Indian Space Program Discussion

girish.r · Post by **girish.r** » 26 Apr 2012 15:14

keshavchandra wrote:[youtube]Gv1CId2aKAw&feature=endscreen[/youtube]
India Launches Indigenous Radar Imaging Satellite (RISAT-I) - PSLV-C19.

Congrats to all! Bravo!

adityadange · Post by **adityadange** » 26 Apr 2012 15:22

congratulations ISRO and my fellow Indians!

Picklu · Post by **Picklu** » 26 Apr 2012 15:44

Was it a conscious decision to gift the nation not just a rocket launch but also some spectacular visual as a brand recall for Indian space program? Sort of like those MIRV impact images associated with US Missile program? Because these launch images at sun rise are going to create exactly that.
So, good job ISRO on PR and Marketing (apart from the flawless rocket science part).

vdutta · Post by **vdutta** » 26 Apr 2012 16:27

Picklu wrote:Was it a conscious decision to gift the nation not just a rocket launch but also some spectacular visual as a brand recall for Indian space program? Sort of like those MIRV impact images associated with US Missile program? Because these launch images at sun rise are going to create exactly that.
So, good job ISRO on PR and Marketing (apart from the flawless rocket science part).

i wish next time they put a camera at the launching tower, and few cameras right above each stage so we can get live feed of the voyage and stage separations

vdutta · Post by **vdutta** » 26 Apr 2012 16:31

gakakkad · Post by **gakakkad** » 26 Apr 2012 16:52

vina wrote:
Talk about self goals and other idiocies. I remember when IRS was launched first, the media went to town about it as a "spy satellite".

turns out this is the 6th "first spy satellite" launched by des .

Varoon Shekhar · Post by **Varoon Shekhar** » 26 Apr 2012 17:32

Outlook India's article on the launch is surprisingly good, and well informed. It says virtually nothing about 'spying' capabilities of RISAT-1, and concentrates on agriculture etc. Outlook is usually DDM on anything to do with defense, nuclear and space.

http://news.outlookindia.com/items.aspx?artid=760730

Rahul M · Post by **Rahul M** » 26 Apr 2012 17:46

vdutta wrote:Up up.... and away

[img http://cache.daylife.com/imageserve/06p ... Z/x610.jpg[/img]

[img http://cache.daylife.com/imageserve/0cB ... y/610x.jpg[/img]

awesome shots ! where did you get them ?

jaladipc · Post by **jaladipc** » 26 Apr 2012 19:20

What is the difference between C band SAR and X band SAR?

While we imported israeli made X band SAR, why did ISRO choose C band?

Can any guru point out the advantages and dis-advantages in both systems?

And why is the service life only 5 years? is it due to the MTBF of SAR or the fuel capacity for station keeping?

prashanth · Post by **prashanth** » 26 Apr 2012 21:55

^^
Not an expert in this field, but this is what I can say.

C and X bands are different bands of microwaves.
C: 4-8GHz.
X:8-12GHz.

http://en.wikipedia.org/wiki/C_band#Oth ... wave_bands

X band T&R modules for radar applications require advanced high power GaN amplifiers, a technology not yet perfected by India (iirc).
We however have the capability to produce GaAs amplifiers. It is possible to achieve better radar image resolution using the X band.

Here is a wiki article on MMICs, used for T&R modules in radars.
http://en.wikipedia.org/wiki/Monolithic ... ed_circuit

nachiket · Post by **nachiket** » 26 Apr 2012 22:03

prashanth wrote: X band T&R modules for radar applications require advanced high power GaN amplifiers, a technology not yet perfected by India (iirc).
We however have the capability to produce GaAs amplifiers. It is possible to achieve better radar image resolution using the X band.

GaN technology is not in widespread use yet. The X-band AESA radars on military aircraft are still GaAs based. But yes, designing and manufacturing C-band T/R modules will be less complex than X-band modules.

PratikDas · Post by **PratikDas** » 26 Apr 2012 22:16

vina wrote:Can any electronics/communication/physics/engg physics etc folks comment on this.

