Indian Space Programme Discussion

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Re: Indian Space Programme Discussion

Postby symontk » 27 Aug 2015 21:40

RonyKJ wrote:ISRO needs to develop satellites which can be refuelled.
Then we can use the proven PSLV or even a resuable vehicle
to go refuel the sats. For this we need to develop docking technology
which will be needed anyway for manned flights, space station and so on.


After 10-15 years, the satellite will have serious issues with particle damage, weak battery, solar cell life etc. Less amount of fuel is only one of the problems

Apart from all this, the satellite and transmission technologies would have galloped and I dont think you would gain anything by refuelling it

Again it occupies a precious GS slot which could be replaced with a better performance satellite

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Re: Indian Space Programme Discussion

Postby PratikDas » 27 Aug 2015 21:58

Mort Walker wrote:Any status on the GSAT-6? Has it been placed in position and has the 6m antenna unfurled?

Was wondering the same and eagerly awaiting information.

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Re: Indian Space Programme Discussion

Postby Ashokk » 27 Aug 2015 22:17

PratikDas wrote:Mort Walker wrote:
Any status on the GSAT-6? Has it been placed in position and has the 6m antenna unfurled?

Was wondering the same and eagerly awaiting information.

I think during the post launch speeches it was mentioned that the 6m antenna would be unfurled on 30th Aug after tests were done
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Re: Indian Space Programme Discussion

Postby PratikDas » 27 Aug 2015 22:20

Thanks, ashokk!

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Re: Indian Space Programme Discussion

Postby member_28108 » 27 Aug 2015 22:23

The 6 m Antenaa will be unfurled on 30 August once it reaches its parking orbit. as per the satellite director Dr Prakash Rao
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Re: Indian Space Programme Discussion

Postby PratikDas » 27 Aug 2015 22:24

prasannasimha wrote:The 6 m Antenaa will be unfurled on 30 August once it reaches its parking orbit.

Yes, August, not September.

ISRO Press Release: GSLV Successfully Launches India’s Latest Communication Satellite GSAT-6

In the coming days, GSAT-6's orbit will be raised from its present GTO to the final circular Geostationary Orbit (GSO) by firing the satellite's Liquid Apogee Motor (LAM) in stages. The satellite will be commissioned into service after the completion of orbit raising operations, deployment of its 6 m wide sieve shaped unfurlable antenna, the satellite’s positioning in its designated orbital slot of 83 degree East longitude in the GSO and in-orbit testing of its communication payloads.

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Re: Indian Space Programme Discussion

Postby SaiK » 27 Aug 2015 22:41

symontk wrote:
RonyKJ wrote:ISRO needs to develop satellites which can be refuelled.
Then we can use the proven PSLV or even a resuable vehicle
to go refuel the sats. For this we need to develop docking technology
which will be needed anyway for manned flights, space station and so on.


After 10-15 years, the satellite will have serious issues with particle damage, weak battery, solar cell life etc. Less amount of fuel is only one of the problems

Apart from all this, the satellite and transmission technologies would have galloped and I dont think you would gain anything by refuelling it

Again it occupies a precious GS slot which could be replaced with a better performance satellite

NP at all.
all dock-ables are mini-satellites and LRU components/plug&play.
- battery pack are mini-satellites with its own docking units. it is an embedded system in itself! :)
- solar panels are mini-satellites dispatched as piggy on some other launch. old panels gets detached on command, and the new panels docks in.

besides reusable launch vehicles can also be designed to do these.. depends on the constraints, drivers and needs. all things are possible.

one the tradeoffs, we must see how much of this cost saving? we need a CBA on component wise dockables and the launch cost. who knows 8-10 components embedded systems can launched in one shot using our PSLV bro.

but the benefit of extending the life-span to another 10-15 years should be studied. the benefits include the user of the satellite, and his/her business use cases and how antrix is billed/ nation-public is benefited.
Last edited by SaiK on 27 Aug 2015 22:47, edited 2 times in total.

