ISRO is planning three more satellite launches this year including Oceansat -2, the second in the series of IRS satellites dedicated for ocean research, ISRO Chief G Madhvan Nair told reporters on Monday, May 11. Photo Credit: ISROMay 11, 2009, (Sawf News) - ISRO is planning three more satellite launches this year including Oceansat -2, the second in the series of IRS satellites dedicated for ocean research, ISRO Chief G Madhvan Nair told reporters on Monday, May 11.
According to ISRO plans announced earlier, a GSLV-D3 developmental flight will be launched in July to validate the indigenously developed cryogenic engine that is to replace the Russian cryogenics engine currently used as the fourth stage of the GSLV.
Later in the year ISRO plans to launch the RISAT satellite atop a PSLV launcher.
Oceansat -2 is the second in the series of IRS satellites dedicated for ocean research. Photo Credit: ISROOceansat – 2
The Oceansat -2 is a three axis body stabilized satellite that will be placed into a near circular sunsynchronous orbit, at an altitude of 720 Km, with an equatorial crossing time of around 1200 hrs. The orbital period is 99.31 minutes and the repetevity cycle is 2 days.
It will provide continuity to the services and applications of the Oceansat-1 with the Ocean Colour Monitor (OCM) 2. It will additionally feature a Ku-band pencil beam Scatterometer (SCAT) and an Italian payload called Radio Occultation Sounder for the Atmosphere (ROSA).
OCM-2 will be used for potential fishing zones (PFZs) forecast and feature a solid-state camera operating in push broom scanning mode, using linear array Charge Coupled Devices (CCDs) as detectors. This camera has eight narrow spectral bands operating in visible and near infrared (NIR) bands (402-885 nm). Since the ocean observation is planned at the local time of equator crossing time of 1200 hrs noon, the camera can be tilted up to ± 20° in the along track direction to avoid sun glint.
OCM data will be available in two spatial resolutions: Local Area Coverage (LAC) of 360 m and Global Area Coverage (GAC) of 4 km.
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.
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.
GSLV D3
GSLV D3 launcher will carry an Indian developed cryogenic third stage which will eventually be capable of launching 2500 kg into Geostationary Transfer Orbit (GTO).
The cryogenic engines that have powered the GSLV rocket so far were sold to India by Russia. Of the seven cryogenic engines supplied, five have now been used. Eventually, all GSLVs will use the Indian Cryogenic Upper Stage (CUS) that develops 9 ton of thrust against 7.5 ton of the Russian CUS and carries 15 ton of propellant against 12.5 ton.
The GSLV D3 will carry a 2.4 ton GSAT – 4 satellite, primarily to monitor the performance of the launcher.
RISAT
The radar imaging satellite is scheduled for launch by the end of FY 2009.
The 1,780-kg RISAT features a C-band Synthetic Aperture Radar (SAR) operating in a multi-polarization and multi-resolution mode. It has a 6 x 2 meter planar active array.
The radar will be able to provide day and night imaging through dust, cloud and smoke.
The satellite will provide 3-50 meters spatial resolution. Various modes such as Scan SAR, strip-and-spot modes are planned to provide images with coarse, fine and high spatial resolutions.
Some of the new technological elements in RISAT are: 160 x 4 Mbps data handling system, 0.3 Nm (50 Nms) reaction wheels, antenna deployment mechanism, 70 V power bus, thermal control of SAR antenna and phased array antenna (with Dual Polarization).
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