Cryogenic rocket engine has been developed from scratch: Isro chief

Cryogenic rocket engine has been developed from scratch: Isro chief
Isro chief A.S. Kiran Kumar speaks to Mint on the launch of GSLV Mark III, the largest launch vehicle ever built by India’s space program
Twenty-sixteen was a remarkable year for the Indian Space Research Organisation or Isro, with nine launches placing 32 satellites in orbit, the most ever in a single year until then, and the successful testing of a Reusable Launch Vehicle-Technology Demonstrator and a SCRAMJET, both developed indigenously. The first half of 2017 saw an even bigger leap—with a world record 104 satellites deployed from a single launch.

Now comes the next big step, the launch of the Geosynchronous Satellite Launch Vehicle or GSLV Mark III, the largest launch vehicle ever built by India’s space program. The GSLV Mark III has been in development for over 15 years, with multiple failures and a gritty focus on developing a completely indigenous cryoengine. The previous class of GSLV, the Mark II, had a cryogenic stage modelled on a Russian engine, now dropped in favour of home-grown technology.

The Mark III’s launch has been made possible after years of patient testing of its various stages and components, including the cryoengine, which also powered the Mark II on its four successive launches starting from January 2014.

The Mark III will be used for injecting heavy satellites into orbit, which is currently mostly outsourced to Arianespace, the launch service run by the European Space Agency, because India has not had a rocket powerful enough for such launches.

Mint spoke to Isro chairman A.S. Kiran Kumar in the week leading up to the launch. Edited excerpts from an interview:

The launch of the Mark III has been a long time coming. In fact the first launch was scheduled back in 2010 when the Mark II had a failure and you had to drop it. Are you nervous about this launch?

No, not really. We have gone through the various steps needed and each process now many times. Yes, because of our cryoengine development problems we had to reschedule, and to overcome those problems and develop the indigenous cryo for Mark II, we needed to do a lot of testing.

So whatever we were developing for Mark III test facility, to some extent we had to modify so we could test Mark II. Now we have had four consecutive successful launches of the Mark II with the cryoengine. That process of realizing a fully functional cryoengine also gave us a lot of inputs and as far as the Mark III’s cryo stage is concerned, we’ve now gone through almost 200 tests, from sub units up to stage level.

So we are confident of the whole process. Now all the things are assembled and waiting. It’s going through its final checks at Sriharikota and the satellite is integrated on the heat shield. So now we have to wait and like any event, until the event is over, you wait.

Tell us more about the CE-20, the cryogenic rocket engine that you developed for Mark III.

It was a very big challenge because this engine has been developed from scratch. It’s a fully independent realization. We had to establish new facilities at Mahendragiri (Isro’s liquid propulsion systems centre) and other places. We’ve done full duration engine level on more than one hardware, then we’ve done the stage tests.

Whereas in the case of Mark II we had initially some interaction with Russia, there was a version of theirs from which we had flown a number of the missions. But here, it’s a completely independent system, with a different design, and the advantage of that is that you know the ins and outs of it.

You know each stage. For example, in the previous version, the turbo pumps are all fitted inside the tank so once it’s put inside, we don’t have access to the pumps and there are limitations on testing them.

Here, the stage configuration itself is designed in a different way so that it’s completely testable but then it has a small penalty because in terms of Isp performance (Specific Impulse, a measure of the efficiency of rocket engines—the total impulse delivered per unit of propellant), this will be slightly less than the other one.

You are hoping that this will be the rocket that will now carry India’s heavy satellites. What kind of cost saving will that result in?

Well we don’t disclose numbers, but you are looking at nearly 25% savings. To give you some example of costs, we launched the INSAT 3DR (a heavy communication satellite) on GSLV Mark II. Previously, when we have launched the same class of satellite through Ariane, you can say that for the launch cost of that we are now able to make both the launcher and the satellite. In remote sensing, Low Earth Orbit satellites or even planetary missions, we are doing everything indigenously.

But we still depend on foreign procurement for heavy satellites. For example the GSAT17 is launching end of June from Ariane. In the very near future, this will not be required. The payload on the Mark III with be the GSAT19, a heavy communication satellite with multi-beam capability, a forerunner to our high throughput satellite.

We have been continuously developing both our technology and our capacity. There is a continuous demand for launches for smaller satellites now, both for national missions—navigation, remote sensing, etc—as well as commercial demand globally. So that was and is an opportunity we wanted to take. As you build your capacity, whatever excess capacity is there you can make use of it commercially.