On September 2, 2023, the Polar Satellite Launch Vehicle (PSLV-C57) accomplished the successful launch of the Aditya-L1 from Satish Dhawan Space Centre (SDSC) located in Sriharikota.

The Aditya-L1, following a flight duration of 63 minutes and 20 seconds, achieved a successful injection into an elliptical orbit around the Earth.

The Aditya-L1 is scheduled to undergo a series of four earth-bound orbital manoeuvres prior to its placement in the transfer orbit towards the Lagrange point L1.

Aditya L1 is the first space based Indian mission to study the Sun.

The spacecraft shall be placed in a halo orbit around the Lagrange point 1 (L1) of the Sun-Earth system, which is about 1.5 million km from the Earth.

The Aditya-L1 mission will take around 109 Earth days after launch to reach the halo orbit around the L1 point.

Lagrange Points

Lagrange Points are positions in space where the gravitational forces of a two body system like the Sun and the Earth produce enhanced regions of attraction and repulsion.

Lagrange points are positions in space where objects sent there tend to stay put.

At Lagrange points, the gravitational pull of two large masses precisely equals the centripetal force required for a small object to move with them.

These can be used by spacecraft to reduce fuel consumption needed to remain in position.

There are five special points where a small mass can orbit in a constant pattern with two larger masses.

Of the five Lagrange points, three are unstable and two are stable.

The unstable Lagrange points – labeled L1, L2 and L3 – lie along the line connecting the two large masses.

The stable Lagrange points – labeled L4 and L5 – form the apex of two equilateral triangles that have the large masses at their vertices. L4 leads the orbit of earth and L5 follows.

The L1 point of the Earth-Sun system affords an uninterrupted view of the sun. A satellite placed in the halo orbit around the L1 point has the major advantage of continuously viewing the Sun without any occultation/eclipses.

This will provide a greater advantage of observing the solar activities and its effect on space weather in real time.

L2 is ideal for astronomy because a spacecraft is close enough to readily communicate with Earth, can keep Sun, Earth and Moon behind the spacecraft for solar power and (with appropriate shielding) provides a clear view of deep space for our telescopes.

L3 point remains hidden behind the Sun at all times.

Objects found orbiting at the L4 and L5 points are often called Trojans. There are hundreds of Trojan Asteroids in the solar system. Most orbit with Jupiter, but others orbit with Mars.

Objectives of Aditya L1 mission

The suits of Aditya L1 payloads are expected to provide most crucial informations to understand the problem of coronal heating, coronal mass ejection, pre-flare and flare activities and their characteristics, dynamics of space weather, propagation of particle and fields etc.

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)

Payloads of Aditya L1 along with their major capability

The spacecraft carries seven payloads to observe the photosphere, chromosphere and the outermost layers of the Sun (the corona) using electromagnetic and particle and magnetic field detectors.

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.

Using the special vantage point L1, four payloads directly view the Sun and the remaining three payloads carry out in-situ studies of particles and fields at the Lagrange point L1, thus providing important scientific studies of the propagatory effect of solar dynamics in the interplanetary medium

Remote Sensing Payloads

1 Visible Emission Line Coronagraph(VELC) – Corona/Imaging & Spectroscopy

2 Solar Ultraviolet Imaging Telescope (SUIT) – Photosphere and Chromosphere Imaging- Narrow & Broadband

3 Solar Low Energy X-ray Spectrometer (SoLEXS) – Soft X-ray spectrometer: Sun-as-a-star observation

4 High Energy L1 Orbiting X-ray Spectrometer(HEL1OS) – Hard X-ray spectrometer: Sun-as-a-star observation

In-situ Payloads

5 Aditya Solar wind Particle Experiment(ASPEX) – Solar wind/Particle Analyzer Protons & Heavier Ions with directions

6 Plasma Analyser Package For Aditya (PAPA) – Solar wind/Particle Analyzer Electrons & Heavier Ions with directions

7 Advanced Tri-axial High Resolution Digital Magnetometers – In-situ magnetic field (Bx, By and Bz).