Fleet of NASA Spacecraft Finally Solve Mystery of the Earth’s Magnetic Field

A fleet of Nasa spacecraft have finally helped solve a long-standing mystery about the Earth’s magnetic field.

Scientists have used the data from the four spacecraft that are part of a Nasa mission to finally understand the energy in the swirling magnetic fields that surround the Earth.

That magnetic field helps protect us from solar wind, the stream of plasma coming from the Sun. As such, it protects life on Earth – and occasionally that solar weather breaks through and hits Earth hard, disrupting electrical and communications equipment on our planet, meaning that understanding how we are protected can be vitally important.

NASA’s Magnetospheric Multiscale (MMS) is flying four different spacecraft Earth to try and understand the phenomenon of magnetic reconnection. And it is that effect that explains the strange and intense energy contained in the magnetic fields around Earth.

The solar wind that comes from the Sun is made up of plasma – which is rare on Earth but makes up 99 per cent of the visible universe. That plasma becomes very turbulent when it arrives at the Earth’s magnetic field, in the “magnetosheath”.

Scientists now understand some of what causes that important turbulence, and where the energy and motion that erupt eventually go. The energy from the magnetic field is transferred to the particles, creating hot jets of plasma – and dissipating it into space.

The new study, published in Nature, marks the smallest scale observations of that event happening.

“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,” said Jonathan Eastwood, one of the researchers involved in the study. “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.”

But the finding opens as many questions as it answers. Researchers now hope to create new models of the magnetosphere to account for how that magnetic reconnection could actually be happening.

First Ever Direct Analysis of Magnetic Loop Reconnect

In a paper published on May 12th 2016 in the scientific journal Science, a research team that includes a West Virginia University physicist helped shed light on the process of magnetic reconnection — which occurs when magnetic fields, such as those around the planet, break and reconnect. The paper details discoveries from NASA’s unprecedented Magnetospheric Multiscale, or MMS, mission that launched four identical spacecraft into Earth’s magnetic shield to measure reconnection.

Magnetospheric Multiscale spacecraft2

On Oct. 16, 2015, MMS flew through the heart of a reconnection region, and scientists were able to perform the first-ever physics experiment in that environment. It is the first time that researchers have detected the exact point of reconnection.

Scientists are making new discoveries about a process that causes some of the most explosive events in the universe. At the same time, they are answering questions about Earth’s magnetosphere — the protective bubble around Earth that shields the planet from the Sun’s constant barrage of superheated, electrically charged particles.

electrically charged particles

The satellites directly measured the energy being converted during reconnection; it produced heat at a rate comparable to 10 million 200-watt solar panels. They also directly measured the mixing of charged particles from outside and inside the magnetic bubble, confirming that reconnection had occurred.

“Magnetic reconnection leads to events like solar flares and auroral displays so it is easy to see its aftereffects, but scientists have never been able to directly observe the point where it occurs until now,” says Paul Cassak, associate professor of physics in the Eberly College of Arts and Sciences and co-author of the paper. “The tiny sizes involved and the extreme speed of the reconnection process make it difficult to study.”

Magnetospheric Multiscale spacecraft

Up until MMS, scientists were unable to measure the smallest scales of reconnection because it was impossible to process data fast enough to determine what was occurring. With this mission, instruments were able to record data 100 times faster than ever before, fast enough to see where magnetic fields break.

Magnetospheric Multiscale spacecraft2

“The amount of data collected and the speed at which it was collected is remarkable,” says Cassak, whose role on the project was developing numerical simulations to help scientists understand what happens in the region where reconnection occurs. “Nobody thought the mission would be this successful this soon.”

As part of the MMS Theory and Modeling team, Cassak used MMS observations and sophisticated computer simulations to analyze how magnetic fields reconnect around Earth.

Along with the research team, Cassak determined the properties in the reconnection region. He ran a simulation using a supercomputer operated by the Department of Energy that put the observed results in a two-dimensional context, as opposed to the one-dimensional data that comes from the satellites.

The simulations produced a large amount of data — almost a third of a terabyte — and would have taken almost a year and a half to do on a single computer.

The simulation ultimately illustrates how magnetic reconnection happens. One goal of this type of research is to help space weather scientists predict how the magnetosphere will behave so that appropriate preparations can be made.

“Learning what causes magnetic fields to break has significant, fundamental implications for scientists because it is very difficult to resolve these types of scales, even in the lab,” says Cassak. “If scientists are able to use MMS to understand what is happening at small scales in the magnetosphere, they can apply this knowledge to other settings where reconnection is important, from space weather to fusion applications in the laboratory.”

Cassak says that the mission is still very young and there is much more to observe. MMS’s orbit will continue to focus on the day-side of Earth for another six months. Then, the orbit will be changed and it will focus on the night-side with the hopes that the spacecraft will encounter another reconnection region. Scientists expect the reconnection process to look different on the night-side, and hope to understand what drives events that cause auroral displays.

Cassak’s work is the latest groundbreaking research to come from WVU’s physics and astronomy department. Among other discoveries, WVU researchers were part of teams that recently detected gravitational waves for the first time and discovered that fast radio bursts are found to repeat.