Why is the RISAT a C band Radar while others like the German TerraSar-X (roughly comparable,weight , performance, altitude etc) are X band and so are mostly other space based SARs, including the RISAT-2 which used an Isreali X band SAR.

DDM and esp the TV kinds are total morons. India already has a dedicated military satellite the RISAT-2 with a mil-grade SAR, with far higher resolution and which flies lower and probably has a greater revisit, but they want to put a "military" dog and pony show on RISAT-2 . So will the German TerraSar-X and TerraDem-X be classified as miliatary by those same dorks.

Talk about self goals and other idiocies. I remember when IRS was launched first, the media went to town about it as a "spy satellite".

Vina ji, since the project was started in 2002, X-band SAR would've been too high a target. The TR modules for X-band, as prashanth said, need different technology for good efficiency. GaAs will not give the power efficiency and density that GaN can. IMHO opinion, the C-band SAR in RISAT-1 was challenging enough for ISRO. In hindsight, that it took 10 years instead of 5 as envisaged says much. This from project director Smt. N. Valarmathi:
NYDailyNews: Woman behind Risat-1 feels on top of the world

She does not agree the project got inordinately delayed or it got speeded up after a point.

'From the beginning the project progressed at a good pace,' remarked Valarmathi who loves nature and reading books.

I guess there was more to learn than they'd predicted. She also says, "There will be several Risats working in various bands". So RISAT-1 was a stepping stone to the higher bands. Fair enough.

Neela · Post by **Neela** » 26 Apr 2012 22:42

^^^
Pratik summed it up well.

Looks like DRDO has GaAs in the kitty as is evident from this page here. http://drdo.gov.in/drdo/labs/SSPL/Engli ... cility.jsp . The things listed there are various process es and equipment required to make a chip. This stuff goes into mmW seeker of Nag.

GaN is relatively new and I guess the problem is to get the heat out of the transistor.
DRDO 2008 techfocus has a mention : http://www.drdo.gov.in/drdo/pub/techfoc ... /oct08.pdf

If this is the state of DRDO, we are at striking distance of AESA.

disha · Post by **disha** » 26 Apr 2012 22:46

vina wrote:Why is the RISAT a C band Radar while others like the German TerraSar-X (roughly comparable,weight , performance, altitude etc) are X band and so are mostly other space based SARs, including the RISAT-2 which used an Isreali X band SAR.

Simple. Different applications.

C-Band Radar has the advantage over x-band that it is not as widely dispersed by the cloud cover. Hence for the given transmitter power, wider and better coverage than an x-band radar. A C-Band radar will enable broader swathes to be covered at a given time.

X-Band Radar on the other hand gives more detail, and hence ideal for spot coverage (a smaller spot). An ideal combination will be a C-band and an X-Band radar with some VHF/UHF frequencies as well (for ground penetrating). That will be an ultra-wide band radar., but that will come only if a double-decker bus size of satellite powered with a nuclear reactor is launched. That is quite ways off in cost (and launch).

Note a larger receiving antenna can compensate for a given disperson, but a larger antenna may result in more weight and power requirements which will go against launch parameters. So an optimum balance has to be achieved for the cost of the satellite, launch of the satellite, mission up-keep, data analysis and distribution etc.

PratikDas wrote:
Vina ji, since the project was started in 2002, X-band SAR would've been too high a target. The TR modules for X-band, as prashanth said, need different technology for good efficiency. GaAs will not give the power efficiency and density that GaN can. IMHO opinion, the C-band SAR in RISAT-1 was challenging enough for ISRO. In hindsight, that it took 10 years instead of 5 as envisaged says much. This from project director Smt. N. Valarmathi:

She does not agree the project got inordinately delayed or it got speeded up after a point.

'From the beginning the project progressed at a good pace,' remarked Valarmathi who loves nature and reading books.

