Prime Minister Narendra Modi in his last 'Mann ki Baat' programme of this year on 29 December 2019 said that the Indian Space Research Organisation (ISRO) is planning to launch a satellite called Aditya to study the sun. India is quite advanced in the field of astronomy, and we have taken path-breaking initiatives in this field. ISRO has an astronomical satellite called ASTROSAT. Moreover, they are planning to launch a satellite called Aditya, to study the sun," said Modi. 
 
What's Mission Aditya?
  1. Mission Aditya seeks to place a satellite to earth's low earth orbit (around 800 km) in such an orientation (halo orbit) that it has a continuous vision of the Sun, uninterrupted by occultation or eclipses. 
  2. The satellite would be of 400kg class and will be launched by the PSLV-XL from Sriharikota. Its objective is to study the Sun's corona, the outer layers extending to thousands of km.
Unlike NASA's:
  1. To put it in context, Mission Aditya is less ambitious than NASA's Parker Solar Probe. Launched in August 2018, Parker Solar Probe aims to orbit around the Sun, coming as close as 6.1 million kilometres to its surface
  2. That distance means the satellite would have to withstand almost 1400 degree Celsius. Parker has already made 3 circuits around the Sun, coming as close as 24 million km — the closest any man-made object has been to the Sun. 
  3. In its seven-year lifespan, it orbits around the Sun 24 times, drawing closer to it with every circuit. But it has already sent some valuable information, including the revelation that the solar wind rotates around the Sun at around 35 to 50 kilometres a second, rather than a few km per second previously thought.
AstroSat MISSION
  1. AstroSat is the first dedicated Indian astronomy mission aimed at studying celestial sources in X-ray, optical and UV spectral bands simultaneously
  2. The payloads cover the energy bands of Ultraviolet (Near and Far), limited optical and X-ray regime (0.3 keV to 100keV). 
  3. One of the unique features of AstroSat mission is that it enables the simultaneous multi-wavelength observations of various astronomical objects with a single satellite.
  4. AstroSat with a lift-off mass of 1515 kg was launched on September 28, 2015 into a 650 km orbit inclined at an angle of 6 deg to the equator by PSLV-C30 from Satish Dhawan Space Centre, Sriharikota. The minimum useful life of the AstroSat mission is expected to be 5 years.
  5. After injection into Orbit, the two solar panels of AstroSat were automatically deployed in quick succession. The spacecraft control centre at Mission Operations Complex (MOX) of ISRO Telemetry, Tracking and Command Network (ISTRAC), Bengaluru manages the satellite during its entire mission life.
  6. The science data gathered by five payloads of AstroSat are telemetered to the ground station at MOX. The data is then processed, archived and distributed by Indian Space Science Data Centre (ISSDC) located at Bylalu, near Bengaluru.
The scientific objectives of AstroSat mission are:
  1. To understand high energy processes in binary star systems containing neutron stars and black holes;
  2. Estimate magnetic fields of neutron stars;
  3. Study star birth regions and high energy processes in star systems lying beyond our galaxy;
  4. Detect new briefly bright X-ray sources in the sky;
  5. Perform a limited deep field survey of the Universe in the Ultraviolet region.