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Re: Indian Space Programme Discussion

Postby member_28108 » 27 Aug 2015 22:46

There is already a satellite docking experiment on the cards by ISRO.

http://antariksh-space.blogspot.in/2013/07/isro-rendezvous-docking-experiment.html

Image

Image

ISRO has been working on a rendezvous and docking (RVD) experiment mission involving two IMS (Indian Micro Satellite) series spacecrafts. ISAC, a ISRO centre, has been involved in developing navigation and guidance algorithm for RVD. In this experiment, two IMS Spacecrafts, one designated as target and the other designated as chaser, will be launched by a PSLV launcher into two slightly different orbits. There will be no communication link between the target and chaser during the far range rendezvous phase in which relative separation between the spacecrafts will be around 50km to 5km range and this phase will be a ground guided phase. In the docking phase of the mission, docking sensors such as Laser Range Finder during the relative separation of 5 km to 0.25km, Docking Camera during the relative separation of 300m to 1m ,Visual Camera for real time imaging during the relative separation of 1m to docking will be used respectively.

For the purpose of testing and verification of vision based docking algorithms before a real world implementation is carried out, ISRO has developed a 3D simulation environment that is being used to simulate docking phase of the mission.

Targeted Applications of RVD: RVD technology is one of many enabling technologies for ISRO's human space flight program. Another promising application of this technology will be increasing age of ISRO's satellites like that from IRS, INSAT and IRNSS systems. RVD technology will allow a resupply (fuel, power pack etc) spacecraft to dock with a satellite in orbit and allow for replenishment of fuel and power pack, thereby increasing satellites age. To facilitate this, as per my research, ISRO has been designing its newest satellite bus called I-6K, which is a unified bus with modular design ,multi EV panels and scalable structure (Bus module & payload module). A modular design will allow easy and fast replacement of bus module in the orbit by the resupply space craft. The resupply spacecraft might itself be a new bus module (with fuel, power pack etc.) that will dock with the payload module in the orbit after the old bus module undocks.

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Re: Indian Space Programme Discussion

Postby SaiK » 27 Aug 2015 22:52

I think it must be an excellent design considering say one or two PSLV launches to deliver these as payloads to other satellites. The challenge there would be different satellites are different orbits. Say 4-8 of them needs to get into its own orbit, its own guidance and small engine (or solar powered), etc.

that would be interesting.. it can increase cost if it is not mass produced or on a larger scale.

--

ps: instead of detaching and docking.. they can also design to dock over (sandwiching and layering) one on top (or wichever direction you feel good :) ) of the other. The old dockable still remains, but not functional. the new docked unit becomes functional, and also exposes its interface to another dockable.
dockable chain architecture (DAC) .. pay royalty to me on this patent. :wink: [in another words, two dockables would be entirely mimicing each other - borglets - its own solar panels, battery units, etc /cost savings]

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Re: Indian Space Programme Discussion

Postby member_28108 » 27 Aug 2015 23:06

SaiK wrote:I think it must be an excellent design considering say one or two PSLV launches to deliver these as payloads to other satellites. The challenge there would be different satellites are different orbits. Say 4-8 of them needs to get into its own orbit, its own guidance and small engine (or solar powered), etc.

that would be interesting.. it can increase cost if it is not mass produced or on a larger scale.

--

ps: instead of detaching and docking.. they can also design to dock over (sandwiching and layering) one on top (or wichever direction you feel good :) ) of the other. The old dockable still remains, but not functional. the new docked unit becomes functional, and also exposes its interface to another dockable.
dockable chain architecture (DAC) .. pay royalty to me on this patent. :wink: [in another words, two dockables would be entirely mimicing each other - borglets - its own solar panels, battery units, etc /cost savings]

Actually that is how the ISS was built It is an already existing technology.

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Re: Indian Space Programme Discussion

Postby rgosain » 27 Aug 2015 23:18

Can I humbly request or suggest to the admins of this forum to change the title of this thread from India Space Programme Discussion to India Space Industry as this is a key industry which employs thousands of people across a wide variety of industrial sectors and builds capacity in a number of key areas for development and education.
Calling it a programme devalues the efforts, goals and achievements such as the launch we have just witnessed today. People like Dreze and Sonia G came very close to terminating this industry at the behest of of their paymasters.

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Re: Indian Space Programme Discussion

Postby Neela » 28 Aug 2015 00:05

ESA has some wonderful videos on Youtube on ISS docking. ISS use IR cameras and the whole process is automated with a possibilty to manually override. Begins with orbital maneuvers.

