ISRO begins countdown for launch of PSLV-C42 that will carry NovaSAR and S1-4.

A PSLV (polar satellite launch vehicle) will be launched on September 16 night from the Satish Dhawan Space Centre in Sriharikota to put two earth observation satellites from the United Kingdom to space. The 33-hour countdown for the launch began at 1.08 p.m. on Saturday.

There is no Indian satellite on this flight. PSLV-C42 will be the first fully commercial trip of the year, breaking a five-month-long lull, for the Indian Space Research Organisation (ISRO).

ISRO did not make any launch post April 12, after it put replacement navigation satellite IRNSS-1I to space on PSLV-C41. A few days after that, it recalled its GSAT-11 from the South American launch port of Kourou, weeks before it was due for launch.

ISRO Chairman K. Sivan said the interval was not connected with the satellite recall but for the sake of readiness of the two customer satellites. He spoke from Tirupati en route to Sriharikota.

The PSLV is being flown in its core-alone format, minus the external boosters. The two satellites together weigh nearly 889 kg; this is the optimum payload that a core-alone PSLV can launch, Dr. Sivan said.

PSLV-C42 is scheduled for launch at 10.08 p.m. from the first launch pad. It will lift NovaSAR and S1-4 to a sun-synchronous ('pole-to-pole') orbit 583 km from the Earth.

The entire flight up to the release of the satellites is designed to happen within 17.5 minutes.

ISRO’S PSLV-C42 sits on the First Launch Pad at the Satish Dhawan Space Centre in Sriharikota. Photo: Twitter/@isro

The satellites are owned by Surrey Satellite Technologies Ltd., which signed a commercial launch contract with Antrix Corporation, an ISRO release said.

NovaSAR is an S-Band synthetic aperture radar satellite, which will map forest, land use and monitor ice cover, flood and disaster.

S1-4 is a high resolution optical Earth observation satellite that will be used for surveying resources, urban management and monitoring of the environment and disasters.

Antrix has so far contracted over 280 foreign customer satellites for a fee; most of them are small experimental or earth observation spacecraft.

This will be the 44th PSLV and the 12th time it will fly as core-alone.