The process that forms Earth’s first line of defence against killer solar storms has been revealed for the first time.
In a groundbreaking study four NASA spacecraft observed a process known as magnetic reconnection, which is the planet’s first line of defence against the intensity of the solar wind.
It occurred in a turbulent region of the Earth’s outer atmosphere known as the magnetosheath, and could radically change what we know about protecting the planet, and future astronauts.
This animation shows near-Earth space, where the magnetic environment around Earth can trap electrons and charged particles, and where NASA made its latest discovery.
WHAT IS MAGNETIC RECONNECTION?
Magnetic reconnection is one of the most important processes in the space — filled with charged particles known as plasma — around Earth.
This fundamental process dissipates magnetic energy and propels charged particles, both of which contribute to a dynamic space weather system that scientists want to better understand, and even someday predict, as we do terrestrial weather.
Reconnection occurs when crossed magnetic field lines snap, explosively flinging away nearby particles at high speeds.
The new discovery found reconnection where it has never been seen before — in turbulent plasma.
Dr Jonathan Eastwood, from the Department of Physics at Imperial College London, who worked on the study, said: ‘Turbulence is one of the last great concepts in classical physics that we do not understand well, but we know it’s important in space as it redistributes energy.
‘With this observation, we can now make new theories or models that will help us understand observations of other places like the Sun’s atmosphere and the magnetic environments of other planets.’
Magnetic reconnection has been observed innumerable times in the magnetosphere — the magnetic environment around Earth — but usually under calm conditions.
The new event occurred in a region called the magnetosheath, just outside the outer boundary of the magnetosphere, where the solar wind is extremely turbulent.
The mission, known as Magnetospheric Multiscale (MMS), was commissioned to study magnetic reconnection, a common event throughout the universe that occurs when magnetic fields change by connecting and then breaking apart.
It found a new breed of magnetic reconnection, known as electron magnetic reconnection, that is much different than the kind that happens in the much less turbulent magnetosphere closer to Earth.
Previously, scientists didn’t know if reconnection even could occur there, as the plasma is highly chaotic in that region.
Earth is surrounded by a protective magnetic environment — the magnetosphere — shown here in blue, which deflects a supersonic stream of charged particles from the Sun, known as the solar wind. As the particles flow around Earth’s magnetosphere, it forms a highly turbulent boundary layer called the magnetosheath, shown in yellow. Scientists, like those involved with NASA’s Magnetospheric Multiscale mission, are studying this turbulent region to help us learn more about our dynamic space environment.
MMS found it does, but on scales much smaller than previous spacecraft could probe.
The new insights could help us understand how such phenomena affect Earth’s atmosphere because of the potential impact on astronauts in space, satellites and electrical power industries.
‘The turbulence in the magnetosheath contains a lot of magnetic energy,’ said Tai Phan, lead author of the Nature article and senior fellow in the Space Sciences Laboratory at the University of California at Berkeley.
‘People have been debating how this energy is dissipated and magnetic reconnection is one of the possible processes.’
The energy comes directly from the sun’s corona, a blazing hot environment that shoots particles out in all directions at speeds around 1 million miles per hour.
This is the forceful solar wind.
When its power hits the magnetosheath, waves of plasma chaos roll through it.
Scientists don’t know yet how all of that turbulent energy is dissipated.
But this new discovery – electron magnetic reconnection – may help them learn more.
The MMS mission has four spacecraft flying in formation about four miles apart, gathering data as they go.
Its array of instruments gave researchers one of their first opportunities to search for reconnection in the magnetosheath.
They got what they hoped to get – evidence that magnetic reconnection was happening even in that chaotic turbulence.
WHAT IS NASA’S MISSION TO SEE THE MAGNETOSPHERE?
MMS is made up of four spacecraft, which fly in a pyramid formation, according to NASA.
This allows it to ‘see’ fields and particles in three dimensions.
The array measures the electric and magnetic fields as it flies around Earth.
It also counts electrons and ions to measure energy and direction of motion, and can study small-scale particle dynamics.
The four Magnetospheric Multiscale, or MMS, spacecraft (shown here in an artist’s concept) have now made more than 4,000 trips through the boundaries of Earth’s magnetic field, gathering observations of our dynamic space environment.
Because the spacecraft fly incredibly close together — at an average separation of just four-and-a-half miles, they hold the record for closest separation of any multi-spacecraft formation— they are able to observe phenomena no one has seen before.
MMS’s instruments are designed to capture data at speeds a hundred times faster than previous missions.
But in the process, they discovered magnetic reconnection here works much differently than the kind observed elsewhere.
Instead of huge jets of ionized hydrogen atoms, triggered by many collisions of magnetic fields, this form of magnetic reconnection shoots off much tinier electron jets with very few collisions occurring, Shay said.
This has never been recognized before, partly because no instruments could capture the process.
The relative difference in size between the electrons and the ions is similar to the difference between ball bearings and basketballs, Shay said.
The electrons are harder to spot, and moving 40 times faster.
‘I had simulated this possible kind of reconnection,’ Shay said.
‘But no one had ever observed it happening in space.’
The analysis could reveal many more surprises as scientists continue to explore the data MMS has sent.
‘MMS has taken us to a whole new level,’ Shay said.
‘It’s like knowing about atoms and then finding out about even tinier parts like the nucleus or the electrons.
‘People were not expecting it.’
WHAT ARE SOLAR STORMS AND ARE THEY DANGEROUS?
Solar storms, or solar activity, can be divided into four main components that can have impacts on Earth:
- Solar flares: A large explosion in the sun’s atmosphere. These flares are made of photons that travel out directly from the flare site. Solar flares impact Earth only when they occur on the side of the sun facing Earth.
- Coronal Mass Ejections (CME’s): Large clouds of plasma and magnetic field that erupt from the sun. These clouds can erupt in any direction, and then continue on in that direction, plowing through solar wind. These clouds only cause impacts to Earth when they’re aimed at Earth.
- High-speed solar wind streams: These come from coronal holes on the sun, which form anywhere on the sun and usually only when they are closer to the solar equator do the winds impact Earth.
- Solar energetic particles: High-energy charged particles thought to be released primarily by shocks formed at the front of coronal mass ejections and solar flares. When a CME cloud plows through solar wind, solar energetic particles can be produced and because they are charged, they follow the magnetic field lines between the Sun and Earth. Only charged particles that follow magnetic field lines that intersect Earth will have an impact.
While these may seem dangerous, astronauts are not in immediate danger of these phenomena because of the relatively low orbit of manned missions.
However, they do have to be concerned about cumulative exposure during space walks.
This photo shows the sun’s coronal holes in an x-ray image. The outer solar atmosphere, the corona, is structured by strong magnetic fields, which when closed can cause the atmosphere to suddenly and violently release bubbles or tongues of gas and magnetic fields called coronal mass ejections
The damage caused by solar storms
Solar flares can damage satellites and have an enormous financial cost.
The charged particles can also threaten airlines by disturbing Earth’s magnetic field.
Very large flares can even create currents within electricity grids and knock out energy supplies.
When Coronal Mass Ejections strike Earth they cause geomagnetic storms and enhanced aurora.
They can disrupt radio waves, GPS coordinates and overload electrical systems.
A large influx of energy could flow into high voltage power grids and permanently damage transformers.
This could shut off businesses and homes around the world.
Source: NASA – Solar Storm and Space Weather