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Indian Space News and Discussion
Quote:India notches another space success

July 15, 2011 4:58:24 PM

[url="http://www.dailypioneer.com/353352/India-notches-another-space-success.html"]link[/url]

IANS | Sriharikota (Andhra Pradesh)

India notched another milestone in its space programme Friday evening when it successfully launched a heavy-duty rocket that placed a major communications satellite in space.



A beaming Indian Space Research Organisation (ISRO) chief K. Radhakrishnan told reporters after the 4.48 p.m. launch Friday that the mission was a success.



"I am extremely happy to state that the PSLV (Polar Satellite Launch Vehicle)-C17 GSAT-12 mission is successful. The satellite was launched in the intended orbit."



"Within the next 30 minutes information about the GSAT 12's health and how it is working will be known," he told cheering scientists at the launch site here, 80 km north of Tamil Nadu's capital Chennai.



V. Narayanasamy, Minister of State in the Prime Minister's Office, said: "I am extremely happy (at the successful launch). I am coming here for the second time, and it is a second successful launch. On behalf of the prime minister, UPA chairperson Sonia Gandhi, I congratulate the ISRO scientists for the wonderful performance."



The PSLV blasted off successfully at 4.48 p.m., carrying the 1,410 kg GSAT-12 satellite from the spaceport here.



With this, India added 12 more communication transponders to its space-based network.



The launch took place under a cloudy sky, with the Rs.90 crore rocket PSLV-C17 - measuring 44 metres in height and weighing 320 tonnes - soaring off into space with a roar.



It ferried the Rs.80 crore GSAT-12 having 12 extended C-band transponders - automatic receivers and transmitters for communication and broadcast of signals.



With a rich orange flame at its rear, the one-way ticket rocket left behind a huge tail of white plume as it rose into the sky to the cheers of ISRO scientists and media team assembled at the launch centre.



People perched atop of the nearby buildings too happily applauded as PSLV-C17 went up.



Around 20 minutes after the blast off, the rocket achieved its mission by placing the latest Indian communication satellite in the intended sub geosynchronous transfer orbit (sub GTO).



The GTO is an intermediate orbit from where normally communication satellites will be moved to its final geosynchronous orbit by firing the on-board motors.



The GSAT-12 carries around 851 kg of fuel on-board to fire the motors. (A geosynchronous orbit is one directly above the earths' equator. For an observer from the earth a satellite in geosynchronous orbit will seem motionless, stationary at one point in the sky).



The rocket placed the satellite in sub GTO with a 284 km perigee (nearest point to earth) and 21,000 km apogee (farthest point from the earth). The satellite will be raised to 36,000 km apogee from 21,000 km.



Immediately after satellite ejection, ISRO with its network of ground stations monitored its health.



The satellite with a life span of about eight years will augment transponder capacity of Indian National Satellite (Insat) system which at present comprises of eight satellites - Insat-2E, Insat-3A, Insat-3C, Insat-3E, Insat-4A, Insat-4B (working at 50 percent capacity) Insat-4CR and GSAT-8 providing 175 transponders in the S, C, extend C and Ku bands.



The Indian space agency has leased 86 more transponders from various foreign satellites. It is estimated there is an unmet demand for 170 transponders.



The GSAT-12 satellite is expected to serve the Very Small Aperture Terminal (V-SAT) sector. VSATs are used to transmit data like point of sale transactions or to provide satellite internet access.



It will also be useful for various communication services like tele-education, tele-medicine and for village resource centres.



ISRO used its third PSLV rocket variant - PSLV-XL - with longer strap-on motors with higher fuel capacity - to put the latest communication satellite in the space.



The other two rocket variants are the PSLV standard with 11.3 metres six strap-on motors and the PSLV Core Alone (CA) rocket without the six strap-on motors.



The PSLV-C17 that went up Friday had 13.5 metres long strap-on motors carrying 12 tonnes of solid fuel than the normal strap-on motors measuring 11.3 metres with nine-tonne fuel capacity.



This is the second time ISRO has launched a rocket with this specification. The earlier one was for the Chandrayaan moon mission.



This is also only the second time ISRO is using a PSLV rocket for launching a satellite to be finally placed in geostationary orbit. The first satellite was Kalpana-1 (originally named as Metsat), a meteorological satellite launched in 2002.



The PSLV has an excellent success record since 1994, launching many Indian and foreign satellites.



