ISRO’s GSLV Mark III rocket lifts off July 22 carrying the Chandrayaan-2 lunar mission. (credit: ISRO)
Just two days after the world celebrated the 50th anniversary of the Apollo 11 landing, India’s second mission to the Moon, Chandrayaan-2, began its 48-day journey to the Moon. Chandrayaan-2, an orbiter and a lander and rover system, launched from Indian soil using an Indian rocket called GSLV Mark III on the afternoon of July 22.
The Indian Space Research Organisation (ISRO) is expected to attempt a soft landing of the Chandrayaan-2 lander at a location close to the south pole of the Moon on September 6 or 7. It will be the first time ISRO has attempted a soft-landing on any world. The orbiter weighs 2,379 kilograms and is expected to operate for one year. The lander, called Vikram, weighs 1,471 kilograms while the rover, Pragyan, weighs 27 kilograms. The lander-rover would operate minimum for 14 Earth days.
The launch was scheduled for a week earlier, early on July 15. However, the mission was called off just 56 minutes before liftoff because of a technical glitch.
ISRO has not provided the specific details about the exact nature of what it called a “technical snag.” There are indications that sufficient pressure had not built up in the helium tanks in the rocket. There is a possibility that the leak could have been at multiple places in the tanks. Whatever might the case, the fact that ISRO successfully performed the launch just a week after detection of the fault shows their professionalism.
This is not the first time ISRO has called off a mission during the countdown stage. The GSLV-D5 mission was called off on August 19, 2013. The launch, with the Indian Cryogenic Stage, was called off due to a leak observed in the UH25 fuel system of the liquid second stage, during the final phases of the countdown. ISRO ultimately performed the launch, successfully, on January 5, 2014.
ISRO’s GSLV Mark III is a three-stage rocket with first and second stages filled with solid and liquid propellants, respectively. The third stage is a cryogenic stage. A cryogenic system is sought after since it provides more thrust per kilogram of propellants. The cryogenic engine uses liquid oxygen (LOX) and liquid hydrogen (LH2) as propellants. ISRO, which has made reasonable technological progress is various arenas of space technologies, has found cryogenic technology as a “horse difficult to mount.” It could be said that ISRO has been under a “cryogenic curse” for many years, with the launch scrub on July 15 only the latest sign.
During the 1990s, ISRO had a major focus towards development of launch vehicles, since India had achieved spacefaring nation status a decade earlier and was keen to expand its space program. The 1990s was the period when ISRO’s PSLV (Polar Satellite Launch Vehicle) had started operations. Since this rocket has the capability only to put satellites having less than two tons weight into orbit, ISRO felt the need to have a vehicle to put heavy satellites into geostationary orbits. That led to an offer from Glavkosmos, a Soviet agency.
Glavkosmos was to transfer cryogenic engine technology to India. However, when the actual transfer was to take place the geopolitical situation had changed, but Russia was required to honor the deal. However, during the 1991–1993 period the wind started blowing against this deal. It was argued that transfer this technology to ISRO could also help India’s missile program. The Missile Technology Control Regime (MTCR) bogie was raised, and finally Boris Yeltsin and Bill Clinton worked on a compromise formula that stopped any technology transfer, but allowed Russia to sell seven cryogenic engines to India. It is important to note that cryogenic engines are considered as unusable engines in the development of long-range missiles like ICBMs. Hence, India was rejected access to the technology not owing to any missile fears, but more out of geopolitical (perhaps geo-economic) considerations.
All this led ISRO to slowly start developing cryogenic technology indigenously. ISRO took on itself to develop the GSLV programme, meant for heavy satellites in the range of 4 to 6 tons to GEO.
In the first decade of 21st century ISRO suffered three failures using this technology. Of those, one failure was due to an Indian-made cryogenic engine, while in case of other two disappointments, the engines were Russian. During the second decade of the 21st century, India was forced to call-off two missions during the countdown phase, but the launches were ultimately successful.
ISRO took significant amount of time—almost two decades—to develop the cryogenic technology. Normally, a cryogenic stage would include the engine, propellant tanks, motor casing, and wiring. Initially, there was very limited expertise available with ISRO regarding cryogenics. Such cryogenic engine technology is complex to design, develop, and build. ISRO started with a clean slate. They were required to work on various aspects, from developing special igniters and turbopumps to identifying and making special alloys. The entire process required them to develop new technologies and techniques.
India has developed two types of cryogenic engines. The first one is based on the Russian design and specifications, called CE-7.5 (and variants with minor changes.) The burn time for this engine was 720 seconds. ISRO had one failure and three successes with this engine. When ISRO was using this engine, it was also developing the fully indigenous CE-20 engine and the C25 cryogenic stage. Obviously, working on the Russian design must have helped ISRO towards making indigenous engine development. The normal burn time for CE-20 is 580 seconds. There have been three successful tests with the CE-20 but Chandrayaan-2 is only the first operational flight of GSLV Mark III. More successful flights would be required to establish the vehicle as a commercial product. However, with the CE-20 engine this rocket can only lift around four tonnes.
Realising the limitations in regards to lift of heavy payloads with existing cryogenic technology, ISRO started working a couple years ago on a project to develop semi-cryogenic engines. The proposal is to use a highly refined form of kerosene termed RP-1, along with liquid oxygen, to increase the payload capacity of its GSLV Mk III. The first test with this new engine is expected to happen by December 2020.
ISRO has major ambitions like human spaceflight, a mission to Venus, and second mission to Mars. Also, there are proposals like an Indian space station. However, it is important to note that instead of praiseworthy execution of few important projects and successfully establishing a “brand ISRO” owing to frugal engineering, ISRO continues to remain a small player in a few arenas of space domain. ISRO successfully conducted its first missions to Moon and Mars a few years ago. However, because of the lack of a heavy launch vehicle, ISRO was able to carry a very limited payload to these planets. Even with Chandrayaan-2, ISRO could be conducting an experiment on the Moon surface only lasting for one lunar day. All deep space missions of ISRO have proven to be mainly technology demonstration missions. More science could have been possible if these missions would have been capable of carrying more payloads. Even today, ISRO remains only partially capable of launching heavy communications satellites to geostationary orbit.
It has taken time for ISRO to develop cryogenic technology. Recently ISRO has had some good successes with the GSLV. However, there is a need to leapfrog in the heavy-lift launch vehicle sector. If ISRO has to grow, this program has to grow rapidly. At this point in time ISRO has just barely solved the cryogenic riddle, yet much needs to be done.
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