Just under an hour before liftoff, India’s first attempt at landing a spacecraft on the moon was aborted early Monday morning after a technical snag was detected in the GSLV-MkIII rocket.
Without giving any details, an Indian Space Research Organisation (ISRO) statement said: “Revised launch date would be announced later.”
It was not clear immediately how soon that new launch date could be. ISRO officials indicated that it could take up to a few days to assess the seriousness of the problem. It could rule out another attempt at the launch in the current window of opportunity which is available only until Tuesday (July 16). The next launch date could be months later.
The countdown to the launch was stopped at 56 minutes ahead of the scheduled time after scientists detected a problem in the rocket. While ISRO did not specify it, there were indications that the problem was detected in the upper stage of the rocket carrying the cryogenic engine where liquid hydrogen fuel had been filled less than half an hour earlier.
Amongst all rocket fuels, hydrogen is known to provide the maximum thrust. But hydrogen, in its natural gaseous form, is difficult to handle, and therefore not used in normal engines in rockets like the PSLV. However, hydrogen can be used in liquid form.
The problem is hydrogen liquefies at very low temperature, nearly 250 degrees Celsius below zero. To burn this fuel, liquid oxygen is also required, and that happens at about 90 degrees Celsius below zero. Creating such a low temperature atmosphere in the rocket is a difficult proposition because it creates problems for other material being used in the rocket.
The GSLV-MkIII is the most powerful rocket built by ISRO and is designed to carry heavier payloads, weighing up to 4,000 kg, into geosynchronous transfer orbit (GTO), at least 35,000 km from Earth. It is supposed to be the rocket for the future.
It has made only two successful flights until now – the first one of the GSLV Mk-III D1 in June 2017 that carried the GSAT-19, a communication satellite weighing more than 3,000 kg, and then in November last year, when the GSLV Mk-III D2 launched the 3,423-kg GSAT-29 communication satellite.
The proposed human mission to space, to be launched by 2022, is also planned to be carried on the GSLV Mk-III rocket. Chandrayaan-1 and Mangalyaan, India’s first mission to Mars, launched n 2013, were carried by the PSLV rockets, ISRO’s most reliable launch vehicle. The PSLV has a capacity to deliver payloads only up to 1,500 kg in sub-GTO orbits, but it has had a remarkably successful run.
Between 1994, when it made its maiden flight, and 2017, PSLV has had 48 successful launches, and has failed only twice. However, it is not suitable for heavier payloads, like Chandrayaan-2 which weighed close to 4,000 kg.
Chandrayaan-2, which has an orbiter, lander and rover component, was originally scheduled to be launched as early as in 2010 or 2011, immediately after the 2008 Chandrayaan-1 mission. But at that time, it was supposed to be a joint India-Russia mission, with Russia contributing the lander and rover, while ISRO was to provide the launcher and the Orbiter.
The planned mission could not take off because of design flaws detected in the Russian lander and rover. The Russians eventually pulled out of the collaboration, leaving ISRO to build its own lander and rover. That took time, and the mission was finally ready by 2017.
The mission was initially slated to be launched last year, but was postponed at least twice due to unavailability of a suitable window of opportunity to land on the moon.
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