ISRO Missions and Discoveries

Indian, US satellites find black hole that spins near maximum possible ratesPrelims OnlyPriority 1


Mains Paper 3: Science & Technology | Awareness in the fields of IT, Space, Computers, robotics, nano-technology, bio-technology

From UPSC perspective, the following things are important:

Prelims level: Black Hole, AstroSat

Mains level: Space related discoveries by NASA-ISRO collaboration


India’s AstroSat helps in finding blackhole

  • Scientists using data from India’s first dedicated astronomy satellite, AstroSat, and NASA’s Chandra X-ray Observatory have found that a black hole in the binary star system 4U 1630-47 spins close to the maximum possible rate.

Details of the finding

  1. Relatively smaller black holes are exotic end states of massive stellar cores.
  2. The gravity of such a collapsing core is so strong that its entire mass is crushed into a point.
  3. This point, however, cannot be directly seen, because nothing, not even light, can escape from a region around it, thus justifying the name of the object.
  4. Surprisingly, astronomical black holes are the simplest known objects in the universe, because they can be fully characterized by only two properties, mass and spin rate.
  5. Therefore, measurements of these two properties are uniquely important to probe some extreme aspects of the universe, and the fundamental physics related to them.

Extreme aspects of the universe

  1. The scientific measurement of the spin rate of the black hole, an extremely exotic but the simplest object of the universe, comes out to be close to the maximum possible value.
  2. This is generally very important to probe some extreme aspects of the universe, and the fundamental physics (for example, the theory of gravitation) related to them.
  3. Such measurements, especially of the spin rate, are very difficult to make, and can be done only by high-quality X-ray observations in the correct state of the binary stellar system.

AstroSat-Chandra study

  1. This first cooperation of India and US using AstroSat and Chandra satellites regarding black hole studies should open up ways for future such collaborations.
  2. The SXT and the Large Area X-ray Proportional Counter (LAXPC) aboard the first dedicated Indian astronomy satellite AstroSat played a key role to measure the black hole spin rate, which was consistent with results from our contemporaneous Chandra satellite data.
  3. AstroSat was launched in 2015 by the Indian Space Research Organisation (ISRO). It is the first dedicated astronomy satellite of India, and the SXT aboard AstroSat is the first Indian X-ray telescope.
  4. Apart from Japan, India is the first Asian country to build an X-ray Telescope (for example, China could not build such a telescope till now).



  1. Astrosat is India’s first dedicated multi-wavelength space observatory launched on a PSLV-XL on 28 September 2015.
  2. It is a multi-wavelength astronomy mission on an IRS-class satellite into a near-Earth, equatorial orbit.
  3. On board ASTROSAT are five astronomy payloads for simultaneous multi-band observations.
  4. The assembly is placed on a rotating platform to scan the available sky once every six hours in order to locate transient X-ray sources. They are:
  • Twin 38-cm Ultraviolet Imaging Telescopes (UVIT) covering Far-UV to optical bands.
  • Large Area Xenon Proportional Counters (LAXPC) covering medium energy X-rays.
  • Soft X-ray Telescope (SXT) with conical foil mirrors and X-ray CCD detector
  •  A Cadmium-Zinc-Telluride coded-mask imager (CZTI)
  •  A Scanning Sky Monitor (SSM) consisting of three one-dimensional position-sensitive proportional counters with coded masks.

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