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Re: Indian Space Programme Discussion

Postby member_29172 » 28 Aug 2015 01:15

So, can we expect a space station for India, in the next decade or so? That'd be an exiciting venture with possibly a moon base in the future. Colonizing moon and the surrounding solar system would be quite a revolutionary concept. If only it wasn't so capital intensive.
I hope ISRO folks won't be too timid to try something like a moon base, it's something the country needs.

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Re: Indian Space Programme Discussion

Postby SaiK » 28 Aug 2015 01:32

prasannasimha garu, same same..

but all modules will have common minimalist setup for survival.

--

I think, India may not have a space station for human occupation, but it would be totally un-manned.
btw, there is nothing stopping us joining the ISS.

bejo ek number module!

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Re: Indian Space Programme Discussion

Postby rahulm » 28 Aug 2015 02:05

From ISRO press release

168 km x 35,939 km with an orbital inclination of 20.01 deg. Previous numbers mentioned by the broadcast commentator were incorrect. Still a very good GTO orbit compared to target.

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Re: Indian Space Programme Discussion

Postby VenkataS » 28 Aug 2015 02:49

One of the commentators in the broadcast mentioned that the target was to have 6 PSLV launches and 2 GSLV launches in a year in the near future.

The next GSLV MK II launch will be in June/July 2016 according to the mission director.

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Re: Indian Space Programme Discussion

Postby member_23370 » 28 Aug 2015 03:18

So next GSLV-II and III launch are only in 2016. Just a measly PSLV to look forward to for the rest of the year. :(( :((

Well anyway not ISRO related but hopefully DRDO/SFC/IN will keep us jingos entertained with K-4/A-4 & A-5.

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Re: Indian Space Programme Discussion

Postby Gagan » 28 Aug 2015 04:14

Congrats ISRO!
I missed the launch. My internet doesn't even allow streaming joo tube video :((

Delighted that the Parfaarmance was Naarmaal

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Re: Indian Space Programme Discussion

Postby Vipul » 28 Aug 2015 04:23

India to Launch a Heavier US Satellite With GSLV Rocket.


ISRO will also be launching four nano-satellites from US as a piggy back luggage for its Astrosat to be launched next month using its another rocket polar satellite launch vehicle (PSLV).

ISRO officials told IANS that around 10 satellites have been identified for launch using GSLV-Mk II.

Queried about the status of testing a reusable launch vehicle, Mr Kumar said the plan is to test fly a scaled down model (1/6th size of real size model) later this year.

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Re: Indian Space Programme Discussion

Postby SriKumar » 28 Aug 2015 04:44

Quite a lot of progress....I can recall the launch where the first desi cryostage was used and it ignited but did not sustain. I think the centrifugal pumps were the culprit. And the next one with the ruskie stage which collapsed during launch due to fairing issues. THere is brochure out there that covered all the things that were redesigned/modified after those two launch failures.

This CUS used variable thrust ...not sure if this the the first time that was done or did they do this with the previous launch as well. Learnt one new thing today.... rocket ko kehte hain 'pramochan yaan'. Wish they have a channel (even just audio, no video) where the mission control callouts are the only voices and no commentary. 'cryogenic stage parfaarmans naarmal' was called out several times during the 12 minute CUS burn ....and for each time there was applause. The guys (and one gal) at mission control must have been relieved. It is gutsy to publicly show the predicted velocity and altitude. Does any other launch group do this?
I think ISRO probably has one more ruskie cryo stage.....I doubt if it will be used...it must have been opened up for post-mortem after the ealier ruskie cryostage in GSLV failed.

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Re: Indian Space Programme Discussion

Postby Shreeman » 28 Aug 2015 05:24

prasannasimha wrote:There is already a satellite docking experiment on the cards by ISRO.

http://antariksh-space.blogspot.in/2013/07/isro-rendezvous-docking-experiment.html

Image

Image

ISRO has been working on a rendezvous and docking (RVD) experiment mission involving two IMS (Indian Micro Satellite) series spacecrafts. ISAC, a ISRO centre, has been involved in developing navigation and guidance algorithm for RVD. In this experiment, two IMS Spacecrafts, one designated as target and the other designated as chaser, will be launched by a PSLV launcher into two slightly different orbits. There will be no communication link between the target and chaser during the far range rendezvous phase in which relative separation between the spacecrafts will be around 50km to 5km range and this phase will be a ground guided phase. In the docking phase of the mission, docking sensors such as Laser Range Finder during the relative separation of 5 km to 0.25km, Docking Camera during the relative separation of 300m to 1m ,Visual Camera for real time imaging during the relative separation of 1m to docking will be used respectively.

