What was the Aditya-1 Mission?
The Aditya-1 mission was conceived as a 400kg class satellite carrying one payload, the Visible Emission Line Coronagraph (VELC) and was planned to launch in a 800 km low earth orbit.
Why is it revised and renamed Aditya-L1 mission?
A Satellite placed in the halo orbit around the Lagrangian point 1 (L1) of the Sun-Earth system has the major advantage of continuously viewing the Sun without any break like eclipses. Therefore, the Aditya-1 mission has now been revised to “Aditya-L1 mission” and will be inserted in a halo orbit around the L1, which is 1.5 million km from the Earth.
What are Lagrange Points?
Lagrange Points are positions in space where the gravitational forces of a two body system like the Sun and the Earth produce enhanced regions of attraction and repulsion. These can be used by spacecraft to reduce fuel consumption needed to remain in position. Lagrange points are named in honor of Italian-French mathematician Josephy-Louis Lagrange.
When will the launch be and by which vehicle?
The satellite will be launched during 2019 – 2020 timeframe by PSLV-XL from Sriharikota.
What is the payload- (instruments)?
The main payload is the coronagraph with improved capabilities. The new satellite carries additional six payloads with enhanced science scope and objectives.
What other differences are there between the two Adityas?
Aditya-1 was meant to observe only the solar corona. The outer layers of the Sun, extending to thousands of km above the disc (photosphere) is termed as the corona. It has a temperature of more than a million-degree Kelvin which is much higher than the solar disc temperature of around 6000K. How the corona gets heated to such high temperatures is still an unanswered question in solar physics.
Aditya-L1 with additional experiments can now provide observations of Sun's other layers also.