With latest launch, India en route to its own GPS system by midyear
Bengaluru, INDIA — In its first mission for 2016, the Indian Space Research Organisation on Wednesday successfully launched the fifth satellite of its space-based navigational system that it says will become fully operational by middle of this year.
The nationally televised launch took place at 9:31 a.m. local time from Satish Dhawan Space Center, the country’s spaceport in Sriharikota on India’s southeastern coast.
The 14.2 billion rupee ($212 million) Indian Regional Navigation Satellite System (IRNSS) is a constellation of seven near-identical satellites, three in geostationary orbit fixed above the equator; two in geosynchronous orbit inclined at 29 degrees; and two spares. It is designed to provide positioning service to users in India as well as the region extending up to 1,500 kilometers from its borders. Four of the satellites — IRNSS-1A to 1D — are already in place.
In Wednesday’s launch, ISRO’s Polar Satellite Launch Vehicle injected the fifth satellite — IRNSS-1E — into the sub-geosynchronous transfer orbit with a perigee of 282 kilometers and an apogee of 20,655 kilometers with an inclination of 19.21 degrees with respect to the equator, very close to the intended orbit. “It was the 32nd consecutive success for the ISRO’s workhorse,” said K.Sivan, director of the Vikram Sarabai Space Centre in Tiruvnathapuram that produced the rocket.
ISRO said the “satellite is in good health and its solar panels have been deployed.” After four orbit-raising maneuvers using the satellite’s onboard motor, it will be positioned at its allotted geosynchronous orbit with a 28.1 degree inclination at 111.75 degrees East longitude, it said.
“We have started the year with a grand success but we have still a long way to go,” ISRO Chairman Kiran Kumar said in a post-launch address. “Two more satellites have to be launched in the next two months to complete our navigational system and we have to test fly the heavy launch Mark-3 version of our Geostationary Satellite Launch Vehicle this year”.
Like its predecessors, the 1,425-kilogram IRNSS-1E satellite has two payloads: a navigation payload operating in L5-band and S-band; and a ranging payload consisting of a C-band transponder and retro reflectors for laser ranging. A Rubidium atomic clock is part of the navigation payload for navigation and ranging. According to ISRO the design of the satellites makes the IRNSS system interoperable with the U.S. GPS and European Galileo systems.
ISRO said the four IRNSS satellites already in space have started functioning from their designated slots and their “signal-in-space” has been validated by various agencies inside and outside the country.
“The current achieved position accuracy is 20 meters over 18 hours of the day with the four satellites. With the launch of IRNSS-1E and subsequent 1F and 1G in February and March 2016, the IRNSS constellation will be complete for total operational use,” ISRO said.
ISRO said the IRNSS will make available two types of services — a standard positioning service open to all users, and a restricted service with encrypted signals in the bands reserved for authorized users. The IRNSS satellites are designed to operate for 10 years.