Instrument Type
Particle

The APL-built Energetic Ion Spectrometers, or EIS, ride on each of the four identical spacecraft that make up NASA鈥檚 Magnetospheric Multiscale (MMS) mission. Continuing the legacy of APL-built instruments for the Juno, New Horizons, and Van Allen Probes missions, EIS鈥� primary objective is to measure the composition and abundance of energetic charged particles during and associated with a phenomenon called magnetic reconnection.

Magnetic reconnection is a universal process in space plasmas in which a planet鈥檚 magnetic field lines on the daytime side are forced apart by the Sun鈥檚 solar wind and then 鈥渞econnected鈥� on the planet鈥檚 nighttime side. This process can be explosive, heating and accelerating charged particles that are tied to the magnetic fields. At Earth, magnetic reconnection between the Sun鈥檚 magnetic field and Earth鈥檚 magnetic field drives Earth鈥檚 magnetosphere and much of the space weather we experience, such as the aurora. EIS detects the ions and electrons energized by magnetic reconnection in Earth鈥檚 magnetosphere to understand fundamentally how energy is exchanged in the near-Earth space environment and which charged particles are most affected by these intense processes.

MMS

Launched in March 2015, the Magnetospheric Multiscale (MMS) mission set off four spacecraft around Earth to uncover how the Sun鈥檚 and Earth鈥檚 magnetic fields connect and disconnect through a universal, explosive transfer of energy called magnetic reconnection, which can affect Earth鈥檚 technosphere and telecommunications networks.