as a military launch, but maybe, just maybe? (TBH, the heart also wants it to be one :))

Haridas
BRFite
Posts: 201
Joined: 26 Dec 2017 07:53

Re: Indian Space Programme Discussion - Sept 2016

Postby Haridas » 02 Apr 2018 11:32

ramana wrote:So it's a satellite raising issue.
Could be a battery short.that drained it.

There is lot of thought that goes into electronics, communication systems & control circuit redundency. It's a adequacy question where subjective judgement is excercised to balance redundency (accompanied by weight wastage ) and system reliability.

Just wait for the professionals to their job. There is no end to speculation, and it's not going to be helpful or productive.
Jmt.

Manish_P
BRFite
Posts: 1185
Joined: 25 Mar 2010 17:34

Re: Indian Space Programme Discussion - Sept 2016

Postby Manish_P » 02 Apr 2018 11:36

Philip wrote:...this was a well- advertised mil. launch....Why advertise to all our foes the details of such a sensitive launch?


+1

juvva
BRFite
Posts: 243
Joined: 20 Oct 2008 17:34

Re: Indian Space Programme Discussion - Sept 2016

Postby juvva » 02 Apr 2018 13:48

Could be a space debris impact...(?)

Philip
BRF Oldie
Posts: 18861
Joined: 01 Jan 1970 05:30
Location: India

Re: Indian Space Programme Discussion - Sept 2016

Postby Philip » 02 Apr 2018 15:39

Did the Chin sat that crashed into the Pacific take a swipe at it before crashing? :rotfl:

Bur seriously, both the US and Russia never advertise their mil launches until thr very last moment if at all, usually after launch.No pics given.This will make it v.difficult for thd enemy to try and sabotage the same, better done when the final stage/ sat is in space and establishing first contact with ground/ master control.With intl. hacking a new art form, we cannot be too careful.

It would be ironic ( farfetched though) if like a Bond movie the enemy has captured it and it is now being used to spy on us/ against us!

JayS
Forum Moderator
Posts: 3209
Joined: 11 Aug 2016 06:14

Re: Indian Space Programme Discussion - Sept 2016

Postby JayS » 02 Apr 2018 16:25

This China sabotaging Indian Stuff is very boring type of dhoti shivering. Yawn....!! Please think of something new now.

prasannasimha
Forum Moderator
Posts: 693
Joined: 15 Aug 2016 00:22

Re: Indian Space Programme Discussion - Sept 2016

Postby prasannasimha » 02 Apr 2018 18:51

Seeing the time now it looks like salvage will not be possible.

Haridas
BRFite
Posts: 201
Joined: 26 Dec 2017 07:53

Re: Indian Space Programme Discussion - Sept 2016

Postby Haridas » 02 Apr 2018 21:27

^^ re acquisition of the signal via low gain wide angle antenna for secondary control channel might take longer time due to long orbital period of current orbit, and unknown tube rate (if any).

There is hope in next 10 days window imho.

prasannasimha
Forum Moderator
Posts: 693
Joined: 15 Aug 2016 00:22

Re: Indian Space Programme Discussion - Sept 2016

Postby prasannasimha » 02 Apr 2018 22:07

^ supposed to be toast. Power surge related.

Mort Walker
BRF Oldie
Posts: 6735
Joined: 31 May 2004 11:31
Location: The rings around Uranus.

Re: Indian Space Programme Discussion - Sept 2016

Postby Mort Walker » 02 Apr 2018 22:08

Haridas wrote:^^ re acquisition of the signal via low gain wide angle antenna for secondary control channel might take longer time due to long orbital period of current orbit, and unknown tube rate (if any).

There is hope in next 10 days window imho.


Good point. It’s in an elliptical orbit by 164x36,000 KM, so re-acquisition of signal could take several days.

Mort Walker
BRF Oldie
Posts: 6735
Joined: 31 May 2004 11:31
Location: The rings around Uranus.

Re: Indian Space Programme Discussion - Sept 2016

Postby Mort Walker » 02 Apr 2018 22:10

prasannasimha wrote:^ supposed to be toast. Power surge related.