ISRO officials told IANS that a remote sensing satellite - Megha-Tropiques - is being planned for launch later this year.
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[url="http://articles.economictimes.indiatimes.com/2011-07-23/news/29806502_1_cryogenic-gsat-8-transponders"]ISRO to focus on domestic needs for satellites[/url]

Quote:ET Bureau Jul 23, 2011, 02.38am IST

HASSAN: Indian Space Research Organisation (Isro) chairman, Dr K Radhakrishnan said on Thursday, that the country's nodal space agency will be focused more on meeting the nation's domestic requirements for satellites, than looking for export orders.



At a meeting with reporters at Isro's Master Control Facility at Hassan, Karnataka, Radhakrishnan said there was a significant lag in meeting India's societal and strategic requirements, a situation Isro expects to correct. "At the moment, we have a strong need to fill up the gap we have in the domestic market for transponders. That is our first priority. We face a shortage of about 200 transponders, and augmenting them will be the main focus of the space agency rather than looking for business from foreign countries to build satellites," he said.



Isro has around 150 of its own transponders currently in operation, while leasing 86 transponders from abroad. It expects to have 36 more transponders in operation through its recent launches of GSAT-8 and GSAT-12. Radhakrishnan said that the country was facing a major shortage of transponders, a situation that has forced it to talk to a number of foreign agencies to hire the same



"We have a few satellites lined up, like the GSAT-7, GSAT-9 and GSAT-11. We are also in the process of leasing some more satellite transponders from foreign operators, and trying to get a few satellites moved into our orbit for a couple of years," he said.



Separately, on the issue of building in its own [color="#8B0000"]cryogenic engine[/color], the Isro chairman said that corrective measures,[color="#8B0000"] including the re-design of the critical fuel booster turbo component, [/color]had been undertaken.



"[color="#8B0000"]We need to have groundtesting of the cryogenic engine, with the modified fuel booster turbo component. This has been planned for 2011 itself[/color]. We are also preparing the flight stage, which is expected to be ready by March 2012," Radhakrishnan said.



Isro plans on assembling the flight stage on to the GSLV vehicle after a series of ground tests, and expects to conduct the flight testing in the second-quarter 2012. Further, another cryogenic development called the GSVL Mark-III is also on the anvil.



"It is a heavier cryogenic engine. A major test facility is getting commissioned, where the engine – [size="4"][color="#8B0000"]CE-20[/color][/size]- will be tested for short durations, and also simulating the background conditions. We expect to commission this by August 2011. Then we start testing of the engine.



The Isro chairman did not comment on the ongoing Antrix-Devas spat, the latest development of which has seen Devas approach the International Court of Arbitration, seeking the restoration of its 2005 agreement for S-band spectrum.



"The procedure to be followed by the arbitrators is that of the International Chamber of Commerce. Indian law will apply and the seat of arbitration will be New Delhi," he reiterated.



Antrix had entered into an agreement with the Bangalore-based Devas for leasing of S-band capacity on two satellites, GSAT 6 and 6A to be launched by Isro.



The deal had come under scrutiny, after the Comptroller and Auditor-General of India pointed out several discrepancies, and was scrapped by the government in February earlier in the year.



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[url="http://www.thehindu.com/news/national/article2260309.ece?css=print"]GSAT-12 reaches its home in a circular geo-synchronous orbit[/url]

Quote:July 19, 2011 23:49 IST | Updated: July 20, 2011 02:10 IST


  • T. S. Subramanian
India's communication satellite GSAT-12, put in orbit on July 15, reached its home in a circular geo-synchronous orbit at an altitude of 36,000 km on Tuesday. The Polar Satellite Launch Vehicle (PSLV-C17) of the Indian Space Research Organisation (ISRO), which lifted off from the space station at Sriharikota on July 15, 2011, put the 1,410 kg GSAT-12 in a sub geo-synchronous transfer orbit (sub-GTO) with an apogee of 21,020 km and a perigee of 284 km.



Challenging operation



After the satellite was put in a sub-GTO, the liquid apogee motor (LAM) on board was fired once each day from July 16-19 to circularise the orbit at an altitude of 36,000 km. On July 16 and 17, commands were given from the Master Control Facility (MCF) at Hassan in Karnataka to the LAM to take the satellite's apogee from 21,020 km to 36,000 km when the satellite was at its perigee. Similarly, the commands to the LAM to fire to take the perigee from 284 km to 36,000 km were given on July 18 and 19 when the satellite was at its apogee. “Thus, it was a challenging operation,” said an ISRO official.



