Monitoring sunspots with Mars rovers

Space weather events, including active regions on the Sun responsible for significant and potential space weather, have been monitored from Earth and space. However, this coverage does not generally include all longitudes of the Sun at any given time. Serendipitously, images from the Mars rovers show sunspots and can supplement traditional solar imaging. The Perseverance rover on Mars carries the Mastcam-Z stereo camera, which has the potential for monitoring sunspots from a Mars vantage point. Color and monochrome (880-nm) solar images were taken using neutral density filters that allow solar imaging. Images were taken with the primary purpose of monitoring the direct flux at the surface and thus determining the time-variable aerosol load of the atmosphere via extinction. The 67 microradian pixel size corresponds to 15,000 km on the Sun, a very low resolution compared to purpose-built solar cameras. However, it can detect >40% of sunspots and resolve the largest 5-10% of spot umbras. In addition, the Curiosity rover has a nearly 10-year record of 440-nm solar images at a somewhat lower resolution that still detects the largest active areas. We will present a catalog of the sunspot record as observed from Mars. We shall also discuss the following:

Dates for which another asset can validate the observations;Times for which Mars had a unique vantage and thus provide data that might be useful for localizing space weather events or validating models of farside activity (e.g., from helioseismology);Prospects for future monitoring of regions of the Sun that are about to become Earth-facing when Mars has a unique vantage (e.g., several months during 2023 and 2025).