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MMS 1, 2, 3, 4


MMS (Magnetospheric Multiscale) is a Solar-Terrestrial Probe mission comprising four identically instrumented spacecraft to discover the fundamental physics of magnetic reconnection using Earth's magnetosphere as a laboratory.

The four identically instrumented spin-stabilized spacecraft were launched on a single expendable launch vehicle and configured in a tetrahedral formation to probe dayside and nightside reconnection regions.

The MMS spacecraft are being developed at NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Maryland. GSFC is also responsible for the overall management of the MMS mission and mission operations. The mission is to be launched in October 2014 and will have an duration of two years (Prime Mission) + 6 months (launch, checkout, commissioning)

Orbit: 1.2 Earth radii by 12 Earth radii (day side); 1.2 Earth radii by 25 Earth radii (night side)

The four MMS spacecraft will carry identical suites of plasma analyzers, energetic particle detectors, magnetometers, and electric field instruments as well as a device to prevent spacecraft charging from interfering with the highly sensitive measurements required in and around the diffusion regions. The plasma and fields instruments will measure the ion and electron distributions and the electric and magnetic fields with unprecedentedly high (millisecond) time resolution and accuracy. These measurements will enable to MMS to locate and identify the small (1-10 km) and rapidly moving (10-100 km/s) diffusion regions, to determine their size and structure, and to discover the mechanism(s) by which the frozen-in condition is broken, the ions and electrons become demagnetized, and the magnetic field is re-configured. MMS will make the first unambiguous measurements of plasma composition at reconnection sites, while energetic particle detectors will remotely sense the regions where reconnection occurs and determine how reconnection processes produce such large numbers of energetic particles.

Instrument Suite on the satellites will consist of:

  • Fast Plasma Instrument;
  • Hot Plasma Composition Analyzer;
  • Energetic Particles;
  • Active Spacecraft Potential Control;
  • Central Instrument Data Processor
Nation: USA
Type / Application: Magnetospheric Research
Operator: NASA SwRI
Contractors: NASA SwRI
Equipment: see above
Power: Solar cells, batteries
Lifetime: 2.5 years
Mass: ~ 1250 kg
Satellite COSPAR Date LS Launch Vehicle Remarks
MMS 1 (John, STP 4A) 2015-011A 13.03.2015 CC SLC-41 Atlas-5(421) with MMS 2, 3, 4
MMS 2 (Paul, STP 4B) 2015-011B 13.03.2015 CC SLC-41 Atlas-5(421) with MMS 1, 3, 4
MMS 3 (George, STP 4C) 2015-011C 13.03.2015 CC SLC-41 Atlas-5(421) with MMS 1, 2, 4
MMS 4 (Ringo, STP 4D) 2015-011D 13.03.2015 CC SLC-41 Atlas-5(421) with MMS 1, 2, 3


  • Goddard Space Flight Center: MMS Website
  • Southwest Research Institute, Space Science and Engineering Division: MMS

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