To solve one of space science’s most enduring puzzles, University of Iowa researchers have been awarded a $733,873 NASA grant to investigate how turbulence in the solar wind heats plasma. Led by University of Iowa Professor Gregory Howes and Dr. Daniel McGinnis, the team will utilize data from the Solar Orbiter spacecraft to uncover the mechanisms behind this turbulent dissipation, aiming to protect Earth from the impacts of extreme space weather.

“Understanding how this turbulent energy is deposited in near-Earth space is essential for the development of models needed to protect our spaceborne technology from the ravages of extreme space weather, which can disrupt or destroy communication and GPS navigation satellites or can cause severe damage to the electrical power grid on Earth,” Howes said. 

The solar wind carries the energy of violent events from the Sun to the Earth, where it can drive extreme space weather, such as the aurora. Some of this energy is contained in the turbulent flow of the solar wind, much like a section of rapids on a swiftly flowing river. How the dissipation of this turbulence heats the plasma---an ionized gas of protons and electrons---that makes up the solar wind remains a long-standing question for space scientists.  Answering this important question of how turbulence is dissipated in space plasmas is critical to solving major mysteries about our solar system. For example, scientists do not presently understand how the atmosphere of the sun, known as the solar corona, gets heated to temperatures of over a million degrees Celsius, while the surface of the sun below is a much cooler 6000 degrees Celsius.  The plasma of the solar corona is heated by the dissipation of turbulence is likely to be the answer, but we still do not understand exactly how this occurs, Howes explained. 

The study "Identifying the Physical Mechanisms of Turbulent Dissipation in the Inner Heliosphere," will tackle this formidable scientific problem using measurements of the electric and magnetic fields and plasma particles from the Solar Orbiter spacecraft, a joint mission by the European Space Agency and NASA orbiting close to the Sun just inside the orbit of Mercury.  

By combining the spacecraft measurements of the electric fields and particles using an innovative analysis technique developed at the University of Iowa, known as the field-particle correlation technique, Professor Howes and Dr. McGinnis will generate "fingerprints" that can be used to identify the process by which the turbulence is dissipated, and the plasma is consequently heated. The goal is to identify conclusively how the turbulence is dissipated and predict how the protons and electrons in the plasma are heated.