What Happened At 2.51 am Monday When Chandrayaan 2 Launch Was Called Off

As the clock struck 1 this morning, the countdown to the launch of Chandrayaan 2 was well on its way. A successful launch for India's most ambitious space mission yet would propel the country into an elite club. Only three other countries - the US, Russia and China - have successfully soft-landed a spacecraft on the moon's surface.

With less than hour to go, there was an "atmosphere of expectation", Jyotsna Dhawan, the daughter of Dr Satish Dhawan, after whom the space centre is named, told NDTV exclusively.

"There was this tremendous atmosphere of expectation as we walked in and we sat there watching the countdown. We sat there for half an hour watching the countdown and watching the way in which the scientists went about their work. It was remarkable," Ms Dhawan, who was in the viewing gallery, said.

Chandrayaan 2, the successor to the Chandrayaan 1 mission that confirmed the presence of water on the moon - a landmark achievement - was scheduled to spend 14 Earth days checking for more water reserves. 

However, all was not well behind the scenes because checks of the rocket system uncovered a problem and ISRO officials decided to abort the launch.

A "technical snag" was announced by ISRO on its Twitter account and the space agency said the launch had been "called off for today as a measure of abundant precaution".

ISRO officials later said the problem was with the critical cryogenic stage. Reacting swiftly, they ensured that the rocket and satellite were safe, and that the highly flammable liquid hydrogen and liquid oxygen were removed from the rocket.

This was a worst-case scenario, for ISRO had a lot riding on this launch. After all, more than $120 million had been poured into the mission by an agency whose entire budget is 20 times less than NASA, its US counterpart.

"For experts around the world... this was a reminder that the best of rocket science does not always work to a plan.. there was a technical glitch and safety comes first. Before everything else," an ISRO spokesperson said. 

"When the hold was placed, for a minute there was disbelief and I thought, for sure it's going to be removed but as the seconds ticked by, it was clear that it was going to be a go-no-go kind of a situation," Ms Dhawan explained, adding that everybody in the gallery "crashingly disappointed". 

ISRO officials were unfazed, according to Ms Dhawan, and worked with a skill and confidence that was impressive.

"They didn't miss a beat. They just kept working because obviously these eventualities are something that they have prepared for, so they have thought about every scenario," she said.

"They were professionals. They knew what they had to do and they did it. And I think that was what was the most impressive and really heartening to see."

"They have thought about every scenario - failure, success, has a particular system performed what it is supposed to do - and to ensure that the investment in time and money and people has actually gone well. That is what we saw yesterday," she said.

For those in the know, this professionalism should not come as a surprise. ISRO has won praise for its efforts in the field of space exploration. 

Two years ago, Elon Musk, founder of private space agency SpaceX, tweeted congratulations after ISRO set a record by launching 104 satellites in a single rocket. And back in 2012, US space agency NASA sought to partner with ISRO on future space endeavours.

Chandrayaan 2 may not have launched at the originally scheduled time and date, but ISRO officials have confirmed that a second attempt is likely to take place later this month.