Solar wind particle experiment payload onboard Aditya-L1 starts ops: Isro

The Aditya Solar wind Particle Experiment payload on board India's Aditya-L1 satellite is operational and functioning normally, ISRO said on Saturday.

ISRO's Polar Satellite Launch Vehicle (PSLV-C57) had successfully launched the Aditya-L1 spacecraft from the second launch pad of Satish Dhawan Space Center, Sriharikota on September 2.

Aditya-L1 is the first Indian space observatory to study the Sun from a halo orbit around the first Lagrangian point between the Sun and Earth (L1), which is about 1.5 million km from Earth.

In a statement, ISRO said the Aditya Solar wind Particle Experiment (ASPEX) includes two advanced instruments – the Solar Wind Ion Spectrometer (SWIS) and the SupraThermal and Energetic Particle Spectrometer (STEPS). The STEPS instrument was operational on September 10, 2023. The SWIS instrument was activated on November 2, 2023 and has delivered optimal performance.

“SWIS uses two sensor units, each with a remarkable 360-degree field of view and operates in planes perpendicular to each other,” the statement said.

According to ISRO, the instrument successfully measured solar wind ions, mainly protons and alpha particles.

A sample energy histogram obtained from one of the sensors over two days in November 2023 illustrates variations in the number of protons and alpha particles (doubly ionized helium, He2+), the agency said.

“These variations were recorded with a nominal integration time, providing a comprehensive snapshot of the solar wind behavior,” ISRO said.

SWIS's directional capabilities enable precise measurements of solar wind protons and alphas, significantly helping to answer long-standing questions about the properties of solar wind, underlying processes and their impact on Earth, the space agency explains.

“The change in the ratio of protons to alpha particles, as observed by SWIS, has the potential to provide indirect information about the arrival of Coronal Mass Ejections (CMEs) at the Lagrange point L1 of the Sun and Earth,” ISRO said.

Enhanced alpha-proton ratio is often considered one of the sensitive markers of the passage of interplanetary coronal mass ejections (ICMEs) at the L1 and is therefore considered crucial for space weather studies.