Chandrayaan 2 mission not shelved, just delayed: Here is everything we know

In a dramatic but very anti-climactic turn of events, the Indian Space and Research Organisation (ISRO) called off the much-awaited Chandrayaan 2 launch last night. The mission was cancelled 56 minutes before the planned launch at 2.51 am on 15 July.

ISRO send out a tweet saying that the mission had to be cancelled due to a technical snag, but it did not specify anything nor did the ISRO Associate Director (Public Relations Officer) B R Guruprasad say much when he read out a small announcement at 2.40 am saying almost the same things like the tweet.

Chandrayaan 2 technical snag

The Geosynchronous Satellite Launch Vehicle Mark III (GSLV Mk-III) is a three-stage launch vehicle that has been built by India and uses liquid hydrogen and oxygen as fuel.

An ISRO scientist told TOI, although in an unofficial capacity, that the launch was called off due to a drop in pressure detected after helium was filled into the tank. The pressure drop indicated a leak in the fuel tank.

Another source told The Economic Times that the drop was detected in the upper stage of the rocket.

 Chandrayaan 2 mission not shelved, just delayed: Here is everything we know

Representational image. Credit: ISRO/Twitter

The scientist said, “After filling liquid oxygen (oxidiser) and liquid hydrogen (fuel), helium was being filled. The procedure is to pressure the helium bottle up to 350 bars and regulate the output to 50 bars. After filling helium, we found the pressure was dropping, indicating there was a leak. The team is yet to pinpoint the exact spot of the leak in the gas bottle; there could be multiple leaks.”

The ET source explains the importance of Helium in the rocket. He said that the nine tanks of helium are used to maintain the temperature of the liquid hydrogen at a certain temperature ( -253 degrees Celcius). The pressure dropped in one these tanks and since the mission is very significant, ISRO decided against going ahead with the launch.

A similar leak was detected in the oxygen tank in a ground test in the cryogenic engine on 22 June. But ISRO decided to go ahead with the launch in a calculated risk.

The source said that the leak might have happened in a weak joint in the chambers which he explains with a metaphor of a pressure cooker.

Chandrayaan2

ISRO engineers hoist the L110 i.e. the core stage to integrate it with the two S200 solid rocket boosters. Image credit: ISRO

Former ISRO chief K Madhavan Nair, in an interview with My Nation, said that a similar leak took place in the Chandrayaan-1 mission but it was rectified and as we now know, the mission was a success. He also said that these “glitches were not uncommon” and that a “catastrophe was avoided as the anomaly was detected in time.”

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What happens next?

An ISRO source speaking to IANS said that to check for leaks, the entire fuel will have to be unloaded. The rocket will then be taken back to the launch room and investigated. This process will take 10 days. They will then need to calculate a new trajectory for the rocket which means figuring burn times for the engines, orbits, fuel load, etc. Only then will they be able to decide the schedule.

A report on the failure should be ready by Thursday according to sources. Maybe ISRO will also make public more information on the leak and the nature of the technical snag.

An illustration of Chandrayaan 2 orbiter lander rover composite orbiting the Moon. Image courtesy: ISRO

An illustration of Chandrayaan 2 orbiter lander-rover composite orbiting the Moon. Image courtesy: ISRO

In an earlier press statement, ISRO said that they have a launch window from 9 July to 16 July. But they have said that the launch will be rescheduled on a later date.

The next launch date for the mission that will allow the rover and lander to have 14 days on the Moon will be available in September.

Updated Date: Jul 17, 2019 12:10:06 IST