Introduction
ASTROSAT is the first dedicated Indian astronomy mission aimed at studying distant celestial objects. The mission is capable of performing observations in Ultraviolet (UV), optical, low and high energy X-ray wavebands at the same time.
The project was conceived following the success of the Indian X-Ray Astronomy Experiment, carried on a remote sensing satellite launched in 1996.
The government cleared the Astrosat project In 2004 at a cost of Rs. 178 crore. The satellite was planned to be launched in about 4 years.
ASTROSAT would be India's first multiwavelength astronomy satellite. It will facilitate simultaneous observations of celestial bodies and cosmic sources in X-ray and UV spectral bands. The uniqueness of ASTROSAT lies in its wide spectral coverage extending over visible (3500-6000 Å), UV (1300-3000 Å), soft X and hard X ray regions (0.5-8 keV; 3-80 keV).
The following extract from a
page on NASA's High Energy Astrophysics Science Research Archive Center (HEASRAC) website gives a perspective on the Astrophysics website.
"Most astronomical objects in the known Universe emit radiation spanning the complete electromagnetic spectrum stretching from long wavelength radio emission to extremely short wavelength gamma rays. Hence for a detailed understanding of the physical processes that give rise to frequency-dependent, time-variable phenomena, it is essential to carrry out nearly simultaneous multi-frequency observations. Important areas requiring broad band coverage include studies of astrophysical objects ranging from the nearby solar system objects to distant stars, to objects at cosmological distances; timing studies of variables ranging from pulsations of the hot white dwarfs to active galactic nuclei (AGN) with time scales ranging from milliseconds to few hours to days."
Research Institutions Involved with the Project
Other research institutions contributing to the collaborative effort of the project include:
- ISRO
- Indian Institute of Astrophysics, Bangalore
- Raman Research Institute, Bangalore
- Inter-University Center for Astronomy and Astrophysics, Pune
- Nuclear Research Laboratory, Bhabha Atomic Research Centre, Mumbai
- S.N. Bose National Center for Basic Sciences, Kolkata
- Canadian Space Agency.
Launch and Orbital Parameters
The 1,650 kg satellite with a science payload of 750 kg is scheduled to be launched in the second half of 2015 atop PSLV C-34.
It will be placed in a 650-km (400 miles) orbit with an 8° inclination for spectroscopic studies of X-ray binaries, supernova remnants, quasars, pulsars, galaxy clusters and active galactic nuclei at a number of different wavelengths simultaneously, from the ultraviolet band to energetic x-rays.
Project Progress
The satellite is planned to be launched during the second half of 2015 by PSLV C-34 to a 650 km near equatorial orbit around the Earth. It is significant to note that ASTROSAT is the first mission to be operated as a space observatory by ISRO.
ISRO in a
press release on May 19, 2005 stated, "All the payloads and sub-systems are integrated to the satellite. Mechanical fit checks of the satellite with PSLV payload adaptor were performed successfully. Last week, the spacecraft was fully assembled and switched ON. Spacecraft parameters are normal, which indicates everything is functioning well. In the coming days, Spacecraft will undergo several environmental tests like Electromagnetic Interference (EMI) – Electromagnetic Compatibility (EMC), Thermal Vacuum, Vibration, Acoustic tests before shipment to Satish Dhawan Space Centre, Sriharikota.
The Hindu in July 2012 that the telescope took 11 years to develop. It has 320 mirrors of aluminium that had to be made with great precision and given a fine gold coating. These mirrors were arranged in the form of concentric shells, with struts to hold them in place. They had to be positioned with an accuracy of 20 microns, which was less than the width of a human hair.
Attitude Control System
TIFR is also developing the satellite’s attitude control system, consisting of two star trackers and gyros, to facilitate accurate pointing of the instruments towards a specific direction in the sky.
The challenges associated with developing the Attitude Control System have been overcome and delivery of the payload to the ISRO satellite center will begin from the middle of this year.
In particular, it will train its instruments at active galactic nuclei at the core of the Milky Way that is believed to have a super massive black hole.
