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Mr M C Dathan - Former director, Vikram Sarabhai Space Center, Part-1

Mr M C Dathan
Former Director***, Vikram Sarabhai Space Center, Trivandrum
Part-1

Madhavan Chandradathan is an Indian space researcher and the leader of the launch authorization board of the Chandrayaan-1 space project. The Government of India respected him, in 2014, by granting him the Padma Shri, the fourth most noteworthy regular citizen grant, for his commitments to the fields of science and innovation. He graduated in chemical engineering from the Government Engineering College, Thrissur in 1971 and secured a graduate degree (M.Tech) from the Birla Institute of Technology in 1985. Chandradathan began his career in 1972, by joining the Indian Space Research Organization (ISRO) where he worked for the SLV-3 venture, the development of solid propellant formulations.Later, Chandradathan took up the task of creating rocket spouts basically for solid engines. He turned into the leader of the ablative nozzle production unit in 2000, where he stayed till 2004.

 

Amid this period, his group added to the flex nozzle for the S200 engine and the S200 booster for the GSLV Mk-III venture. He was elevated to Chief Executive of the Solid Propellant Plant (SPROB) for the PSLV and GSLV supporters. In this position, Chandradrathan administered the foundation of new Solid Propellant Plant (SPP), which was commissioned in 2008.In 2008 he additionally served as executive of Satish Dawan Space Center(SDSC).In January 2013, he turned into the Director of the Liquid Propulsion Systems Center (LPSC),and now he is Director of the Vikram Sarabhai Space Center (VSSC) since 2014 June.

 

 

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How hard it was during the initial time of ISRO  when you joined and what are the principle things which contributed ISRO'S development from SLV to GSLV?

It's a long a period of more than 43 years, It started in 72 January, 72 Jan to now it's about 43 years about 4 months. Total space program was initiated during that period(late 60'and early 70's).SLV 3 was the first program DR. Sarabai conceived. We were in the very primitive stage that time, technology was not available, before launch station established in Thumba near the sea shore, we had support from most of the  three four countries for launching the sounding rockets, sounding rockets means smaller rockets for studying the atmosphere(with in 100km).

To study about Ionosphere, stratosphere, gas composition and something like that. The first launching was in 63 November  that was with foreign satellites by Americans. Russians gave  satellites, French people also gave satellites to us that time and they were  sounding rockets. There the sounding rockets will have  smaller payload inside. Payload may be 20kg,to50 kg going to altitude of 50 kms to 200 kms. From that pace  we went on to satellite launch vehicle  like SLV3.SLV3 was totally a different concept  since vehicle has to go to still higher altitude and it has to carry heavy payload. When we started the first rocket launching here , the Americans were sending orbiter to mars. So we are  lagging by almost 50 years. From that we came to this level by learning, by doing lot of mistakes learning from mistakes, and all mistakes have been converted to lessons and now we reached here.


Now GSLV Mk111, last December we had experimental mission, it was very very successful. Of course we haven't used actual cryo stage  in this mission. By next year end we are planning to use Cryo stage in  Mahendragiri - IPRC. Recently there was very successful  cryo engine test- C20 engine, that is meant for Mk111 vehicle .Now things are going smooth.

What are the propellants which is being utilized by our rockets furthermore, might you be able to please toss some light on recent improvement in propellants?

Combination of fuel + oxidizer is called propellant. We use chemical propellant which is very popular. First one what we started  with was solid after  that we  have liquid, now we are doing cryo, next is semi cryo. Semi cryo means in  the cryo, liquid oxygen is retained  in place of liquid hydrogen, liquid refined kerosene is used. This liquid kerosene is cheaper and also handling of kerosene is less complex, less hazardous .Now semi cryo work is going on in Mahendragiri and also in LPSC. With in another two three years we will come up with semi cryo.


Does throttling is possible in Semi cryo?

Throttling is possible in semi cryo since both are in liquid stage.


Share us  something about S200 engine and S200 booster for GSLV MK-111 venture.

It's a very big booster, the development of that booster was very challenging. It happened when I was in sriharikota. I was here(in Trivandrum) for more than 30 years and then I have been asked to go to sriharikota( 2004-2012) about 8.5 years I was there, during that period only we have established the plant. So now it is a world class plant for making booster. Booster production plant will be always near or on the same site as the launch pad. Because Transportation of the booster will be very difficult. See for example now in America NASA, their booster plant is in UTK, from there to Florida launch center they transport it in segment wise in rails. But in our case smaller segment what we make in Thumba is transported to sriharikota through explosive track but bigger and bigger when the  booster comes transportation of the booster segments(live propellant) is dangerous. Generally best combination is production plant of the booster should possibly nearer to the launch site.

In sriharikota we have excellent plant and launch site. In 2008 we made first booster in 2010 we ground tested. Every booster or engine before qualifying for the flight we have to ground test it with enough time and see their performance is pakka then only we can clear it for the flight. Now we have completed two test for S200. Experimental mission for MK111 was one  of the most challenging for proving the booster in the flight. In fact  foreign people were wondering  for , how we could have confidence of  flying it with 2 test. Generally they will do minimum half a dozen test. That is their protocol. We don't have money so we limit it to 2.

 


Could you please name top 3 nations which uses our rocket service  regularly ?

