| Name: Vaishnav Sankar K |
| Affiliation: Homi Bhabha Centre for Science Education |
| Conference ID: ASI2026_1162 |
| Title: A Catalogue of Solar Energetic Particle Events Observed by Chandrayaan-2 CLASS at the Moon |
| Abstract Type: Poster |
| Abstract Category: Sun, Solar System, Exoplanets, and Astrobiology |
| Author(s) and Co-Author(s) with Affiliation: Vaishnav Shankar(Homi Bhabha Centre for Science Education (HBCSE)), Shyama Narendranath(Indian Space Research Organisation) |
| Abstract: Moon is a globally sought-after destination with the ambitious goal of establishing a sustained human presence in the coming decades. A detailed characterisation of the lunar radiation environment to build the capability to assess risk factors and implement mitigation strategies is an essential step towards this. For long term missions, lunar space weather and its effect on spacecraft and humans cannot be overstated.
We have used the observations of high energy particle events in Chandrayaan-2 Large Area Soft X-ray Spectrometer (CLASS) to identify Solar Energetic Particle (SEP) events during the period from 2019 to 2023. Galactic Cosmic Ray particles constitute the dominant particle background in the lunar orbit that appears as a continuum in the 7-16 keV energy range of CLASS distinct from the lunar X-rays that it primarily measures. Geotail electrons significantly increases the counts in this band during geotail passages once in 29.5 days. We developed a semi-automated pipeline utilizing a moving median filter for dynamic background subtraction and a sigma-thresholding algorithm to identify SEP events from GCR and geotail particles.
We further characterized the events to estimate rise time, decay time and peak flux. The identified events were corroborated using high-energy (>6.5 MeV) proton data from GOES-16 and catalogued Coronal Mass Ejections (CMEs) from SOHO/LASCO. We identify 12 unique events at the Moon not observed in GOES that emphasises the need for such measurements in the heliosphere and in the near planetary environment.
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