SLV-3 lessons help Isro take call on launch

Was a leak in the GSLV-Mk III’s cryogenic engine big enough to abort the launch of India’s most ambitious moon mission, the Chandrayaan-2? Yes, and the Indian Space Research Organisation (Isro) had learnt its lessons from a gas-leak that led to the SLV-3 launch failure, 40 years ago.

Suspecting multiple leaks indicated by dropping pressure levels, Indian Space Research Organisation (Isro) chose to play safe early Monday morning. But the scientists were well aware of a similar gas leak that hit the Satellite Launch Vehicle -3 (SLV-3), India’s first experimental satellite launch vehicle in 1979.

The elementary computer then had raised an alarm. But Isro officials then decided to override the alert and paid the price. The gas leak, worsened by a faulty valve caused the vehicle to crash into the Bay of Bengal, 317 seconds after launch on August 10, 1979.

But playing out in the minds of Isro officials was also a propellant leak, barely four hours before the Chandrayaan-1 launch on October 22, 2008. A space industry source recalled how that leak was plugged in two hours and the launch undertaken without delay.

By 2008, computers had come of age, tracking every parameter in minute detail. Unlike 1979, when Isro had only black and white cameras, the Chandrayaan-1’s leak was quickly detected by the yellow fumes, the source recollected. However, the Chandrayaan-2 leak was minimal but Isro had exercised ‘extreme precaution’.

Chandrayaan-2 had much in stake. Dubbed ‘Baahubali’ for its massive power and size, the GSLV-Mk III was too precious a resource to take chances. And with barely 56 minutes and 24 seconds before blast-off, Isro simply had no choice but to put off the mission.

The leak was first noticed when helium-filling into the cryogenic engine was completed. Scientists attached to the project have revealed that they found something amiss when the pressure began to drop. This was a clear indication of a leak.

But at that stage, the mission was yet to enter the automatic launch sequence. If this timeline had been breached, it would have been virtually impossible to put off the launch. Isro is now in a rush to plug every leakage.