The ELFIN Mission

Area of Science:

• Space Physics
• Heliophysics
• Atmospheric Science

Background:

• The Electron Loss and Fields Investigation with a Spatio-Temporal Ambiguity-Resolving option (ELFIN) mission utilizes two identical 3U CubeSats in a polar, low-Earth orbit.
• Launched in 2018, ELFIN aims to understand storm-time relativistic electron precipitation, a key space weather phenomenon.

Purpose of the Study:

• To resolve the mechanism of storm-time relativistic electron precipitation, identifying the role of electromagnetic ion cyclotron (EMIC) waves.
• To differentiate between EMIC wave scattering and other processes responsible for electron precipitation using pitch-angle-resolving capabilities.

Main Methods:

• ELFIN employs two identical CubeSats with a slowly-variable along-track separation for spatio-temporal ambiguity resolution.
• Each satellite is equipped with an energetic particle detector (EPDE) for electrons (50 keV–5 MeV) and a fluxgate magnetometer (FGM) for magnetic field waves (DC–5 Hz).
• Satellites use magnetorquers for attitude control, enabling full pitch-angle resolution twice per spin.

Main Results:

• ELFIN captures broad energy precipitation events (tens of keV to >1 MeV) and microbursts at dawn and dusk.
• Observed events show significant backscattered fluxes, indicating the ionosphere's role in modifying magnetospheric electron dynamics.
• Concurrent wave activity suggests multiple wave species contribute to electron scattering.

Conclusions:

• The ELFIN mission provides crucial data for understanding relativistic electron precipitation mechanisms.
• Ionospheric processes significantly influence magnetospheric electron fluxes and wave-particle interactions.
• ELFIN's data, combined with other missions, will advance the understanding of space weather impacts.