Chandrayaan-2: Next launch window by end-July
Scientists are racing against time to plug a suspected leak in the propulsion system of the GSLV Mark-III, India’s most-powerful rocket, and targeting a possible window at the end of the month to take another shot at launching Chandrayaan-2, said scientists and technical experts with knowledge of developments.
Roughly an hour before the blast-off early on Monday morning, scientists at the Indian Space Research Organisation (Isro) noticed that the fuel pressure in the last of the three-stage propulsion system of the GSLV Mark III was falling and suspected a helium leak, said a former scientist who didn’t want to be named. The third stage of the propulsion uses cryogenic fuel – oxygen and hydrogen tanks stored in liquid form at extremely low temperatures – with helium used to pressurise the tanks.
Isro staff is now evaluating whether the hitch can be rectified at the launch pad. “If not, the propellant will have to be emptied out and the rocket disassembled and then reassembled. This can be done in a week to 10 days time and the launch window at the end of the month targeted,” said the former scientist quoted above.
Experts said the problem was detected in the launch vehicle and not the Chandrayaan, meaning the entire mission was not jeopardised. The next window for the launch is during the new moon period on July 29 and 30, after which the next possible liftoff will be possible in September, but this may drive up costs of the lunar mission.
“If the launch window in July is missed, a launch next month will be possible only if the orbit inclination is changed, which will require more fuel. This will reduce the payload capacity of the launch vehicle...,” said the scientist.
Another person, who has worked on an Isro launch-vehicle development programme in past, said in addition to the leak, other things could have gone wrong, including the vent valves in the propellant tank failing, resulting in building up of pressure.