Indian Space Programme Discussion

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Re: Indian Space Programme Discussion

Postby member_28108 » 29 Aug 2015 21:06

Electric propulsion currently is more useful for station housekeeping rather than actual transfer an it takes a very long time for the meaningful velocity to be achieved despite a very high Isp. That is why currently most of these thrusters are in research stage with most current ion thrusters etc being used for station keeping.
satellites like Hayabusa tried to use ion propulsion

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Re: Indian Space Programme Discussion

Postby SSridhar » 30 Aug 2015 07:17

One piece of information that was new to me was an ISTRAC station at Singapore. I was not aware of it earlier.

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Re: Indian Space Programme Discussion

Postby member_23694 » 30 Aug 2015 09:27

http://www.thehindu.com/news/isro-to-bo ... 594838.ece

the Indian Space Research Organisation (ISRO) is geared up to add more heft to the three-stage rocket to enable it to lob satellites weighing up to 2.5 tonnes into geosynchronous orbit.
ISRO scientists are confident that the indigenous Cryogenic Upper Stage (CUS) could be tweaked further to enhance the performance of the GSLV rocket.
The proposed modifications to CUS involve reducing the mass of the vehicle and augmenting the thrust.
He said a series of tests would be carried out next year to upgrade CUS and enable it to handle satellites up to 2.5 tonnes
The project to add muscle to the GSLV also involves tweaking the liquid strap on boosters and the second stage liquid propellant engine and reducing the mass of the avionics bay package.


Between D5 and D6 :
Strapons moves from 680 to 760 KN
First stage from 4800 to 4815
Second stage from 720 to 799
Further if i heard correctly CUS weight reduced by around 70 Kg.

Going forward CUS could go from 75 to 90 KN
Also use of 4 m payload fairing first tried in D3 could be back

All the above optimization and some more could probably take the GTO capability between 2.5 to 3 T in very near future

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Re: Indian Space Programme Discussion

Postby SSridhar » 30 Aug 2015 10:12

Singha wrote:is this LAM thing similar to what is used behind the RV of 3-stage ICBMs to hugely extend the range of the RV after the 3rd stage motor has burned out and separated away?


No, LAMs are not used for that purpose. In the case of a MIRV, the RV reorients itself slightly to release different warheads in different trajectories. In the case of MaRV, the range is increased by using flaps to produce a lift just as they are also used in glide bombs (Garuthma).

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Re: Indian Space Programme Discussion

Postby member_28108 » 30 Aug 2015 10:44

GSAT-6 Update:
Third orbit raising operation of GSAT-6 was successfully completed by firing the Apogee Motor for 580.32 seconds at 07:46 hr IST on Aug 30, 2015. Preparation for deployment of the unfurlable antenna (UFA) is in progress.

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Re: Indian Space Programme Discussion

Postby member_28108 » 30 Aug 2015 11:17

Regarding the cryogenic engines there is a difference in the requirement in the higher stages versus the lower stages.The power requirement in the higher stages are lower and are not comparable to the ones in the lower stages.For eg the F1 semicryogenic engines of Saturn V were huge and much more powerful and are incomparable to the ones in the higher stages.

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Re: Indian Space Programme Discussion

Postby member_28108 » 30 Aug 2015 11:21

The once a year launches of the GSLV Mk2 are more related to the otpimization path that is being taken to allow better launches. In fact the actual campaign time is 100 days so they could easily launch 3 -4 per year but due to the improvements and thhe testing required they are slowing down. I think this may be related more to the learning that is going on with the GSLV Mk2 which will be transferred to the Mk3 and ULMV. Each launch has got substantial differences than the next. So the vehicle technically each time is not the "same"

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Re: Indian Space Programme Discussion

Postby SSridhar » 30 Aug 2015 11:42

Singha wrote:must be a whole lotta hard math involved in these firings to know when to fire and how long to get circular orbit with least fuel burn

Ranging is important to know the precise position of the orbit to determine the burn and duration. Apart from circularizing the orbit, the inclination has also to be corrected using the same LAM firing. For example, the first orbit raising of GSAT-6 reduced the orbital inclination from ~20deg to 7.5 deg. If no such inclination correction were required, meaning if SrihariKota had been on the equator, LAM firing would have been much less. Plane corrections are costly operations in terms of fuel expenditure.

