Aditya-L1: India’s maiden Sun mission to lift off Sept 2

🚀PSLV-C57/🛰️Aditya-L1 Mission:

The launch of Aditya-L1,
the first space-based Indian observatory to study the Sun ☀️, is scheduled for
🗓️September 2, 2023, at
🕛11:50 Hrs. IST from Sriharikota.

Citizens are invited to witness the launch from the Launch View Gallery at… pic.twitter.com/bjhM5mZNrx

— ISRO (@isro) August 28, 2023

But why aim for the Sun? According to the mission's objective, the Sun is not only the nearest star to Earth but also a natural laboratory for understanding eruptive phenomena and solar dynamics. Studying the Sun in granular detail could reveal key insights into the behaviors of other stars in the Milky Way and even other galaxies.

A close-up of Aditya-L1

The Aditya-L1 mission aims to put India on the global map of space-based solar science. The spacecraft will be placed in a halo orbit around Lagrangian point 1 (L1), situated roughly 1 million miles (1.5 million kilometers) from Earth. This unique vantage point will allow continuous observation of the Sun, free from obstructions like eclipses.

The spacecraft is equipped with seven payloads, designed to study various layers of the Sun—ranging from its photosphere to the outer corona. Among the instruments are the Visible Emission Line Coronagraph (VELC), which will study the solar corona and dynamics of Coronal Mass Ejections, and the Solar Ultra-violet Imaging Telescope (SUIT), designed to capture images in the Ultra-Violet spectrum.

Primary objectives and uniqueness of the mission

The objective of the Aditya-L1 mission is to study the Sun and its influence on the space environment around the Earth and other planets. The Sun is the nearest star to us and can provide valuable insights into the nature and evolution of other stars in our galaxy and beyond. The Sun also affects our planet with its radiation, heat, and magnetic fields, which can cause disturbances in communication systems, satellites, and even human health. By observing the Sun from a unique vantage point at the Lagrangian point 1 (L1), where the gravitational forces of the Earth and the Sun balance each other, the mission will be able to monitor the solar activity continuously without any interruption from the Earth or the Moon. The mission will also help to understand the physical processes that drive solar activity, such as coronal heating, solar wind acceleration, coronal mass ejection, flares, and space weather.

The Aditya-L1 mission is unique in several ways. It is the first Indian mission to explore a celestial body other than the Moon or Mars. It is also the first mission to observe the Sun in the near UV band, which is important for studying the lower layers of its atmosphere. The mission will also be able to observe the dynamics of coronal mass ejections close to their origin, where they are still accelerating and changing their shape. This will provide crucial information about how these eruptions are initiated and propagated. The mission will also have a smart onboard system that will automatically detect coronal mass ejections and flares using image processing algorithms. This will enable the spacecraft to prioritize data transmission based on scientific importance and reduce data volume. The mission will also measure the solar wind particles in different directions relative to the Sun-Earth line. This will help to study how the solar wind varies with angle and distance from the Sun. It will also help to measure the energy distribution and anisotropy of the solar wind, which can indicate the presence of waves, shocks, and turbulence.

Seven scientific payloads of Indigenous Innovation

The indigenous development of Aditya-L1's payloads reflects India's growing expertise in space technology. Developed by different labs across the country, including the Indian Institute of Astrophysics and the Physical Research Laboratory, the mission symbolizes a new era in collaborative, home-grown space research.

The Aditya-L1 mission is equipped with an ensemble of seven scientific instruments designed for an in-depth exploration of the Sun. Among these, the Visible Emission Line Coronagraph (VELC) is focused on examining the solar corona and the mechanics of Coronal Mass Ejections. The Solar Ultra-violet Imaging Telescope (SUIT) is tasked with capturing images of the Sun's Photosphere and Chromosphere in the near Ultra-violet (UV) spectrum, as well as monitoring variations in solar irradiance within that range. Other specialized instruments like the Aditya Solar wind Particle EXperiment (ASPEX) and the Plasma Analyser Package for Aditya (PAPA) are set to investigate solar wind characteristics and the distribution of energetic ions. Further extending the mission's reach, the Solar Low Energy X-ray Spectrometer (SoLEXS) and the High Energy L1 Orbiting X-ray Spectrometer (HEL1OS) are devoted to studying X-ray flares from the Sun across a broad energy spectrum. Additionally, the Magnetometer payload is capable of gauging interplanetary magnetic fields at the Lagrangian L1 point.

Each of these payloads has been meticulously developed at different research institutions across India, underlining the collaborative nature of the mission. The VELC was crafted at the Indian Institute of Astrophysics in Bangalore, while the SUIT instrument was developed at the Inter-University Centre for Astronomy & Astrophysics in Pune. The ASPEX instrument came to life at the Physical Research Laboratory in Ahmedabad, and the PAPA payload was designed at the Space Physics Laboratory at the Vikram Sarabhai Space Centre in Thiruvananthapuram. The SoLEXS and HEL1OS instruments were constructed at the U R Rao Satellite Centre in Bangalore, and the Magnetometer payload was developed at the Laboratory for Electro Optics Systems, also located in Bangalore. All these contributions were synthesized through the coordinated efforts of various ISRO centers.

Journey to L1

The Aditya-L1 mission is set to be propelled into space aboard a PSLV-C57 rocket, lifting off from the Sathish Dhawan Space Centre SHAR (SDSC SHAR) in Sriharikota. Upon launch, the spacecraft will initially be positioned in a low Earth orbit. Following this initial placement, its orbit will be elongated into a more elliptical shape using on-board propulsion systems. As Aditya-L1 continues its voyage toward the Lagrangian L1 point, it will move beyond the Earth's gravitational Sphere of Influence (SOI). After crossing this boundary, the mission will transition into its cruise phase and eventually be inserted into a large halo orbit around the L1 point. The estimated duration for the complete journey from Earth to the L1 point is approximately four months.