New dawn for space storm alerts could help shield Earth's tech

Space storms could soon be forecasted with greater accuracy than ever before thanks to a big leap forward in our understanding of exactly when a violent solar eruption may hit Earth.

Scientists say it is now possible to predict the precise speed a coronal mass ejection (CME) is travelling at and when it will smash into our planet -- even before it has fully erupted from the Sun.

CMEs are bursts of gas and magnetic fields spewed into space from the solar atmosphere.

They can cause geomagnetic storms that have the potential to wreak havoc with terrestrial technology in Earth's orbit and on its surface, which is why experts across the globe are striving to improve space weather forecasts.

Advancements such as this one could make a huge difference in helping to protect infrastructure that is vital to our everyday lives, according to researchers at Aberystwyth University, who will present their findings today at the Royal Astronomical Society's National Astronomy Meeting in Hull.

They made their discovery after studying specific areas on the Sun called 'Active Regions', which have strong magnetic fields where CMEs are born. The researchers monitored how these areas changed in the periods before, during and after an eruption.

A vital aspect which they looked at was the "critical height" of the Active Regions, which is the height at which the magnetic field becomes unstable and can lead to a CME.

"By measuring how the strength of the magnetic field decreases with height, we can determine this critical height," said lead researcher Harshita Gandhi, a solar physicist at Aberystwyth University.

"This data can then be used along with a geometric model which is used to track the true speed of CMEs in three dimensions, rather than just two, which is essential for precise predictions."

She added: "Our findings reveal a strong relationship between the critical height at CME onset and the true CME speed.

"This insight allows us to predict the CME's speed and, consequently, its arrival time on Earth, even before the CME has fully erupted."

When these CMEs hit the Earth they can trigger a geomagnetic storm which is capable of producing stunning aurorae, often referred to in the northern hemisphere as the Northern Lights.

But the storms also have the potential to disrupt vital systems we rely on daily, including satellites, power grids, and communication networks, which is why scientists worldwide are working hard to improve our ability to better predict when CMEs will hit Earth.

This requires knowing a more accurate speed of the CME shortly after it erupts from the Sun to better provide advance warnings of when it will reach our planet.

Accurate speed predictions enable better estimates of when a CME will reach Earth, providing crucial advance warnings.

"Understanding and using the critical height in our forecasts improves our ability to warn about incoming CMEs, helping to protect the technology that our modern lives depend on," Gandhi said.

"Our research not only enhances our understanding of the Sun's explosive behaviour but also significantly improves our ability to forecast space weather events.

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A roadmap for deepening understanding of a puzzling universal process

A puzzling process called magnetic reconnection triggers explosive phenomena throughout the universe, creating solar flares and space storms that can take down mobile phone service and electrical power grids. Now scientists at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) have detailed a roadmap for untangling a key aspect of this puzzle that could deepen insight into the workings of the cosmos.

Reconnection converts the magnetic field energy to particle eruptions in astrophysical plasmas by snapping apart and explosively reconnecting the magnetic field lines -- a process that occurs within what are called dissipation regions that are often enormously smaller than the regions they impact.

Stressed magnetic field

"Plasma doesn't like reconnection," said Hantao Ji, a PPPL physicist and Princeton University professor who is first author of a paper that details the roadmap in Nature Reviews Physics. "However, reconnection does happen when the magnetic field is sufficiently stressed," he said.

"Dissipation scales are tiny whereas astrophysical scales are very large and can extend for millions of miles. Finding a way to bridge these scales through a multiscale mechanism is a key to solving the reconnection puzzle."

The roadmap outlines the role of developing technologies with multiscale capabilities such as the Facility for Laboratory Reconnection Experiment (FLARE), a recently installed collaborative facility that is being upgraded and will probe facets of magnetic reconnection never before accessible to laboratory experiments. Complementing these experiments will be simulations on coming exascale supercomputers that will be 10 times faster than current computers. "The hope is for FLARE and exascale computing to go hand-in-hand," Ji said.

The working theory the PPPL roadmap proposes is that multiple plasmoids, or magnetic islands, that arise from reconnection along lengthy plasma current sheets could bridge the vast range of scales. Such plasmoids would correspond more closely to the affected reconnection region, with multiscale laboratory experiments planned to provide the first tests of this theory and to evaluate competing hypotheses.

"Exascale will allow us to do more credible simulations based on high-fidelity FLARE experiments," said PPPL physicist Jongsoo Yoo, a coauthor of the paper. The increased size and power of the new machine -- its diameter will be twice that of the sports-utility-vehicle-sized Magnetic Reconnection Experiment (MRX), PPPL's long-standing laboratory experiment -- and will enable scientists to replicate reconnection in nature more faithfully.

"FLARE can access wider astrophysical regimes than MRX with multiple reconnection points and measure the field geometry during reconnection," said William Daughton, a computational scientist at Los Alamos National Laboratory and a coauthor of the paper. "Understanding this physics is important for predicting how reconnection proceeds in solar flares," he said.

Key challenge

A key challenge to the coming experiments will be innovating new high-resolution diagnostic systems free from restrictive assumptions. Once developed these systems will enable FLARE to build upon satellite sightings such as those produced by the Magnetospheric Multiscale mission, a fleet of four spacecraft launched in 2015 to study reconnection in the magnetosphere, the magnetic field that surrounds the Earth.

"Progress in understanding multiscale physics critically depends on innovation and efficient implementation of such diagnostics systems in the coming decade," the paper said. The new findings will address open questions that include:

• How exactly does reconnection start?
• How are explosive plasma particles heated and accelerated?
• What role does reconnection play in related processes such as turbulence and space shocks?

Overall, "The paper lays out plans to provide the entire space physics and astrophysics communities with methods to solve the multiscale problem," Yoo said. Such a solution would mark a major step toward a more complete understanding of magnetic reconnection in large systems throughout the universe.

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