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Re: Indian Space Programme Discussion

Postby JTull » 30 Aug 2015 11:43

We often wonder why GTRE is not able to deliver while ISRO is able to and there were even suggestions to hand over Kaveri development to ISRO.

ISRO can incrementally improve the output and can take a decade extra to deliver what was promised. They follow a path of de-risking all along the development cycle.

GTRE is required to deliver more than what was initially required, without delay, and with a constant threat from the customer to import alternatives with brochure specs.

We should indeed hand over Kaveri development to ISRO. It will be much more difficult for esteemed 'customer' to defame a national institution and may be forced to take a slightly inferior product while better one is being continually developed.

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Re: Indian Space Programme Discussion

Postby Singha » 30 Aug 2015 12:16

So the Chinese must be burning more fuel than us for inclination correction and Russia even more

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Re: Indian Space Programme Discussion

Postby SSridhar » 30 Aug 2015 12:34

Some more info on what dhiraj has already posted on tweaking GSLV-MkII
Series production

S. Somanath, Director, LPSC, said the success of the GSLV D6 had proved the maturity of CUS and its evolution into a reliable engine. The challenge, he said, was to take up series production of the engine to meet the launch requirements. “The target is to produce two engines per year.” ISRO has plans to use the GSLV for 10 of the 30 launches over the next three years. {GSLV alone would be 3 launches a year?}

The CUS which powered GSLV D6 flight on Thursday was lighter by 40 kg and had an 11 per cent higher thrust than the engine used in the previous flight of the GSLV in 2014, enabling the rocket to carry an additional satellite mass of 100 kg. LPSC scientists hope to enhance the thrust of the engine by 26 per cent. “It may take two more launches over the next three years to reach this stage,” Mr. Somanath said.

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Re: Indian Space Programme Discussion

Postby SSridhar » 30 Aug 2015 12:36

Singha wrote:So the Chinese must be burning more fuel than us for inclination correction and Russia even more

oh yes. Ariane from French Guyana gets 6deg inclination while we get ~20deg. Srihari Kota is already 13.7178° N

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Re: Indian Space Programme Discussion

Postby member_28108 » 30 Aug 2015 12:36

SRO ‏@isro 5m5 minutes ago
GSAT-6 update :
Deployment of the unfurlable antenna (UFA) is in progress. :D

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Re: Indian Space Programme Discussion

Postby member_28108 » 30 Aug 2015 12:40

GSAT-6 update :
Deployment of the unfurlable antenna (UFA) is in progress.
UFA mid-hold down release successful. Primary arm deployed successfully.
UFA second hold-down release successful and pop-up confirmed.

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Re: Indian Space Programme Discussion

Postby SSridhar » 30 Aug 2015 13:24

GSLV Mk3 is the next milestone - The Hindu
ISRO is ramping up efforts for the mock trial of GSLV Mark 3 by mid-2016, prior to the first developmental flight scheduled for December 2016.

The biggest rocket made in India, the Mk3 will be capable of launching 4-tonne satellites into geosynchronous orbit.

Designed and developed by the LPSC, the high-thrust cryogenic rocket engine (C25) for the Mk3 was successfully ground-tested for a duration of 800 seconds on July 16 at the ISRO Propulsion Complex, Mahendragiri.

The next phase involves integration of the engine and stage. A series of ground and high altitude simulation tests will be carried out over the next eight to 10 months.

With GSLV Mk3, ISRO hopes to have a triad of launch vehicles, enabling it to capture a major share of the market for commercial satellite launches.

While the workhorse PSLV rocket would be used to launch satellites into lower orbit, the GSLV would be a strong candidate for satellites in the 2.2 to 2.5-tonne category and the Mk3 is expected to emerge as the favoured choice for heavier satellites up to 4 tonnes.

