Authors: Lengying Khoo (Princeton University)

The 15 February 2022 event is one of the largest solar energetic particles (SEP) events observed so far in Solar Cycle 25. This widespread SEP event was observed by a fortuitous configuration of spacecraft. We report the first concurrent observations of an SEP event at 0.35-0.38 AU by Parker Solar Probe and BepiColombo, which exhibit excellent agreement with each other. About a 100° in the retrograde direction and 1.5 au from the Sun, very high energy protons were detected at Mars’ orbit by the SEP detector onboard the MAVEN spacecraft, while at the surface, the radiation detector onboard the Mars Science Laboratory’s Curiosity rover observed one of the largest ground level enhancement events ever measured on Mars. At intermediate heliocentric distances, the presence of corotating interaction regions (CIRs) during the SEP arrival time makes it challenging to differentiate the contributions of CME-driven vs CIR-driven SEP events observed by spacecraft around 0.7-1 au such as Solar Orbiter, STEREO-A, and SOHO/WIND. Together, these spacecraft allow us to study the influence of a widespread SEP event over a large longitudinal range and heliocentric distances. These observations highlight the importance of multi-spacecraft measurements to advance our understanding of the acceleration and transport of SEPs in the heliosphere as well as the current difficulties in discerning the relative contribution of CMEs and CIRs on the SEP profiles observed away from the Sun.