“But all operations went off well. The sub-systems on board the satellite are functioning normally. The satellite has now made it to its final, circular geo-synchronous orbit of 36,000 km,” he added.



The LAM will be fired again on Wednesday for final trimming of the satellite's orbit.



With 12 extended C-band transponders, the satellite will be useful in tele-education, tele-medicine, disaster management support, telephone services and so on.



Two more this year



[color="#8B0000"]This year ISRO will launch two more satellites.[/color]



It is now getting ready for the launch of Megha-Tropiques satellite, an Indo-French joint venture, from the spaceport at Sriharikota by the end of September.



The PSLV-C18 will put the 1,000-kg Megha-Tropiques (Megha in Sanskrit means cloud and Tropiques in French means tropics), being built by the ISRO Satellite Centre, Bangalore, into an 867 km orbit. It will be useful in studying the weather in tropical countries.



For surveillance



ISRO is also building for surveillance,[color="#8B0000"] RISAT-1 (Radar Imaging Satellite)[/color] which will be put in orbit by the end of December by PSLV-C19.



It can take pictures of the earth day and night and in all weather conditions.



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[size="3"][url="http://www.thehindu.com/sci-tech/science/article2512630.ece"]PSLV-C18 to put four satellites in orbit[/url]: The Hindu, October 5, 2011

-- T. S. Subramanian



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Quote:It will be launched from Sriharikota on October 12; two satellites built by students
Preparations are on for the lift-off of the Polar Satellite Launch Vehicle (PSLV-C18) from the spaceport at Sriharikota at 11 a.m. on October 12.



Global tropical weather



The rocket will put four satellites in the orbit: Megha-Tropiques, built by India and France to understand global tropical weather and climate; SRM Sat, built by the students of SRM University, near Chennai; Jugnu, a satellite integrated by students of the Indian Institute of Technology (IIT), Kanpur; and VesselSat from Luxembourg.



The information sent by the instruments on board the Megha-Tropiques will help understand the behaviour of Indian monsoons and occurrence of cyclones, floods and droughts.



Heat shield



The PSLV has been fully integrated, said K. Radhakrishnan, Chairman, Indian Space Research Organisation (ISRO), on Tuesday from Bangalore. “The Megha-Tropiques and the three co-passenger satellites have been fully integrated with the vehicle. The heat-shield was closed last morning.” The heat-shield around the satellites protects them from the intense heat during the launch and the vehicle's ascent into the atmosphere. After the rocket reaches a certain altitude, the heat-shield falls off.



Dr. Radhakrishnan said the final checks were under way. “On October 8, we will have a launch rehearsal. The vehicle readiness review will take place on October 9 followed by the Launch Authorisation Board meeting the same day itself. As of now, the launch is scheduled on October 12 at 11 a.m.”



The PSLV-C18 — which will be the 20th PSLV to be launched — is the core-alone version of the four-stage PSLV, without the strap-on booster motors that will put the four satellites in orbit.



Megha-Tropiques (Megha in Sanskrit means cloud and Tropiques in French is tropics) is one of the most advanced and complex satellites built to monitor the weather in the short-term and climate in the long-term in the tropical regions of the world. It is a joint project of ISRO and the French space agency, Centre National d'Etudes Spatiales (CNES).



Thermal engine



ISRO officials said the 1,000-kg satellite had been built to investigate the tropical regions which received the maximum energy from the sun than they radiated back into space.



The excess energy received in the tropical region is used as a thermal engine and provides circulation in the atmosphere and the oceans.



‘Life cycle'



“The complex processes between solar radiation, water vapour, clouds, humidity, precipitation and atmospheric motion determine the life-cycle of convective systems and influence the Indian monsoon in the tropical region,” the ISRO officials explained.



From its perch in the sky at an altitude of 867 km, the Megha-Tropiques would help study, on a sustained basis, the rapidly developing weather systems in the entire tropical world. Thus, the information beamed by the Megha-Tropiques will be useful not only to India but to all the countries in the Indian Ocean region and other parts of the world.



Scientific payloads



The satellite has four scientific payloads. The Microwave Analysis and Detection of Rain and Atmospheric Structures (MADRAS), built by ISRO and the CNES, will provide an estimation of rainfall, water vapour, liquid water, ice and surface wind. Scanner for Radiative Budget (SCARAB) will study the radiation received by the earth and reflected by it. The third instrument, Sondeur Atmospherique du Profil d'humidite Intertropicale par Radiometrie (SAPHIR) will investigate the humidity present in the tropical atmosphere.



