ADITYA-L1 MISSION
- Our Sun is the nearest star and the largest object in the solar system. The estimated age of sun is about 4.5 billion years. It is a hot glowing ball of hydrogen and helium gases. The distance to the sun from the earth is about 150 million kilometres, and is the source of energy for our solar system. Without the solar energy the life on earth, as we know, can not exist. The gravity of the sun holds all the objects of the solar system together. At the central region of the sun, known as ‘core’, the temperature can reach as high as 15 million degree Celsius. At this temperature, a process called nuclear fusion takes place in the core which powers the sun. The visible surface of the sun known as photosphere is relatively cool and has temperature of about 5,500°C.
The sun is the nearest star and therefore can be studied in much more detail as compared to other stars. By studying the sun we can learn much more about stars in our Milky Way as well as about stars in various other galaxies. The sun is a very dynamic star that extends much beyond what we see. It shows several eruptive phenomena and releases immense amount of energy in the solar system. If such explosive solar phenomena is directed towards the earth, it could cause various types of disturbances in the near earth space environment. WHY STUDY SUN? Various spacecraft and communication systems are prone to such disturbances and therefore an early warning of such events is important for taking corrective measures beforehand. In addition to these, if an astronaut is directly exposed to such explosive phenomena, he/she would be in danger. The various thermal and magnetic phenomena on the sun are of extreme nature. Thus, the sun also provides a good natural laboratory to understand those phenomena which cannot be directly studied in the lab.
ABOUT ADITYA-L1
The Aditya-L1 mission marks India’s first dedicated space-based observatory designed to study the Sun. Launched by the Indian Space Research Organisation (ISRO) on September 2, 2023, aboard the PSLV-C57 rocket, this mission represents a major leap in solar physics and space weather research.
After a 126-day journey through space, the spacecraft successfully reached its destination and was inserted into its final orbit on January 6, 2024.
The Destination: What is the L1 Point?
Unlike satellites that orbit the Earth, Aditya-L1 is parked in a “halo orbit” around a specific location in space called Lagrange Point 1 (L1). This point is located approximately 1.5 million kilometers away from Earth, directly moving towards the Sun.
To understand L1, imagine a gravitational tug-of-war between the massive Sun and the Earth. L1 is a balanced “sweet spot” where the gravitational pull of the Sun and the Earth roughly cancel each other out. Placing a spacecraft here offers two major advantages:
- Uninterrupted View: The spacecraft can observe the Sun continuously, 24 hours a day, without any eclipses or Earth’s shadow blocking the view.
- Fuel Efficiency: Because the gravitational forces are balanced, the spacecraft requires very little fuel to remain in its position over the years.
- Primary Scientific Objectives
The Sun is a dynamic star, and its behavior directly impacts the entire solar system, including Earth. Aditya-L1 was designed to solve several mysteries regarding solar behavior:
- Coronal Heating Problem: The Sun’s visible surface (photosphere) has a temperature of about 6,000°C. However, its outer atmosphere (the corona) is mysteriously much hotter, reaching temperatures of over 1,000,000°C. Aditya-L1 aims to find out why this happens.
- Coronal Mass Ejections (CMEs): To study massive explosions of hot gas and magnetic energy from the Sun, known as CMEs, and understand how they are triggered.
- Space Weather Forecasting: Solar storms can disrupt Earth’s satellites, GPS navigation, and power grids. By studying solar winds and flares in real-time from L1, scientists can predict and prepare for dangerous space weather.
The Seven Scientific Instruments (Payloads)
The spacecraft carries seven advanced scientific instruments, developed indigenously by ISRO and various Indian research laboratories. Four instruments directly view the Sun (Remote Sensing), while the other three measure the local space environment at the L1 point (In-situ).
S.No. | Payload Name | Primary Function |
1 | Visible Emission Line Coronagraph (VELC) | Studies the solar corona and Coronal Mass Ejections (CMEs). |
2 | Solar Ultraviolet Imaging Telescope (SUIT) | Captures high-resolution images of the Sun’s lower layers (photosphere and chromosphere). |
3 | Solar Low Energy X-ray Spectrometer (SoLEXS) | Observes soft X-rays to study solar flares. |
4 | High Energy L1 Orbiting X-ray Spectrometer (HEL1OS) | Observes hard X-rays to study the explosive energy release during solar flares. |
5 | Aditya Solar wind Particle Experiment (ASPEX) | Analyzes the particles that make up the solar wind. |
6 | Plasma Analyser Package for Aditya (PAPA) | Studies the composition and energy distribution of solar plasma. |
7 | Advanced Tri-axial High-Resolution Digital Magnetometers | Measures the strength and changes of interplanetary magnetic fields at the L1 point. |
- Major Discoveries and Contributions
Since becoming fully operational, Aditya-L1 has provided ground-breaking data to the global scientific community. Some of its notable achievements include:
- Decoding Extreme Solar Storms: During a massive solar storm in May 2024, Aditya-L1’s precise magnetometer readings helped scientists map a giant “magnetic reconnection” region inside a solar eruption. The area was nearly 100 times the size of Earth, marking the first time such a giant magnetic breakup was observed from space.
- Capturing Solar Flares: The SUIT payload successfully captured unprecedented, close-up images of a powerful solar flare ‘kernel’ in the Near Ultraviolet (NUV) wavelength, providing new insights into how these massive explosions develop.
- Understanding Geomagnetic Disturbances: Data from Aditya-L1 helped researchers explain unusual dawn-time magnetic disturbances on Earth. It proved that during severe solar storms, Earth’s invisible magnetic shield gets heavily compressed, pushing auroral currents much closer to the equator than normal.
By continuously monitoring the Sun, Aditya-L1 not only advances fundamental physics but also plays a crucial role in safeguarding Earth’s modern technological infrastructure from the harsh realities of space weather.
For a two body gravitational system, the Lagrange Points are the postions 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. For two body gravitational systems, there are total five Lagrange points 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.