I would go with the above quote of N. Valarmathi and even taken out of context, indicates that it is not just about mastering TR modules for X-band in GaN or GaAs. It is about putting it in a package that can be launched and have a generally good usage (data analysis and disbursement processes is part of the learning curve) over a feasible life time.

I guess there was more to learn than they'd predicted. She also says, "There will be several Risats working in various bands". So RISAT-1 was a stepping stone to the higher bands. Fair enough.

So they are going with best of breed approach instead of all in one approach. Given the launch capacity and different usage scenarios that makes sense. Also the risk is spread across a constellation of satellites. All the data gathered than can be integrated and various services can be provided from a single nodal agency.

disha · Post by **disha** » 26 Apr 2012 22:51

Dharma R wrote:And why is the service life only 5 years? is it due to the MTBF of SAR or the fuel capacity for station keeping?

Fuel capacity for station keeping being the primary. Also degradation of the batteries and the solar cells, remember they are working in space and not in idea STP conditions.

jaladipc · Post by **jaladipc** » 26 Apr 2012 23:30

^^^
Probably station keeping role and other military needs(which burns out more fuel).

I dont think the battery life as a point of concern,since other remote sensing sats stay there for a life of 10-15 years.

And other could be the MTBF of the TR modules,since unlike ground radars, these will be continuously operating 24/7 with no backup and maintainance?

The ultra-wide band radars might be the way forward,given that our own GSLV MKIII can put a 10 tonne sat in LEO,if we start on the drawing board now, by the time MKIII becomes fully operational we might be able to orbit such a satellite.

Like the ex-scientist said, a remote sensing sat with both cameras and infra-red and radars all onboard a single system might be much more suitable and economical. For that a 4K bus structure might be good enough?

vdutta · Post by **vdutta** » 26 Apr 2012 23:57

Rahul M wrote:
vdutta wrote:Up up.... and away

[img http://cache.daylife.com/imageserve/06p ... Z/x610.jpg[/img]

[img http://cache.daylife.com/imageserve/0cB ... y/610x.jpg[/img]
awesome shots ! where did you get them ?

daylife.com . its a very common news photos website.

sanjaykumar · Post by **sanjaykumar** » 27 Apr 2012 07:39

Rraakit tchnlgy mubarak.

symontk · Post by **symontk** » 27 Apr 2012 08:29

The life of 5 years is due to the orbit, its clsoe to 500Kms unike other IRS satellites of 800+. There will be rapid degradation. Also we dont know the abilities of C-BAND SAR at higher altitudes. That also would be a consideration. Unlike other IRS satellites which uses optics for recon, this one uses RADAR and so may be made effective at lower altitudes

The orbit is comparable to RISAT-2 though

SaiK · Post by **SaiK** » 27 Apr 2012 08:47

disha · Post by **disha** » 27 Apr 2012 08:49

SaiK wrote:Interesting.. Is this the normal way they lift and assemble?

Where are the elephants and buffaloes? Must be having emmissions issue.

Nick_S · Post by **Nick_S** » 27 Apr 2012 08:50

Informative video on RISAT.

- AESA radar
- 576 TR modules

Plus finally figured out how to embed youtube videos

Anujan · Post by **Anujan** » 27 Apr 2012 09:10

And Old photo, the SAR of RISAT being tested over Coorg (if I recall correctly)

vina · Post by **vina** » 27 Apr 2012 10:03

Good. Now that we have an AESA radar in space with SAR implemented, and the DRDO Awacs flying (I think it is L Band) and in today's Al-Hundi right at the first page there was an advert from Astra Microwave congratulating ISRO ,with an Oh.. Many of our components are on the RISAT

.. I guess that they have supplied some of the microwave components.

All in all good. Now to get over the hump and develop a X band fighter sized tactical AESA radar with all the bells and whistles, as an enhancement of the MMR on the LCA !1

SaiK · Post by **SaiK** » 27 Apr 2012 21:11

Well the L wala could be needed to tail on raptoriskies. A wide bandwidth array sets integrated into FCR would be fantastic, especially when we are forging ahead for AMCA.

