Aditya L1 Misson orbit entry in January

 Aditya-L1 was launched from the Satish Dhawan Space Centre in Srihari Kota on September 2, days after the Chandrayaan-3 mission made a soft landing on the Moon's south pole. It carried seven different payloads to have a detailed study of the sun, four of which will observe the light from the sun and the other three will measure in-situ parameters of the plasma and magnetic fields. These instruments were intended to provide data on solar activities, such as solar flares and coronal mass ejections.

Indian Space and Research Organization (ISRO) Chief S Somnath on October 15 declared that the Aditya-L1 spacecraft, India's first solar mission, will reach the Lagrange Point 1 (L1) by mid-January.

This mission is expected to reach its destination after a 110-day journey from Earth. Somath in a talk with reporters in Tamil Nadu's Madurai said, “Currently, it takes almost 110 days to travel from Earth to the L1 point. So, by the middle of January, it will reach the L1 point."  "Then at that point, we will do the insertion into the Lagrange Point. That is called the halo orbit. It's a big orbit."

The spacecraft carries seven distinct payloads designed to conduct a comprehensive study of the sun. Four of these instruments will observe the sun's light, while the other three will measure in-situ parameters of the plasma and magnetic fields. Aditya-L1 will be placed in a halo orbit around Lagrange Point 1 (L1), situated approximately 1.5 million km away from Earth in the direction of the sun. It is expected that Aditya L1 will cover the distance in four months' time.

The primary goal of the Aditya-L1 mission is to study the outer atmosphere of the Sun, which is a vast sphere of gas. 

The primary objective of the Aditya-L1 mission is to study the Sun's outermost layer, the solar corona, and to investigate various aspects of the Sun-Earth relationship. The mission is planned to be launched into a halo orbit around the first Lagrange point (L1), which is a stable point in space located between the Earth and the Sun. This orbit allows for continuous observation of the Sun without being obstructed by the Earth.

The main objectives of Aditya L1 are to:

Understand the coupling and dynamics of the solar atmosphere.

Study the photosphere, chromosphere, and corona layers of the Sun. This will help to understand coronal heating.

Study the solar wind, the stream of charged particles that flows from the Sun. This will help to understand solar wind distribution and temperature anisotropy.

Study coronal mass ejections (CMEs), solar flares, and the physics of the solar atmosphere.

As per ISRO, the mission consists of:

Onboard intelligence to detect CMEs and solar flares for optimized observations and data volume.

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 on the acceleration regime of CME which is not observed consistently.

Directional and energy anisotropy of solar wind using multi-direction observations.

At the beginning of this article, we mentioned that initially the Aditya L1 spacecraft shall be launched in LEO. Subsequently, the orbit of the spacecraft will be made more elliptical and will be launched towards the Lagrange Point L1 between the Sun-Earth system with the help of onboard propulsion.

When traveling towards the L1, the spacecraft will exit the earth’s gravitational Sphere of Influence (SOI). Finally, Aditya L1 will be placed in a large halo orbit around the Sun-Earth Lagrange Point L1. This is a point in space that is located about 1.5 million kilometers from Earth. The L1 point is a stable location where the gravitational forces of the Sun and Earth balance each other out.

The Aditya L1 spacecraft will be placed in the large halo orbit around the Sun-Earth Lagrange Point L1 as it will aid in having a continuous view of the Sun without any occultation or eclipses. To explain scientifically, let us understand the Lagrange Points.

As per ISRO, at the Lagrange point, the gravitational pull of the two large bodies equals the necessary centripetal force required for a small object to move with them.

With its placement in the special vantage point of L1, the spacecraft will have the advantage of continuously viewing the Sun without any occultation/eclipse. This will help us to better understand the Sun and its impact on Earth.

The data gathered from the mission will be used to improve our ability to study or predict space weather events, such as solar flares, CMEs, solar wind, etc that affect the functioning of space technology near or on the Earth as well as other planets.

In the case of the Earth, the interaction of the Earth's magnetic field with the field carried by CME can trigger a magnetic disturbance near the Earth. Space weather events can have a significant impact on our power grids, communication systems, and satellites. By understanding the Sun, we can better protect ourselves from these events.

The ISRO Chief also spoke about the 'Gagan Yaan' mission.

"Test Vehicle-D1 mission is scheduled for October 21. This is the Gagan Yaan program. The Gagan Yaan program requires testing, demonstrating the crew escape system. The crew escape system is a very critical system in Gagan Yaan. If anything happens to the rocket, you have to save the crew by moving the crew away from the exploding rocket at least by two km. So, this test is to demonstrate the crew escape system in one condition of the flight. So, this condition we are demonstrating is called the Transonic condition...", Somnath said.

The Gagan Yaan project envisages a demonstration of human spaceflight capability by launching a crew of three members to an orbit of 400 km for a three-day mission and bringing them back safely to Earth, by landing in Indian sea waters.