European flavour to India's satellite launch

India's indigenous Oceansat-2 satellite will be launched next month from Sriharikota spaceport on the east coast and will also carry with it a set of six nano satellites, all of European origin.

Besides Rubin 9.1 and Rubin 9.2 nano satellites from Germany, the four cubesats lined up for the mission on board India's workhorse rocket Polar Satellite Launch Vehicle are: Beesat, built by Technical University Berlin, UWE-2 (University of Wuerzburg Germany), ITU-pSat (Istanbul Technical University Turkey) and SwissCube-1 (Ecole Polytechnique Federal de Lausanne, Switzerland).

Oceansat-2, which weigh around 970 kg, is an in-orbit replacement to Oceansat-1 that has completed 10 years of service, ISRO Spokesperson S Satish said.

"It (Oceansat-2) will carry an OCM (Ocean Colour Monitor) and a Ku-band pencil beam Scatterometer. In addition, it will carry Radio Occultation Sounder for Atomospheric studies (ROSA), developed by the Italian Space Agency (ASI)," he said.

Oceansat-2 would help identify potential fishing zones, assist in coastal zone studies and significantly enhance expertise in understanding surface temperature and winds.

"Earlier, we had launched Oceansat (Oceansat-1) which essentially could look at (only) the colour of the ocean. Now, colour alone is not sufficient, we should look at the temperature and surface winds and so on," ISRO Chairman G Madhavan Nair said.

"This Oceansat (Oceansat-2) will have such space for looking at the surface winds and temperature and all those things. It will be a very comprehensive system," Nair said.

ISRO officials said the Scatterometer is an active microwave radar operating at 13.515 GHz in Ku-band with a ground resolution cell of 50 KM x 50 KM. It is expected to provide the wind vector range of four to 24 metres/second with better than 20 per cent accuracy in speed and 20 degrees in wind direction.

The OCM payload with 360 metres spatial resolution and a swath of 1420 KM, with eight narrow spectral bands is similar to Oceansat-1 OCM, but with appropriate spectral bandwidth modifications based on the experience gained.

The Spectral bands are modified for Band-6 and Band-7 to improve the reflectance from suspended sediments and to avoid Oxygen absorption. OCM provides a two-day coverage of the world.

Considering that Oceansat-2 is a continuity mission to the earlier Oceansat-1, the same polar sun-synchronous orbit of 720 km has been retained.

ROSA payload is a dual channel GPS receiver with two antennas and a receiver package. The Radio-Occultation antenna looking along the satellite velocity vector receives signals from the 'rising' GPS satellites near the earth horizon. These signals get refracted by the atmosphere and from the bending angle, the temperature and humidity profiles are derived, ISRO officials said.