Power surge would have to be caused by a faulty power supply or an overload of in-rush of current from the solar panels.

ramana
Forum Moderator
Posts: 49309
Joined: 01 Jan 1970 05:30

Re: Indian Space Programme Discussion - Sept 2016

Postby ramana » 02 Apr 2018 22:12

Mort Walker wrote:Preliminary data shows chances of recovery of GSAT-6A: ISRO

My guess is that a secondary comms link via some other subsytem may be trying to get the primary link back on line. If anything - this is a fantastic learning process which has incredible applications to other weapon system development in terms of reliability. The downside is that it is a $40 million lesson.



Usual PTI report.
|
Wonder who pays their paycheck for the extra comments.

Singha
BRF Oldie
Posts: 61959
Joined: 13 Aug 2004 19:42
Location: the grasshopper lies heavy

Re: Indian Space Programme Discussion - Sept 2016

Postby Singha » 02 Apr 2018 23:15

in case of a mars mission, i recall a sw flaw had led to computer crashing and lander going dark when the log file overran some disk space it was supposed to be corralled in. eventually the jpl pasadena people were able to reset the computer , rm the logfile and get it working.
but in that case i guess the comms link was still working....a different class of problem.

prasannasimha
Forum Moderator
Posts: 693
Joined: 15 Aug 2016 00:22

Re: Indian Space Programme Discussion - Sept 2016

Postby prasannasimha » 02 Apr 2018 23:19

the I2K buus is rated upto 3 KW. I think GSAT6-A had a rating of 3.2 KW. Could that have been an issue ?
Power 3,119 watts actually as a a precise value

For I2K Bus

Total Power: 2800 W.
Payload Power: 2400 W.

SSridhar
Forum Moderator
Posts: 22431
Joined: 05 May 2001 11:31
Location: Chennai

Re: Indian Space Programme Discussion - Sept 2016

Postby SSridhar » 03 Apr 2018 06:20

Mort Walker wrote: It’s in an elliptical orbit by 164x36,000 KM, so re-acquisition of signal could take several days.

The orbit should be more circular now as the second LAM firing was almost for an hour.

Added later: Currently, it is 36000 X 20000 Kms

Mort Walker
BRF Oldie
Posts: 6735
Joined: 31 May 2004 11:31
Location: The rings around Uranus.

Re: Indian Space Programme Discussion - Sept 2016

Postby Mort Walker » 03 Apr 2018 06:48

prasannasimha wrote:the I2K buus is rated upto 3 KW. I think GSAT6-A had a rating of 3.2 KW. Could that have been an issue ?
Power 3,119 watts actually as a a precise value

For I2K Bus

Total Power: 2800 W.
Payload Power: 2400 W.


I would NOT expect ISRO to make a simple error like that.

prasannasimha
Forum Moderator
Posts: 693
Joined: 15 Aug 2016 00:22

Re: Indian Space Programme Discussion - Sept 2016

Postby prasannasimha » 03 Apr 2018 07:35

Surprisingly in aerospace going by past history some obvious ( in hind sight ) error has brought missions down. Simple things like conversions ,reversed connectors etc etc throughput history of aerospace engineering.

prasannasimha
Forum Moderator
Posts: 693
Joined: 15 Aug 2016 00:22

Re: Indian Space Programme Discussion - Sept 2016

Postby prasannasimha » 03 Apr 2018 07:37

GSAT 6 had 2 KW whereas GSAT 6A 3.119 KW

SSridhar
Forum Moderator
Posts: 22431
Joined: 05 May 2001 11:31
Location: Chennai

Re: Indian Space Programme Discussion - Sept 2016

Postby SSridhar » 03 Apr 2018 08:10

^ But, payload wouldn't have been switched on.

prasannasimha
Forum Moderator
Posts: 693
Joined: 15 Aug 2016 00:22

Re: Indian Space Programme Discussion - Sept 2016

Postby prasannasimha » 03 Apr 2018 09:02

Once the solar panels are activated various systems are switched on. Power electronics guys may be able to tell better but once the solar panels start charging that current has to be stored/ used or dissipated. Certain portions of the circuitry would be energised and probably that gave rise to problems probably frying some electronics during a surge. This has happened to other satellites of various countries in the past as well.

