BENGALURU, Dec 2: The Aditya Solar wind Particle Experiment payload onboard India’s Aditya-L1
satellite has commenced its operations and is performing normally, ISRO said on Saturday.
ISRO’s Polar Satellite Launch Vehicle (PSLV-C57) on September 2 had successfully launched the Aditya-L1
spacecraft, from the second launch pad of Satish Dhawan Space Centre, Sriharikota.
Aditya-L1 is the first Indian space-based observatory to study the Sun from a halo orbit around first Sun-
earth Lagrangian point (L1), which is located roughly 1.5 million km from Earth.
In a statement, ISRO said Aditya Solar wind Particle Experiment (ASPEX) comprises two cutting-edge
instruments ‘the Solar Wind Ion Spectrometer (SWIS) and 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 exhibited optimal performance.
“SWIS, utilising two sensor units with a remarkable 360° field of view each, operates in planes
perpendicular to one another,” the statement read.
According to ISRO, 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 and alpha particle (doubly ionized helium, He2+) counts, the agency said.
“These variations were recorded with nominal integration time, providing a comprehensive snapshot of
solar wind behaviour,” ISRO said.
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 space agency explained.
“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,” ISRO said.
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. (PTI)
