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A tad too long but very informative.. Interview of ISRO chairman.
In mission mode
THERE is excitement at the various centres of the Indian Space Research Organisation (ISRO) across the country. It has 12 missions lined up between now and March 31, 2014. But the focus will be on the launch of its Geosynchronous Satellite Launch Vehicle (GSLV) with an indigenous cryogenic engine in August 2013 to put GSAT-14 into orbit and the Mars Orbiter Mission in October/November 2013 to send a spacecraft into a Mars orbit. “We have geared up for a tough schedule,” said K. Radhakrishnan, ISRO Chairman, in a recent interview to Frontline in his office at the ISRO headquarters in Bangalore. He added: “We are preparing ourselves and are on schedule for the launch of the Mars Orbiter Mission [MOM] any day between October 21 and the second week of November…. A mission to Mars is far more complex than Chandrayaan-1 in terms of the distance involved. At its nearest distance to the earth, Mars is 55 million kilometres away and it can be as far as 400 million km [when it is farthest from the earth]…. We want to tell this country that Mars has a relevance.” Radhakrishnan, who is also Secretary, Department of Space, and Chairman, Space Commission, explained: “The primary objective of our mission is to see if we can reach the Mars orbit. That is the acknowledged objective. There are also scientific objectives and a set of instruments for carrying them out.”
But the big task on hand for ISRO is the development of the GSLV-Mark III. It is a gigantic vehicle which will stand 42.4 metres tall and have a lift-off weight of 630 tonnes. Its experimental mission with a passive cryogenic stage will take place in Sriharikota in January 2014.
Radhakrishnan spoke in detail about the battery of tests that the indigenous cryogenic engine for the forthcoming GSLV-D5 flight had undergone and about three other “important developments” taking place in ISRO: the development of the Re-usable Launch Vehicle–Technology Demonstrator, the semi-cryogenic engine, and air-breathing propulsion.
Radhakrishnan graduated in Electrical Engineering from Kerala University in 1970 and obtained his MBA from the Indian Institute of Management, Bangalore (1976). The Indian Institute of Technology, Kharagpur, awarded him a PhD in 2000. He began his career in ISRO as an avionics engineer at the Vikram Sarabhai Space Centre (VSSC) in Thiruvananthapuram. He became the VSSC’s Director before taking over as ISRO Chairman in 2009. Excerpts from the interview:
In the coming few months, ISRO’s priority will be the mission to send a spacecraft to Mars. Unlike the Chandrayaan-1 mission, it looks as if the Mars Orbiter Mission has not got the attention it deserves.
We are geared up for six missions in the coming three months. The PSLV-C22 has already put the Indian Regional Navigation Satellite System [IRNSS-1A] into orbit on July 1/2. INSAT-3D has already been shipped to French Guiana and the launch is scheduled for July 26 on board Ariane-5. INSAT-3D contains, in addition to its imaging system, a sounder which gives vertical profiles of the atmosphere and, in this respect, it is an advanced meteorological satellite.
The much-awaited GSLV launch with the indigenous cryogenic engine is scheduled for August 2013. The vehicle assembly is progressing at Sriharikota. The S-139-tonne booster and the four strap-on liquid stage have already been integrated. The integration of the second stage has already commenced. The cryogenic stage is already at Sriharikota and it is going through various preparations.
Are the high altitude tests and other tests of the cryogenic engine over?
This flight stage has an [cryogenic] engine that has already gone through 200 seconds of testing and the stage is getting ready for assembly with the vehicle. In this mission called GSLV-D5, we are launching a communication satellite called GSAT-14, which will weigh about 2,000 kg. It is an important mission.
Over the last three years, after the flight of GSLV-D3 with India’s cryogenic stage, which was unsuccessful, we have done a series of ground tests on the sub-systems and the cryogenic engine at the Liquid Propulsion Systems Centre at Mahendragiri [near Nagercoil in Tamil Nadu] after making the necessary design changes in the fuel booster turbo pump [FBTP] and the oxidiser turbo pump. An important test that was devised this year was testing the FBTP in operating conditions at cryogenic temperatures, which was not done in the past. After doing the test, we wanted to see the ignition of the cryogenic engine in high-altitude conditions. It is called a high altitude test [HAT]. This cryogenic engine had not gone through high-altitude tests earlier.