The CNES has built the SCARAB and the SAPHIR. The GPS-ROS (Global Positioning System- Radio Occultation System) from Italy will study the temperature and humidity at different altitudes.



The ISRO Satellite Centre, Bangalore, integrated the entire satellite.



The 10-kg SRM Sat will help in understanding global warming and pollution by studying carbon-dioxide and carbon-monoxide present in the atmosphere. The three-kg Jugnu has a camera to take pictures of the earth to monitor, vegetation, reservoirs, lakes, and ponds. VesselSat will help in locating the ships in the sea-lanes of the world.

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Live feed indicates 3'rd stage successfully separated and coasting, and the fourth stage will be a cake walk now. Picture perfect mission till now.
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[size="3"]^[/size][size="3"]

Thanks for the latest. Waiting for news of back-thumpings. <img src='http://www.india-forum.com/forums/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />

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Coasting phase shows slight deviation from ideal, whereby the altitude gain was more than target.



Fourth stage performed good has finished orbit injection correcting the third stage velocity error. Meghatropiq separated successfully. Now the rest of teh nano sats will be a piece of cake.



Final orbit altitude, accentricity and inclination are very very close to target.



Congratulations to ISRO and all its partners/suppliers.
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[size="3"][size="4"]Congrats ISRO!! [/size][Image: prize-cup.gif]

[Image: booga-wooga-drum.gif][/size]
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[size="3"]Arun saar, if possible, an analysis/comment on the latest achievement, in terms of our further progress in space science?

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My quick two cents are as following:

  1. PSLV has yet gain proven to be reliable, cost effective and accurate space vehicle.
  2. The Megha-tropoque satellite IMHO is a very very capable and enabling satellite. With recent progress in statistical physics, sky is the limit in what it will unravel and how it can/will be used. (subject to abelity of Indian physicists to catch the latest papers on the domain. Else teh French or europeans will do teh needful and claim teh glory and apply it to their national interest).
  3. It is duel edged sword with possible strategic usage too.
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Quote:The next flight of the Geostationary Launch vehicle (GSLV) with indigenous cryogenic engine is likely to be launched in the second quarter of next year, Indian Space Research Organisation (ISRO) chairman K Radhakrishnan said in Sriharikota today.



the ISRO chief said,"We have a major task ahead of us... development and perfection of indigenous cryogenic stage. We are making good progress and we plan to have the next flight of GSLV with indigenous cryogenic engine in the second quarter of 2012,".
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[size="3"][font="Courier New"]^

Kindly specify sources as a policy whenever something is quoted, or matter is copy-pasted.

Not giving credits to the source of information is plagiarism.

Thanks for understanding!<img src='http://www.india-forum.com/forums/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='Smile' />[/size][/font]
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[size="3"][url="http://www.thehindu.com/todays-paper/tp-opinion/article2538959.ece"]A Megha bonanza[/url] The Hindu, October 15, 2011



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[indent][size="3"][quote name="THE EDITORIAL"]The Indo-French atmospheric research satellite, Megha-Tropiques, is now safely ensconced in orbit, a fact that will gladden the hearts of many scientists around the world. This is just the second satellite that will gaze down on the formation of clouds and powerful storms in the tropical regions of the world. The ageing U.S.-Japanese Tropical Rainfall Measuring Mission (TRMM), launched in 1997 and still operational, has provided a bonanza of information. There are high expectations from Megha-Tropiques, which will concentrate even more on the tropics and provide greater coverage of the region. This satellite will measure the flow of energy and the build-up of water vapour at different levels in the atmosphere, both critical factors in the evolution of large cloud systems. By deciphering the complex linkages between land, ocean, and atmosphere, it will be possible to greatly improve weather and climate models, making for better monsoon prediction. It should also provide vital clues for determining whether a warming climate could lead to more rain or less. And the benefits will not be restricted to India. That the 21 science teams formed for the mission have drawn scientists from 11 countries is a testament to its global importance. After a three-month period during which the instruments on the satellite will be calibrated and another six months when data will go only to the international science teams, data from the satellite will be freely accessible to all. A number of groups from various countries, including India, have plans to feed the data in real-time into their simulation models for weather prediction. In the meantime, another Indo-French satellite, SARAL, which will study the oceans, is being prepared for launch next year.



