Solid Boosters and Liquid Engines

Solid boosters are relatively simpler to make while liquid engines are difficult as they have many rotating parts involving complex manufacturing. Solid and liquid engines use hydrazine-based fuel with nitrous oxide as the oxidizer. The entire quantity of fuel onboard is burnt to develop a thrust of about 200T in 150 secs. Solid boosters are ideal for developing a large thrust essential at the lift-off stage. Liquid engines are like any other engines but have large exhaust cones from which the gases at high temperatures and pressure are ejected to develop the required thrust. Liquid engines can be fired for more than 12-15 minutes to cover long distances. These can be stopped and restarted to gain ejection velocity.
After traveling the required distance which can be 1,000 kms to 36,000 kms, the Yaan needs to have a minimum velocity of 10 km/sec to have sufficient centrifugal force, so that it escapes out of the Earth’s gravitational force and does not begin to return to the Earth.
At appropriate point in time of the journey, the used boosters and the stages were ejected out by special mechanisms. This was done after the LV had gained adequate speed and momentum. The ejection was controlled by onboard computers, and the ejection process ensured that the ejections happened in different directions to prevent any collisions with the main craft. The payload was provided with special protection as it would travel through the dense atmosphere of the Earth, up to a height of 20kms after which, the protection was ejected to gain speed and save on the fuel. All these operations were carried out to ensure that the Yaan had a minimum velocity of 10 km/sec for its onward journey.

Cryogenic Engine

The second stage of the LV is always cryogenic, as it is essential to give that specific impulse to the payload and place it in the required orbit. The cryogenic engine uses liquid Hydrogen and Oxygen, and in this combination Hydrogen is used as a fuel and Oxygen as the oxidizer. This combo is ideal for having the required thrust and burn time. Hydrogen and Oxygen are stored at cryogenic temperatures of -240 °C to -265 °C. This engine is extremely complex to manufacture but is realized successfully in India by ISRO and its industry partners, which is a matter of great pride.

The Journey Of the Yaan

In its second journey, the Yaan was ejected into an elliptical orbit which was progressively enlarged so that the Yaan could escape the Earth’s gravitational force and begin its journey towards the moon.
This journey was controlled with great precision to ensure that the Yaan entered the moon’s orbit at the right juncture when the moon was closest to Earth.
After the above, the next move was to ensure the entry of the Yaan into the moon’s gravitational force. In this move, it was critical to maintain the required velocity and the orbit. Once the Yaan stabilized in this 100km orbit, 25 thrusters mounted on the Yaan were activated to make adjustments in the velocity in preparation for landing at the pre-identified spot on the moon.

Lunar Transfer Trajectory

Landing On the Moon

In this last and most important stage, the speed of the Yaan was progressively reduced to begin the descent towards the surface of the moon. During this stage, lots of sensors were used to judge accurately, the distance to the moon’s surface and adjust the velocity of the Yaan, accordingly. As the Yaan did not have any landing gear, reverse thrusters were used to reduce its velocity. The Yaan was provided with long legs and had shock-absorbing capabilities built in for safe landing. Also, a parachute-like structure was provided to make it float before the final landing.
All these mechanisms were activated remotely at a distance of 3,84,000 kms away from the surface of the Earth- a remarkable technological achievement!
The AI module onboard of the Yaan, carried out various operations meticulously to ensure that the lander Vikram landed successfully. Once the soft landing was made, the Rover on the lander Vikram was activated to slide off the lander. The Rover was planned to operate for 14 earth days or 1 moon day during which it carried out many activities and operations as planned. Solar-powered Rover collected lots of data and images, that were sent to ISRO for analysis and study. All this is beyond the imagination of a common man, but the fact is, that we have landed successfully on the surface of the moon. It is also noteworthy that ISRO and its partners have achieved this outstanding feat at a cost that is 1/10th of the cost incurred by the advanced nations for similar missions. A fabulous feat of frugal engineering in practice! So much about the Chandrayaan 3 mission, Now let me dwell on the determinants of ISRO’s success, contributions of the Indian industry, as well as that of Godrej Aerospace.

Determinants of ISRO’s Success

The historic feat of Chandrayaan 3 has been much praised in the media as an event that has made all of us proud. Notwithstanding this praise, not much has been written about the determinants of ISRO’s consistent successes over the years. Although, ISRO had its share of failures, those have been far less when compared to many advanced nations such as Russia, China, and Japan. In my view, ISRO’s success has been particularly noteworthy as it is a Government owned entity and hence, it operates under various systemic constraints that apply to all Government owned entities. This fact notwithstanding, on digging deeper, you will find that ISRO is fundamentally a different organization than any other Government owned organization. The edifice of ISRO’s success is built on five strategic choices made by the founders, right at its inception.

Strategic choice made were, that ISRO would

Focus only on R&D, international collaborations, sourcing/ developing of critical raw materials, design assembly, integration, and testing.

Strive to have a low-cost operating model, where it will not attempt to do everything itself. It would cultivate and develop numerous partnerships with India’s public and private sector players to facilitate the building of critical infrastructure and absorption of advanced technologies. ISRO would also fund such endeavors and encourage collaborations among all.

