Sun Observations by Aditya-L1: ISRO Activates Second Instrument on Indian Solar Spacecraft


The Aditya Solar Wind Particle Experiment (ASPEX) payload on India’s Aditya-L1 satellite has initiated its operations and is functioning as expected.

On Saturday, the Indian Space Research Organisation (ISRO) marked another milestone as the Aditya Solar Wind Particle Experiment (ASPEX) payload aboard India’s Aditya-L1 satellite initiated its operations and is now functioning normally.

ISRO reports that ASPEX consists of two instruments—the Solar Wind Ion Spectrometer (Swis) and the SupraThermal and Energetic Particle Spectrometer (Steps).

While the Steps instrument became operational on September 10, 2023, the Swis instrument was activated on November 2, 2023, demonstrating optimal performance.

The Swis instrument utilizes two sensor units with a 360-degree field of view each, operating in planes perpendicular to one another. It has successfully measured solar wind ions, primarily protons and alpha particles. A sample energy histogram 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, recorded with nominal integration time, offer a comprehensive snapshot of solar wind behavior.

The Swis’s directional capabilities enable precise measurements of solar wind protons and alphas, significantly contributing to addressing longstanding questions about solar wind properties, underlying processes, and their impact on Earth.

ISRO notes that the change in the proton and alpha particle number ratio 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. An enhanced alpha-to-proton ratio is considered a sensitive marker for the passage of interplanetary coronal mass ejections (ICMEs) at the L1 and is crucial for space weather studies.

Aditya-L1, India’s first dedicated solar mission, was launched on September 2 from the Satish Dhawan Space Centre (SDSC) on Sriharikota island, Andhra Pradesh. After traveling approximately 1.5 million km from Earth over 125 days, the spacecraft is expected to be placed in a Halo orbit around Lagrangian point L1, considered closest to the Sun.

ISRO chief S Somnath mentioned last week that the Aditya L1 spacecraft is nearing its final phase, with maneuvers to enter the L1 point expected to be completed by January 7, 2024.

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