For the LCA, the 3D AESA FCR may still perhaps get Elta inputs.. the 2052 ban on India, must be repelled by Obama admin, and accept Elta participation for LCA AESA FCR. Now, we have always worked good under sanctions and bannings.. except for a few niche and precision engineering setups.

sukhish · Post by **sukhish** » 28 Apr 2012 03:26

did anybody noticed that the launch pad was different, than the previous one.

Varoon Shekhar · Post by **Varoon Shekhar** » 28 Apr 2012 04:15

"GSLV Mk2 in June
GSLV Mk3 in December
PSLV C20 or C21 August"

It's nice that these are going to be launched this year. But it means that Astrosat and SRE-2 will be pushed back. Commercial considerations with the SARAL and SPOT satellites are no doubt the rationale. Understandable, but still disappointing!

sivab · Post by **sivab** » 28 Apr 2012 06:20

^^^ That is DDM.

http://www.thehindu.com/news/national/a ... 356064.ece

“We are planning a GSLV launch with Indian cryogenic engine during September-October 2012,” Dr. Radhakrishnan said.

However, India's second moon mission Chandrayaan-2, slated for 2014, would have to wait until the ISRO carried out GSLV flights successfully, the ISRO chief said.

“We plan to fly two GSLV rockets at an interval of six months and the third will be for the Chandrayaan-2 mission.”

On the status of the GSLV Mark-III, the upgraded variant of the GSLV, Dr. Radhakrishnan said as the rocket would have a high power cryogenic engine, the engine's various subsystems had to be rigorously tested, and this could take a couple of years.

He said an experimental flight of the GSLV Mark-III without the cryogenic engine is planned during 2012-13 to test the rocket's other parameters.

SSSalvi · Post by **SSSalvi** » 28 Apr 2012 09:24

RISAT 1 Orbital coverage area as seen from Nagpur ( Centre of India )

Varoon Shekhar · Post by **Varoon Shekhar** » 29 Apr 2012 06:35

http://www.isro.org/pressrelease/script ... lease.aspx

April 28, 2012
Radar Imaging Satellite (RISAT-1) successfully placed in its final orbit

The Radar Imaging Satellite (RISAT-1), launched by PSLV-C19 on April 26, 2012, has now been placed in its final Polar Sun-synchronous Orbit of 536 km height.

It may be recalled that PSLV-C19 had placed RISAT-1 in a polar orbit of 470 km X 480 km. As planned, on April 27-28, 2012, the satellite propulsion system was used in four orbital maneuvers to raise height of the orbit of RISAT-1 to 536 km. The satellite is now in its final orbital configuration and in good health. In the coming days, various elements of the C-band Synthetic Aperture Radar will be tested and calibrated as a prelude to payload operations.

As compared to the optical remote sensing satellites that depend upon sunlight, the Synthetic Aperture Radar of RISAT-1 transmits its own radar pulses (at 5.35 GHz) to study the objects on Earth. This facilitates

1.cloud penetration and
2.imaging even without sunlight.

For RISAT-1, imaging sessions around both 6 AM and 6 PM have been chosen.

VinodTK · Post by **VinodTK** » 03 May 2012 04:50

India yet to arrive on military satellite scene: US expert

Chennai: The launch of the Radar Imaging Satellite (Risat-1) is a major step forward for India but it must increase its capacity and launch many more satellites to be considered a serious player in making military satellites, says an official of a US-based space consultancy firm.

"Risat-1 represents another step forward for India. Its synthetic aperture radar (SAR), which enables imaging through bad weather conditions during both day and night, will assist Indian land management, agriculture monitoring and resource observation. The satellite mission is in keeping with India's traditional use of space assets for social benefit," David Vaccaro, programme manager at the Futron Corporation, told IANS in an e-mail interview.

He, however, said India cannot be considered a major force in building military satellites at present.

