Indian Space Research Organization (ISRO) will be making only minor tweaks to its heavy-lifter rocket GSLV MK-III

Chennai: According to top officials, the Indian Space Research Organization (ISRO) will be making only minor tweaks to its heavy-lifter rocket GSLV MK-III, as the agency gears up for Human Spaceflight missions. These changes on its most advanced rocket are meant to improve its reliability for undertaking the daunting task of lifting a human-carrying spacecraft to orbit. Additional emphasis would also be paid to the manufacturing process of the rocket and its components.

ISRO is working towards performing two unmanned flights of Gaganyaan, in order to test and certify its systems, before the actual Human Spaceflight. Mandatory testing and qualifications apart, ISRO would also be launching two satellites that are meant to provide communications support for its human-carrying spacecraft. Known as IDRSS (Indian Data Relay System Satellites), they would be placed nearly 36,000km above the equator(where it would remain in sync with the earth’s rotation or at a constant position when seen from earth) and will offer near-total tracking and communication with India’s space assets. It must be noted that a constellation of 3 satellites positioned in the 36,000km orbit can offer real-time, 24/7 monitoring of almost the entire earth.

ISRO intends to launch two such IDRSS satellites prior to the Gaganyaan Human Spaceflight. Dr. K.Sivan, Chairman, ISRO told Zee Media that the Gaganyaan spacecraft would be placed in a low earth orbit, 400kms above the earth. He added that ISRO was looking at launching the IDRSS satellites in 2022. For context, when Gaganyaan is orbiting earth, but not visible to the ground stations, Gaganyaan can send its signals and communicate to the IDRSS satellites up above, which in turn would relay it down to the ground stations and vice versa. This would ensure constant communication between the astronauts and their mission control on earth.

Referring to the orbital placement of Gaganyaan, he said “The rocket will put the 7.5ton Gaganyaan module into 170x400kms orbit(170kms from earth and 400kms from earth at its nearest and farthest points in orbit respectively). Thereafter, the on-board propulsion will raise the Gaganyaan module to a uniform 400kms orbit (Low earth orbit). He also added that, the same propulsion system would be used to lower the orbit and bring the spacecraft closer to earth for aiding re-entry.

When queried about the astronauts' mission duration in space and the splash-landing site(Bay of Bengal or the Arabian Sea), he said that it would be decided in due course.

On the testing of rocket engines, Dr. S. Somanath, Director of Vikram Sarabhai Space Centre told Zee Media that minor tweaks would be made to the GSLV MK-III rocket, in terms of few materials being used. However, he added that these would be very minor changes that are aimed at improving reliability and not fundamental, technological ones. Also, the space agency would be laying additional emphasis on the manufacturing process of the rocket and its components. It is pertinent to recall that the GSLV MK-III, which is to be used for Gaganyaan has had complete success in all its four flights thus far.

Regarding the engines being used to propel the Gaganyaan spacecraft, he said that it was a cluster of five engines. Here too, the engines being used are the tried and tested 440N thrust engines that are in use in the GSAT series of satellites. A system demonstration model comprising a cluster of five engines were recently test-fired successfully by ISRO, for a duration of 450 seconds. In the coming months, ISRO would be performing long-duration test-fire of its engines, in order to accumulate more data for human-rating of the entire rocket. It essentially means that a rocket that is used for hauling Cargo (Satellites) to space is being modified, certified for carrying humans while ensuring higher safety and reliability.