After a successful Chandrayaan-3 mission, India will study the Sun. Aditya L1 will be the first space-based Indian mission to study the Sun. The spacecraft will be placed in a halo orbit around the Sun at Lagrange point 1 or L1 of the Sun-Earch system. This point is located 1.5 million kilometres from Earth, allowing for continuous observation of solar activities. Notably, the position will help Aditya L1 study the Sun without hindrance from occultations or eclipses.
The satellite will be equipped with seven different instruments or payloads that will be used to study various aspects of the Sun, including the photosphere, chromosphere, and corona. These observations will help scientists better understand our nearest star’s behaviour and how it affects our planet.
Objectives of the solar mission
As per the Indian Space Research Organisation’s (ISRO) website, the main objectives of the mission include:
- Study the upper atmospheric dynamics (chromospheres and corona) of the Sun.
- Study the chromospheric and coronal heating, physics of the partially ionised plasma and initiation of coronal mass ejections and flares.
- Observe the in-situ particle and plasma environment, providing data for studying particle dynamics from the Sun.
- Study the physics of solar corona and its heating mechanism.
- Diagnostics of the coronal and coronal loops plasma are Temperature, velocity and density.
- Development, dynamics and origin of CMEs.
- Identifying the sequence of processes that occur at multiple layers (chromosphere, base and extended corona) eventually leads to solar eruptive events.
- Study of magnetic field topology and magnetic field measurements in the solar corona.
- Study of the drivers for space weather (origin, composition and dynamics) of solar wind.
Seven payloads of the ISRO program
The mission will have two types of payloads, Remote Sensing Payloads and In-situ Payloads. Remote Sensing Payloads will include four payloads. The first one will be the Visible Emission Line Coronagraph(VELC), capable of Corona/Imaging and Spectroscopy. The second payload will be the Solar Ultraviolet Imaging Telescope (SUIT), which can gather information on the Photosphere and Chromosphere Imaging (Narrow and Broadband). The third payload will be a high-energy L1 Orbiting X-ray Spectrometer(HEL1OS) capable of a Hard X-ray spectrometer that will observe Sun-as-a-star.
In-situ Payloads will include three payloads. The first will be the Aditya Solar Wind Particle Experiment(ASPEX), equipped with Solar wind/Particle Analyzer Protons and heavier Ions with directions. The second payload will be the Plasma Analyser Package For Aditya (PAPA), capable of analysing Solar wind/Particle Analyzer Electrons and heavier Ions with directions. The third and last payload will be Advanced Tri-axial High-Resolution Digital Magnetometers capable of analysing In-situ magnetic field (Bx, By and Bz).
What are Lagrange Points
There are five Lagrange points where a small object can stay with reduced fuel consumption for a two-body gravitational system. The two large bodies’ gravitational pull equals the centripetal force required for a small thing to move with them. The five Lagrange points are L1, L2, L3, L4, and L5. L1 lies between the Sun-Earth line and is approximately 1% of the Earth-Sun distance away from Earth.
Trajectory of L1
The Aditya-L1 mission will be launched from Sriharikota by ISRO’s PSLV XL rocket. The spacecraft will first be placed in a Low Earth Orbit and then moved towards the Lagrange point (L1) using onboard propulsion. The total travel time from launch to L1 would take about four months.
Why is it important to study the Sun from space?
To conduct precise measurements in the vast expanse of interplanetary space, it is essential to gather observations from a location beyond the reach of Earth’s magnetic field and atmosphere. This is because the Sun emits various forms of radiation and magnetic fields that are not detectable from the surface of our planet but can be extensively studied in the vast, open expanse of space. By conducting research in this way, scientists can gain a deeper understanding of the complex dynamics that govern our solar system and ultimately advance our knowledge of the Universe.
Is Aditya L1 a complete mission to study the Sun?
The simple answer is no. However, it is a first step. No space mission can be termed a “complete mission” owing to the size of the Solar System, even if not considering the Universe as a whole.
The scientific payloads carried by spacecraft in space are limited by mass, power, and volume, so only a few instruments can be sent on a spacecraft. For example, Aditya-L1 will measure everything from the Lagrange point L1. However, studying phenomena like the directional energy distribution of explosive/eruptive phenomena requires more instruments and viewpoints. L5 is a good vantage point for studying Earth-directed CME events and assessing space weather.
Further, the Sun’s polar regions are not well studied due to the technological challenges of achieving spacecraft orbits for such studies. The Sun’s polar dynamics and magnetic fields play an important role in deriving solar cycles, and studying polarisation measurements of solar radiations at different wavelengths is required to understand the various processes occurring in and around the Sun.