For the purpose of testing and verification of vision based docking algorithms before a real world implementation is carried out, ISRO has developed a 3D simulation environment that is being used to simulate docking phase of the mission.

Targeted Applications of RVD: RVD technology is one of many enabling technologies for ISRO's human space flight program. Another promising application of this technology will be increasing age of ISRO's satellites like that from IRS, INSAT and IRNSS systems. RVD technology will allow a resupply (fuel, power pack etc) spacecraft to dock with a satellite in orbit and allow for replenishment of fuel and power pack, thereby increasing satellites age. To facilitate this, as per my research, ISRO has been designing its newest satellite bus called I-6K, which is a unified bus with modular design ,multi EV panels and scalable structure (Bus module & payload module). A modular design will allow easy and fast replacement of bus module in the orbit by the resupply space craft. The resupply spacecraft might itself be a new bus module (with fuel, power pack etc.) that will dock with the payload module in the orbit after the old bus module undocks.


This refueling, docking business is exceedingly hard. Checkup some khan approaches and you will realize *why* there are still people in the loop in so many places AND goals so limited. This is on stuff sent up to be caught, repaired, recharged, released.

It would be far cheaper to send up new ones AND have better deorbiting. India needs a ton of stuff to go up yet, small and large. The TD/RLV etc is great but no replacement for getting to a dozen GSLV/PSLV each a year. Refueling/repair isnt the TD/RLV goal.

My 2c. With some past exposure to the problem.

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Re: Indian Space Programme Discussion

Postby manjgu » 28 Aug 2015 05:51

can someone in short explain the extra capabilites accruing to the def. services on account of this satellite?

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Re: Indian Space Programme Discussion

Postby member_28108 » 28 Aug 2015 06:10

SriKumar wrote:Quite a lot of progress....I can recall the launch where the first desi cryostage was used and it ignited but did not sustain. I think the centrifugal pumps were the culprit. And the next one with the ruskie stage which collapsed during launch due to fairing issues. THere is brochure out there that covered all the things that were redesigned/modified after those two launch failures.

This CUS used variable thrust ...not sure if this the the first time that was done or did they do this with the previous launch as well. Learnt one new thing today.... rocket ko kehte hain 'pramochan yaan'. Wish they have a channel (even just audio, no video) where the mission control callouts are the only voices and no commentary. 'cryogenic stage parfaarmans naarmal' was called out several times during the 12 minute CUS burn ....and for each time there was applause. The guys (and one gal) at mission control must have been relieved. It is gutsy to publicly show the predicted velocity and altitude. Does any other launch group do this?
I think ISRO probably has one more ruskie cryo stage.....I doubt if it will be used...it must have been opened up for post-mortem after the ealier ruskie cryostage in GSLV failed.

The Russian stage will not be used. If you remember right after a successive series of failures, a shake test was done (typical Indian solution to many problems -shake it to see whats wrong- and it worked !!)and rocks were found in the tanks. Seems this was done to sabotage development. After this indegenous development went ahead with full force as they now understood that the Russian stage could not be relied on. Oh the games played by the MTCR gang.

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Re: Indian Space Programme Discussion

Postby member_28108 » 28 Aug 2015 06:15

SriKumar wrote:Quite a lot of progress....I can recall the launch where the first desi cryostage was used and it ignited but did not sustain. I think the centrifugal pumps were the culprit. And the next one with the ruskie stage which collapsed during launch due to fairing issues. THere is brochure out there that covered all the things that were redesigned/modified after those two launch failures.

This CUS used variable thrust ...not sure if this the the first time that was done or did they do this with the previous launch as well. Does any other launch group do this?
I think ISRO probably has one more ruskie cryo stage.....I doubt if it will be used...it must have been opened up for post-mortem after the ealier ruskie cryostage in GSLV failed.


