When Arun Raj shared the link of his interview with the LPSC Director (along with Shorts on Gaganyaan and NGLV), I shared the video link with Gemini and asked it to give me a post I could post here. It did a really poor job. So, I decided to listen to it and translate and put this post together.
The interview is with Liquid Propulsion Systems Center (LPSC) Director, N Jayan. He was formerly Project Director, Next Generation Launch Vehicle (NGLV) at VSSC.
The theme of World Space Week (October 4 – 10) this year is Rocket Revolution. Jayan says this is a timely and critical theme for ISRO this year.
NGLV
ISRO has been working on improving the present rockets. Work has been progressing on improving the cryogenic stage and inducting the semi-cryogenic engine into LVM3 to make it capable of lofting payloads of 5 tons into orbit.
But, we need a rocket revolution. We can no longer just keep making improvements in the current rockets to meet the new requirements. Requirements for satellites and spacecrafts have changed. We now need Heavy Lift Vehicles. We need rockets capable of lofting 30 tons to Low Earth Orbit.
NGLV will be 100 m high, which is more than twice the height of the rockets we have so far, and more powerful. All design and configuration work is completed. It has three stages.
We have generally used solid, earth-storable, cryogenic fuels but this is a new fuel that we will be using. You have seen many other heavy lift vehicles from other countries with reusability, specially in the last 10 years using fuels like liquid oxygen and liquid methane engines.
NGLV will have 10 such engines (Liquid Oxygen + Liquid Methane). 7 in the first stage. 3 in the second stage. Cryogenic stage C20 will be on the third stage.
Design work is completed. Work on the engines is progressing in LPSC. Vehicle structural design, tests, hardware drawings and manufacturing-related work is progressing in various ISRO centers. The development of a launch pad for NGLV is in progress at Sriharikota.
This is a low-cost rocket. We are moving away from technology and moving into it as an industry. If we have to compete with other countries, rockets must be low-cost. We must master reusability of rocket stages as this leads to low-cost of the rockets. We must bring reusability to our rockets as soon as possible.
70% of the cost of the NGLV is in the first stage. If we can recover this stage, we can reuse this stage again and again. We have designed all aspects of this stage with this requirement in mind.
After NGLV, we are working on the Lunar Module Launch Vehicle (LMLV). We are proposing that as a project. We have only started initial work on this project. We will add two stages as strap-on to the first stage of the NGLV. So, the first stage will have 21 engines. It will be capable of lofting 90 tons into Low Earth Orbit or 30 tons into Trans Lunar Injection orbit.
Landing a rocket is much more difficult than putting a satellite into orbit. A high velocity rocket returning to Earth has to be killed. It has to withstand friction (and the resulting high temperature) that is experienced when it returns to Earth. We have to develop materials that can withstand it. We then have to bring the rocket in for a controlled landing at a designated site. It is very difficult. It is difficult but it has been done.
We are incorporating this in the design-phase of the NGLV itself. There are many ways of landing a rocket. One is return to launch site. This is difficult because the rocket has a long distance to return and hence it will require more fuel. Second is barge recovery. We place a barge in the sea at a precise location. It is easier for the rocket because the distance it has to cover can be reduced. The problem with this approach is building the barge, returning the barge with the landed rocket to the coast, and the associated infrastructure development is costly. The third approach is chopstick recovery that you have seen with Starship. This does away the requirement for landing legs.
We are studying the best way to recover the first stage of the NGLV right now.
ADMIRE
We are thinking of using L40 stage to test Vertical Take-off and Vertical Landing. Instead of testing the whole vehicle, we can test a small stage to master the technology. We have to find a way so that the thrust of the vehicle and mass of the vehicle are the same so that the vehicle floats.
