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A recently selected NASA heliophysics mission of opportunity, the Electrojet Zeeman Imaging Explorer (EZIE), will study the electric currents that play a crucial role in the interactions between Earth and the surrounding magnetosphere. The aurora is a spectacular manifestation of these interactions. EZIE consists of three 6U CubeSats flying in a pearls-on-a-string orbit configuration, each carrying a Microwave Electrojet Magnetogram (MEM) instrument. Four beams on each satellite measure polarimetric radiances that contain the magnetic signatures of the intense currents in ionospheric plasmas (electrojets) based on the Zeeman splitting of molecular oxygen thermal emissions. This novel measurement technique allows for the remote sensing of the electrojets at altitudes notoriously difficult to measure in situ. The EZIE constellation will provide, for the first time, measurements with the spatial and temporal resolution required to distinguish between proposed hypotheses for the physical mechanisms behind the auroral and equatorial electrojets. A series of observing system simulation experiments demonstrate how EZIE will explore the impacts of space weather near Earth. Each MEM instrument consists of four compact 118-GHz heterodyne spectropolarimeters, leveraging technologies demonstrated by TEMPEST-D and CubeRRT; the 6U CubeSat bus heritage includes RAVAN, CAT, TEMPEST-D, and CubeRRT. Differential drag maneuvers, akin to those pioneered by CYGNSS and CAT, will be used to manage satellite along-track temporal separation to within 2–10 minutes, eliminating the need for on-board propulsion. EZIE success is possible because of past CubeSat demonstrations and strong commercial partnerships. |
