Significance of Aditya-L1’s Solar wind particle experiment payload explained

Aditya-L1, India’s maiden solar probe, is a mission dedicated to observing the Sun and its various phenomena. Launched on September 2, 2023, by a PSLV-XL rocket from Sriharikota’s Satish Dhawan Space Centre, the satellite is currently on the way to the Lagrange Point 1 (L-1)—a point of gravitational equilibrium between the Earth and the Sun, about 1.5 million kilometres away from the Earth. 

It will reach its designated orbit around L-1 on January 7, 2024, after performing a series of orbit-raising manoeuvres. Earlier today, ISRO stated that the Aditya Solar wind Particle Experiment (ASPEX) payload on the Aditya spacecraft had commenced operations, providing insights into the enigmatic nature of solar wind to enhance our understanding of space weather. 

ASPEX, includes tools such as the Solar Wind Ion Spectrometer (SWIS) and SupraThermal and Energetic Particle Spectrometer (STEPS). They are functioning smoothly without any hitches. The SWIS payload was activated on November 2 and has been functioning effectively.  It is responsible for measuring the mass and energy levels of various solar wind ions and isotopes. On the other hand, STEPS captures data on fast-moving charged particles generated by solar processes. These instruments play a crucial role in unravelling the mysteries of solar wind, space weather and the origins and evolution of our solar system. 

“SWIS is a remarkable instrument that enables the measurement of minuscule particles originating from the Sun, known as solar wind ions. These ions consist of different types—including protons and alpha particles. With its two components strategically positioned to observe its surroundings from varying perspectives, SWIS provides valuable insights into the behaviour and transformations of solar wind ions,” explained space and aerospace expert Girish Linganna. 

SWIS can apparently measure the solar wind ions with infinite precision because it can see them from different directions and angles. This helps scientists answer some old questions about how solar wind ions affect Earth. SWIS can also notice when the number of alpha particles changes compared to the number of protons. This change can tell researchers when big blobs of matter from the Sun are shooting off towards Earth. As per ISRO these blobs are called interplanetary coronal mass ejections (ICMEs) and they can cause space weather problems. 

“ASPEX is a great tool for studying solar wind, which is the stream of matter that emanates from the Sun. Solar wind can affect Earth and other planets in many different ways. Scientists around the world are excited to see what ASPEX can reveal about nature of solar wind and its secrets. ASPEX is ready to share a lot of new information that can help us understand the Sun and its influence better,” remarked  Linganna. 

The Aditya L-1 satellite weighs 1,475 kg and carries seven scientific payloads to study the solar atmosphere, solar wind, magnetic field and space weather. The payloads, aim to investigate different aspects of the Sun, known for its ever-changing and unpredictable nature. “Of these instruments, four are specifically designed to directly observe the Sun, while the other three focus on gathering data about space weather in the region of interplanetary space influenced by the Sun. Various laboratories and research facilities across the country have collaborated to develop these seven payloads for the Aditya L-1 mission,” added Linganna. 

The seven payloads include the VELC instrument created at the Indian Institute of Astrophysics, Bangalore, the SUIT instrument developed at the Inter University Centre for Astronomy and Astrophysics, Pune, the ASPEX instrument manufactured at the Physical Research Laboratory, Ahmedabad, the PAPA payload designed at the Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram, the SoLEXS and HEL1OS payloads developed at the UR Rao Satellite Centre, Bangalore and the Magnetometer payload created at the Laboratory for Electro-Optics Systems, Bangalore. 

Interestingly, ISRO announced on November 7, 2023, that the HEL1OS instrument on the Aditya-L1 spacecraft had detected the initial phase of a solar flare, which is characterized by the release of a substantial amount of energy.