Space radiation BepiColombo is Europe’s first mission to Mercury. Launched in October 2018, it is on a seven-year journey to the smallest and least explored terrestrial planet in the solar system ESA’S ROLE IN SAFEGUARDING HUMAN EXTRAPLANETARY EXPLORERS As European Space Agency (ESA) probes voyage outward through the distant reaches of our solar system, they are protected by information from the Space Weather Office, which has networked pre-existing European capabilities into a resilient federated architecture. “Our pleasure is to observe space weather anywhere in the solar system,” comments Juha-Pekka Luntama, head of the Space Weather Office. “Our heliospheric weather group has tools to make propagation estimates in any direction from the sun. We began by providing space weather information to the Venus Express mission as it started experimentally orbiting through the upper layers of the Venusian atmosphere,” he adds. Now, Luntama’s office provides regular bulletins to the BepiColombo mission bound for Mercury and will support ESA’s Jupiter Icy Moons Explorer (Juice) launched last year. These missions are unmanned, but Luntama anticipates a near future in which accurate radiation forecasts will safeguard human extraplanetary explorers. Unfortunately, the ability to accurately forecast solar eruptions remains limited by an incomplete grasp of their causes. Nevertheless, a problem well framed is often half solved. “If you’re planning a picnic, you don’t want a thunderstorm forecast,” Luntama observes. “You want a forecast of when there won’t be a thunderstorm. We cannot tell when an active solar region will produce an eruption. But if no active regions are visible, we can say there is a lower chance of eruptions,” he continues. “A moon flight is relatively simple because it takes only a couple of days,” he continues. “Mars will be different. Even the shortest flight will take six months, and today we cannot make a six-month forecast. Personally, I think we should build a permanent base on the moon and practice working in that somewhat hostile environment, before we move on to Mars.” The ESA/JAXA BepiColombo mission on a close flyby of Mercury in June 2023, passing the planet’s surface at an altitude of about 236km disadvantages,” says Zhao. “Our center will integrate those to provide comprehensive prediction. We have limited knowledge of what triggers flares or CMEs but can use machine learning to monitor the sun’s magnetic fields and extract features leading to solar eruptions.” The newly established CLEAR Center expects to produce SEP forecasting that is analogous to a smartphone weather app for future space missions. Zhao will lead a team of more than 20 scientists in this five-year, US$10m NASA-funded project, and notes that the application of machine learning to solar observation has already shown promising results. “Our center will use physics-informed or interpretable machine learning methods,” she explains. “We can train models to identify features already developed in efforts to predict flares. Or, if a model extracts its own features and performs well, our statisticians can do a feature importance analysis to potentially understand things we didn’t know.” One challenge is the shortage of comprehensive solar observations on which the models may train. Zhao’s team will compile historic observations from some 20 instruments scattered among different spacecraft and dating back to 1973, to create a benchmark data set available to the entire scientific community, useful to both train and validate forecast models. “We already have empirical, physics-based and machine learning models,” says Zhao. “But they may not be ready to run in real time. By validating their outputs against past observations, we can understand the uncertainties and fine-tune parameters to increase their robustness.” The next mission Our heliospheric weather group has tools to make propagation estimates in any direction from the sun” Juha-Pekka Luntama, European Space Agency Beyond the moon, Mars beckons. The M2M Office, established to study space weather not merely on the sun-Earth line but 360° around the sun, collaborates with current robotic Mars missions to develop the prerequisite capabilities for human exploration. “It’s a longer trip through interplanetary space without the protection of Earth’s magnetic fields,” says Romano. “Mars is sometimes on the opposite side of the sun, so there’s a whole logistics of communication. We’re just starting to push the boundaries to understand how phenomena could be observed from Mars and how quickly such observations could be used to support real-time analysis.” 18 • www.meteorologicaltechnologyinternational.com • April 2024