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Magnetospheric Multiscale Mission

Magnetospheric Multiscale Mission

Introduction: The Magnetospheric Multiscale Mission (MMS) is a NASA unmanned space mission to study the Earths magnetosphere. It is a constellation of 4 spacecraft that packs several new, game-changing capabilities to unlock the secrets of magnetic reconnection at an unprecedented level of detail. It is designed to gather information about the microphysics of magnetic reconnection, energetic particle acceleration, and turbulence, processes that occur in many astrophysical plasmas. Magnetic reconnection occurs where the Sun and the Earths magnetic fieldsconnect with each other from opposite directions, resulting in the two canceling each other and the explosive conversion of the magnetic energy stored in the two fields into kinetic energy. Reconnection limits the performance of fusion reactors and is the final governor of geospace weather that affects modern technological systems such as telecommunications networks, GPS navigation, and electrical power grids. Four identically instrumented spacecraft measure plasmas, fields, and particles in a near-equatorial orbit that will frequently encounter reconnection in action. Science Goals: MMS reveals, for the first time, the small-scale three-dimensional structure and dynamics of the elusively thin and fast-moving electron diffusion region. It does this in both of the key reconnection regions near Earth, where the most energetic events originate. Mission Objective: By observing magnetic reconnection in nature, MMS provides access to predictive knowledge of a universal process that is the final governor of space weather, affecting modern technological systems such as communications networks, GPS navigation, and electrical power grids. MMS will establish knowledge, methods and technologies applicable to future space weather missions and the future growth and development of space weather forecasting. The four identically instrumented MMS spacecraft fly in an adjustable pyramid-like formation that enables them to observe the three-dimensional structure of magnetic reconnection. This enables them to determine whether reconnection occur in an isolated locale, everywhere within a larger region at once, or traveling across space. MMS sensors will measure charged particle velocities, as well as electric and magnetic fields, with unprecedented (milliseconds) time resolution and accuracy needed to capture the elusively thin and fast-moving electron diffusion region. MMS probes reconnection of solar and terrestrial magnetic fields in the dayside and nightside of Earths magnetosphere, the only natural laboratory where it can be directly observed by spacecraft. Significance: These satellites operate in a highly elliptical orbit around Earth and incorporate GPS measurements into their precise tracking systems. When these satellites are closest to Earth, they move at up to 35,405 km/hour, making them the fastest known operational use of a GPS receiver. This system which require extremely sensitive position and orbit calculations to guide tight flying formations. Achievements: Earlier in 2016, MMS had achieved the closest flying separation of a multi-spacecraft formation with only 7.2 km between the four satellites. It has set the Guinness world record for highest altitude fix of a GPS signal at 70,000 kilometres above the surface of the Earth. Operating in a highly elliptical orbit around Earth, the four MMS spacecraft incorporate Global Positioning System (GPS) measurements into their precise tracking systems, which require extremely sensitive position and orbit calculations to guide tight flying formations.

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