Cubesats Above Atmosphere
© NASA/Johns Hopkins APL
This illustration shows the three CubeSats of NASA’s EZIE mission flying in formation above Earth. The spacecraft will study electrical currents in Earth’s atmosphere that link changes in the magnetosphere to effects at the Earth’s surface during geomagnetic storms – the same storms that trigger the colorful auroral displays.
NASA's Electrojet Zeeman Imaging Explorer (EZIE) project - a mission to explore electrical currents in Earth's upper atmosphere - has passed a crucial developmental milestone, after rigorous review, moving the mission from the design phase to the construction phase.

EZIE will investigate auroral electrojets, which are powerful electrical currents flowing approximately 65 miles (100 kilometers) above the ground in the ionosphere, a region of Earth's atmosphere rich in ions ( charged atoms). These electrojets are connected to the beautiful auroras that dance across the polar night skies. They are part of a vast electrical circuit flowing between Earth and the surrounding space, out to some 100,000 miles (160,000 kilometers) away. The discoveries of EZIE will help to resolve decades-old arguments regarding the structure and evolution of the electrojets, paving the way for a more thorough understanding of Earth's space weather — magnetic events in space that can affect our ever increasingly technological society.

EZIE will fly three identical CubeSats that will orbit the globe in a pearls-on-a-string formation when it launches, which will be no earlier than September 2024. Each spacecraft will measure the electrojet current by imaging its "fingerprint." The spacecraft will look at light being emitted from oxygen molecules below the electrojets at just 50 miles (80 kilometers) above the surface. The spacecraft will do this by exploring a phenomenon called Zeeman splitting, which is the splitting of a molecule's light spectrum when placed near a magnetic field. Doing this means they can derive the magnetic field created by the electrojets as they flow and, in turn, detect the electrojets' current. This new application of the Zeeman effect will allow scientists to infer the magnetic field produced by an electrojet current in the overlying ionosphere and, in turn, learn how the size and strength of these electrojets change when solar storms impact the magnetosphere.

Funding for EZIE comes from the Heliophysics Explorers Program, managed by the Explorers Program Office at NASA's Goddard Space Flight Center in Greenbelt, Maryland. The principal investigator for the mission is Jeng-Hwa (Sam) Yee of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. NASA's Jet Propulsion Laboratory will build the satellite instruments. Blue Canyon Technologies will provide the spacecraft and mission operations center, and it will perform systems integration and testing as well as mission operations. Maverick Space Systems will provide launch and deployment operations.