The FINE Mission - Demonstrating a New Capability to Measure Species-Dependent Fine-Scale Irregularities in LEO

This collaboration between the University of Michigan (UM), NASA Marshall Space Flight Center (MSFC), and The Aerospace Corporation (Aerospace) will develop a 6U scientific satellite named FINE-the Fine scale plasma Irregularities Near the Equator mission. Various studies have demonstrated that equatorial and low-latitude ionospheric plasma is subject to dynamic processes that cause multi-scale turbulence. FINE seeks to answer: can the modes of plasma irregularities be discovered and thus enable determination of their drivers and potential mitigation techniques? FINE will measure low Earth orbit plasma turbulence in order to distinguish: 1. density from temperature fluctuations, 2. ion from electron turbulence, and 3. Maxwellian from non-Maxwellian plasmas. These are necessary when investigating the specific modes of the plasma irregularities.

Three instruments will provide fine-scale ( 1 m) measurements of density and temperature for both ionospheric ions and electrons. The Charge Analyzer Responsive to Local Oscillations is a frequency-domain ion spectrum analyzer designed to measure the distributions of ionospheric turbulence from 1 Hz to 10 kHz (i.e., spatial scales from a few kilometers down to a few centimeters) (MSFC). The Compact Total Electron Content Sensor is a GPS radio occultation instrument that observes scintillation through rapid changes in received signal strength and ionospheric density through radio occultation measurements of various GNSS signals (Aerospace). The Langmuir Probe Spacecraft Potential will simultaneously measure electron density/temperature fluctuations and spacecraft potential (UM).

FINE complements existing/planned space weather missions (ICON, GOLD, SPORT) in several ways, with the ability to 1. cross-calibrate in situ measurements of plasma parameters during overlapping operational periods; 2. provide greater spatiotemporal resolution of in situ turbulence; and 3. provide subsequent observations of the ionosphere extending beyond the nominal lifetimes of the other missions. A FINE launch in 2021/2 would set up a transition from observations during solar min to observations during solar max (expected 2023).