Countdown begins to launch first satellite in key constellation

Countdown begins to launch first satellite in key constellation


Countdown begins to launch first satellite in key constellation

The countdown for the first satellite of the Indian Regional Navigation Satellite System (IRNSS) constellation — IRNSS-1A — began at 7.11 am on Saturday. Its launch is scheduled for July 1.

Sources in the Indian Space Research Organisation (Isro), while stating that the countdown began at Sriharikota in Andhra Pradesh, said: “The 64.5-hour countdown began smoothly.”

The launch rehearsal, which was in progress on Thursday, was completed on Friday, the source added.

The satellite, which was initially scheduled for a June-12 launch, was delayed due to an electrical glitch.

Satellites of the IRNSS group, an independent navigation satellite system being developed by India, will be launched on the Polar Satellite Launch Vehicle (PSLV). IRNSS-1A will be launched using the PSLV-C22 XL from the Satish Dhawan Space Centre in Sriharikota.

 The IRNSS will initially consist of a constellation of seven satellites, which will enable its users to determine their location and time accurately.

Accurate position

Designed to provide position accuracy to better than within 10 metres over India and the region extending about 1,500 km around the country, the system will also provide real-time Position, Navigation and Time (PNT) services to users on a variety of platforms with 24x7 service availability under all weather conditions.

“The IRNSS provides two basic services — standard positioning service for civilian
users and restricted service for special authorised users,” Isro Chairman Radhakrishnan said on May 28.  He had added that the system would help in terrestrial, aerial and marine navigation services, along with disaster and fleet management.

The satellites will be positioned in suitable geostationary and inclined geosynchronous orbits to provide regional coverage over India and its neighbourhood, and will be equipped with high-precision atomic clocks and continuously transmit navigation signals to users.

Isro has also launched its Navigation Centre, responsible for the time reference, generation of navigation messages and monitoring and control of ground facilities including ranging stations.

The Centre will host several key technical facilities for supporting these navigation functions.

Sources, while pointing out that key to navigation support is the time reference to which all ground-based systems and satellite clocks are synchronised, said: “This reference is generated by a high-precision timing facility located at the Isro Navigation Centre. This timing facility is equipped with high-stability, high-precision atomic clocks to provide stable and continuous time reference to the navigation system,” said one of them.