NASA Probes Giant Magnetic Explosions Around Earth
Nine months after launch, NASA’s MMS probes return "promising initial results."
We tend to think of space as this totally empty vacuum, although the reality is that it's bubbling over with activity from electrically charged particles and electromagnetic fields.
The interplay of these electrically charged particles creates what is considered to be a fourth state of matter called plasma. Plasma, which makes up 99 percent of the visible universe, is essentially a gas that is so hot that many of its atoms are split into electrons and ions that move independent of one another, yet still possesses its own magnetic field that affects how the particles in the plasma interact with one another. When these plasmas interact with electromagnetic fields around the Earth or the Sun the results can be pretty wild, ranging from stunning auroras to solar flares several times the size of Earth.
The mechanism behind auroras, solar flares, coronal mass ejections (CMEs), and other similar space events is not well understood, although cosmologists are pretty confident they are directly related to a process called magnetic reconnection. Events driven by magnetic reconnection have proven to be very disruptive on Earth in the past, so in an effort to better understand this phenomenon NASA launched its four Magnetospheric Multiscale (MMS) satellites into Earth orbit last March. Only four months into the science phase of the mission, on Friday NASA declared that the MMS is already providing "promising initial results."
Briefly, magnetic reconnection involves the sudden realignment of magnetic field lines, a process which converts the energy stored in a magnetic field into an explosion of heat and kinetic energy. Usually the magnetic field lines inside plasmas don't merge with other field lines, but when the plasma interacts with another magnetic field (such as around Earth or the Sun), the lines can get so close to one another that they snap into a new formation, releasing large amounts of energy latent in the plasma. This explosive release of energy can propel electrically charged particles along magnetic field lines at near the speed of light, which scientists think account for everything from solar flares to auroras.
Although the hypotheses about magnetic reconnection are fairly well established at this point, scientists have yet to observe the process in nature. They have recreated magnetic reconnection in laboratory experiments and seen the results of magnetic reconnection, but observing the process while it's underway has proven to be difficult.
"We can see the effects of reconnection on the sun in the form of coronal mass ejections and solar flares," Michael Hesse, lead co-investigator for theory and modeling on the MMS mission at NASA's Goddard Space Flight Center, said in a statement. "But with MMS, we're finally able to observe the process of magnetic reconnection directly."
The MMS mission is the first ever dedicated solely to studying the magnetic reconnection process. It is comprised of four probes flying in a tetrahedron formation, which allows for a 3D configuration of the areas of Earth's magnetosphere the probes happen to be passing through. Each probe is also independently operated, meaning they can be maneuvered to allow scientists to effectively zoom in or out of a region by a factor of ten.
Initially, the probes will be flying through the dayside boundaries of Earth's magnetosphere, a region called the magnetopause which serves as the boundary between the magnetosphere and interplanetary magnetic field. This meeting of the terrestrial and interplanetary magnetic fields facilitates the transfer of particles and energy to Earth's magnetosphere, and was thus considered a prime spot to observe magnetic reconnection as it happens. So far, it seems as though the MMS mission scientists' hunches have been correct.
"We've recorded over 2,000 magnetopause crossings since our science phase began," Jim Burch, principal investigator for the MMS mission at Southwest Research Institute said in a statement. "In that time, we've flown through hundreds of promising events."
After its observations on the dayside of Earth's magnetosphere, the MMS probes will make their way to Earth's night side. Here, the probes will observe the connected field from Earth's dayside flow around the planet to a second reconnection point—called the magnetotail—where the fields once again disconnect.
"All in all, the data we have gotten so far has just been astounding," said Burch. "Now we're sifting through those observations and we're going to be able to understand the drivers behind magnetic reconnection in a way never before possible."