P E O P L E

ON RECORD
Dr K. Radhakrishnan talks to Raj Chengappa
After the Moon, it is Mission Mars
— Dr K. Radhakrishnan, Chairman, Indian Space Research Organisation

GSLV has had a string of failures, including the one involving an indigenously built cryogenic engine stage, in 2010. What were the main reasons?

GSLV-D5, the cryogenic- engine powered launch vehicle that is to put GSAT-14, a communications satellite, into orbit on Monday.

Before I get to that, let me state we have had the PSLV (Polar Satellite Launch Vehicle) that has gone through 22 successful flights using varying configurations. As far as the GSLV is concerned, the first mission in 2000 was not fully successful as the satellite it launched flew only for less than two months. Basically the mixture ratio of the cryogenic upper stage was not optimised, so we had under-performance. But the second and third missions of the GSLV were successful and they orbited GSAT-2 and EDUSAT satellites. In 2006 we had the launch of GSLV-F02 with the INSAT-4C communication satellites. In that flight one of the strap-on motors worked up to 55 seconds very vigorously and then it stopped and then the flight was a failure. We found out it was a small defect in the manufacturing of a component. It was not a problem with the GSLV vehicle; it was a problem with the component. Then within a year we had the GSLV-F04 flight to launch INSAT-4CR. We reached a lower orbit because one of the control systems failed. We were lucky that we could salvage that mission though it cut the overall life of the satellite. These two failures are basically because of component failures, and have nothing to do with the GSLV configuration.

The first attempt with a GSLV using an Indian cryogenic engine also failed. What were the reasons?

That was on the GSLV-D3, which was essentially the first flight of an Indian cryogenic engine in April 2010. In that flight, the cryogenic engine ignited successfully, which by itself was a great achievement. But after 800 milliseconds the fuel-booster turbo-pump stopped working and the mission had to be aborted. The same year we had the GSLV-F06 flight in December. This used a cryogenic stage made in Russia. But this too failed because the tunnel carrying wires to communicate signals from the on-board computer to the various systems snapped as did the standby within 46 seconds of the flight. The sum-up in this again is that the configuration of the GSLV per se had no basic issues. The problems were because of components.

Were you able to pinpoint the causes of the failure of the Indian cryogenic stage?

We looked at the various scenarios as to why the fuel-booster turbo pump stopped working. We also studied whether — if it had performed — the rest of the systems would have worked for the entire flight duration. When we analysed the problem we found that the fuel-booster turbo-pump had not been tested in the extreme temperatures it operates but only under standard room conditions on ground. Secondly, when you get to cryogenic temperatures, there will be contractions that will not be uniform for different metals and the bearings and casings may have had failures. The third, were there any contaminants in the fuel that stopped the action? Out of all possible scenarios these three were looked at and tackled. We created a test facility where the turbo pump would be tested in the cryogenic condition. Then we also redesigned it to take care of the bearings and casing issue. As regards the contaminant we found that the propellant acquisition system used in the cryogenic hydrogen tank was from Russia. When we did tests on them we found that it generated particles. So we redesigned it and made the propellant acquisition system in India and that is also going up now.

What other tests did you do to ensure reliability and prevent another failure?

In cryogenic engines basically we deal with liquid oxygen and hydrogen at very low temperatures. If they come into contact there is no spontaneous combustion; it is not hypergolic like the other propellants we used. So you have to have igniters and the ignition has to take place. During the ignition process, the main engine has to ignite, there is a gas generator which has to ignite and two steering engines have to ignite in a sequence. If all this happens in the first five seconds of the stage, half of the mission is achieved. Then you have to sustain the ignition — that is the next job. When you go to the high altitude there is a vacuum condition and the question is will the ignition take place in that vacuum condition? Earlier, we did not have any vacuum tests and we assumed on the basis of calculations that it should take place. Now we wanted to be sure of it — not only in that one particular condition but in varying input conditions. We have a high-altitude test facility in Mahendragiri hills that is being set up for the GSLV Mark 3 (an advanced version of the GSLV) for a bigger cryogenic stage that it would use. We did fast-track activity to modify that to suit this engine. We tested the engine twice and both times it worked. That gives us again confidence that it will not only it ignite, but ignited as we predict.