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[size="3"]Along with the Megha-Tropiques, the Polar Satellite Launch Vehicle (PSLV) also carried three tiny satellites as co-passengers, two of them designed and developed by the faculty and students of Indian academic institutions. The three-kilogramme Jugnu nanosatellite came from IIT Kanpur and the 11-kilogramme SRMSat from the SRM University near Chennai. The PSLV had launched the 40-kilogramme ANUSAT from Anna University in 2009, and last year it put up the STUDSAT, weighing less than one kilogramme, built by a consortium of seven engineering colleges in Bangalore and Hyderabad. This sort of effort must be encouraged. For one thing, novel technologies can be tested quite cheaply. More importantly, putting together any satellite, however small, that will survive the rigours of launch and then work in the hostile environment of space is a tremendous challenge. It is unquestionably an excellent way to train the technology leaders of tomorrow that India needs.[/quote][/size]

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Few nuggets from this news report highlighted.





[url="http://www.dnaindia.com/print710.php?cid=1680937"][b]ISRO announces two new missions
[/url][/b]

Quote:PTI / Thursday, April 26, 2012 13:42 IST



Buoyed by the successful launch of all-weather radar imaging satellite RISAT-1, ISRO today announced it would launch two GSLVs and a PSLV this fiscal and the second Indian moon mission of Chandrayaan 2 in 2014 on board a GSLV.



"The launch of Chandrayaan 2 will be in 2014. We are working towards it. [color="#0000ff"]It would be on a GSLV, after we launch two GSLVs within an interval of six months," [/color]ISRO chief K Radhakrishnan told reporters here soon after the launch of RISAT-1.



TK Alex, Director, ISRO Satellite Centre said ISRO is working with Russian scientists on Chandrayaan 2. "We will discuss on site selection like where we have to land," he said, adding other related works are progressing well.



On launch of two Geosynchronous Satellite Launch Vehicle (GSLVs) and Polar Satellite Launch Vehicle (PSLV) this fiscal, Radhakrishnan said ISRO has studied the reasons for the failure in 2010. "Now GSLV will undergo an endurance test of 1,000 seconds and a vacuum test at a special facility at the Liquid Propellant System Centre at [color="#0000ff"]Mahendragiri in Tamil Nadu, where a Rs300 crore facility for vacuum test has been made[/color]," he said.



"Once we get the green signal from the Ground Testing Team, we would be ready for the GSLV launch,” he said.



PS Veeraraghavan, Director, Vikram Sarabhai Space Centre, who was present, said ISRO will launch a low cost communication satellite GSAT-14 on board GSLV D5 in September/October 2012.



PSLV C-20 with Indo French satellite SARAL and four small satellites would be launched in October, 2012 and PSLV C-21 with a commercial payload SPOT, a French satellite on earth observation this August, he said.



On GSLV Mark III, he said various subsystems of engines are being tested and it would take two years for it to be completed. "After all the tests, the[color="#0000ff"] experimental flight without cryogenic engines could be in 2012-13[/color]," he said.



Radhakrishnan also said ISRO had spent over Rs20,000 crore in 29 missions in the 11th five year plan against Rs13,000 crore in 20 missions in the 10th five year plan. Much of the amount was spent on procuring six to eight Russian cryogenic engines and equipment for remote sensing programmes, he said.



[color="#0000ff"]RISAT-1 cost Rs 488 crore, with Rs110 crore spent on the launch vehicle and Rs378 crore on the satellite,[/color] he said.



ISRO earns over Rs45 crore from vending images through its satellites, he added.



Alex said many colleges and universities are now keen on launching satellites made by their students through ISRO.



"Many colleges have approached us for sending their satellites made by their students. We have many more such proposals in the pipeline," he said.





Asked about the present status of Indo French satellite Megha Tropiques, launched during the last PSLV mission, he said, "The satellite is sending good images. They are giving details on the clouds and water content, etc. Earlier, we did not get so many details from the earlier satellites," he said.



Alex said many colleges and universities are now keen on launching satellites made by their students through ISRO.



"Many colleges have approached us for sending their satellites made by their students. We have many more such proposals in the pipeline," he said.



