Space weather event is hard to extrapolate from 60 years of reliable observations. A University of Reading study surveyed 144 experts, 52% of whom believe future geomagnetic storms could surpass even Carrington-like magnitudes. “Space-based observations only started in 1961,” says Barnard. “We have some geomagnetic observations back to the 1880s. Beyond that, we can make informed judgments from our knowledge of physical processes. Recorded observations from cosmogenic isotopes Carbon-14 and Beryllium-10, found in trees and ice cores respectively, show historic spikes most plausibly attributable to an extreme SEP event.” In the University of Reading study, 40% of experts surveyed lacked confidence in current forecasts, while many saw deploying small-satellite constellations close to the sun as the most promising means to improve them. Barnard underlines the promise of Vigil to provide continuous, three-dimensional visibility of CMEs and advance notice of structures forming on the side of the sun rotating round to face us. He expects models to rapidly evolve. “Data assimilation revolutionized meteorological forecasts and is now being applied to space weather,” says Barnard. “Combining model estimates with observations of a system state could reduce the uncertainties in CME arrival-time forecasts from 12 to 6 hours. Ensemble modeling will allow us to simultaneously run many forecasts, initialized with different conditions reflecting uncertainties in CME or ambient solar wind structures.” Besides more observations, there may be new types of observation. Barnard himself uses a heliospheric imager, which resembles a baffle camera and observes the solar wind by isolating one part in 1,014 of solar white light. NASA’s PUNCH (Polarimeter to Unify the Corona and Heliosphere) mission, using a T ESA’S REVOLUTIONARY VIGIL SPACECRAFT polarizing heliospheric imager to record structures transitioning from the corona to the solar wind, may advance our ability to locate Earth-bound CMEs. Luntama emphasizes a need to formalize the availability of current measurements. “Ground-based instruments that monitor space weather worldwide are based on proposals for academic research, so their future is always uncertain,” he says. “We work with member states to ensure the safety of systems critical to protecting our infrastructure, which should in future be operationalized.” he Lagrange points are points in space where the sun and Earth exert a balanced gravitational influence on small-mass objects. While L 1 , L 2 and L 3 occur on a line transecting the two bodies, L 4 and L 5 each form the third vertex of an equilateral triangle relative to our planet and star. In development and scheduled for launch later this decade, ESA’s Vigil spacecraft is destined for orbit at L 5 , 60° from the sun-Earth line, to provide transformative sideways solar observation capability. “For the first time in history, we will have permanent stereoscopic visibility of solar events,” says ESA’s Juha-Pekka Luntama. “We currently lose sight of CMEs about two hours from onset. But Vigil will allow us to follow the plasma cloud traveling toward Earth, see whether it slows or merges with another plasma cloud, and thereby better predict arrival times and impacts.” Vigil’s comprehensive payload will include a coronagraph to observe CMEs, a heliospheric imager to follow their propagation toward Earth and a magnetograph to measure the solar disk’s magnetic field and enable models of background solar wind. NASA will provide an extreme UV imaging instrument. “Typically, L 1 missions split the instruments between the L 1 satellite, Earth-orbiting satellites and even ground-based observations,” says Luntama. “Because L 5 has no planet behind, we have to put all the instruments on the spacecraft.” Vigil will also provide in-situ measurements of the solar wind and its magnetic field at L 5 . This will enable forecasting of high-speed solar wind streams hitting Earth and help forewarn satellite operators of conditions conducive to problems like surface charging of satellites. ABOVE: ESA’s space weather mission – ESA Vigil BELOW: Observations of the coronal mass ejection, October 14, 2014, as seen by various sun-watching spacecraft SDO/NASA; SOHO (ESA & NASA); NASA/Stereo; ESA/Royal Observatory of Belgium Demand for space weather information continues evolving, notably through the privatization of space. In February 2022, 40 Starlink satellites deorbited and were lost shortly after launch because a minor geomagnetic storm heating the upper atmosphere caused additional drag. “They weren’t paying attention to space weather,” says Dahl. “Space tourism will soon be a thing, if billionaires’ visions hold true. We can educate private enterprises and support them indirectly with our models and forecasts.” Dahl and Barnard counsel against alarmism engendered by sensationalist headlines, as space weather poses no direct physical threat at ground level and SWPC provides US citizens with information from a trusted source. Yet Dahl, who liaises with federal emergency planners, acknowledges the unpredictable social consequences of a latter-day Carrington Event. “If people living off-grid suddenly see the aurora, what do they think?” he asks. “We’re talking no water, heating or power, traffic lights and ports not working, billions lost in commerce. We all love buying frozen items from the grocery store, which these events could inhibit.” Luntama notes that for two decades, Earth has seen so little space weather that his role has almost seemed boring. But the risks remain real, as does the vulnerability inherent in the technological dependence we have chosen. “We’re overdue a Carrington event,” says Dahl. “In 2023, a CME at Carrington-like speeds on the sun’s far side was strong enough to cross all the magnetic field lines necessary to cause radiation storms on Earth. We haven’t not seen them – we’ve just had some near misses.” European Space Agency Space privatization 10 • www.meteorologicaltechnologyinternational.com • April 2024