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Re: Indian Space Programme Discussion

Postby member_28108 » 30 Aug 2015 14:31

What is done exactly in a "Mock trial"

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Re: Indian Space Programme Discussion

Postby SSridhar » 30 Aug 2015 15:42

Do we assume that the antenna is now fully unfurled?

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Re: Indian Space Programme Discussion

Postby member_23694 » 30 Aug 2015 15:57

ISRO - Indian Space Research Organisation
43 mins ·
GSAT-6 UPDATE:
Deployment of the unfurlable antenna (UFA) is successfully completed.

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Re: Indian Space Programme Discussion

Postby SSridhar » 30 Aug 2015 15:58

Fantastic news.

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Re: Indian Space Programme Discussion

Postby deejay » 30 Aug 2015 16:26

^^^ Great, so all the sequences are now complete?

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Re: Indian Space Programme Discussion

Postby member_28108 » 30 Aug 2015 16:46

^^
GSAT-6 UPDATE:
Deployment of the unfurlable antenna (UFA) is successfully completed.

The satellite antenna has been completely unfurled.
I think this will be the first step to bigger antennae.
I believe the largest antenna deployed(Miitary) is 100 meters wide and the widest commercial antenna is 22 meters(Harris and astromesh)

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Re: Indian Space Programme Discussion

Postby member_23694 » 30 Aug 2015 17:20

I believe the largest antenna deployed(Miitary) is 100 meters wide and the widest commercial antenna is 22 meters


largest antenna deployed(Miitary) is 100 meters wide : NRO LR-32
widest commercial antenna is 22 meters : SkyTerra-1 mobile communications satellite
18m antenna : TerreStar-1

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Re: Indian Space Programme Discussion

Postby SSSalvi » 30 Aug 2015 18:05

Singha wrote:i used to think such motors were fired for few secs looking at movies, 1 hr sure is a long burn....are these apogee motors solid fuel based or liquid fuel and how much thrust? do we make them inhouse? are the same motors used for periodic station keeping manouvers in final orbit?

I must admit my heart was in my mouth when telemetry blinking light looked a bit unusual at 2nd stage and looking at the Mt everest type climb graph towards the end of the launch mission.


If it is useful:

SSSalvi wrote:IRNSS 1D may reach its home longitude today.

A post on Orbit Raising of IRNSS 1D has been created here.

Image Image Image


Also

http://indiaspaceactivity.blogspot.in/2 ... lyaan.html

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Re: Indian Space Programme Discussion

Postby member_28108 » 30 Aug 2015 18:20

India's inflatable antenna project
Image

Based on standard drum size must be around 9 meters (got 8.137 meters but would have to factor in oblique perspective etc) inflatable antenna.

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Re: Indian Space Programme Discussion

Postby RoyG » 30 Aug 2015 19:25

Scroll down to just a little before half the page :wink: . Interesting website overall.

http://www.dailywireless.org/2010/11/19 ... to-launch/

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Re: Indian Space Programme Discussion

Postby SriKumar » 30 Aug 2015 20:57

SSSalvi wrote:

Image Image Image


SSSalvi, regarding the middle picture showing the two inclined orbits...is it technically correct with respect to the orientation of the orbits relative to earth? The orbit is shown to be inclined 'upwards', i.e. the satellite goes from India 'towards' China i.e. southwest to northeast (if you trace the path on the ground).
However, the launch path of the PSLV that put it in orbit started at Srihari Kota and went south and east i.e. towards australia. I believe this should be the general direction of the satellite's orbit even if the inclination is changed by some degrees. What do you think?

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Re: Indian Space Programme Discussion

Postby Bade » 30 Aug 2015 21:07

Those are intermediate transfer orbits, no ? The orbital period is not the same as earth's 24 hr rotation. At some point the launch direction was what you say, towards Aus. Think the globe rotated by 180 deg.