Why is the success of the indigenous cryogenic engine important for the Indian space programme?

If you look at rocket technology, there are three main technologies — solid, liquid and cryogenic engines. In solid rockets, India is already in the big league, especially with the S200 solid rocket for the GSLV Mark 3 that we tested successfully on the ground recently. It is the third largest solid booster in the world. As far as liquid rocket engine is concerned, we have Vikas, which is essentially the Viking engine, acquired by India through a technology transfer process. We have made more than 100 engines, which have been used in a variety of ways. In cryogenics technology, we will see fructification of 20 years of ISRO’s efforts if the current GSLV test is successful. Cryogenics is a key technology for the country because in a GSLV, 50 per cent of the velocity for the launch vehicle is given by the lower stages and the rest is given by the cryogenic stage — so you get more bang, or boost, for the buck, which means you can carry heavier payloads.

Coming to satellites in the 12th plan, the proposal was to have 500 communications transponders. But we are way below target.

Yes, we have not been able to keep the planned targets. We had 250 transponders up in the beginning of the 11th Five-Year Plan, but we did not have many additions after that because of failure to put some satellites into orbit. As of now we have 195 transponders working on the nine satellites of ours that are up there. We have today about 95 leased transponders on foreign satellites being used by various users — that adds up to 290. There is a large demand coming for two reasons — one is that of the accumulated past, apart from the replacement of old satellites which are at the end of their lives. Second is the DTH demand which went up fast in the past few years.

What have you done to meet the gap in transponders?

We have done three things to meet this gap. As we can’t create indigenous capacity overnight, we went in for leasing transponders. We are also adding more of our own satellites by using foreign launchers like the Arianne. We are also looking to see if we can get a foreign satellite moved to our Indian administered slot in space if required. We are now planning 14 communication satellites in the 12th Five-Year Plan. That will take us to 415 transponders in all by the end of this Plan.

The other requirement is setting up India’s own GPS system. Where has that reached?

In the world today, for navigation you have a constellation of Global Navigation Satellite systems, or Global Positioning System (GPS). The Russians and the Americans have their own GPS systems. The Europeans, Chinese and Japanese are also in the process of building their own GPS systems. Now India is building its own regional navigational system called Indian Regional Navigation Satellite Systems, IRNSS. It will have a constellation of seven satellites at 36,000 km altitude, which when set up will give us the assured availability of signals even during hostile conditions. The first satellite of the series, IRNSS-1A, went up last month and the entire constellation would be up and ready in 2014.

What about ISRO meeting the defence needs, including spy satellites?

Let me just say, we make satellites and the uses can be from any of the sectors, whether government, including the strategic sector, or non-government, including the commercial sector. We build according to the requirement — communication, navigation or earth observation satellites. On the strategic side, the users are satisfied with what we have developed for them so far. We are also in the process of sending up the Astrosat next year, which would be India’s first dedicated astronomy satellite. It would essentially be a multi-wave-length Indian observatory to look at outer space.

ISRO had announced a mission to Mars. Why should India explore the planet and what is the current status of the project?

Basically one of the driving forces for the Indian space programme has been space sciences and we have been doing it since its inception. More recently in 2000, India decided to start the Chandrayaan mission that is looking at the Moon and Chandrayaan 1 was the first mission. Chandrayaan 1 gave us a lot of learning and I would say it was a turning point in India’s space programme. It’s the first time we got out of the earth’s field of gravity and then we also knew how to capture the lunar orbit, how to move a spacecraft to 4 lakh kilometres from earth and control and command it.

Why should India go to Mars after the Moon?

