AsianScientist (Sep. 30, 2015) – The first Indian astronomy satellite Astrosat was launched on September 28, 2015 by the Indian Space Research Organisation (ISRO) on a Polar Satellite Launch Vehicle (PSLV) rocket.
Cosmic objects (stars, galaxies, quasars etc.) emit in multiple wavebands. Therefore, in order to unravel their mysteries it is essential to observe them in as many wavebands as possible. As X-rays and ultraviolet (UV) energy from cosmic objects cannot penetrate the Earth’s atmosphere, suitable instruments must be sent above the atmosphere by satellites.
Astrosat has the capability to simultaneously observe cosmic objects in visible light, the ultraviolet waveband and the entire X-ray waveband from very low energy to very high energy X-rays. This unique ability to simultaneously observe the universe in multiple wavelengths is aimed at performing cutting-edge research in astrophysics.
As Professor P.C. Agrawal, one of the lead scientists who gave shape to the concept of this mission, says, “Astrosat is a quantum leap from previous modest sized payloads on other Indian satellites. It is an internationally competitive observatory that will enable Indian scientists to work in frontier areas of high energy physics.”
Researchers from the Tata Institute of Fundamental Research (TIFR) have led this multi-institutional effort and have made significant contributions to the design, fabrication and development of three out of five payloads that are on board Astrosat.
The Large Area Xenon Proportional Counters (LAXPC), a Soft X-ray Telescope (SXT), and a Cadmium-Zinc-Telluride Imager (CZTI), all of which will observe the universe in the X-ray wavebands, are the three payloads built in the Department of Astronomy and Astrophysics (DAA) of TIFR Colaba, Mumbai.
The LAXPC detectors with the largest collecting area among any X-ray instrument ever built in the world, have been fully fabricated at TIFR. For the next five to ten years LAXPC will be the only instrument in the world that will be able to study X-ray intensity fluctuations of cosmic objects on time scales as small as a millisecond. This will be essential to probe the fundamental physics of exotic objects, like black holes and super-dense neutron stars.
“It is common knowledge that X-rays easily penetrate through materials but it is extremely difficult to focus x-rays with a telescope. Placing the 320 mirrors in the telescope, required great precision,” says Professor K.P. Singh, lead scientist of the SXT team.
The focal plane camera for the SXT containing a cooled charge coupled device (CCD) was built in collaboration with the University of Leicester, UK.
The CZTI, will image celestial objects in the high-energy X-ray band using a coded mask. It has the ability to also perform unique polarization measurements in very high energy X-rays. Built under the leadership of Professor A.R. Rao of TIFR, the team overcame several challenges to ensure a uniform response from a large number of detectors, as the development of such detectors and electronics for use in high-energy X-ray imaging is a recent technology.
Scientific data obtained through Astrosat will be distributed from a few payload operation centers (POC), two of which will be located at TIFR. These two POCs, will control the operations of SXT and LAXPC, making DAA/TIFR a major center of worldwide X-ray astronomical activities for the next few years.
Astrosat is expected to help address fundamental scientific problems that cannot be probed in terrestrial laboratories. These include testing Einstein’s general theory of relativity, studying superdense cold matter deep inside a neutron star which is a fundamental problem of particle physics, and understanding flow of matter in astronomical scales, often in extremely strong gravity regions, relativistically accelerated plasma jets, extremely hot ionized plasmas, and absorption by cold matter.
Astrosat will observe a variety of objects in the universe, such as black holes, neutron stars, white dwarfs, explosive events like supernovae, stars, galaxies, and clusters of galaxies.
“The instruments developed by TIFR will give us a capability unrivaled in the world for the next five to ten years. We look forward to some great science results,” says Professor S. Trivedi, Director TIFR.
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Source: Tata Institute of Fundamental Research; Photo: Indian Space Research Organisation.
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