From the Lagrange Point 1 (L1) located between the Earth and the Sun, India’s Aditya-L1 mission is closely observing solar activity and delivering data that has surprised scientists across the world. For nearly four decades, scientists believed that energy particles emitted by the Sun reach space uniformly from all directions. Until now, this remained a theoretical assumption. Aditya-L1 has provided the first experimental proof of this phenomenon, validating a long-standing scientific theory. A key role in this breakthrough has been played by a payload developed in Ahmedabad. Divya Bhaskar spoke exclusively with Physical Research Laboratory (PRL) professor and scientist Dr Divyendu Chakraborty to understand the importance of this discovery and the wider impact of the mission. Understanding key scientific terms Scientific terminology can often appear complex. To simplify the discussion, here are explanations of some commonly used terms in straightforward language. Payload: All satellites and scientific instruments carried inside a rocket are collectively referred to as the payload. Coronal Mass Ejection (CME): The Sun’s outer atmosphere is known as the corona. When intense magnetic disturbances occur, massive amounts of hot plasma and magnetic energy are expelled into space. This event is called a coronal mass ejection. Photosphere: The visible surface of the Sun that can be seen with the naked eye. In Gujarati, it is also known as Tejavaran or Prakashmandal. Chromosphere: The layer of the Sun’s atmosphere located just above the photosphere. Ultraviolet Wavelength: Radiation with a wavelength shorter than visible violet light. Parker Transport Equation: A mathematical equation that explains how high-energy particles move and spread through the solar system. Lagrange Point: A position in space where the gravitational forces of the Earth and the Sun balance each other. There are five such points; L1 is the closest to Earth. Why is Aditya-L1 data crucial ? Aditya-L1 is designed to study the Sun’s behaviour in detail. It seeks to answer vital questions: how and when solar flares and storms originate, how solar wind behaves, what it contains, and how these events may affect Earth. Crucially, the mission provides early data on solar storms, allowing precautionary measures to be taken. For the first time in India, scientists are receiving real-time data that can help determine whether solar activity could disrupt satellites, GPS systems, communication networks, and power grids. Scientific payloads on board Aditya-L1 carries seven advanced payloads, each with a specific function- 2 types of solar particles identified Dr Chakraborty explained that PRL developed the ASPEX payload, which measures the energy, speed, temperature, and density of particles carried by solar winds. According to him, particles emitted by the Sun fall into two categories. The first type travels at extremely high speeds—around 300 to 400 times faster than a bullet, and can penetrate the Sun’s magnetic surface. The second type is slower and carries magnetic fields along with it. Aditya-L1 aims to understand both types so their direction, speed, energy, and impact on Earth can be predicted accurately.
Proof of a 40-year-old theory Analysis revealed that during quiet phases of the Sun, medium-energy particles arriving at L1 are uniformly distributed in all directions. Until now, this directional uniformity was considered purely theoretical. Aditya-L1 has provided the first experimental confirmation of this phenomenon, effectively validating the Parker Transport Equation after nearly four decades. This discovery is critical, as high-energy particles formed from medium-energy ones can damage satellites and pose risks to astronauts. Scientists are now studying how this uniformity changes during solar flares and coronal mass ejections. First-ever images across solar layers The VELC payload, developed by the Indian Institute of Astrophysics in Bengaluru, has, for the first time observed coronal mass ejections near the Sun’s surface in visible wavelengths. Meanwhile, the SUIT payload, built by IUCAA Pune, has captured images of the Sun’s entire disk across all atmospheric layers using 11 ultraviolet filters. Observations revealed that solar flares originate very close to the surface, accompanied by a rise in coronal temperature. Dr Chakraborty described Aditya-L1 as an observatory-class mission, effectively placing a complete scientific laboratory in space. Global scientific impact Aditya-L1 data is being widely used by scientists in India and abroad. ASPEX data, in particular, has been downloaded extensively, making it the most accessed dataset on the ISRO portal. For the first time, detailed information on solar wind velocity, density, and temperature has been made freely available at national and international levels. Risks posed by solar storms Earth’s magnetic field usually shields it from solar particles. However, during intense solar activity, particles carrying magnetic fields can breach this protection. Without prior warning, such events can damage satellites and disrupt GPS, navigation, and communication systems, potentially bringing daily life to a standstill. Global scientific impact Aditya-L1 data is being widely used by scientists in India and abroad. ASPEX data, in particular, has been downloaded extensively, making it the most accessed dataset on the ISRO portal. For the first time, detailed information on solar wind velocity, density, and temperature has been made freely available at national and international levels. Risks posed by solar storms Earth’s magnetic field usually shields it from solar particles. However, during intense solar activity, particles carrying magnetic fields can breach this protection. Without prior warning, such events can damage satellites and disrupt GPS, navigation, and communication systems, potentially bringing daily life to a standstill. Mission lifespan and future projects Aditya-L1 has a minimum operational lifespan of five years, which may be extended depending on fuel and system health. Once its mission ends, it will be directed towards the Sun to safely disintegrate. Looking ahead, ISRO plans to launch the Venus Orbiter Mission around 2028, with PRL contributing an instrument to study energetic particles affecting Venus’s atmosphere. PRL is also involved in upcoming Chandrayaan missions, astronomy research, and exoplanet studies. The DISHA mission, planned for 2028, will study the impact of solar activity on Earth’s upper atmosphere using two satellites. Combined data from DISHA and Aditya-L1 will help scientists better predict space weather and its effects on Earth.
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