Indian Microsatellite-1 (IMS-1) Data

The National Remote Sensing Centre (NRSC) is the focal point for distribution of remote sensing satellite data products in India and its neighboring countries. NRSC has an earth station at Shadnagar, about 55Km from Hyderabad, to receive data from almost all contemporary remote sensing satellites.

IMS-1, previously referred to as TWSat (Third World Satellite), is a low-cost microsatellite imaging mission of ISRO (Indian Space Research Organization). The overall objective is to provide medium-resolution imagery for developing countries for free. The data from this mission will be made available to interested space agencies and student community from developing countries to provide necessary impetus to capacity building in using satellite data.

Launch: A launch of IMS-1 as a secondary payload on a PSLV vehicle (PSLV-C9) took place on April 28, 2008 from the SDSC-SHAR launch site (Sriharikota, India) of ISRO. The primary payload on this flight was CartoSat-2A (launch mass of 690 kg), an Indian military high-resolution panchromatic imaging satellite (based on CartoSat-2 of ISRO).

TWSat carries two payloads: the Mx-T (Multispectral Camera) and the HySI (Hyperspectral Imager). However, since the data of both imagers is rather high, only one of them will be powered on and data transmitted at any given time. The spatial resolution of Mx camera is 37 metre with a swath of 151 km while that of HySI is about 506 metre with a swath of about 130 km.

Mx-T (Multispectral Camera). The instrument of modular design provides four spectral bands in VNIR, where each band employs an individual lens, a separate CCD detector, and separate front-end electronics. The camera operates in a pushbroom scanning mode to image the Earth. The spatial resolution at nadir is 36 m on a swath of 151 km. The 12 bit video output is coded to 10 bit with multi-linear gain. Mx-T has a mass of 5.5 kg and a power consumption of 18 W.

All the front end electronics and the video processors are accommodated on the electro optical module (EOM) itself. Each band has one detector which gives out data in 4 ports with 10 bits per pixel. The source data (32 Mbit/s) is sent to the baseband data handling system of the microsatellite bus, compressed and stored in SSR (Solid State Recorder). The recorded data is transmitted to the ground in S-band at 8 Mbit/s.

HySI-T (Hyperspectral Imager). The prototype instrument providing a total of 64 spectral bands in the VNIR region. Spectral separation is realized using the wedge filter technique. Detection is provided with a CMOS/APS (Active Pixel Sensor) area device. - The HySI-T data may be used for resource characterization and detailed studies. The HySI-T is being used on an experimental basis to obtain experience of such a payload and also of handling the hyperspectral data and generating the application models.

The data from the two payloads is being downlinked separately. The Mx-T data is compressed at a ratio of 3.4:1, formatted, RS (Reed Solomon) encoded and stored on SSR (Solid Sate Recorder). The downlink is in near real-time via the S-band transmitter. The SSR has the storage capacity of 16 Gbit providing a maximum storage volume of 20 minutes data in segmented form.

[Summary provided by the following online resources:
http://directory.eoportal.org/get_announce.php?an_id=15158
http://www.isro.org/pslv-c9/