PSLV versus GSLV

BENGALURU: The Rs 978-crore Chandrayaan-2 mission, India’s first attempt to soft-land on the Moon has entered its last leg, with the countdown for the mission scheduled to start at 6.51am Sunday (July 14) , after the full dress rehearsal (FDR) of the spacecraft and launch rehearsals scheduled in the days preceding that.Scientists at the Isro Telemetry, Tracking and Command (Istrac) are spending tense moments preparing for the launch rehearsal. One Chandrayaan-2 scientist told TOI: “The full dress rehearsal (FDR) of the spacecraft will take place on Thursday when we will check all the links from the Lander (Vikram) and the Orbiter.”Once the FDR is complete, Isro will begin preparations for the launch rehearsals—simulations at the launchpad in Sriharikota—which will involve ‘dummy’ commands sent to see how the systems respond. All the signals and communication links will be tested too in this rehearsal scheduled for Friday.After this, the sequence of events will include a series of tests, including checks on the health of the Orbiter and Vikram, the launch vehicle (GSLV-MkIII) systems, et al.The two big missions before this—the Chandrayaan-1 and Mars Orbiter Mission (MOM)—were launched using the PSLV class of launch vehicles, while this will be launched using India’s heaviest rocket so far.But scientists have their fingers crossed given that this is only the second operational launch of GSLV-MkIII. “The PSLV is out go-to launch vehicle. It has proven itself over the years with a great track record. The GSLV programme, on the other hand, has had a chequered past and a lot will depend on how this launch vehicle behaves,” one scientist said.However, Isro chairman K Sivan and other senior scientists from the space agency have reiterated the capabilities of GSLV, and have pegged it as the rocket of the future. In fact, it is also being converted to become human-rated as it is scheduled to carry India’s first crew to space as part of Gaganyaan.