Europeans use our launching pad for launching smaller rockets. In the same time we depend on them for our bigger satellite. Arian vehicle which we make use for launching our satellite of above 2.5 tons. For European satellite which is one ton weight our vehicle PSLV is better vehicle in cost wise. Then Americans also use our launch pad for some smaller satellites. Other countries like Malaysia, Singapore, Brazil, south Korea are always there because such countries don't have their own launch pad

How VSSC is contributing to India's ambitious human space flight program?

Human space program we call it as HSP(Human in Space Project).About 5,6 years back we prepared a project report and submitted to government ,that time it was around 1000crores it was a big money now it will be much higher. But government  has not fully approved it since the quantity of budget involved is high. For doing initial R & D government gave us about 200crores, we are utilizing it now. Lets say  that the module proposed has been sent in the launch vehicle MK111 and got it proved .

So now we are continuing the work, whatever spade work we  done is we are doing. Two things are there in human space flight program, one is launch vehicle with very good reliability  because it is a matter of human life. So vehicle with very high reliability should be proved. Now PSLV vehicle has got excellent reliable in similar way we have to qualify another bigger vehicle to take human  because limitation of the weight. In whatever way we try with all systems like life supporting systems, escaping systems, safety arrangements, service module ,and etc., will minimum go to about 3 tons. So MAK111 is ideal vehicle for us to think about human space program.

That vehicle is yet to be proved. only one experimental mission has been over. Still half a dozen test is left back. That is one part. Another part is crew module ,the service module , crew escape system which means in case something happens crew should  get ejected to some safer place. Such system have to  be proven by our renowned officials in  parallel  the vehicle gets ready. Now this is going on. It take some time, and also accordingly when government is giving some more money to us to continue the work, but project is yet to be approved.


When can we expect GSLV series of rockets to be as reliable as PSLV family of rockets? Could you please throw some light on it?

It takes time in the sense. Without cryo stage we have done experimental mission ,now the solid booster S200 and  L110 liquid core vehicle both are proved. So along with the live cryo stage, in 2016 we are trying to planning to fly it, that will be D1 flight( Development 1).What we made is E1 which is Experimental 1.D1 when we make it D2,D3 it may come. We planned to have maximum of two flights in one year. so it will take 2 -3 years. By 2018 or 2019 it may.

What are the favorable climatic conditions for launching a rocket ? What are all preparations are done before any launch?


We are supposed to make  the vehicle rugged enough to launch in any weather condition. In last minute we have checking for adverse situation. Adverse situation is mainly wind. Wind is the main culprit. Wind can give external disturbance to the vehicle flying path because of the forces and for that we have our own prediction methods experimentally and by modeling. There are ground stations in which we will be sending balloons with instruments  to 40 ,60 kms. Wind is classified as ground wind, lower altitude wind, higher altitude wind and like that. Wind  will suddenly change. The changing phenomena is called gust wind also may have some parameter called sheer. Sheering means kind of turbulence.

These are all very dangerous for the aerodynamics stability of the vehicle. For taking care of the disturbances due to wind we have our own control systems for the vehicle, that we call it as steering of the vehicle. Like left right up and down etc., for that, vehicle is in built with control rockets, ( small liquid engines for firing).  If one side some deviations comes in other opposite side you give a kick by firing the an engine, this is called control system. That control system are operated with respect to a package( sensing and  the disturbance )assessing what is quantum of disturbance, then  give to the computer for processing it. The computer just immediately take actions with respect to guidance. There are instruments called gyroscope. Gyroscope sense the direction of the vehicle namely yaw, pitch , roll.

The gyroscope senses the Quantum of deviation and gives it to computer. Computer understand by programming ,it simulate then decides how much forces have to be created by the control rockets to correct it to the  normal .This is called control guidance and simulation, these are all done in ground station N number of time and program is made. After doing a ground level test they create command, program and load it to the equipment bay. Equipment bay is the electronic package.(like loading software to hardware).So the electronics will absorb the total program and according to the input what we are giving (data input) it act to give what are all the control forces required and it gives command to the working of the actuators. These side forces and other systems are made by actuators.

Actuators are for making movements- execution. Electronic, electro mechanic actuators are there which are run by servo motors. That will be given signal. They get power from battery sometimes it gets power from electric motor or it get power from gas motors. If we give power via battery it is like adding inert mass we can have a gas motor ,a motor which works on out gas. Like a small turbine. For running the turbine, gas can be obtained from the rocket bled (exhaust gas) ,make a line pump it to turbine and like that. Other Natural calamities like  rain , thunder should not be there . Thunder is classified in to level 1,2,3.Launching will not be there during thunder, Since the Launch pad  get affected by  charge from thunder.


Level 3 is extreme so we should not launch during that time. It can give problem in spite  of all earthing  circuits and  some time it can give damages to electronic components. Rain will not affect much but rain always affect with thunder and wind. so that is why in most of the launches there is last minute  postponing.

I  want to say thanks to Mrs Ushakumari D, Secretary for Dhathan sir, for her support in this interview.

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*** This interview was taken a few days before his retirement as the director of VSSC.

Author
Ms. Kokila
Intern, Indian Space Station
Amrita Vidyapeetham, Coimbatore

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