Aditya-L1
Aditya L1( ) is a planned coronagraphy spacecraft to study solar atmosphere, currently being designed and developed by Indian Space Research Organisation (ISRO) and various other Indian research institutes. It will be inserted in a halo orbit around the L1 point between Earth and Sun where it will study solar atmosphere, solar magnetic storms and it's impact on environment around Earth. The spacecraft will study coronal heating, solar wind acceleration, coronal magnetometry, origin and monitoring of near-UV solar radiation and continuously observe photosphere, chromosphere and corona, solar energetic particles and magnetic field of the Sun. First dedicated  Indian mission to observe Sun, it is planned to be launched in Sept/Oct 2022 aboard a PSLV-XL launch vehicle. History. Aditya was conceptualised in January 2008 by the Advisory Committee for Space Research. It was initially envisaged as a small , low-Earth orbiting satellite with a coronagraph to study the solar corona. An experimental budget of 3 Crore INR was allocated for the financial year 2016–2017. The scope of the mission has since been expanded and it is now planned to be a comprehensive solar and space environment observatory to be placed at the Lagrange point L1, so  the mission was renamed "Aditya-L1". , the mission has an allocated cost of ₹378.53 crore excluding launch costs. Overview. The Aditya-L1 mission will take around 109 Earth days after launch to reach the halo orbit around the L1 point, which is about from Earth. The satellite carries seven science payloads with diverse objectives, including but not limited to, the coronal heating, solar wind acceleration, coronal magnetometry, origin and monitoring of near-UV solar radiation (which drives Earth's upper atmospheric dynamics and global climate), coupling of the solar photosphere to chromosphere and corona, in-situ characterisations of the  space environment around Earth by measuring energetic particle fluxes and magnetic fields of the solar wind and solar magnetic storms that have adverse effects on space and ground-based technologies. Aditya-L1 will be able to provide observations of Sun's photosphere, chromosphere and corona. In addition, an instrument will study the solar energetic particles' flux reaching the L1 orbit, while a magnetometer payload will measure the variation in magnetic field strength at the halo orbit around L1. These payloads have to be placed outside the interference from the Earth's magnetic field and hence could not have been useful  in the low Earth orbit as proposed on the original Aditya mission concept. One of the major unsolved issues in the field of solar physics is that the upper atmosphere of the Sun is hot whereas the lower atmosphere is just . In addition, it is not understood how exactly the Sun's radiation affects the dynamics of the Earth's atmosphere on shorter as well as on longer time scale. The mission will obtain near simultaneous images of the different layers of the Sun's atmosphere, which reveal the ways in which the energy may be channeled and transferred from  one layer to another. Thus the Aditya-L1 mission will enable a comprehensive understanding of the dynamical processes of the Sun and address some of the outstanding problems in solar physics and heliophysics.