SLAM Waves Offer New Clues For NASA Scientists

NASA scientists are excited over squiggles in data from a series of missions to better understand the magnetosphere.

Between 1998 and 2002, NASA's Wind spacecraft went up into the magnetosphere -- a "bubble" created around the Earth by its own magnetic fields -- to study the conditions of how the magnetosphere behaves as Earth orbits the sun.

One thing that occurs as the magnetosphere plows through space is a bow wave, a foreshock that's created by the movement of the planet through space, much like water would break in front of a moving ship. Scientists have been analyzing data from the Wave missions to better understand the physics behind the bow waves and to learn what happens at that boundary of the magnetosphere to better understand how radiation and energy from the sun can cross it and move closer to Earth.

"I stumbled on some cool squiggles in the data," said Lynn Wilson, who is deputy project scientist for Wind at NASA's Goddard Space Flight Center in Greenbelt, Md. "They turned out to be a special kind of magnetic pulsations called short large amplitude magnetic structures, which we call SLAMS for short."

Wilson and colleagues studied the SLAM waves as a way to better understand what causes incredibly powerful rays that travel from other solar systems across interstellar space toward Earth.

According to a NASA statement, SLAMS are waves with a single, large peak, a little like giant rogue waves that can develop in the deep ocean. By studying the region around the SLAMS and how they propagate, the Wind data showed SLAMS may provide an improved explanation for what accelerates narrow jets of charged particles through space.

"One of the unique things about space weather is how little things can have big effects," said David Sibeck, a space scientist at Goddard who is a co-author on the paper. "An event might seem small and just generate local turbulence, but it can have profound effects downstream. The front of the magnetosphere is right in the line between sun and Earth, so it's a crucial place to understand which small things can lead to big results."