"With the development of SAR imagers and applications, India is increasingly capable of producing satellites that could be used for surveillance and military reconnaissance. However, for it to become a greater player in this regard, it must first increase its capacity to build and launch such satellites quickly, and in larger volumes," Vaccaro said.
:
:

Craig Alpert · Post by **Craig Alpert** » 03 May 2012 05:24

more than that, ISRO needs to look into the possibility of jamming satellites uplinks/downlinks.... This should be the main focus if India wants to deny it's enemies that advantage and force them to fight blind!

jaladipc · Post by **jaladipc** » 03 May 2012 07:29

PratikDas wrote:
vina wrote:Can any electronics/communication/physics/engg physics etc folks comment on this.

Why is the RISAT a C band Radar while others like the German TerraSar-X (roughly comparable,weight , performance, altitude etc) are X band and so are mostly other space based SARs, including the RISAT-2 which used an Isreali X band SAR.

DDM and esp the TV kinds are total morons. India already has a dedicated military satellite the RISAT-2 with a mil-grade SAR, with far higher resolution and which flies lower and probably has a greater revisit, but they want to put a "military" dog and pony show on RISAT-2 . So will the German TerraSar-X and TerraDem-X be classified as miliatary by those same dorks.

Talk about self goals and other idiocies. I remember when IRS was launched first, the media went to town about it as a "spy satellite".
Vina ji, since the project was started in 2002, X-band SAR would've been too high a target. The TR modules for X-band, as prashanth said, need different technology for good efficiency. GaAs will not give the power efficiency and density that GaN can. IMHO opinion, the C-band SAR in RISAT-1 was challenging enough for ISRO. In hindsight, that it took 10 years instead of 5 as envisaged says much. This from project director Smt. N. Valarmathi:
NYDailyNews: Woman behind Risat-1 feels on top of the world
She does not agree the project got inordinately delayed or it got speeded up after a point.

'From the beginning the project progressed at a good pace,' remarked Valarmathi who loves nature and reading books.
I guess there was more to learn than they'd predicted. She also says, "There will be several Risats working in various bands". So RISAT-1 was a stepping stone to the higher bands. Fair enough.

This means we do have the tech required for X-band SAR.

IF DRDO has the tech, it also means ISRO can get its hands on

PratikDas · Post by **PratikDas** » 03 May 2012 07:51

Dharma R wrote: This means we do have the tech required for X-band SAR.

IF DRDO has the tech, it also means ISRO can get its hands on

Those will most probably be Selex Galileo's TR modules
http://m.upi.com/m/story/UPI-13121335558614/

Europe's electronics giant Selex Galileo this month said it was plumbing the Indian market with a joint venture with India's Data Patterns Group.

"This joint venture will bring a technology value to India's growing defense program," said S Rangarajan, Data Patterns chief executive officer. "Selex Galileo is a leading global player and we are happy and proud to form a joint venture with them.

vic · Post by **vic** » 03 May 2012 11:35

I was comparing the specifications of RISAT-1 C Band Satellite with Terrasar which is X band satellite and the specifications seem pretty close:-

http://en.wikipedia.org/wiki/TerraSAR-X

With its active phased array X-band SAR antenna (wavelength 31 mm, frequency 9.6 GHz), TerraSAR-X acquires new high-quality radar images of the entire planet whilst circling Earth in a polar orbit at 514 km altitude. The orbit is selected such that the satellite flies in a sun-synchronous dusk-dawn orbit, which means that it moves along the day-night boundary of the Earth and always presents the same face to the sun, ensuring an optimum energy supply via the solar cells. TerraSAR-X is designed to carry out its task for five years, independent of weather conditions and illumination, and reliably provides radar images with a resolution of up to 1m.

Features of TerraSAR-X:
resolution of up to 1m,

TerraSAR-X Imaging Modes

TerraSAR-X acquires radar data in the following three main imaging modes:

SpotLight: up to 1m resolution, scene size 10 km (width) x 5 km (length)
StripMap: up to 3m resolution, scene size 30 km (width) x 50 km (length*)
ScanSAR: up to 18 m resolution, scene size 100 km (width) x 150 km (length*)

Hiten · Post by **Hiten** » 09 May 2012 15:17

NDTV did a news segment on the GSLV Mk. III

http://www.youtube.com/watch?v=jBmyUMDLDPM

jaladipc · Post by **jaladipc** » 09 May 2012 19:01

PratikDas wrote:
Dharma R wrote: This means we do have the tech required for X-band SAR.