CUS is a dialable configuration by design. There were certain things done in the period between the two GSLV launches and that was optimization of the configuration - this was mentioned in the launch briefing.
Incidentally if you go through the video ISRO does have camera's on the spacecraft. I think they just do not release it to the public. Two of the monitors seemed to be beaming back pictures of some part of the launch vehicle /satellite.

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Re: Indian Space Programme Discussion

Postby member_28108 » 28 Aug 2015 06:42

This is from the GSLV D6 brochure
Inclusion of Video Imaging System to monitor lower
shroud movement during various phases of flight

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Re: Indian Space Programme Discussion

Postby Mort Walker » 28 Aug 2015 06:54

manjgu wrote:can someone in short explain the extra capabilites accruing to the def. services on account of this satellite?



Secure voice and data communications with a lot bandwidth for regular operations and coordinating air, land and naval operations. Also in the event of natural disaster or a nuclear war. Additionally, those who have nefarious designs and communicate voice and data in extended Akhand Bharat and IOR will be known and located, thereby scotching their plans. The TSPA rats can't plan another Mumbai attack via satellite phone to terrorists on fishing trawlers.

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Re: Indian Space Programme Discussion

Postby Mort Walker » 28 Aug 2015 07:00

prasannasimha wrote:
SriKumar wrote:Quite a lot of progress....I can recall the launch where the first desi cryostage was used and it ignited but did not sustain. I think the centrifugal pumps were the culprit. And the next one with the ruskie stage which collapsed during launch due to fairing issues. THere is brochure out there that covered all the things that were redesigned/modified after those two launch failures.

This CUS used variable thrust ...not sure if this the the first time that was done or did they do this with the previous launch as well. Learnt one new thing today.... rocket ko kehte hain 'pramochan yaan'. Wish they have a channel (even just audio, no video) where the mission control callouts are the only voices and no commentary. 'cryogenic stage parfaarmans naarmal' was called out several times during the 12 minute CUS burn ....and for each time there was applause. The guys (and one gal) at mission control must have been relieved. It is gutsy to publicly show the predicted velocity and altitude. Does any other launch group do this?
I think ISRO probably has one more ruskie cryo stage.....I doubt if it will be used...it must have been opened up for post-mortem after the ealier ruskie cryostage in GSLV failed.

The Russian stage will not be used. If you remember right after a successive series of failures, a shake test was done (typical Indian solution to many problems -shake it to see whats wrong- and it worked !!)and rocks were found in the tanks. Seems this was done to sabotage development. After this indegenous development went ahead with full force as they now understood that the Russian stage could not be relied on. Oh the games played by the MTCR gang.



Did the Russians put rocks in the tanks or was it something else like shoddy workmanship by Ivan having a few extra vodkas?

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Re: Indian Space Programme Discussion

Postby sum » 28 Aug 2015 07:09

Mort Walker wrote: The TSPA rats can't plan another Mumbai attack via satellite phone to terrorists on fishing trawlers.

Do we have sat phone decrypting capabilities to be able to make sense of the captured intercepts?

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Re: Indian Space Programme Discussion

Postby member_28108 » 28 Aug 2015 07:19

Mort Walker wrote:
Did the Russians put rocks in the tanks or was it something else like shoddy workmanship by Ivan having a few extra vodkas?


Supposed to be a complex interplay between the then superpowers and others having cryogenic technology - it ended up with "seen to be giving but did not" type of thing. It was a murky cat and mouse game. Once we got through critical steps no one could stop us. I bet the same will happen with fighter engine technology.

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Re: Indian Space Programme Discussion

Postby SriKumar » 28 Aug 2015 07:23

1 I know CUS is dialable, but it was not known to me if the variable thrust was _actually_ used in the previous GSLV flight or is this the first flight where it was actually used during flight (the commentators mention this one going 11% beyond nominal and then back to nominal). I am sure it would have been done on ground test.
2 About the last ruskie stage that flew (and failed), there was an interstage fairing..the shroud, that was weaker (thinner) than expected and that collapsed, breaking the connectors between the top stage and the rest of the rocket, and that was the end of the flight. I think it was traced to the weak shroud. This is when they went looking at the last remaining ruskie stage. I am not aware of a shake test but there was some note in the press that the ruskies did not give permission to ISRO to open up the reminaing stage for a post-mortem, so it makes sense that they might have atleast shaken it. (As for finding actual rocks, that's bizarre, this is the first I am hearing about it).
3 Cameras- I am sure they had a camera pointed to the shroud that had collapsed in the previous (ruskie CUS) flight.....if one recalls, the payload fairing was larger for the rusike CUS GSLV than the previous (desi CUS) GSLV.
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Re: Indian Space Programme Discussion

