Fifth navigation satellite set for launch on January 20

The year’s first domestic space mission will take off on Wednesday morning

The year’s first domestic space mission will take off on the morning of Wednesday, January 20, at Sriharikota with the fifth regional navigation spacecraft, the IRNSS-1E.

At the Satish Dhawan Space Centre, the launch team began a 48-hour countdown for the flight of the satellite launch vehicle, PSLV-C31, at 9.31 a.m. on Monday. The flight was cleared by two high-level review committees on Sunday, according to the Indian Space Research Organisation.

IRNSS-1E is a 1,425-kg spacecraft carrying navigation and ranging payloads. It is similar to the earlier four navigation satellites IRNSS-1A to 1D which were put in orbit between July 2013 and March 2015.

Two more navigation spacecraft – IRNSS-1F and 1G – are due to follow in February and March, an ISRO official said. They will then complete the seven-satellite constellation, otherwise called the ‘Indian GPS’.

The full fleet is likely to be switched on for regular use by end-2016 after it is tested and tried for a few months.

Already, the first four navigation spacecraft have been giving 18-hour positional information with good accuracy of the Indian region; the duration will improve with new satellites, the official said.

After a series of orbit corrections post-launch, IRNSS-1E will be placed in a geosynchronous orbit over 111.75 degrees east longitude. It will go around Earth at a distance of 20,000 km and inclined at 28.1 degrees.

For the current mission, ISRO is using the XL (extended) version in the first stage of the four-stage PSLV rocket. This format is being used for the 11th time.