Mars is a terrestrial planet. With a possible comparison with planet earth and life, Mars is an important planet that the world is trying to understand. The space faring nations have also put a target that by 2030 or 2040 they could have a human habitat established in Mars. So these are all the essential motivators. If you look at the history of exploration, both the US and Russia have done nearly 40 missions, including the landing of Rovers, on the surface of Mars. What India is trying to do now — after having established the capability to do lunar explorations — is to establish the technology to put an orbiter around Mars and have a launch by November 2013.

What are the new challenges you would have to face as compared to sending an orbiter around Moon?

The first and foremost challenge is that we are talking about a distance of 55 million kilometres, as compared to 4 lakh kilometres going to the Moon. Number two is that we have to also capture the orbit of Mars by firing the propulsion system, 300 days after we have operated it around the earth orbit. The mission is the following: First you launch the satellite in an elliptical orbit around earth. The apogee will be about 20,000 km. From there you raise that apogee in steps and reach to about 2 lakh kilometres around the earth. And then you take off towards Mars and that journey is 300 days, as compared to the Moon mission that took two weeks. Thirdly — in terms of complexities — again when you talk about a distance of 55 million km there is a communication delay of 20 minutes for any signal to reach, so it would take 40 minutes to react in all. What we require is a level of autonomy to be built into the spacecraft. The fourth aspect that is important is the precise understanding of the entire space around it, the model of Mars gravity and how to navigate there.

What are the experiments you are planning on Mars?

We have shortlisted five at the moment. We have a colour camera that we can use to take pictures of Mars. Then we have a methane sensor, because when you talk about life methane is an indicator, and it can be of geological or biological origin. There is also a thermal infrared camera, which can look at volcanic action. We are also studying the Martian atmosphere, one is looking at particles and the other is looking at the deuterium and other elements. As of now there is a good confidence that we will meet the schedule of a November launch. If we are able to succeed, it will be a great achievement strategically and open up a new phase for scientific exploration.

When is the second mission to the Moon being planned and how is it different from the first one?

Chandrayaan 1 was an orbiter. Chandrayaan 2 is supposed to be a rover to be put on the surface of the Moon and for that you require a lander. That lander is supposed to come from Russia. It is a joint mission with the orbiter and launcher from India and Russia providing the lander. Originally it was supposed to be by 2014, but the schedule remains uncertain.

ISRO had also proposed a manned mission — where does that stand?

For the manned mission we started the process in 2006. We prepared a study report and presented it to a large section of the scientific community, based on two projects. The first was pre-project activity for critical technologies related to human space flight. The second was a project report for a specific mission to put a two-member crew in an orbit around earth and then keep them for seven days and bring them back safely. The first one — which is the critical technology required — is being pursued and the second project has not been taken up as yet. Among the critical technologies are a prototype module development, environmental control and life support system, the flight suit, and the crew escape system that is to be attached to the rocket. There is a human space flight core team, including a project director, and there are teams from all centres that are contributing into this. There is a very good amount of development that has been taken up in this area.

When are you going to approach the government to clear the second stage of the manned mission?

The key to that is we need to have a launch vehicle with ‘man’ rating — and in that the reliability should be 0.99. It should also have the capacity to take the crew module and a two or three-member crew, besides whatever is required for the experiment. The assessment in 2006-07 was we have the GSLV already in hand; it can be man-rated, but it had a limitation that it could take only a two-member crew, which means in a low earth orbit of 275 to 400 km you can have a payload of 5 tonnes in total. If we use the GSLV Mark 3, which is under development, it can lift 10 tonnes, which means we can have a three-member crew and we can also have some space for doing experiments. The other aspect is the crew escape system. It is required when the vehicle is at the launch pad as well as when it is going up in the ascent phase. One is at the launch pad, or pad abort test. That part is being tested now. The second one is a crew escape system with a set of rockets which will lift the crew module and push it to a safe area. That is also being tested on the ground and that escape system requires a reliability of 0.998. While there is no specific programme in the last two years we have made very good progress in that area and we will approach the government at the appropriate time for clearance. In short, whether planetary explorations, outer-space sciences or in manned missions, we are determined to show that for ISRO the sky is no more the limit.