Editing Magnetospheric Multiscale Mission

{{Infobox spaceflight
| name                  = Magnetospheric Multiscale Mission
| image                 = Atlas V MMS 2015-03-15 NASA.jpg
| image_caption         = <!--image caption-->
| image_size            = <!--include px/em; defaults to 220px-->

| mission_type          = [[Magnetosphere]] research
| operator              = [[NASA]]
| COSPAR_ID             = 2015-011A, 2015-011B, 2015-011C, 2015-011D
| SATCAT                = 40482, 40483, 40484, 40485
| website               = [http://mms.gsfc.nasa.gov/ mms.gsfc.nasa.gov]
| mission_duration      = Planned: 2 years, 5.5 months<ref name="presskit"/> <br/> Elapsed: {{Age in years, months and days|2015|03|13}}

| manufacturer          = [[Goddard Space Flight Center]]
| launch_mass           = {{convert|2998|lb|kg|abbr=on|order=flip}}<ref name="presskit"/>
| dry_mass              = <!--spacecraft mass in orbit without fuel-->
| payload_mass          = <!--total mass of instrumentation/equipment/experiments for mission-->
| dimensions            = Stowed: {{convert|11|xx|4|ft|m|abbr=on|order=flip}}<ref name="presskit"/> <br /> Deployed: {{convert|369|xx|94|ft|m|abbr=on|order=flip}}<ref name="presskit"/>
| power                 = <!--end-of-life power, in watts-->

| launch_date           = {{start-date|df=yes|13 March 2015, 02:44|tz=y}}&nbsp;UTC
| launch_rocket         = [[Atlas V]] 421
| launch_site           = [[Cape Canaveral Air Force Station|Cape Canaveral]] [[Cape Canaveral Air Force Station Space Launch Complex 41|SLC-41]]
| launch_contractor     = [[United Launch Alliance]]
| entered_service       = <!--date on which the spacecraft entered service, if it did not do so immediately after launch-->

| orbit_reference       = [[Geocentric orbit|Geocentric]]
| orbit_regime          = [[Highly elliptical orbit|HEO]]
| orbit_semimajor       = <!--semimajor axis-->
| orbit_eccentricity    = <!--orbital eccentricity-->
| orbit_periapsis       = {{convert|2550|km|abbr=on}}<ref name="presskit"/>
| orbit_apoapsis        = {{nowrap| Day phase: {{convert|70080|km|abbr=on}}<ref name="presskit"/> <br/> Night phase: {{convert|152900|km|abbr=on}}<ref name="presskit"/>}}
| orbit_inclination     = 28.0°
| orbit_period          = <!--time taken to complete an orbit-->
| orbit_RAAN            = <!--right ascension of the ascending node-->
| orbit_arg_periapsis   = <!--argument of perigee/periapsis-->
| orbit_mean_anomaly    = <!--mean anomaly at epoch, only use in conjunction with an epoch value-->
| orbit_mean_motion     = <!--mean motion of the satellite, usually measured in orbits per day-->
| orbit_repeat          = <!--repeat interval/revisit time-->
| orbit_velocity        = <!--speed at which the spacecraft was travelling at epoch - only use for spacecraft with low orbital eccentricity-->
| orbit_epoch           = <!--the date at which the orbit parameters were correct-->
| orbit_rev_number      = <!--revolution number-->
| apsis                 = gee

| insignia              = Magnetospheric Multiscale Mission logo.png
}}

The '''Magnetospheric Multiscale Mission''' ('''MMS''') is a [[NASA]] [[unmanned space mission]] to study the [[Earth]]'s [[magnetosphere]], using four identical spacecraft flying in a [[Tetrahedron|tetrahedral]] formation.<ref name=MMSSpacecraft>{{cite web |title=MMS Spacecraft and Instruments |url=http://www.nasa.gov/mission_pages/mms/spacecraft/index.html |publisher=NASA}}</ref> The spacecraft were launched on 13 March 2015 at 02:44&nbsp;UTC.<ref name=MMSLaunch>{{cite web |title=MMS Launch |url=http://www.nasa.gov/mission_pages/mms/launch/index.html |publisher=NASA}}</ref> It is designed to gather information about the [[microphysics]] of [[magnetic reconnection]], energetic particle acceleration, and [[turbulence]], processes that occur in many astrophysical [[Plasma (physics)|plasmas]].<ref>{{cite web |url=http://mms.space.swri.edu/quick_facts.html |title=MMS-SMART: Quick Facts |publisher=[[Southwest Research Institute]] |first=W. S. |last=Lewis |accessdate=5 August 2009}}</ref>