IF DRDO has the tech, it also means ISRO can get its hands on
Those will most probably be Selex Galileo's TR modules
http://m.upi.com/m/story/UPI-13121335558614/
Europe's electronics giant Selex Galileo this month said it was plumbing the Indian market with a joint venture with India's Data Patterns Group.

"This joint venture will bring a technology value to India's growing defense program," said S Rangarajan, Data Patterns chief executive officer. "Selex Galileo is a leading global player and we are happy and proud to form a joint venture with them.

No Saar.

The seeker was developed by DRDO. Datapatterns was a component supplier and was outsourced some of the design process.Take a peek into the companys client list

this is the actual seeker http://1.bp.blogspot.com/-TLf6zifdyqM/T ... C01814.JPG

We sure do have the X-band T/R module tech.

According to B.V.Ramesh project director of LRDE`s LSTAR programme ,an LRDE developed X-band AESA radar couild be fitted on Tejas by 2014.Two modules of AESA radar have already been launched

http://drdo.gov.in/drdo/English/dpi/200 ... 8_2009.pdf

Dr DR Jahagirdar, Sc 'F', Research Centre Imarat (RCI), Hyderabad has made significant contributions in the development of antennae and arrays for missile-borne microwave systems. The contributions include development of unique trans-twist reflect-array for MMW seeker, planer monopulse slotted array antennae for seekers in Ku and Ka band, monopulse printed seeker antennae at X and Ku band and development of flight-worthy antennae for systems in Prithvi, Akash, Trishul, Astra, Agni-III, PJ-10 and K-15 projects.

http://pib.nic.in/newsite/erelease.aspx?relid=62090

PratikDas · Post by **PratikDas** » 09 May 2012 19:15

Then the next RISATs might not be far away

Prem Kumar · Post by **Prem Kumar** » 10 May 2012 04:40

An X band seeker for a missile is not the same as an X band SAR. The SAR on a satellite would need to tackle other aspects like range, classification algorithms etc. There will be commonalities of course. But having one doesnt mean the other is ready. For instance, we dont have an X Band AESA yet for LCA. All of these have different mission profiles and have their own challenges. We will get there - eventually.

alexis · Post by **alexis** » 10 May 2012 17:38

vic wrote:I was comparing the specifications of RISAT-1 C Band Satellite with Terrasar which is X band satellite and the specifications seem pretty close:-

http://en.wikipedia.org/wiki/TerraSAR-X

With its active phased array X-band SAR antenna (wavelength 31 mm, frequency 9.6 GHz), TerraSAR-X acquires new high-quality radar images of the entire planet whilst circling Earth in a polar orbit at 514 km altitude. The orbit is selected such that the satellite flies in a sun-synchronous dusk-dawn orbit, which means that it moves along the day-night boundary of the Earth and always presents the same face to the sun, ensuring an optimum energy supply via the solar cells. TerraSAR-X is designed to carry out its task for five years, independent of weather conditions and illumination, and reliably provides radar images with a resolution of up to 1m.

Features of TerraSAR-X:
resolution of up to 1m,

TerraSAR-X Imaging Modes

TerraSAR-X acquires radar data in the following three main imaging modes:

SpotLight: up to 1m resolution, scene size 10 km (width) x 5 km (length)
StripMap: up to 3m resolution, scene size 30 km (width) x 50 km (length*)
ScanSAR: up to 18 m resolution, scene size 100 km (width) x 150 km (length*)

Whatever may be the published data, x band radar will have better resolution than C band due to the inherent advantages of the x band and will be more suitable for military applications. RISAT 3 would hopefully have an X band radar.