We have started with tests of throttling the Vikas engines. We were able to throttle it down from 62 bars to 25 bars. We were able to reduce the thrust from 100% to 40%. We have planned a series of missions where it is flown to different heights and try to achieve controlled landing. Once we learn the technology, we can adapt it to NGLV, etc. Engine testing-related work is completed. Work is in progress on the landing gear. We will be doing the VTVL experiments soon. The test could be done in a few months. Perhaps within a year. We will be doing hop test soon.
LVM3
LVM3’s capability must be improved to beyond 5 tons if we have to launch Chandrayaan 4. We have been planning this for a long time. One, we have to improve C25 stage using the CE20 engine. We are operating the CE20 engine at 19 tons. We are upgrading the C25 stage to a C32 stage. It can carry 32 tons of fuel. We are changing the length and dimensions of the tanks. We have made minor changes in the CE20 engines so that it can operate at 22 tons. This helps increase the mass capacity by 350 kg.
We are replacing the earth-storable L110 stage with Liquid Oxygen (Cryogenic) and Kerosene (Earth-storable, hence semi-cryogenic) combination Semi-Cryogenic stage that can operate at a thrust of 200 tons. We have developed Vikas at 80 tons. This is a direct jump to a 200 tons engine.
We recently completed the Power Head Test. Leaving aside the combustion chamber, we have tested the rest of the assembly. This system has to deliver the fuels at the correct flow rate and desired quantity into this combustion chamber. We tested that the quantity and flow rates were correct with the Power Head Test. We have tested this till 200 tons thrust.
Work is in progress on the combustion chamber which should be ready in 1-2 months. Once the combustion chamber is attached to the power head, it becomes the full engine. In a few months after that, we should be able to test the full engine. We have plans for that. We plan to complete the full development of the engine and test the stage in 1.5 years.
Chandrayaan 4 is planned for 2028. We want to test this engine in a flight before that.
Reasons behind the Delay of Semi-Cryogenic Engine
We had started work on the SCE in 2010. At that time, the cryogenic engine on the GSLV-D3 failed. Once that failed, the focus shifted to make the cryogenic engine project successful. We had worked on both cryogenic and semi-cryogenic engines.
It was 2014 by the time GSLV succeeded. At the same time, development of LVM3 and CE20 engine became the focus. The development of SCE was thus not a primary focus area. Once LVM3 was successful, the full focus shifted to SCE development.
The biggest challenge here was the material technology. We were handling materials ISRO had not handled before. We were building an Oxidiser Rich Pre Burner. In cryogenic engine, it is usally fuel-rich and so materials are easier to handle. A hot gas that is rich in oxidiser destroys most of the material. The material is not able to withstand this environment.
India did not have technology in handling the material needed to withstand this oxidiser rich environment. We did not have experience in welding, brazing, etc. We faced a lot of issue with fabrication of the material. The material we fabricated would not withstand the pressure test and hence we lost a lot of material and hardware. We developed many specimens and studied them. We learned to work with this material called high-nickel alloy. We have solved all of these issues now.
Gaganyaan
Gaganyaan G-1 will fly a month after the flight of the NVS-03, expected in the end of October. Rocket stages are at Sriharikota. Stacking is in progress. Reviews are in progress. Orbital Module is undergoing some final tests in Bangalore. Orbital Module will be moved to Sriharikota thereafter.
LPSC is working on the Environment Control and Life Support System (ECLSS). It has to give astronauts a comfortable living conditions. Temperature, Radiation protection, Humidity Control, maintaining the levels of oxygen, handling water and food supply, and waste mangement.
ECLSS on G1 will be experimental and for gathering data. Some part of the ECLSS is in the Crew Module and some in the Service Module. This integration and testing is completed.
Work is progressing on G2 as well at LPSC. The fully functional ECLSS will be flown on G2. Testing of the systems is in progress at LPSC. By the time of G2 launch, ECLSS system will be ready incorporating changes according to our experience in G1.
Electric propulsion
Electric propulsion is 5 times more efficient than chemical propulsion. If we consider 5 ton satellite with chemical propulsion satellite, we can realise the same satellite with a mass of about 3 to 3.5 tons for the same purpose.