==Background==
[[File:Magnetospheric Multiscale Mission - NASA.webm|thumb|left|MMS mission overview video]]
The mission builds upon the successes of the ESA [[Cluster II (spacecraft)|Cluster mission]], but will surpass it in spatial resolution and in temporal resolution, allowing for the first time measurements of the critical electron diffusion region, the site where magnetic reconnection occurs.  Its orbit is optimized to spend extended periods in locations where reconnection is known to occur: at the dayside [[magnetopause]], the place where the pressure from the [[solar wind]] and the planets' magnetic field are equal; and in the [[magnetotail]], which is formed by pressure from the solar wind on a planet's magnetosphere and which can extend great distances away from its originating planet.

Magnetic reconnection in [[Earth]]'s [[magnetosphere]] is one of the mechanisms responsible for the [[aurora]], and it is important to the science of controlled nuclear fusion because it is one mechanism preventing [[magnetic confinement]] of the fusion fuel. These mechanisms are studied in outer space by the measurement of motions of matter in stellar atmospheres, like that of the Sun. Magnetic reconnection is a phenomenon in which energy may be efficiently transferred from a magnetic field to the motion of charged particles.<ref name="Vaivads2006">{{cite journal |title=Microphysics of Magnetic Reconnection |journal=[[Space Science Reviews]] |publisher=Kluwer Academic Publishers |first1=Andris |last1=Vaivads |first2=Alessandro |last2=Retinò |first3=Mats |last3=André |volume=122 |issue=1-4 |pages=19–27 |date=February 2006 |doi=10.1007/s11214-006-7019-3}}</ref>

==Spacecraft==
The MMS mission consists of four spacecraft. Each has a launch mass of {{convert|2998|lb|kg|abbr=on|order=flip}}.<ref name="presskit"/> In their stowed launch configuration, each are approximately {{convert|11|by|4|ft|m|abbr=on|order=flip}}, and when stacked together they have a total height of {{convert|16|ft|m|abbr=on|order=flip}}.<ref name="presskit"/> After being deployed in orbit, a total of eight axial and wire booms are deployed, increasing vehicle size to {{convert|369|by|94|ft|m|abbr=on|order=flip}}.<ref name="presskit"/>

The MMS spacecraft are spin stabilized, turning at a rate of three revolutions per minute to maintain orientation. Each spacecraft contains 12 thrusters connected to four hydrazine fuel tanks. Position data is provided by highly sensitive GPS equipment, while attitude is maintained by four [[star tracker]]s, two [[accelerometer]]s, and two [[sun sensor]]s.<ref name="presskit"/>

The mission is broken into three phases. The commissioning phase will last approximately five and a half months after launch, while the science phases will last two years. The first science phase will focus on the magnetic boundary between the Earth and Sun (day side operations) for one and a half years, with the spacecraft formation orbiting the Earth at {{convert|2550|by|70080|km|abbr=on}}. The second science phase will study reconnection in Earth's magnetic tail (night side operations) for half a year, increasing the orbit to {{convert|2550|by|152900|km|abbr=on}}.<ref name="presskit"/>

==Instruments==
Each spacecraft carries several experiments, divided into three suites: the Hot Plasma Suite, the Energetic Particles Detector Suite, and the Fields Suite.<ref>{{cite web |url=https://www.nasa.gov/mission_pages/mms/spacecraft/mms-instruments.html |title=Instruments Aboard MMS |publisher=NASA |date=30 July 2015 |accessdate=2 January 2016}}</ref>

The Hot Plasma Suite measures [[plasma (physics)|plasma]] particle counts, directions, and energies during reconnection. It consists of two instruments:
*Fast Plasma Investigation (FPI), a set of four dual electron [[spectrometer]]s and four dual ion spectrometers.
*Hot Plasma Composition Analyzer (HPCA), detects particle speed in order to determine its mass and type.