After the last failure in April 2010, we decided to conduct an HAT and we needed a facility for this. An HAT facility was being established for the development of the high-thrust cryogenic engine required for GSLV-Mark III. That facility was ready and we made modifications to that facility to accommodate the GSLV’s cryogenic engine and this was done on a war-footing. After the commissioning of the facility, we successfully carried out two simulated high-altitude tests [of the indigenous cryogenic engine] in March and April 2013. The duration was 3.5 seconds, when the ignition of the main engine, the gas generator and the two steering engines were expected to take place in a given sequence. This happened. This test was done with a stand-by engine, called A-4 engine, which was used for the ground tests. So today we have completed the design changes required for the FBTP based on the failure analysis done after the last flight of the indigenous cryogenic engine.
When the GSLV flight with the Russian cryogenic engine failed in December 2010, there was the problem of the connectors snapping.
That was a different issue. I will come to that. During the April 2010 flight with the indigenous cryogenic engine, the cryogenic engine ignited. The steering engines and the gas generator ignited. But the ignition could not be sustained beyond 800 milli-seconds and the FBTP stopped. So an experts’ team went into the possible reasons for this failure and it concluded that there were three possibilities. One was related to the clearances of the three bearings of the FBTP, essentially with respect to the differential contraction taking place in the turbo pump because we are using different materials there at cryogenic temperatures. The second possibility was the failure of the casing of the FBTP acquisition. This essentially required a design change in the FBTP. We have taken care of the first and second possibilities.
To take care of the third possibility, we designed and made in India the propellant acquisition system of the hydrogen tank with the necessary volume. The flight engine that we will be using on GSLV-D5 has already gone through 200 seconds of acceptance tests, and after the tests, the necessary inspection and refurbishment have been done.
So, on the one side, based on various flight tests and results, we have taken concerted action. Secondly, we have done extensive test sequences. Thirdly, the flight acceptance test of the engine has been done. Fourth, we have done vigorous inspection and quality control of the components and sub-systems that will go into the cryogenic engine and the stage. In this flight, we are also using indigenously developed polyimide pipes after due qualification. We used to import them earlier from Russia. This has gone through extensive qualification tests. This pipe was developed at the VSSC. This is with respect to the cryogenic stage.
If you look at the last seven GSLV flights, the first flight was aborted. We, however, had a successful flight within a month. But there was a malfunction in the Russian cryogenic stage and the spacecraft had a life of less than two months. The second and third flights of the GSLV successfully placed GSAT-2 and GSAT-3 into orbit. The GSLV-F02 flight in July 2006 failed because one of the strap-on stages stopped functioning after about 55 seconds. The next mission in September 2007 had a problem: the control system of one of the strap-on stages stopped. The vehicle could place INSAT-4C in orbit with an apogee of 30,000 km only [instead of the targeted 36,000 km]. But we were able to recover the spacecraft and place it in the proper orbit. So I will say that it was a partially successful mission.
In April 2010, GSLV-D3 was flown with an indigenous cryogenic stage. The lower stages functioned extremely well, that is S-139, the four strap-ons and GS-2. The cryogenic stage ignited but the ignition could not be sustained. That was the failure. The seventh flight, that of GSLV F-06 of December 25, 2010, was a failure due to the opening of a shroud in the Russian cryogenic stage, resulting in two connector sets getting disengaged, because of which signals from the equipment bay could not reach the control actuators of the strap-on stage. So the vehicle started losing control after 47 seconds of flight and we had to destroy the vehicle. The failure analysis committee’s [FAC] report was published.
We went through an analysis of all the seven GSLV flights and tried to see what the gaps were that we could fill up. In the GSLV-D5 configuration, we are using a heat-shield with a diameter of 3.4 metres and the spacecraft mass is nearly 2,000 kg. We have incorporated a design change in the way the connectors are mounted in the cryogenic stage. The mounting of connectors is redesigned. We have done extensive aero-structural tests of the GSLV. We have also done wind-tunnel tests on the GSLV model.
Where did you do the wind tunnel tests? In Russia?
Both in Russia and at the National Aerospace Laboratories [NAL], Bangalore. We have done structural testing of the modified connector mounting system. We have analysed the test results of the previous seven flights and necessary corrections have been incorporated.
The Mission Readiness Review [MRR] team, headed by Dr B.N. Suresh, former Director, VSSC, and comprising experts from ISRO, and directors and deputy directors of R & D and academic institutions, has been reviewing the work on the indigenous cryogenic engine preparations for the GSLV-D5 mission for nearly two years. The first task was to finalise the configuration of the GSLV-D5 vehicle, incorporating the changes required which are based on our learning from the previous seven flights. The MRR committee and the Flight Readiness Review committee have been monitoring the realisation of the sub-systems and the vehicle stages as well as the results of the tests that have been carried out, and they have already given the clearance for assembling the vehicle. On January 31, 2013, we started stacking the vehicle.
