In May 2024, two European Space Agency missions, the Mars Express and ExoMars Trace Gas Orbiter, observed a significant solar storm that not only affected Earth but also impacted Mars. This storm was the strongest we’ve seen in over two decades, creating vibrant auroras on Earth, even stretching to regions like Mexico.
The storm brought a drastic increase in radiation levels to Mars. In just 64 hours, both orbiters encountered radiation equivalent to 200 days of normal exposure. Jacob Parrott, an ESA researcher, noted, “Mars’ upper atmosphere received a flood of electrons. This was the biggest response we’ve seen from a solar storm on Mars.” The upper atmosphere showed a 278% spike in electron levels at high altitudes.
This incident underscores the challenges posed by space weather to our technology. Both orbiters experienced computer glitches, typical for spacecraft during such solar events. Fortunately, they were designed to handle these issues, recovering quickly thanks to their radiation-resistant components.
Colin Wilson, a project scientist with ESA, explained how they used a method called radio occultation to study the storm’s effects. By sending a radio signal from Mars Express to the ExoMars orbiter as it dipped behind Mars, researchers could analyze changes in the atmosphere. This technique, traditionally used to gather data from Earth-based signals, has recently been adapted for Martian observations.
Earth and Mars react differently to solar storms due to their magnetic fields. Our planet’s magnetosphere protects it by deflecting charged particles, which causes auroras mainly at the poles. In contrast, Mars lacks this protective shield, making it vulnerable to solar activity. Despite modern technology allowing us only a couple of observations weekly at Mars, the team timed their research perfectly just after a significant solar flare.
The study also revealed that solar storms can alter radio signal transmissions, crucial for Mars exploration. They analyzed three key solar events linked to this storm: a radiation flare, a surge of charged particles, and a coronal mass ejection. The impact of such events might help explain why Mars has transformed into a dry and barren landscape over time.
Understanding how solar storms deliver energy and particles to Mars’ atmosphere is vital. Wilson highlighted that not only does this help us fill in the gaps about Mars’ water loss and atmospheric erosion, but it also influences our exploration strategies. If the upper atmosphere is saturated with electrons, it could obstruct radar signals used for mapping the Martian surface, posing challenges for future missions.
The findings from this remarkable event were published in *Nature Communications*. As we look to future explorations of Mars and other celestial bodies, research like this gives us critical insights into the effects of solar activity and helps refine our approaches in space exploration.
