December 01, 2023
The Aditya Solar wind Particle Experiment (ASPEX) payload onboard India's Aditya-L1 satellite has commenced its operations and is performing normally. ASPEX comprises two cutting-edge instruments – the Solar wind Ion Spectrometer (SWIS) and STEPS (SupraThermal and Energetic Particle Spectrometer). The STEPS instrument was operational on September 10, 2023. The SWIS instrument was activated on November 2, 2023, and has exhibited optimal performance.
SWIS, utilizing two sensor units with a remarkable 360° field of view each, operates in planes perpendicular to one another. The instrument has successfully measured solar wind ions, primarily protons and alpha particles. A sample energy histogram acquired from one of the sensors over two days in November 2023 illustrates variations in proton (H+) and alpha particle (doubly ionized helium, He2+) counts. These variations were recorded with nominal integration time, providing a comprehensive snapshot of solar wind behaviour.
The directional capabilities of SWIS enable precise measurements of solar wind protons and alphas, contributing significantly to addressing longstanding questions about solar wind properties, underlying processes, and their impact on Earth.
The change in the proton and alpha particle number ratio, as observed by SWIS, holds the potential to provide indirect information about the arrival of Coronal Mass Ejections (CMEs) at the Sun-Earth Lagrange Point L1. Enhanced alpha-to-proton ratio is often regarded as one of the sensitive markers of the passage of interplanetary coronal mass ejections (ICMEs) at the L1 and hence considered crucial for space weather studies.
As researchers delve deeper into the collected data, the international scientific community eagerly awaits the wealth of knowledge that Aditya-L1's ASPEX is set to unveil about the enigmatic solar wind and its implications for our planet.