Satellite propulsion is used for orbit raising and station keeping. This saves on mass of the fuel in the satellite. This reduces the cost of launch to almost half.
We are using a technology where gases like Xenon and Argon are ionized and accelerated by an electric field. We are in very advanced stage with electric propulsion at ISRO. We have developed engines with multiple thrust levels – like 75 mN, 18 mN and the most important is the 300 mN stationary plasma thruster.
The 300 mN thruster development and qualification is completed. It will fly on the TDS-01 satellite on the PSLV-C63 mission. The thruster and satellite are tested and are ready in Bengaluru. The thruster will be used for all operations of the TDS-01 satellite.
We are building thrusters for micro-satellites and high power thrusters for larger satellites. We have started work on the high power thruster project. We have developed 1 N thruster for bigger satellites.
Once successful on TDS-01, we are planning another TDS-02 mission with an improved version of the 300 mN thruster. Once successful on these two missions, electric propulsion will slowly be implemented in all of our satellites. These can be developed in 6 months to a year.
Launch Frequency
For increasing the launch frequency, we must increase the number of industries we welcome into the sector in a profitable way. We must be able to reduce the cost of future rockets like NGLV. We must be able to invite international customers. We must develop our industry towards that end. We are discussing with industry.
We must be able to build 100 engines in a year as against 5-6 engines in a year. Just like building Maruti cars in a production line. Only large industries will be able to build a production line. We have spoken to industry about this during the NGLV Industry Meet. They are enthusiastic and ready to develop the infrastructure for the same.
We need to be able to test multiple engines at the same time. This could mean 5-6 bays in which 4-5 engines are tested at the same time in each bay. Design of building such a facility at Mahendragiri are in progress. 1-2 engines can be tested in a week.
We are looking at integrating the manufacturing process under a single roof. Currently, the parts are being made elsewhere and there is delay in transportation. If the full manufacturing process comes under one roof, an industry produces a finished engine comes out just like a car or a bus.
Building propellant tanks in Sriharikota, integrated with engines, and launched in Sriharikota is also being considered. We are working on implementing such a model to improve the launch frequency. Something like an assembly line system. We have to also reduce transportation time.
New Technology
Technology is limited only by your imagination. Our youth can think in new ways. There will be failures. But, one spark can lead to new innovations. Space is moving from being a technology to an economic industry. If Indian human resource is utilized to develop new technologies and a space ecosystem is built, then it has the potential will transform India just like IT revolution did. This is what we are doing with Indian startups, hand-holding, etc.
NGLV is 80-90% built using additive manufacturing. Additive manufacturing has a big role to play in mass production of engines. NGLV has been designed with this in mind.
AI centers are opened in many ISRO centers. It is used from defect detection, design, and testing (testing data is fed to AI to reduce failures).
The biggest challenge in rocket propulsion technology is building a rocket with materials that are not exotic. This is important for it to be mass-produced.
Air-breathing propulsion like Scramjet engine is another challenge.
Our final dream is a single stage to orbit. A rocket goes into orbit and returns just like an aeroplane. Development of propulsion systems that are hybrid air-breathing and rocket based combustion combined cycles. We have started work on this. Youngsters in our units are looking for such challenging tasks.
Satellite electric propulsion efficiency can be improved by 20 times. Theoretically, it can be 25-30 times.
We are planing a green propellant on-board a POEM payload.
We are working on nuclear electric propulsion system.
Chandrayaan 4 will use higher thrust chemical propulsion engines. Engines have been defined, thruster development is almost in its final stage. For Chandrayaan 5, will use higher thrust engine than Chandrayaan 4. We are using 3.1 kN engine instead of 500 N engines. We have built a prototype hardware for the same and tested them. There is very little technical uncertainity as these are mainly upgrades.
— End of Interview —
Feel free to leave any corrections in the comments. Will be happy to incorporate them here.