At 11:41 pm on Monday night, PSLV-C22 is set to blast off from the Satish Dhawan Space Centre at Sriharikota. This will be the first time that the Indian Space Research Organisation (ISRO) will be launching a rocket in the dead of the night. The PSLV-C22 will use the PSLV-XL launch vehicle, the most powerful in the PSLV stable, to place India’s first navigational satellite in orbit.
The PSLV-C22 is set to inject the IRNSS-1A satellite into a Geosynchronous Transfer Orbit. The IRNSS-1A will be the first of seven satellites to be part of the Indian Regional Navigation Satellite System that is being developed by ISRO. The IRNSS-1A will have two payloads. The navigation payload will be used for the transmission of navigation signals to users, with an accuracy of less than 20 metres. The ranging payload will be used for accurate range determination of the satellite.
The navigation payload is designed to have a Primary Service Area that covers the country, as well as regions extending up to 1,500 km from India’s boundaries. The Extended Service Area will cover the rectangular zone enclosed between 30 degree South and 50 degree North latitudes and the 30 degree East and 130 degree East longitudes. Though ISRO has carried out launches in the dark, early in the morning or late in the evening, this will be the first time a launch operation is carried out in the dead of the night. Sources in ISRO have said the timing was picked because of its suitability to placing the satellite into its desired orbit.
This will be the fourth time the PSLV-XL will be used. It has earlier been used to launch Chandrayaan-1 moon mission (PSLV-C11), for the GSAT-12 (PSLV-C17) and for the launch of the RISAT-1 (PSLV-C19).
PSLV stands for Polar Synchronous Launch Vehicle. But it has been reengineered by ISRO to place heavier payloads into geosynchronous orbit, in the face of persistent failure of its Geosynchronous Satellite Launch Vehicle (GSLV) platform. The PSLV-XL does not place satellites directly into a geosynchronous orbit. It instead places the satellite into a Geosynchronous Transfer Orbit (GTO), from where the satellite is moved into geosynchronous orbit using thrusters.
IRNSS-1A has been designed for a mission life of 10 years and will have a lift off mass of 1,425 kg, and a dry mass of 614 kg. The difference would account for the liquid fuel used to fire the thrusters while moving it into geosynchronous orbit. It has two solar panels that can generate 1,660 watts of electrical power. These solar panels would be deployed as soon as the satellite is injected into a GTO, with 284 km perigee (point in the orbit that is closest to earth) and 20,650 km apogee (farthest from earth). At the same time, the Master Control Facility in Hassan will take control of the craft, and raise the orbit of the satellite over the following days.