Using Green Bank Observatory in West Virginia, PSI Associate Research Scientist Elizabeth A. Jensen’s team observed radio signals from the MESSENGER spacecraft and discovered that solar eruptions known to cause communication disruptions and electrical grid failures as they hit Earth have secondary trailing impacts.

Jensen is lead author of “Plasma Interactions with the Space Environment in the Acceleration Region: Indications of CME-trailing Reconnection Regions” that appears in The Astrophysical Journal. Co-authors include PSI Senior Scientists Deborah Domingue Lorin and Faith Vilas.

Coronal mass ejections, or CMEs, are powerful, massive solar eruptions that can trigger geomagnetic storms, Jensen said. CMEs are often associated with solar flares.

“The most powerful CMEs may travel at 2,000 kilometers per second, passing the Earth in seconds. We have discovered reconnection regions trailing behind a CME traveling 750 kilometers per second,” Jensen said. “This suggests that the impact of a CME on the Earth’s space weather consists of the initial shock from the CME and also secondary shocks from powerful electrical currents and accelerated plasmas trailing in the CME’s wake.”

These events can affect human activity and technology not only in space but also within the atmosphere and ultimately on the ground, Jensen said. In 1989, a powerful CME caused problems in satellites orbiting the Earth, the space shuttle Discovery, and electric grids resulting with 6 million people in Canada losing power.

“These secondary regions trailing the CME front have never been seen before because we have had few opportunities to probe this area with spacecraft. The MESSENGER spacecraft orbiting Mercury on the other side of the Sun was in the right place at the right time to observe a CME safely by passing radio signals through it to the Earth,” said Jensen. “Understanding the three-dimensional structure of these eruptions that strike the Earth is essential to properly preparing for their potential effects.”

“Plasma Interactions with the Space Environment in the Acceleration Region: Indications of CME-trailing Reconnection Regions,” Elizabeth A. Jensen et al., 2018 July 11, Astrophysical Journal [].

This work was supported by the MESSENGER Participating Scientist program, NASA Contracts NNX07AT38G and NASW-00002 to the Planetary Science Institute. Jensen is also supported by ACS Consulting, LLC. Green Bank Observatory is supported by the National Science Foundation. The MESSENGER Mission was supported by the National Aeronautics and Space Administration.

About the Planetary Science Institute:
The Planetary Science Institute is a private, nonprofit 501(c)(3) corporation dedicated to solar system exploration. It is headquartered in Tucson, Arizona, where it was founded in 1972.

PSI scientists are involved in numerous NASA and international missions, the study of Mars and other planets, the Moon, asteroids, comets, interplanetary dust, impact physics, the origin of the solar system, extra-solar planet formation, dynamics, the rise of life, and other areas of research. They conduct fieldwork on all continents around the world. They also are actively involved in science education and public outreach through school programs, children’s books, popular science books, and art.

PSI scientists are based in 23 states and the District of Columbia and work from various locations around the world.