Singha
BRF Oldie
Posts: 61959
Joined: 13 Aug 2004 19:42
Location: the grasshopper lies heavy

Re: Indian Space Programme Discussion - Sept 2016

Postby Singha » 03 Apr 2018 10:49

prasannasimha wrote:Surprisingly in aerospace going by past history some obvious ( in hind sight ) error has brought missions down. Simple things like conversions ,reversed connectors etc etc throughput history of aerospace engineering.


another case was two teams working on some nasa lander project did some metric to imperial conversions wrong or missed something, as a result the height was misread and the lander impacted at too high a speed and got junked.
airbus went to extent of having the multiple redundant fcs computers be programmed by different teams with no contact, using different type of hw and different sw languages and tools to reduce the probability of a underlying hw or sw flaw affecting them all.

rrao
BRFite -Trainee
Posts: 95
Joined: 13 Feb 2007 22:17

Re: Indian Space Programme Discussion - Sept 2016

Postby rrao » 03 Apr 2018 15:39

n2yo is showing the following data of GSAT- 6A NORAD ID: 43241
Int'l Code: 2018-027A
Perigee: 25,985.8 km
Apogee: 36,375.3 km
Inclination: 3.3 °
Period: 1,207.0 minutes
Semi major axis: 37551 km
RCS: Unknown
Launch date: March 29, 2018
Source: India (IND)
Launch site: SRIHARIKOTA

rajkumar
BRFite
Posts: 163
Joined: 22 Sep 2000 11:31
Location: London U.K
Contact:

Re: Indian Space Programme Discussion - Sept 2016

Postby rajkumar » 03 Apr 2018 16:23

Singha wrote:
prasannasimha wrote:Surprisingly in aerospace going by past history some obvious ( in hind sight ) error has brought missions down. Simple things like conversions ,reversed connectors etc etc throughput history of aerospace engineering.


another case was two teams working on some nasa lander project did some metric to imperial conversions wrong or missed something, as a result the height was misread and the lander impacted at too high a speed and got junked.
airbus went to extent of having the multiple redundant fcs computers be programmed by different teams with no contact, using different type of hw and different sw languages and tools to reduce the probability of a underlying hw or sw flaw affecting them all.


The conversion issue was on Mars Lander and the teams involved were from NASA & ESA. NASA team used imperial measurements and ESA team used SI

Haridas
BRFite
Posts: 201
Joined: 26 Dec 2017 07:53

Re: Indian Space Programme Discussion - Sept 2016

Postby Haridas » 03 Apr 2018 20:27

prasannasimha wrote:Once the solar panels are activated various systems are switched on. Power electronics guys may be able to tell better & once the solar panels start charging that current has to be stored/ used or dissipated. Certain portions of the circuitry would be energised and probably that gave rise to problems probably frying some electronics during a surge. This has happened to other satellites of various countries in the past as well.

No, power generated by panel is available for use, it is not mandatory to consume it. Like a 220v 15amp rated power outlet can be unused, or we can put a load, whereby load chooses to draw desired power level, be it 5 watt or a kilowatt.

Voltage surge or load surge is bread and butter of power electronics folks and it is not rocket science at all.

Modular power circuits used in space applications allow partitioning (for redundency and graceful failure) yet lower the burden of redundency. Same is true for RF power amplifiers.

prasannasimha
Forum Moderator
Posts: 693
Joined: 15 Aug 2016 00:22

Re: Indian Space Programme Discussion - Sept 2016

Postby prasannasimha » 03 Apr 2018 23:53

Satellite is lost. Its a power system problem from what it seems.

Ashokk
BRFite
Posts: 300
Joined: 11 Aug 2016 06:14

Re: Indian Space Programme Discussion - Sept 2016

Postby Ashokk » 04 Apr 2018 01:07

After ‘cardiac arrest’, Rs 270 crore Gsat-6A cruising on silently :roll:
Isro said efforts were on to resume communication with the satellite. Sources said there was no indication of any system malfunction or fluctuations during or after launch. “Every time there is a discrepancy, there are indications. This time, it could not been seen or felt, which is why it is taking more time to establish contact,” Isro chairman K Sivan said.


Return to “Military Issues & History Forum”

Who is online

Users browsing this forum: adityadange, Denis, Google Feedfetcher, Zynda and 40 guests