About Visible Emission Line Coronagraph (VELC) on board Aditya-L1:
- What is it?It is the largest payload that would fly on the Aditya-L1 mission. It is an internally occulted solar coronagraph capable of simultaneous imaging, spectroscopy and spectro-polarimetry close to the solar limb.
- The VELC consists of a coronagraph, spectrograph, polarimetry module and detectors, aside from auxiliary optics.
- It is built by the Indian Institute of Astrophysics (IIA) at its CREST (Centre for Research and Education in Science and Technology) campus at Hosakote, Karnataka.
- Purpose:
- It will observe the solar corona, which is the tenuous, outermost layer of the solar atmosphere.
- It will analyze the coronal temperature, plasma velocity, density, etc.
- It will also study Coronal Mass Ejections (CMEs) and the solar wind.
What is Aditya-L1 Mission:
- It is India's first dedicated scientific mission to study the Sun.
- The spacecraft will be placed in a halo orbit around the first Lagrange point, L1, which is 1.5 million km from the Earth towards the Sun.
- A satellite around the L1 point has the major advantage of continuously viewing the Sun without occultation/eclipses.
- Aditya-L1 carries seven payloads to observe the photosphere, chromosphere, and the outermost layers of the Sun (the corona) using electromagnetic and particle detectors.
- The satellite will be launched by PSLV-XL launch vehicle from Sriharikota.
What are Coronal Mass Ejections (CMEs):
- (CMEs) are large expulsions of plasma and magnetic fields from the Sun’s corona.
- The blast of a CME carries about a billion tons of material out from the Sun at very high speeds of hundreds of kilometers per second.
- A CME contains particle radiation (mostly protons and electrons) and powerful magnetic fields stronger than what is normally present in the solar wind.
- The resulting shocks ripple through the solar system and can interrupt satellites and power grids on Earth.