Similarly, in the cryogenic stage, the MRR committee has been overseeing the incorporation of the corrections and the results of the tests before giving clearance to the flight stage. The flight cryogenic stage was moved from Mahendragiri to Sriharikota on May 13, 2013, and the flight preparations are going on.
The next mission is the GSAT-7 communication satellite. That will be launched from French Guiana on August 22. IRNSS-1A, INSAT-3D, GSAT-14 and GSAT-7… we have a tough schedule. The IRNSS-1A is a geosynchronous satellite and the others are geostationary satellites.
After they are put into orbit by the PSLV, the GSLV or the Ariane vehicle, the orbit-raising operations will be performed by our team at the Master Control Facility [MCF] at Hassan in Karnataka and it will be followed by in-orbit operations and the in-orbit evaluation of their payloads.
Will the MCF at Bhopal support Hassan?
Bhopal will support Hassan. In addition to the initial operation of these four satellites, Hassan and Bhopal are engaged in the regular operation of the currently operational nine communication satellites. So this is a challenging period for the MCF and the teams from the ISRO Satellite Centre in Bangalore, the ISRO Inertial Systems Unit, the Space Applications Centre, the Liquid Propulsion Systems Centre and so on for managing these four satellites because they have to be put in the right orbit and in the right slot.
We have set up a second Mission Control Centre at Hassan to take care of the overlapping in-orbit operations, and teams have been identified for this. Mission operation rehearsals are going on at the moment at Hassan.
We have set up a ground segment for IRNSS-1A which is essentially a network of satellite control facilities at Hassan where the health of the satellite will be monitored and its station-keeping will be done. Secondly, a set of ranging stations comprising four CDMA [Code Division Multiple Access] and two laser ranging stations to estimate the orbit very precisely, that is, to the extent of a few metres in the CDMA and a few centimetres in the laser ranging, have been set up. Besides, a set of 18 ground stations, geographically distributed across the country, have been set up to monitor the range and integrity of the navigation systems [of the satellites]. Finally, a navigation centre at Byalalu, near Bangalore, has been set up where all the inputs from these ground stations will be brought together and synthesised. This ground network at Byalalu is ready and it was inaugurated on May 20 by V. Narayanasamy, Minister of State in the Prime Minister’s Office.
Chandrayaan-1 was very popular and it fascinated the youth of the country. But the forthcoming Mars mission has not attracted the attention it deserves. Why is the Mars mission being kept low-key?
With the Mars mission, you are talking about opportunities that come once in 26 months when Mars comes the closest to the earth. The first opportunity to launch will be in October 2013 and the next will be in November 2013. On November 27, we have to take the spacecraft from the earth orbit towards Mars and if you look at ISRO’s Mars Orbiter Mission, we started the feasibility study in August 2010. In 2011, we decided to go ahead with the mission and the Prime Minister announced the programme on August 15, 2012.
A mission to Mars is far more complex than Chandrayaan in terms of the distances involved. At its nearest distance to the earth, Mars is 55 million km away and it can be as far as 400 million km away [when it is farthest from the earth]. Secondly, in raising the orbit of Chandrayaan, we moved the spacecraft from the earth [orbit] to the zone of influence of the moon. We were able to capture the lunar orbit precisely by using the propulsion system of the Chandrayaan spacecraft. In the Mars Orbiter Mission, its propulsion system has to function for 300 days after its first phase of operations in the earth orbit. You need to characterise the propulsion systems to restart after a long delay of 300 days. These tests are being done at the LPSC at Mahendragiri.
The next issue is communicating with the Mars Orbiter. This delay could be as high as 20 minutes from the ground station to the orbiter. This means it will take at least 40 minutes for the signal to come from the spacecraft to the ground station and for the command to go from the ground station to the spacecraft. In addition, you need time to take the right decisions. That means, it will be 40 minutes plus. Sometimes, we will not be able to afford this kind of delay if there is an anomaly in the spacecraft. So we have to build a reasonable amount of autonomy in the spacecraft itself to take care of itself. Thirdly, time is of the essence because the launch has to take place in October-end or the beginning of November, and all systems—the launch vehicle, the spacecraft, the payloads, the ground stations and so on—have to be ready. Once the spacecraft is put into the orbit of Mars, which is the primary objective of our mission, we will do some experiments. The challenge here is that they have to be relevant, simple and meaningful experiments. We should be able to realise the instruments in a flight-worthy condition in a tight schedule.
