Goddard Building İnstrument To Study Reconnection

Whether it's a giant solar flare or a beautiful green-blue aurora, just about everything interesting in space weather happens due to a phenomenon called magnetic reconnection. Reconnection occurs when magnetic field lines cross and create a burst of energy. These bursts can be so big they're measured in megatons of TNT. Several spacecraft have already sent back tantalizing data when they happened to witness a magnetic reconnection event in Earth's magnetosphere. However, there are no spacecraft currently dedicated to the study of this phenomenon.

All this will change in 2014 when NASA launches the Magnetospheric Multiscale (MMS) mission, a fleet of four identical spacecraft that will focus exclusively on this dynamic magnetic system that stretches from the sun to Earth and beyond.

At NASA's Goddard Space Flight Center in Greenbelt, Md., a team of scientists and engineers are working on a crucial element of the MMS instrument suite: the Fast Plasma Instrument (FPI). Some 100 times faster than any previous similar instrument, the FPI will collect a full sky map of data at the rate of 30 times per second – a necessary speed given that MMS will only travel through the reconnection site for under a second.

"Imagine flying by a tiny object on an airplane very rapidly," says Craig Pollock, the Co-Investigator for FPI at Goddard. "You want to capture a good picture of it, but you don't get to just walk around it and take your time snapping photos from different angles. You have to grab a quick shot as you're passing. That's the challenge."

Previous spacecraft, such as Cluster and THEMIS have helped narrow down the regions near Earth where magnetic reconnection happens. The solar wind streams towards Earth until it hits our planet's magnetic field, says Tom Moore, the project scientist for MMS at Goddard. "The solar wind comes flying in and the terrestrial stuff is like molasses – slow, cold and reluctant to do whatever the solar wind wants. So there is a contest of wills whenever the two fields connect up via reconnection."

That's what happens on the sun side of Earth. On the other side, the night side, magnetic reconnection in Earth's magnetic tail causes a geometry change in the shape of the field lines. Portions of the magnetic field get disconnected from the rest of the tail and shoot away from Earth.