Speaker
Description
One of the most significant hurdles for safe human exploration to Mars is the exposure to radiation from Galactic Cosmic Rays (GCRs) and transient space weather events during transit and on the planet. Solar Energetic Particle (SEP) events are associated with solar flares and coronal mass ejections, which are notoriously hard to predict. High doses of radiation may be delivered on time scales ranging from hours to days during SEP events. The omnipresent GCR flux, while predictable, is generally even more energetic than SEP events.
Estimations of the accumulated radiation doses from a round-trip to Mars exceed the total career dose limits for astronauts. In addition, spacecraft and human infrastructure on the surface may also be sensitive to radiation. Unlike Earth, Mars no longer possesses a global magnetic field that can provide much protection from incoming radiation. The atmospheric density is around 1% of Earth’s, allowing more energetic particles to reach the ground.
It is necessary to gain more information on space weather events impacting Mars as we increase the human presence on Mars. Records spanning long periods will advance our knowledge on the Martian radiation environment, which can be used in the development of data-driven models and generating accurate forecasts. Our understanding of space weather phenomena and their interactions with planetary systems will also benefit from these.
All data from planetary science missions contain observational gaps, and the temporal resolution may be low. However, all spacecraft possess numerous housekeeping sensors for monitoring spacecraft and instrument health. Energetic particles may penetrate the spacecraft shielding and induce Single Event Upsets (SEUs) in memory devices. Error Detection and Correction (EDAC) is a common technique to track and correct these upsets. A cumulative counter associated with each EDAC is incremented for every SEU fixed. EDAC routines tend to run and log the data continuously, even while instruments are turned off and during spacecraft safe modes.
Space Weather Event EDAC Tracker (SWEET), a method using an EDAC counter from Mars Express, was developed to identify SEP events and Forbush Decreases (FDs), temporary decreases in the GCR flux. MEX has been in orbit around Mars since 2004, and thus its EDAC data covers almost two complete solar activity cycles (2004-2024) from which insights on the long-term space weather conditions at Mars can be retrieved.
SWEET detected several hundred space weather events from January 2004 to July 2024. The detections correlated well with the solar activity cycle. Estimates of the minimum number of space weather events at Mars during the previous solar maximum and solar minimum were also provided by SWEET. An events catalog containing over one hundred detections published in literature was used to cross-check SWEET detections. Comparisons with measurements from the SEP instrument on Mars Atmosphere and Volatile EvolutioN (MAVEN), the Analyzer of Space Plasma and Energetic Atoms (ASPERA-3) on MEX, and the Radiation Assessment Detector (RAD) onboard the Curiosity rover, demonstrate how EDAC counters complement dedicated science instruments.
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