We have five instruments. Their flight models are ready. It has a colour camera [for optical imaging of the surface of Mars]. Then a methane sensor to detect possible life on Mars. This methane can originate in geological activity or biological activity. To find out whether there is geological activity, there is a thermal infra-red camera. Then the Martian atmosphere will be studied using a Lyman Alpha Photometer. There is a Martian Exposheric Neutron Composition Analyser (MENCA) to study the neutral composition of the Martian upper atmosphere. These are the five instruments. All these are being built by ISRO centres and units. The weight of the spacecraft is 1,350 kg. All the sub-systems are now available at the ISRO Satellite Centre, Bangalore, and their integration has commenced.
When will the spacecraft reach Sriharikota?
We expect to go through the thermo-vacuum testing of the spacecraft by mid-July. The spacecraft will be moved to Sriharikota in the beginning of September. Once it reaches SHAR, we will have 45 days to work on it. In parallel, preparations will get under way for the lift-off of PSLV-C25. It is the XL version of the PSLV that will put the Mars spacecraft into orbit. The assembly of the launch vehicle will start in the first week of August.
The next major components are the ground stations, and they will be centred around the Indian Deep Space Network [IDSN] at Byalalu with a 32-metre antenna system. We have augmented this system with a 20-kilwatt transmission power as compared to two kilowatt which we used for the Chandrayaan mission, because we have to send the commands from the ground station to the Mars Orbiter over such a great distance. We have also made arrangements with the Jet Propulsion Laboratory, NASA [National Aeronautics and Space Administration], United States, for using their Deep Space Network, required for the global support of our Mars mission. We are using one station in Australia also.
The next important thing is the navigation of the spacecraft from the earth orbit to the Mars orbit. This part is also being done with the necessary mission design analysis, simulation of autonomy and so on. In a nutshell, we are preparing ourselves and we are on schedule for the launch of the Mars Orbiter Mission any day between October 21 and the second week of November. We can choose a day and launch and then do the initial orbit-raising of the spacecraft from nearly 23,000 km to 2.2 lakh km around Mars. The shortest distance [around Mars] will be 370 km and the longest distance 80,000 km.
When you go around Mars, will the apogee be 80,000 km?
Do not put “gee” there. It is a complicated word. We can say the shortest distance and the largest.
How will you take pictures from a distance of 80,000 km?
There are two things. When it comes to a distance of 370 km, there will be a sequencing and measurements will be done. Secondly, there is the environment. There is a science team which is looking at the instruments. The primary objective of our mission is to see whether we can reach the Mars orbit. That is the acknowledged objective. There are also scientific objectives and a set of instruments for doing them. First we have to reach there.
You had thermal problems with regard to Chandrayaan.
When you talk of the thermal environment, it is much harsher compared to what you see in the earth orbit or the moon orbit. This has to be kept in mind.
Since the moon does not have an atmosphere, the albido that the moon gets is five times that of the earth. This compounds the problem. The other scientific mission we are working on is Astrosat. It will be launched in 2014. Its instruments are in the final stages of qualification.
It will be a useful satellite not only for the Indian scientific community but for the global astronomical community because it will be a multi-wavelength observatory. Probably, this is the first time in a multi-wavelength observatory that you will have instruments from one end of the spectrum to another.
What is the progress in ISRO’s Human Space Flight [HSF] programme of sending Indians into space?
We have done critical technologies for the HSF. They are in the development phase.
What is the Unified Launch Vehicle of ISRO?
That comes later. Today, we have the GSLV, and GSLV–Mark III is being developed. Of course, we have plans for an experimental mission of GSLV–Mark III.
I heard that it will be a passive flight of GSLV–Mark III. What is a passive flight?
It will be a passive cryo. You have the configuration of GSLV–Mark III, which comprises two solid strap-ons, S-200 with a propellant loading of 200 tonnes each; the liquid core stage which has a dual engine; and the high-thrust cryogenic stage [above it]. We call it C-25. That is, it will carry 25 tonnes of cryogenic propellants. The S-200 solid stage has already been qualified. One of the critical requirements is that the performance of the two strap-ons should be identical. The liquid stage has been qualified on the ground. Avionics and other sub-systems are ready. We are waiting for the completion of the development of the cryogenic engine and the stage.
