Astrosat – a long journey for a national space observatory. Next year, India is to launch Astrosat, the country's first satellite dedicated to astronomy, which will gaze out at the universe in x-ray, ultraviolet and visible light bands.
The data its instruments supply should help scientists to have better understanding of the ways of the cosmos, whether it is black holes, with their insatiable appetites, that lurk mysteriously at the centres of galaxies; the violent death throes of stars; or how one star of a duo, known as a ‘x-ray binary,’ cannibalises the other.
In a talk on the spacecraft’s instruments at the ongoing assembly of the Committee on Space Research (COSPAR) on Tuesday, Seetha Somasundaram of the ISRO Satellite Centre in Bangalore noted that most of India’s leading research institutions in astronomy and astrophysics were involved in the project. The Tata Institute of Fundamental Research (TIFR) in Mumbai had overall responsibility for developing three of the spacecraft’s five instruments. In addition, the Canadian Space Agency and the University of the Leicester in the U.K. would test and qualify the detector systems for the ultraviolet and one of the x-ray telescopes.
There had been problems with two of the instruments, according to Ms. Somasundaram. “We are putting our best efforts” to make sure that these instruments too would be ready in time so that the satellite could be launched next year, she added.
Astrosat, as with many space projects, has gone through a long journey, starting with its conception and difficult struggles in developing the various instruments for it.
The satellite’s soft x-ray telescope proved to be a huge challenge that took 11 years, K.P. Singh of the TIFR, who was responsible for its development, told The Hindu .
The telescope required 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. The mirrors had to be positioned with an accuracy of 20 microns, which was less than the width of a human hair.
Just getting the mirrors right took about 3 years, remarked Dr. Singh.
Ideas about having a satellite dedicated to astronomy first began to be considered in the late 1990s, according to P.C. Agrawal, who was with the TIFR till his retirement and had played a leading role in the project. The success of the Indian X-Ray Astronomy Experiment, an instrument carried on a remote sensing satellite launched in 1996, made it possible to consider a more ambitious effort.
In 2004, the government cleared the Astrosat project with a price tag of Rs. 178 crore. The plan then was to launch the satellite in about four years.