Asked about the present status of Indo French satellite Megha Tropiques, launched during the last PSLV mission,he said "The satellite is sending good images. They are giving details on the clouds and water content, etc. Earlier, we did not get so many details from the earlier satellites," he said.
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http://www.thehindu.com/todays-paper/tp-...872620.ece



Historic PSLV launch tomorrow Special Correspondent Manmohan to witnessISRO’s 100th mission The Indian Space Research Organisation (ISRO) on Friday said it was all set to launch the historic PSLV-C21 on Sunday morning. The wholly commercial launch will be the space agency's 100th mission in 49 years. So far it has built 62 satellites and flown 37 launch vehicles. Prime Minister Manmohan Singh is slated to arrive at the space port of Sriharikota, some 120 km from Chennai and located in coastal Andhra Pradesh, on Saturday evening and witness the launch on 9.51 a.m. on Sunday, ISRO officials said. The PSLV will carry France’s SPOT-6 earth observation satellite as the primary payload and PROITERES, a small spacecraft built by a team of Osaka Institute of Technology in Japan, as a secondary rider. They will be put into their respective pole-to-pole orbits at a distance of 655 km from Earth. Scientists at the launch site, Satish Dhawan Space Centre at Sriharikota, began a 51-hour countdown at 6.51 a.m. on Friday, a release said. The Launch Authorisation Board met on Thursday and cleared the event. During the run-up, teams associated with the launch will complete filling liquid propellants in the second and fourth stages (PS2 and PS4) of the launch vehicle. The rocket and the spacecraft will be checked. Batteries will be charged and the fuel tanks on the satellites will be pressurised, the ISRO officials said. “Readiness of various ground systems such as tracking radar systems and communication networks will also be ascertained,” they said.
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India to use geo-stationery satellites for missile defence

Manoj K Das, TNN | May 19, 2013, 04.41 AM IST

http://timesofindia.indiatimes.com/indi ... 130007.cms?

Quote:

KOCHI: India has launched an ambitious programme to use its array of geo-stationary satellites (G-sats) to monitor missile activities in an area of 6,000 km. With this, the country's constellation of G-sats will become the first line of defence in its anti-missile shield. This programme is independent of the observation grid installed by defence and intelligence agencies. The advantage of using geo-stationary satellites is their fixed position at a height of 36,000 km and synchronised with the earth's movement.



Allaying fears that this deployment could compromise India's space policy, sources clarified that it is not meant as an offensive posture and data won't be shared with any other country. "We're using these satellites to warn us of an impending danger even as they continue with their primary tasks of transmission and meteorological observations," sources said.



A top source told TOI that special lens and processing electronics are being developed to significantly improve the power of G-sat cameras and telescope. "The Centre has given ISRO the go-ahead. The programme is into a crucial development phase,'' he said.



The project is aimed at installing sensitive surveillance equipment along with other payload on the G-sats. "They will capture the signature of any missile launch activities happening in a radius of 6,000 km.This signature will be transmitted to a central control unit which would initiate necessary counter-mechanism," sources said.



The Defence Research Development Organisation (DRDO) is developing the interceptor missile which has entered trial phase. "Given their strategic position, we can even have exclusive facility to monitor a country or a particular region. Given the G-sat's capability to map anything to a resolution of one metre, we will be able to capture the slightest of movements or even heat signatures,'' sources said.
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Successful flight of GSLV-D5 was critical for ISRO, and they jumped the hurdle. It has been a week since then. Now that I got a few moments to spare I have few observations.



1. The CUSP is an uprated version of Russian Cryo stage. When Cryo deal was struck w/Russians Indian scientists had already seen the rocket engine has headroom to operate at higher thrust 8.5 tonne for some time, and they asked Russia to test and certify the higher thrust operating regime. The of course unkiil killed the Technology Transfer deal.



2. The temporarily available higher thrust allowed somewhat higher payload capability. For best mission performance the Cryo should be operated with higher thrust (to minimize ISP lost due to gravity) when the rocket has reach a velocity equal to the orbital velocity at current altitude, the thrust can be pared down significantly, and all impulse from that time onwards is gets used to raise orbit. So rated 7.5 tonne is OK as long as the engine is operating at maximum possible ISP.



3. On D5 mission the CUSP stage was operated in conservative thrust profile, to ensure it passes baseline benchmark with confidence. Hence the thrusting phase started with 7.5 tonne thust, and somewhere in the middle of the burn (by then teh engine was basically flight proven) the engine was put to its pace and operated in higher thrust mode.



4. The D6 due for middle of 2014 which is an identical configuration as D5 will however be operated in the preferred thrust profile, whereby when the Cryo stage is lighted it will operate in teh higher thrust mode for a good 1/3rd of the burn time, and then it will revert to slightly higher efficient (higher ISP) mode for GTO insertion. This will result in slightly higher payload.
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