Adapt participative style of management so that the decisions are collectively made and widely owned. Successes and failures would be collectively owned, devoid of any finger-pointing.

Cultivate strong linkages with the academia and other research organizations and would have open communications with them. Jointly with academia, ISRO would learn and deploy modern technologies such as simulations and mathematical modeling, not only to keep costs low but to have shorter development cycles. Innovations will be sourced from academia and industry partners to keep costs low.

Develop methods and processes at its workshops and then transfer the same to the industry partners. Frugal and concurrent engineering would be deployed across the value chain. Learning from each other and sharing technical knowledge would be done continuously so that best practices are widely adopted.

In the context of the choices made about five decades ago, I believe ISRO has adhered to the underlying philosophies to succeed remarkably.
Today, ISRO has one of the best facilities in the world for ground testing in simulated chambers and qualifying sub-systems and components.
Further, various boards formed by ISRO have performed the tremendous task of testing, understanding, and absorbing a plethora of international space rules and regulations. ISRO has established a rigorous set of processes for carrying out pre-and-post mission analysis and for taking corrective and preventive actions. ISRO is perhaps the only Indian Government-owned entity that routinely shares its analysis of the challenges with academia, R&D institutions, and international space agencies. It also shares the relevant details with the partners concerned. In short, ISRO places a huge emphasis on understanding challenges fundamentally and then working for solutions. To ISRO, Why is more important than How?

Role Of Industry

As ISRO has been shouldering its responsibilities, the industry has been playing its role in developing an infrastructure that can meet the requirements of the space sector. This involves mastering sophisticated fabrication and machining, building process capabilities of cpk 1.6 and in some cases, beyond, and finally, building a culture of quality across the value chain. The industry has also learned to work on rare and difficult alloys, composites, and so on. A difficult task, but the industry has now evolved to a level where it can meet such daunting challenges in about two to three years.
Atmanirbharta in manufacturing, now appears to be a reality as opposed to being a dream earlier.
Undoubtedly, industry has played a major role all along. Industry leaders deserve our deep appreciation and hearty congratulations for their contributions over the years. The industry has worked for years, where returns on their investments, in unique and specific facilities, have taken as long as 10-12 years to come about. The industry has also invested heavily in recruiting, developing, and retaining skilled manpower suitable for various functional areas essential for ISRO’s work. To the best of my knowledge, the Indian Industry has spent / or invested more than Rs 3000 crs and employed more than 20,000 persons. These numbers are rapidly growing as India’s space sector pursues growth. ISRO, today has more than 400 private sector entities that have successfully partnered with ISRO in developing and producing launch vehicles, payloads, and ground systems. The above shows that the Indian Industry, if given a chance and adequately supported can successfully participate and contribute significantly to the programs and initiatives of national importance. I salute all the directors and entrepreneurs of the industry for their magnificent contributions. Lastly, with the decades-long efforts of developing industry, ISRO will soon be in a position to transfer to the industry, its well-established platforms such as PSLV, 1K- 2K satellites, and many similar sub-systems. The progress in this direction will leave ISRO free to pursue research and development in a focused, bigger way. This speaks volumes for ISRO and its partners commitment to the cause of the nation. In the future, the real game–changers will be the entrepreneurs of 20-odd startups in the space sector. Their out-of-the-box innovations will help India’s space industry take a lead rather than merely catching up as we have been doing so far.

Contributions Of Godrej

Since 1994, for all critical missions of ISRO, Godrej has been supplying Vikas liquid engines which power the flights for 85% of their flight time. The launch vehicle GSLV MK-3 or LVM-3 deployed in the Chandrayaan 3 mission had two Vikas engines in its first stage along with two solid boosters to develop the required lift to overcome inertia and set the direction for the journey. The second stage of the LV is cryogenic, which has been indigenously developed and supplied by Godrej and its consortium partner. This stage burns for the longest duration of about 15 minutes, takes the payload to the desired orbit, and imparts the required velocity. In the mission, once the Yaan was ejected out of the rocket, it had to travel various transitional orbits and finally escape out of the Earth’s gravitational force with a slingshot methodology. Further, once it reached the moon’s gravitational force and entered into the desired orbit, it took again, a similar spiral path before beginning landing. In the absence of an atmosphere on the moon, parachutes or wings are not deployed, but small rockets, ie., reverse thrusters are used to reduce the speed for smooth landing.
Godrej has been pioneering and mastering technology for these thrusters, 25 in number, used in the Yaan of this mission.
Finally, to track, monitor, receive signals and videos, and communicate with the orbiter, Lander, and Rover we require continuous communication linkages between the Yaan and Earth. For this ISRO has designed and developed Deep Space Network Antenna where Godrej has supplied several critical assemblies.

Conclusion

The success of Chandrayaan 3 has encouraged ISRO to have many more deep space missions as well as manned fights in the coming years. These developments will greatly boost India’s space industry and propel it among the top five worldwide. Shall we say the Golden Age of India’s space industry has arrived?