Aditya-L1 is an Indian solar observation satellite to be placed at the Sun-Earth Lagrangian point L1.
The major scientific objectives of the mission are to achieve a fundamental understanding of the physical processes that heat the solar corona, accelerate the solar wind and produce Coronal Mass Ejections (CMEs).
Originally the mission design started as a small LEO satellite carrying only a coronagraph as a payload. In order to get the best science from the Sun, continuous viewing of the Sun is preferred. A Satellite placed in the halo orbit around the L1 Lagrangian point of the Sun-Earth system has the major advantage of continuously viewing the Sun without any occultation/ eclipses. Based on the technical studies, it was found that PSLV-XL developed at ISRO has the capability to launch a satellite which can be placed at a halo orbit around L1 point.
Following instruments have been selected for the mission:
- Visible Emission Line Coronagraph (VELC), IIA, Bengaluru.
The coronagraph creates an artificial total solar eclipse in space by blocking the sunlight by an occultor. This telescope will have capabilities of spectral imaging of the corona in visible and infra-red wavelengths. The objectives are to study the diagnostic parameters of solar corona and dynamics and origin of coronal mass ejections (using three visible and one infra-red channels); magnetic field measurements of the solar corona down to tens of Gauss. Additional objectives are to determine why the solar atmosphere is so hot, and how the changes in the Sun can affect space weather and Earth's climate. The VELC payload weighs nearly 170 kg.
- Solar Ultraviolet Imaging Telescope (SUIT), IUCAA, Pune
SUIT will observe the Sun between 200-400 nm wavelength range and it will provide full disk images of different layers of the solar atmosphere by making use of 11 filters. The Sun has never been observed from space in this wavelength range. The spacecraft being at the first Lagrange point, SUIT shall be observing the Sun continuously without interruption. The SUIT payload weighs nearly 35 kg.
- Aditya Solar wind Particle Experiment (ASPEX), PRL, Ahmedabad
This instrument is to study the variation and properties of the solar wind as well as its distribution and spectral characteristics.
- Plasma Analyser Package for Aditya (PAPA), SPL/VSSC, Trivandrum
An instrument to analyze the composition of solar wind and its energy distribution.
- Solar Low Energy X-ray Spectrometer (SoLEXS), SAG/ISAC, Bengaluru
An instrument to monitor the X-ray flares for studying the enigmatic coronal heating mechanism of the solar corona.
- High Energy L1 Orbiting X-ray Spectrometer (HEL1OS), SAG/ISAC, Bengaluru
This instrument is to observe the dynamic events in the solar corona and provide an estimate of the energy used to accelerate the solar energetic particles during the eruptive events.
- Magnetometer (MAG), Space Physics Laboratory (SPL)
This instrument, mounted on a deployable 6 meter long boom, is to measure the magnitude and nature of the interplanetary magnetic field.
Launch was planned on a PSLV-XL rocket in the 2019 timeframe, but has been delayed to September 2023. The launch vehicle has put Aditya-L1 into an elliptical earth orbit, from which it will maneuver over 109 days to an L1 halo orbit.