Postby saip » 28 Aug 2015 07:24

Controversial GSAT-6 satellite up in space

Link

What is he trying to prove here, that he has a long memory? Instead of seeing a congratulatory headline i see this and my blood boils. That 'controversy' was over in 2011.

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Re: Indian Space Programme Discussion

Postby Mort Walker » 28 Aug 2015 08:04

prasannasimha wrote:
Mort Walker wrote:
Did the Russians put rocks in the tanks or was it something else like shoddy workmanship by Ivan having a few extra vodkas?


Supposed to be a complex interplay between the then superpowers and others having cryogenic technology - it ended up with "seen to be giving but did not" type of thing. It was a murky cat and mouse game. Once we got through critical steps no one could stop us. I bet the same will happen with fighter engine technology.


My guess is that there were bolts in the tanks which were never properly fastened. It is disturbing that the Russians wouldn't let ISRO do a post mortem.

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Re: Indian Space Programme Discussion

Postby Mort Walker » 28 Aug 2015 08:06

sum wrote:
Mort Walker wrote: The TSPA rats can't plan another Mumbai attack via satellite phone to terrorists on fishing trawlers.

Do we have sat phone decrypting capabilities to be able to make sense of the captured intercepts?


I don't know, but the encryption is probably a standard which can be broken. It would be safe to assume they do.

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Re: Indian Space Programme Discussion

Postby disha » 28 Aug 2015 08:30

The TSPA rats can't plan another Mumbai attack via satellite phone to terrorists on fishing trawlers.
Do we have sat phone decrypting capabilities to be able to make sense of the captured intercepts?


I don't know, but the encryption is probably a standard which can be broken. It would be safe to assume they do.


As somebody higher up the chain indicated to my algorithm., I can easily break your encryption - all I need is the keys.

Encrypted conversation itself may not be easily broken. However one does not always rely on breaking the encryption in an intercepted phone call. Just like every mobile phone has a "device number" - all sat phones have a "device number" which is unique and can be tracked back to the manufacturer. Further, any good encryption is going to be hardware based which further means that the encryption algorithms are burnt into the chips. Further any device which uses encryption algorithm for example AES has to meet the export requirements. Devices using encryption (software or hardware) cannot be easily exported.

So in summary, a baki getting their hands on encrypted satphones can only happen if they "raided" a US supply chain and stole the devices (or the US gave them away) and further can operate it (assuming the stolen device id has not been blacklisted already). And let us say that bakis communicate over that encrypted phone and plane a terror attack., US can be held liable. So it is not easy to get your hands on sat phones that support encryption easily.

Now let us say India intercepts calls from mid-sea on a dhow with destination to bakis and if the intercept indicates an encrypted communication from an unknown or unregistered or stolen device., that in itself is a red flag. And if that red flag'ed dhow starts meandering towards India., coast guard will be sent to investigate and we all know what happened to the terror boat. Of course to destroy evidence is easy., all the comm equipment is thrown overboard or the dhow itself is gutted to sink.

Again one does not have to completely decrypt to eavesdrop. The very fact that two points are talking when they do not have any need to talk itself is information.

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Re: Indian Space Programme Discussion

Postby disha » 28 Aug 2015 09:06

SriKumar wrote:1 I know CUS is dialable, but it was not known to me if the variable thrust was _actually_ used in the previous GSLV flight or is this the first flight where it was actually used during flight (the commentators mention this one going 11% beyond nominal and then back to nominal). I am sure it would have been done on ground test.
2 About the last ruskie stage that flew (and failed), there was an interstage fairing..the shroud, that was weaker (thinner) than expected and that collapsed, breaking the connectors between the top stage and the rest of the rocket, and that was the end of the flight. I think it was traced to the weak shroud. This is when they went looking at the last remaining ruskie stage. I am not aware of a shake test but there was some note in the press that the ruskies did not give permission to ISRO to open up the reminaing stage for a post-mortem, so it makes sense that they might have atleast shaken it. (As for finding actual rocks, that's bizarre, this is the first I am hearing about it).
3 Cameras- I am sure they had a camera pointed to the shroud that had collapsed in the previous (ruskie CUS) flight.....if one recalls, the payload fairing was larger for the rusike CUS GSLV than the previous (desi CUS) GSLV.


