Indian Astronomy Satellite-ASTROSTAT

On September 28th Indian Space Research Organization (ISRO) has scripted yet another milestone by successfully launching Astrostat satellite dedicated exclusively for astronomical studies. Indian astronomers are immensely excited at the prospect of state-of art capabilities offered by this satellite. Designed for effective life span of five years, the satellite will endow Indian astronomers to study “radiation bands that carry information about the exotic neutron stars, newly born or exploding stars” and observe the dense effusion of hot gases around black holes.  Indian ground based telescopes- Giant Meter wave Radio Telescope at Pune and the Indian Astronomical Observatory at Ladakh enable scientists to detect radio waves and infrared radiations that penetrate earth’s atmosphere but don’t have scientific instruments to study astronomical phenomena occurring in the Ultraviolet rays, X-rays and gamma-rays. Till now they used to depend on the NASA’s Nuclear Spectroscopic Array (NuSTAR) and ESA (European Space Agency) to study various radiation bands.

 Astrostat has five instruments on board to detect multi-wavelength radiations ranging from visible light to Ultraviolet and from low-energy through high energy X-ray radiations.  The instruments include- Ultraviolet Imaging Telescope, Soft X-ray imaging telescope, Large Area X-ray proportional Counters, Cadmium Zinc telluride Imagers, Scanning Sky Monitor, and charged particle monitor. The charged particle monitor (CPM) designed to detect charged particles and sensitive to protons above 1 MeV (Mega electron Volt). Astrostat is a collaborative effort of many institutes- Tata Institute of Fundamental Research (TIFR), Mumbai, Indian Institute of Astrophysics Bangalore, Raman Research Institute Bangalore, InterUniversity Centre for Astronomy and Astrophysics Pune, Bhabha Atomic Research centre Mumbai, S.N Bose National Centre for Basic Sciences Kolkata, Canadian Space Agency, University of Leichester. The unique range of observatory capabilities will entail it to have a wide coverage unattained by any of the international space observatories till now.

The first Indian space observatory having payload of 1513  kg was launched into the Low Earth Orbit (LEO) of 650km from the surface of the earth by ISRO’s work horse PSLV-C30 at an inclination of 6 degrees from the equator. Satellites in the low earth orbits have to pass through the dense radiation belts of South Atlantic Anamoly (SAA) region that has high fluxes of protons and electrons. Great care has to be exerted when satellite passes through these regions as the high density of the energetic particles can often cause glitches in the data and can permanently damage sensitive instruments onboard.

The idea of having a space observatory was first conceived by astrophysicist Lyman Spitzer in 1946 as the electromagnetic radiations entering earth’s atmosphere are filtered and thus obstruct the view of the celestial bodies. This objective was realized with the launch of the Hubble Space Telescope named after Edwin Hubble in 1990 by NASA. Till date it is the largest and the most versatile telescope providing extremely high-resolution space images. It was uniquely designed to be serviced by astronauts and eventually it was serviced in 1993 for the first time when its main mirror was grounded inaccurately. Last servicing was done in 2009 and it is expected to last till 2030-40. Its successor James Webb Space telescope (JWST) is scheduled for launch in 2018.

India’s tryst with space observatory began in 1996 when ISRO carried out satellite-bound Indian X-Ray Astronomy Experiment in 1996.  ISRO has approved Astrostat in 2004 but its launch was inadvertently delayed. Along with the Astrostat satellite, the enhanced rocket launcher PSLV in XL configuration on its successful thirtieth launch mission piggy backed six satellites- 76kg LAPAN-A2 of Indonesia, 14kg NLS of Canada and four identical LEMUR satellites of US each weighing 28kg. In all the 320 tonne, 45m tall PSLV-C30 carried seven satellites of payload 1613kg.

The primary objectives of Astrostat are to study binary star systems containing neutron stars and black holes, study and estimate the magnetic fields of neutron stars, study star birth-regions and high energy processes occurring beyond our galaxy. While it is no parallel to the Hubble Space telescope it can be lauded as the Indian Hubble Space Telescope for Astrostat is not as powerful, as precise, as the illustrious NASA observatory. It is culmination of humble efforts of the ISRO and one of its kind bestowed with multi—wavelength capabilities. With this launch India has joined the scientific elite countries- the US, Russia, European Space Agency and Japan that own a space observatory.

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