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Re: Indian Space Programme Discussion

Postby Vayutuvan » 30 Aug 2015 21:19

Prasannasimha: take the drum length. Take the major and minor axis of the ellipse and a linear transform to make into a circle. But then why bother beyond what you have estimated? Good enough for general knowledge and some approximate back of the envelop calcs like what fermi used to do. On another note there is pop sci book called the Fermi Effect which is quite nice - gives insight into the genius of Fermi.

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Re: Indian Space Programme Discussion

Postby member_28108 » 30 Aug 2015 22:10

vayu tuvan wrote:Prasannasimha: take the drum length. Take the major and minor axis of the ellipse and a linear transform to make into a circle. But then why bother beyond what you have estimated? Good enough for general knowledge and some approximate back of the envelop calcs like what fermi used to do. On another note there is pop sci book called the Fermi Effect which is quite nice - gives insight into the genius of Fermi.



I agree that I could do that (In fact did it for the gun scatter to calcualte the CEP of the Tejas gun in the LCA thread) but this was a back of the cover calculation as you said and since most sizes are "standardized" It gave a close enough value to an established size. :D
I also have another reference which would have been less distorted- one of the drums used to prop up the antenna is right at the lower portion of the frame and taking its diameter and the segments of the inflatable structure you can calculate the diamter of the inflatable support/truss and get the diameter of the support etc.

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Re: Indian Space Programme Discussion

Postby SriKumar » 30 Aug 2015 22:20

Bade wrote:Those are intermediate transfer orbits, no ? The orbital period is not the same as earth's 24 hr rotation. At some point the launch direction was what you say, towards Aus. Think the globe rotated by 180 deg.

By intermediate transfer orbits, I assume you mean going from launch orbit to final orbit. I doubt the inclination would be changed (even if the 'ellipsity' of the orbit is changed). But I could be wrong....if it did, it would involve a lot of extra energy. I would like to know if inclinations are changed that significantly from launch to final GSO (perhaps SSSalvi can clarify).

'Globe rotating by 180' is (in my view) a different explanation, and plausible. Indeed, what would be south-east on this face would be north-east on the other side. But then, the other side would be night time :) and one cannot see the landmass as is shown... :P :P. But I agree it would be correct 6 months after launch i.e. when the day-light and orbit directions align.

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Re: Indian Space Programme Discussion

Postby member_28108 » 30 Aug 2015 22:41

SriKumar wrote:
Bade wrote:Those are intermediate transfer orbits, no ? The orbital period is not the same as earth's 24 hr rotation. At some point the launch direction was what you say, towards Aus. Think the globe rotated by 180 deg.

By intermediate transfer orbits, I assume you mean going from launch orbit to final orbit. I doubt the inclination would be changed (even if the 'ellipsity' of the orbit is changed). But I could be wrong....if it did, it would involve a lot of extra energy. I would like to know if inclinations are changed that significantly from launch to final GSO (perhaps SSSalvi can clarify).

'Globe rotating by 180' is (in my view) a different explanation, and plausible. Indeed, what would be south-east on this face would be north-east on the other side. But then, the other side would be night time :) and one cannot see the landmass as is shown... :P :P. But I agree it would be correct 6 months after launch i.e. when the day-light and orbit directions align.

The inclination will have to change as the launch angle and the final parking orbit would be different in a pure Geostationary orbit. This is why a launch on the equator(like as attempted by Sea Launch) uses the least energy)

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Re: Indian Space Programme Discussion

Postby SriKumar » 30 Aug 2015 23:52

^^^Well, clearly the inclinnation will change as SSSalvi has clarified with specific angles in his website that is linked.

[Added later: I see why you mention what you did. In my post above I mention 'change of inclination' but what I had meant (and I was more specific about this in the post prior to that) is the degree to which it changed- as described below]
What I commented about was whether it would change from +theta (Assuming theta is the angle taken by PSLV at launch) to -minus theta (as the posted diagram indicates). It is specifc to his diagram, so he might have a specific reason for it.

As for least energy, yes equatorial launches are least energy, as are launches going along earth's rotation etc. etc.
Last edited by SriKumar on 31 Aug 2015 02:37, edited 1 time in total.