One of the essential requirements is the atmospheric characterisation of this launch vehicle configuration. So without waiting for the cryogenic engine and the stage to be ready, we are going ahead with this experimental mission where we will have S-200 strap-ons and the L-110 [110 tonnes of liquid propellants] stages and the cryogenic stage which [the cryogenic engine] will not ignite. It will not give any acceleration to the vehicle. We will get nearly 5 km per second provided by the solid and liquid stages. It will be a sub-orbital flight. The most important part of it is that it will go through the atmospheric phase and we will make all the measurements in flight required to characterise the vehicle and its performance. This is scheduled for January 2014. This is going to be a major milestone in the GSLV–Mark III development.
There are three important developments taking place in the space transportation area. The first is the development of the semi-cryogenic engine.
The second is the Reusable Launch Vehicle–Technology Demonstrator [RLV-TD]. The third is the air-breathing propulsion. We have made good progress in the RLV-TD. We did a review recently. We expect the flight system to be ready within a year. The first stage will be a solid motor with nine tonnes of solid propellants, that is, S-9 rocket motor and a wind-body mounted on S-9.
The second stage is the air-breathing propulsion. We have a large sounding rocket developed for this purpose and we had a test of the sounding rocket with the passive scram-jet module in 2010. The idea is that when you have to test an active scram-jet module, you need to have a specific window of the acceleration and dynamic pressure. We have seen that this is possible to get. So the next flight of the sounding rocket will be with an active scram-jet module. We are preparing for that flight, that is, to find out the effectiveness of the air-breathing propulsion. In semi-cryogenic engine development, we had one test of the single injector element of semi-cryogenics done, the first combustion. But we have a long way to go. There is a massive test facility to be created for testing the semi-cryogenic engine and the sub-systems. All this is in the early phase, I would say.
You asked about the Unified Launch Vehicle. It is a future expendable launch vehicle concept. It is modular in shape, comprising semi-cryogenics as booster, a cryogenics as upper stage and strap-ons of different magnitudes made of solid rockets. It can be S-200, S-139 or S-9, depending on the payload requirement. The ULV is slightly futuristic.
The immediate task on hand is the development of GSLV–Mark III. Its experimental mission with a passive cryogenic stage will be in January 2014. After three years, a developmental flight with an active cryogenic stage will take place.
So the first GSLV–Mark III flight will be in 2017.
Yes. We should have the testing of the engine and the stage conducted.
What is the progress in the development of Chandrayaan-2?
Chandrayaan-2 essentially comprises an orbiter, a lander and a rover. It is a joint mission of India and Russia. The lander has to come from Russia. It will have some experiments from the Russians. In 2012, the Phobos-Grunt mission of Russia to Mars failed and subsequently the Russians have instituted an internal review of their interplanetary missions. They have to make some programmatic changes based on the outcome of that review, and the indications are that the lander will be heavier.
[Phobos-Grunt mission lifted off on November 8, 2011, to collect soil samples from the Martian moon called Phobos and send them back to the earth in a return capsule. “Grunt” means soil in the Russian language. Phobos-Grunt’s main engine never fired after the lift-off and the mission failed.] Chandrayaan-2 was to originally go in a GSLV and it required a four-metre heat shield. We will put Chandrayaan-2 on board the GSLV with an indigenous cryogenic engine after at least two successful flights. But we should have clarity on the lander schedule now.
So Chandrayaan-2 mission will not take place next year.
Earlier, the limiting factor for Chandrayaan-2 was a reliable GSLV. But today, the limiting factor is lander availability.
What is the cost of the Mars mission?
Rs.460 crore. We want to tell this country that Mars has a relevance. Some people ask, “Why are you spending Rs.460 crore?” Others will say that Rs.460 crore is only some four rupees per head in this country. Then some others will say it is only the price of an aircraft. So there are different ways of looking at it.
But it is a scientific mission and it is bound to capture the imagination of the country’s youth.
Science leads to understanding. We want to tell this country that this is a complex mission. Out of 42 missions that have gone so far [to Mars], many initial missions have been failures. That is because of lack of understanding…. People do not know about this complexity. Every step we take moving forward is a success in this mission. It is not only getting into orbit and doing experiments, but the entire mission is complex. This is what we want to sell to our country.
Our country has to be with us because this involves a year of work: once we launch the orbiter in October 2013, we will capture the Martian orbit only in September 2014. It is a one-year job. We have to watch everything. We did it with Chandrayaan-1 in two weeks. We launched the spacecraft on October 22, 2008. On November 14, 2008, we reached the final orbit. But here the engine aboard the Mars Orbiter has to work for 300 days. You should know the characteristics of the engine. You have to characterise what is the performance degradation taking place during that period. That test is going on at Mahendragiri now.
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