Tuesday, September 22, 2015

India’s first astronomy satellite will be launched on September 28. ISRO has noted that while it has launched payloads capable of making astronomical observations before, this is the first time one dedicated to astronomy will be launched. 

Firstly, what is a ASTRONOMY SATELLITE ?
  • An astronomy satellite is basically a really big telescope floating in space. 
  • Because it is in orbit above the Earth, the satellite's vision is not clouded by the gases that make up the Earth's atmosphere, and its infrared imaging equipment is not confused by the heat of the Earth. 
  • Astronomy satellites, therefore, can "see" into space up to ten times better than a telescope of similar strength on Earth. 
Astronomy satellites have many different applications:
  • they can be used to make star maps
  • they can be used to study mysterious phenomena such as black holes and quasars
  • they can be used to take pictures of the planets in the solar system
  • they can be used to make maps of different planetary surfaces

India’s first astronomy satellite called ASTROSAT, was first scheduled for launch in 2005, then in 2010, and finally in 2015 with delays largely due to putting the scientific payload together. 

  • ASTROSAT will be a multi-wavelength mission, observing the cosmos in X-ray, visible and UV light.
  • ASTROSAT is one of two scientific missions that have long been overdue – the other being the Aditya-1 mission to study the Sun. 
ASTROSAT comprises five scientific instruments, all of which had been delivered to the ISRO Satellite Centre by 2014. 
  • UV Imaging Telescope
  • Scanning Sky Monitor
  • Cadmium-Zinc-Telluride Imager
  • Soft X-ray Telescope and 
  • three identical Large Area Xenon Proportional Counters. 

The Soft X-ray Telescope reportedly took 11 years to be built. ASTROSAT cost Rs.178 crore.

Why this astronomical satellite ? Can't we study this from ground ?
  • X-ray and UV radiation fall in the short-wavelength part of the electromagnetic spectrum, and their emissions in the universe can’t be detected at ground level because the high-energy photons that constitute the radiation can’t easily penetrate Earth’s atmosphere. The opposite is true for long-wavelength radiation like radio waves. 
  • As a result, the most powerful and effective X-ray and gamma-ray satellites are in Earth-orbit whereas radio-telescopes – with their giant telltale antenna dishes – are on ground.

What else ?
  • The launch of the spacecraft will be especially beneficial for the Indian astronomical community, as it will reduce the community's dependence on data from external sources like the Hubble. 
  • The launch will also make India a member of the exclusive space club of countries with space observatories, which currently includes - U.S., Europe, Russia and Japan. 
  • As with the launch of MOM, the scheduled launch of Astrosat will yet again proved to the world, India's space capabilities.

Comparing Astrosat with Hubble Space Telescope !

  • One of the better known examples of multi-wavelength space-borne observatories is the Hubble Space Telescope, which makes observations in the UV, visible and infrared parts of the spectrum. 
  • However, comparisons between the telescopes are unfounded because Hubble’s optical mirror is eight-times as wide as ASTROSAT’s, allowing for a deeper field of view and much better imaging. 
  • Nonetheless, ASTROSAT will be able to contribute in the study of time-variable sources of radiation by being able to observe the sources in UV and X-ray wavelengths simultaneously.

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