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Re: Indian Space Programme Discussion

Postby KrishG » 30 Aug 2015 23:58


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Re: Indian Space Programme Discussion

Postby Varoon Shekhar » 31 Aug 2015 06:07

It's been 8 years( Sept 2/2007) since Insat-4Cr was launched( by a GSLV with Russian cryo). Because of a slight inaccuracy in the orbital parameters, a pronounced shortened life for the satellite was forecast. Insat 4Cr is functioning very well presently, far as can be seen, and is beaming a huge number of channels! When you press a link for Insat-4C, up comes an endless list of channels it is broadcasting. Unlike GSAT-14 or GSAT-16 which is not fully operational. Even GSAT-8 and GSAT-10 do not appear to be exploited to their fullest capacity. Is there a problem in obtaining users, or selling the service to private satellite operators?

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Re: Indian Space Programme Discussion

Postby member_28108 » 31 Aug 2015 06:36

Varoon Shekhar wrote:It's been 8 years( Sept 2/2007) since Insat-4Cr was launched( by a GSLV with Russian cryo). Because of a slight inaccuracy in the orbital parameters, a pronounced shortened life for the satellite was forecast. Insat 4Cr is functioning very well presently, far as can be seen, and is beaming a huge number of channels! When you press a link for Insat-4C, up comes an endless list of channels it is broadcasting. Unlike GSAT-14 or GSAT-16 which is not fully operational. Even GSAT-8 and GSAT-10 do not appear to be exploited to their fullest capacity. Is there a problem in obtaining users, or selling the service to private satellite operators?

GSAT 10 and 8 were mainly for the GAGAN payload

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Re: Indian Space Programme Discussion

Postby SSridhar » 31 Aug 2015 08:35

UAE likely to ask India's assistance in its Mars mission during foreign minister visit - Dipanjan Roy Chaudhury, Economic Times
The United Arab Emirates is expected to seek India's expertise in launching its Mars mission when its foreign minister Sheikh Abdullah Bin Zayed Al-Nahyan visits Delhi this week, opening a new chapter in bilateral ties beyond security and economic partnership within a fortnight of Prime Minister Narendra Modi's maiden trip to the oil-rich Gulf nation.

India's assistance for launching the Mars mission will work out more cost-effective for the UAE than is possible from Europe or USA, and mark the first such collaboration between India and any Gulf country, officials said. Al-Nahyan will be in Delhi on September 2-3 with an 83-member delegation, including top officials of the UAE's space agency and captains of industry.

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Re: Indian Space Programme Discussion

Postby gakakkad » 31 Aug 2015 08:54

In short UAE will finance the next mars mission for India ?

I mean they can't even send a sputnik equivalent anywhere...Mars would be too ambitious ....basically they are looking for a UAE painted indian probe , launched by GSLV /PSLV from India...

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Re: Indian Space Programme Discussion

Postby Karan M » 31 Aug 2015 09:03

So lets do it. It brings us hard cash.

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Re: Indian Space Programme Discussion

Postby Singha » 31 Aug 2015 09:51

yes , people like esa and surrey univ are always looking to make free money on the side and carry forth the narrative of helping the unwashed.

ISRO can and should develop some small sat reference designs, using COTS stuff, and offer to assemble and launch them to anyone who wants.....some section of students who are no good at building 'work experience' models use these shops in chikpet somewhere to get the science models done....you give them the task and budget and they will find the parts and get it done in a agile manner i have heard

the paying country can decide and build the payload, we can offer hand holding if needed and we would give the volume, weight and power draw specs. it can be something useful to them or even just a small tape recorder screaming the glory of their satrap or a bunch of insects in a bag if they want.

its time to demystify the whole onlee-goras-own-space thing and everyone from mali to fiji should have a mars or moon probe or a ping ping keepalive sat.

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Re: Indian Space Programme Discussion

Postby svinayak » 31 Aug 2015 10:03

Karan M wrote:So lets do it. It brings us hard cash.

$50B upfront


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