Magnetospheric Multiscale Mission

The Magnetospheric Multiscale Mission (MMS) is a NASA fleet of four identical spacecraft orbiting Earth, measuring Earth's magnetosphere from different locations. They were launched in 2015 with primary mission specified as two years, and are still in service in July 2024 with the expectation of more than another decade. They are part of an effort to understand the dynamics of Earth's magnetic field, which constantly responds to variations in solar wind, including relatively extreme variations due to solar flares and the like. (The latter affect Earth technology, such as communication by radio, and have the potential to damage equipment.) The mission brings current-technology sensors to such investigation, aiming to increase our understanding. Among its goals is closer recording of magnetic reconnection within Earth's magnetic field. Instruments include:

• FPI - Fast Plasma Investigation.
• HPCA - Hot Plasma Composition Analyzer.
• FEEPS - Fly's Eye Energetic Particle Sensor.
• EIS - Energetic Ion Spectrometer.
• AFG - Analog Fluxgate magnetometer.
• DFG - Digital Fluxgate magnetometer.
• EDI - Electron Drift Instrument.
• SDP - Spin-plane Double Probe.
• ADP - Axial Double Probe.
• SCM - Search Coil Magnetometer.