Countdown begins! ISRO to launch navigation satellite IRNSS-1L

With less than 12 hours to go for the launch of the IRNSS-1L navigation satellite from Sriharikota, the Indian Space Research Organisation (ISRO) won't be resting easy. Especially given the flak it has been facing of-late.

Last month, the Comptroller and Auditor General had tabled a report in Parliament that showed ISRO in poor light. It reported that although over Rs 1,283 crore had been spent on NavIC, the ambitious swadesi GPS programme, it was yet to be operationalised. Moreover, the satellites already launched under the programme have remained idle for up to 4 years, which is significant because a navigational satellite has a lifespan of 10-12 years.

Then, last week, the space agency found itself in the unenviable position of explaining how it managed to lose contact with its latest communication satellite GSAT-6A, two days after its textbook launch. Incidentally, this was the first mission for ISRO Chairman K. Sivan after taking charge of the agency in January.

So he, and the rest of his team, will be hoping things go better with the IRNSS-1L. Their luck already seems to be turning. "With the help of the satellite tracking system and other sources, we now know the exact location of GSAT-6A. Earlier, we were searching in the dark. But now we know the exact position of the satellite and keeping a close watch on its movement round-the-clock," Sivan told The Times of India yesterday.

Here's some trivia about the upcoming launch.  The 1,425-kg satellite, part of the Indian Regional Navigation Satellite System, will be carried by Polar Satellite Launch Vehicle (PSLV) rocket XL variant, an ISRO official told IANS. This will reportedly be the PSLV's 43rd flight and is scheduled to blast off on Thursday at around 4.04 a.m.  Around 19 minutes 20 seconds after the lift-off, the rocket will sling IRNSS-1L at an altitude of around 507 km.

The need for an indigenous satellite-based navigation system was highlighted during the Kargil War, when India was denied GPS access by the US government. Thus NavIC was born and it consists of nine satellites - seven in orbit and two as substitutes.
The IRNSS-1L is meant to be a replacement for IRNSS-1A as its rubidium atomic clocks have failed. These are required to provide accurate positional data. The previous mission to launch a replacement last August - IRNSS-1H-had ended in a failure after a technical fault on the final leg following a perfect launch. ISRO had then said the heat shield had not separated on the final leg of the launch sequence and, as a result, IRNSS-1H had got stuck in the fourth stage of the rocket.

Like its other IRNSS predecessors, IRNSS-1L also carries two types of payloads for navigation and ranging. The former, operating in L5-band and S-band, will transmit navigation service signals to the users. The ranging payload on the other hand consists of a C-band transponder, which facilitates accurate determination of the range of the satellite. IRNSS-1L reportedly also carries Corner Cube Retro Reflectors for laser ranging.

Several more launches are in the pipeline. "Before the Chandrayaan-2 launch in the first week of October, we will launch three to four launches. After IRNSS-1H launch on Thursday, we will be busy in the launch of heaviest satellite GSAT-11 weighing over 5 tonne from the Guiana space centre. Thereafter, we will launch GSLV Mk III D2 (Isro's 'fat boy')," Sivan told the daily, adding, "We are targeting to launch nine satellites after IRNSS-1I launch on Thursday. Almost, one launch every month."

With agency inputs