The variable thrust of the CUS is known. It was used in previous launch as well. The nominal thrust is 75KN (wiki has got it wrong)., the lower-higher range is 73.5 - 82 KN. The higher thrust is used to give the last orbital kick to the sat.

Variable thrust is a standard feature for all liquid engines. CE 7.5 (ISRO should come up with better name like 'laghu urja' or something like that) is indeed a powerful engine., if you study the GSLV MKII., you would notice that the solid boosters provide some 70-75% of the thrust but the CUS provides 50% of the velocity. In layman terms, the solid booster takes the 2 ton satellite some 75% up - but this will fall back to earth (with a parabolic trajectory somewhere nearby in andamans) unless the CUS kicks it enough to make it fall the earth very very very far. In fact the CUS has kicked it so far now that the satellite is constantly falling to earth.

Coming to the failure analysis., the ruskies did not give the shear and other engineering data of the shroud. Basically they did not want to admit that their shroud was not within the tolerances. Lot of information that pinpoints on how the shroud would have behaved under various loads was withheld. On BRF itself we had concluded that the shroud did not perform to the spec and buckled - disconnecting the chords. However that is past.

PSLV when it first launched successfully, it launched *only* @800 Kg IRS sat., and everybody bemoaned it as a disaster for India. But nobody congratulated ISRO when RISAT was launched at @1800 Kgs. This is indicative of the progress being made. As more flight experience is gained (results in more data)., the tolerances are narrowed and also better material is added. I will not be surprised that if the GSLV Mk II is allowed to continue, it will reach some 3.5 tonnes to GTO by say 10th flight.

I still feel ISRO should continue research and development of make the CE 7.5 into CE 25 staged combustion into a monster like the SSME. Also a multi-restartable cryogenic engine is needed. Astute observers would have noted that US, Russia, Japan, ESA and India only have the staged combustion engine.

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Re: Indian Space Programme Discussion

Postby Neela » 28 Aug 2015 09:11

Ce20 providing 200kn thrust is being tested. Has completed endurance test 2 months back.
Ce60 providing 600kn is planning phase.

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Re: Indian Space Programme Discussion

Postby juvva » 28 Aug 2015 09:48

Bheeshma wrote:So next GSLV-II and III launch are only in 2016. Just a measly PSLV to look forward to for the rest of the year. :(( :((

Well anyway not ISRO related but hopefully DRDO/SFC/IN will keep us jingos entertained with K-4/A-4 & A-5.


Plus: Not to forget ISRO's RLV-TD experimental flight.

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Re: Indian Space Programme Discussion

Postby juvva » 28 Aug 2015 10:23

The launch was into a heavily overcast sky, according to the broadcast commentary it was raining significantly even a few minutes before the launch without causing any holds, I think they would have launched even if it continued to rain thru T=0. Speaks volumes for the confidence of ISRO in the all weather specs. of the launcher(s).

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Re: Indian Space Programme Discussion

Postby disha » 28 Aug 2015 10:33

Neela wrote:Ce20 providing 200kn thrust is being tested. Has completed endurance test 2 months back.
Ce60 providing 600kn is planning phase.


Those are gas generator ones, not the staged combustion. I was specifically referring to scale up the current CUS

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Re: Indian Space Programme Discussion

Postby Singha » 28 Aug 2015 11:45

found this on spacenews.com in gslv launch report. what does it mean?

With the advent of electric propulsion aboard commercial telecommunications satellites for both in-orbit station-keeping and orbit-raising to final geostationary position, the future market for a 2,000-kilogram-class vehicle has greatly improved. - See more at: http://spacenews.com/successful-indian- ... NgxqR.dpuf


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