The Aditya L1 mission is poised to become India’s first space-based endeavor aimed at studying the Sun. The term “Aditya” is a Sanskrit word for the Sun and the “L1” denotes the location – Lagrange point where the probe will be placed in space. The Indian Space Research Organization (ISRO) is tentatively planning to launch the Aditya-L1 solar mission on September 2, 2023 at 11:50AM IST from Sriharikota. The Aditya-L1 satellite will be carried into space by the PSLV-XL launch vehicle.
Positioned within a halo orbit encircling the first Lagrange point (L1) of the Sun-Earth system, situated roughly 1.5 million km from Earth, the spacecraft boasts a notable advantage. By residing in this strategic location, it can continually observe the Sun without any interruptions from occultations or eclipses. This positioning offers a significant benefit by enabling real-time monitoring of solar activities and their impact on space weather.
Equipped with a suite of seven payloads, the spacecraft is primed to scrutinize various facets of the Sun, encompassing the photosphere, chromosphere, and the outermost layer, known as the corona. These observations will be conducted through an array of electromagnetic, particle, and magnetic field detectors. Notably, four of these payloads are oriented to directly capture solar phenomena, leveraging the unique vantage point of L1. The remaining three payloads are designed for in-situ investigations of particles and fields at the Lagrange point L1. This approach promises to yield invaluable scientific insights into the manner in which solar dynamics propagate through the interplanetary medium.
The instrumentation within the Aditya L1 payloads is anticipated to offer paramount insights crucial for comprehending various phenomena. These include the enigma of coronal heating, the intricacies of coronal mass ejections, the dynamics underlying pre-flare and flare activities, along with their distinct characteristics. Additionally, these instruments are poised to illuminate the dynamics governing space weather, as well as shed light on the intricate propagation patterns of particles and fields, among other phenomena.
Science Objectives:
The major science objectives of Aditya-L1 mission are:
- Study of Solar upper atmospheric (chromosphere and corona) dynamics.
- Study of chromospheric and coronal heating, physics of the partially ionized plasma, initiation of the coronal mass ejections, and flares
- Observe the in-situ particle and plasma environment providing data for the study of particle dynamics from the Sun.
- Physics of solar corona and its heating mechanism.
- Diagnostics of the coronal and coronal loops plasma: Temperature, velocity and density.
- Development, dynamics and origin of CMEs.
- Identify the sequence of processes that occur at multiple layers (chromosphere, base and extended corona) which eventually leads to solar eruptive events.
- Magnetic field topology and magnetic field measurements in the solar corona.
- Drivers for space weather (origin, composition and dynamics of solar wind.
Uniqueness of the Mission:
- First time spatially resolved solar disk in the near UV band.
- CME dynamics close to the solar disk (~ from 1.05 solar radius) and thereby providing information in the acceleration regime of CME which is not observed consistently.
- On-board intelligence to detect CMEs and solar flares for optimised observations and data volume.
- Directional and energy anisotropy of solar wind using multi-direction observations.
Aditya-L1 Payloads:
The instruments of Aditya-L1 are tuned to observe the solar atmosphere mainly the chromosphere and corona. In-situ instruments will observe the local environment at L1. There are total seven payloads on-board with four of them carrying out remote sensing of the Sun and three of them carrying in-situ observation.
Lagrange Points
For a two body gravitational system, the Lagrange Points are the positions
in space where a small object tends to stay, if put there. These points
in space for a two body systems such as Sun and Earth can be used by
spacecraft to remain at these positions with reduced fuel consumption.
Technically at Lagrange point, the gravitational pull of the two large
bodies equals the necessary centripetal force required for a small object
to move with them.
There are five Lagrange points in a two-body system like Earth and the Moon or Earth and the Sun. These points are denoted as L1, L2, L3, L4, and L5.The Lagrange points for Sun-Earth system are shown in the figure. The Lagrange point L1 lies
between Sun-Earth line. The distance of L1 from Earth is approximately
1% of the Earth-Sun distance, about 1.5Million Kms.
