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India Wednesday successfully launched its 16th remote-sensing satellite, Oceansat-2, to study oceans and climate, and six small Europeans satellites on board a rocket that blasted off from here.

Under a clear blue sky, the 44.4-metre tall, 230-tonne Indian rocket Polar Satellite Launch Vehicle (PSLV) freed itself from the launch pad at the spaceport, 70 km from Chennai, at 11.51 a.m. and soared upwards with a deep throated growl lugging the 960-kg Oceansat-2 and the six nano satellites all together weighing 20 kg.

In copybook style, the rocket first spat out Oceansat-2 at an altitude of 720 km above the earth in a sun-synchronous orbit (SSO), followed by the four nano satellites – also called Cubesats, each weighing one kg. The remaining two, each weighing eight kg, were attached to the rocket’s fourth stage.

The Oceansat2 satellite detached itself from the rocket after 1,081 seconds.

The six nano satellites are owned by European universities – four from Germany and one each from Switzerland and Turkey. They were launched under a commercial agreement.

Soon after the satellites were put into orbit, ISRO’s satellite tracking centres started monitoring them.

The mission objectives of Oceansat-2 are to gather systematic data for oceanographic, coastal and atmospheric applications. The main objectives of OceanSat-2 are to study surface winds and ocean surface strata, observation of chlorophyll concentrations, monitoring of phytoplankton blooms, study of atmospheric aerosols and suspended sediments in the water.

Oceansat-2 will carry two payloads for ocean related studies, namely, Ocean Colour Monitor (OCM) and Ku-band Pencil Beam Scatterometer. An additional piggy-back payload called ROSA (Radio Occultation Sounder for Atmospheric studies) developed by the Italian Space Agency (ASI) is also proposed to be included. The major applications of data from Oceansat-2 are identification of potential fishing zones, sea state forecasting, coastal zone studies and inputs for weather forecasting and climatic studies

The scientific payload contains three instruments. Two are Indian and one is from the Italian Space Agency.

Ocean Colour Monitor (OCM) -

OCM is a 8-band multi-spectral camera operating in the Visible – Near IR spectral range. This camera provides an instantaneous geometric field of view of 360 meter and a swath of 1420 km. OCM can be tilted up to + 20 degree along track. The Ku-band pencil beam scatterometer is an active microwave radar operating at 13.515 GHz providing a ground resolution cell of size 50 x 50 km. It consists of a parabolic dish antenna of 1 meter diameter which is offset mounted with a cant angle of about 46 degree with respect to earth viewing axis. This antenna is continuously rotated at 20.5 rpm using a scan mechanism with the scan axis along the +ve Yaw axis. By using two offset feeds at the focal plane of the antenna, two beams are generated which will conically scan the ground surface. The back scattered power in each beam from the ocean surface is measured to derive wind vector. It is a improved version of the one on Oceansat-1.

Scanning Scatterometer (SCAT) -

SCAT is an active microwave device designed and developed at ISRO/SAC, Ahmedabad. It will be used to determine ocean surface level wind vectors through estimation of radar backscatter. The scatterometer system has a 1-m parabolic dish antenna and a dual feed assembly to generate two pencil beams and is scanned at a rate of 20.5 rpm to cover the entire swath. The inner beam makes an incidence angle of 48.90° and the outer beam makes an incidence angle of 57.60° on the ground. It covers a continuous swath of 1400 km for inner beam and 1840 km for outer beam respectively. The inner and outer beams are configured in horizontal and vertical polarization respectively for both transmit and receive modes. The aim is to provide global ocean coverage and wind vector retrieval with a revisit time of 2 days.

Radio Occultation Sounder for Atmospheric Studies (ROSA) -

ROSA is a new GPS occultation receiver provided by ASI (Italian Space Agency). The objective is to characterize the lower atmosphere and the ionosphere, opening the possibilities for the development of several scientific activities exploiting these new radio occultation data sets