ASTROSAT to be launched in mid-2010

India's Astronomy satellite, ASTROSAT, which would facilitates study of a range of
astrophysical objects, is likely to be launched in mid-2010, scientists from Tata Institute of Fundamental Research (TIFR) said here.

The scientists have completed the developmental phase of complex science payloads and have just begun integrating them before delivery for the 1650 kg satellite.

"The big challenge was that of design of a satellite attitude control system that will enable accurate control of the pointing of the instruments towards a specific direction
in the sky," scientists from TIFR said.

ASTROSAT project is a collaborative effort of a number of reserch institutions, including the Mumbai-based TIFR. The challenges in the design of payloads and Attitude Control System have been overcome and in a recent review committee meeting, it was decided that the delivery of the payload to ISRO satellite Centre will begin from the middle of this year and continue till early next year to enable the launch ASTROSAT in 2010 using ISRO workhorse PSLV. 

The Astrosat will be in an equatorial orbit with inclination of about 8 degrees or less. Two star trackers and gyros will be used for the pointing control of the satellite.    Orbiting at 600 km above the earth's surface, the ASTROSAT satellite costing about Rs 200 crore, will have a lifespan of at least five years.

This would facilitate study of astrophysical objects ranging from nearby solar system objects to distant stars and objects at cosmological distances, scientists actively
working on the instrumentation said.

Out of the five science payloads for this multi-wavelength satellite observatory, three X-ray instruments are developed by TIFR. The Ultra-Violet Imaging Instrument has been developed jointly by Indian Institute of Astrophysics, Bangalore and Inter-university centre for astronomy and astrophysics, Pune with the involvement of TIFR.

The photon counting detectors of this instrument have been developed jointly by the Indian team and the Canadian Space Agency as a science collaboration. The fifth instrument namely X-ray Sky Monitor is being made by ISRO Satellite Centre and is in advanced stages of fabrication and assembly. 

The X-ray CCD used in X-ray imaging telescope is not readily available and very expensive to procure. Hence instead of buying the costly X-ray CCD for 'Astrosat', the Indian side has opted for a scientific collaboration with the British University of Leicester.

A team of engineers from the TIFR went to the University of Leicester's Space Research Centre in UK in February 2009 to monitor the progress of the collaborative
works. The X-ray CCD camera was designed by the University of Leicester, which is also part of the ambitious project and the manufacture of the hardware components and electronics was undertaken by the Tata Institute of Fundamental Research.

In a few months time, when the Leicester built CCD camera is assembled and integrated with the TIFR built electronics, it will be tested to space qualified standards
and shipped back to India for integration into the spacecraft.

Astrosat will carry five instruments to observe exotic objects such as black holes, neutron stars, and active galaxies at a number of different wavelengths simultaneously,
from the visible and ultraviolet band to energetic x-rays.

The scientist said that, with the confidence developed by the scientific community in the making of payloads for the large mission ASTROSAT, discussions are taking place for the development and launch of smaller size satellites for astronomy and other areas of science in the near future.

Its other objectives included broadband spectroscopic studies of galaxy clusters and stellar coronae, studies of periodic and non-periodic variability of x-ray sources,
monitoring intensity of known sources and detecting outbursts and luminosity variations, the scientists said. 

Once begins orbiting in the sky, it is capable of gathering 420 gigabits of data every day that can be down loaded in 10 to 11 orbits visible at Tracking and Data receiving center of ISRO in Bangalore. Other institutes involved in the project are Raman Research Institute, Bangalore, India Space Research Organisation, Indian Institute of Astrophysics, Bangalore, Inter-University Center for Astrophysics, Pune, Bhabha Atomic Reserch Centre, Mumbai, S.N Bose National Centre for Basic Science, Kolkata, Canadian Space Agency.