The Energetic Particles Detector Suite detects particles at energies far exceeding those detected by the Hot Plasma Suite. It consists of two instruments:
*Fly's Eye Energetic Particle Sensor (FEEPS), a set of silicon solid state detectors to measure electron energy. Between two FEEPS per spacecraft, the individual detectors are arranged to provide 18 different view angles simultaneously; hence the term "fly's eye".
*Energetic Ion Spectrometer (EIS), measures energy and total velocity of detected ions in order to determine their mass. The EIS can detect helium and oxygen ions at energies higher than that of the HPCA.

The Fields Suite measures magnetic and electric field characteristics. It consists of six instruments:
*Analog Fluxgate [[magnetometer]] (AFG), determines the strength of magnetic fields.
*Digital Fluxgate magnetometer (DFG), determines the strength of magnetic fields.
*Electron Drift Instrument (EDI), measures electric and magnetic field strength by sending a beam of electrons into space and measuring how long it takes the electrons to circle back in the presence of these fields.
*Spin-plane Double Probe (SDP), consists of [[electrode]]s on the end of four 200-ft wires booms that extend from the spacecraft to measure electric fields.
*Axial Double Probe (ADP), a set of electrodes on two 30-ft antennas mounted axially on the spacecraft.
*Search Coil Magnetometer (SCM), an induction magnetometer used to measure magnetic fields.

==Personnel and development==
The principal investigator is [[James L. Burch]] of [[Southwest Research Institute]], assisted by an international team of investigators, both instrument leads and theory and modeling experts.<ref>{{cite web |url=http://mms.space.swri.edu/team.html |title=The SMART Team |publisher=Southwest Research Institute |accessdate=28 September 2012}}</ref>  The Project Scientist is Thomas E. Moore of [[Goddard Space Flight Center]].<ref>{{cite web |url=http://www.nasa.gov/topics/solarsystem/sunearthsystem/main/tmoore-qanda.html |title=Q&A: Missions, Meetings, and the Radial Tire Model of the Magnetosphere |work=NASA.gov |first1=Karen C. |last1=Fox |first2=Tom |last2=Moore |date=1 October 2010 |accessdate=28 September 2012}}</ref>  Education and public outreach is a key aspect of the mission, with student activities, data sonification, and planetarium shows being developed.

The mission was selected for support by NASA in 2005. System engineering, spacecraft bus design, integration and testing has been performed by [[Goddard Space Flight Center]] in Maryland. Instrumentation is being improved, with extensive experience brought in from other projects, such as the [[IMAGE]], [[Cluster mission|Cluster]] and [[Cassini–Huygens|Cassini]] missions. In June 2009, MMS was allowed to proceed to Phase C, having passed a [[Preliminary Design Review]]. The mission passed its [[Critical Design Review]] in September 2010.<ref name="magnetospheric1">{{cite news |url=http://www.nasa.gov/topics/solarsystem/sunearthsystem/main/mms-cdr.html |title=NASA's Magnetospheric Mission Passes Major Milestone |work=NASA.gov |first=Susan |last=Hendrix |date=3 September 2010 |accessdate=28 September 2012}}</ref> The spacecraft launched on an [[Atlas V]] 421 rocket,<ref>{{Cite press release |url=http://www.ulalaunch.com/site/pages/News.shtml#/26 |title=United Launch Alliance Atlas V Awarded Four NASA Rocket Launch Missions |publisher=[[United Launch Alliance]] |date=16 March 2009 |accessdate=5 August 2009}}</ref> in March 2015.<ref name=MMSLaunch /><ref name="spnews20111219">{{cite news |url=http://www.spacenews.com/article/spending-lags-growing-recognition-heliophysics-contribution |title=Spending Lags Growing Recognition of Heliophysics' Contribution |work=Space News |first=Debra |last=Werner |date=19 December 2011 |accessdate=6 March 2014}}</ref>

==Formation flying==
[[File:MMS Spacecraft Transition to Tetrahedral Flying Formation.webm|thumb|This movie illustrates two orbits of the four MMS spacecraft.]]
In order to collect the desired science data, the four satellite MMS constellation must maintain a tetrahedral formation through a defined region of interest in a highly elliptical orbit. The formation will be maintained through the use of a high altitude rated GPS receiver, Navigator, to provide orbit knowledge, and regular [[Satellite formation flying|formation maintenance]] maneuvers.

==Discoveries==
In 2016 the MMS mission was the first to directly detect [[magnetic reconnection]] (the phenomenon which drives [[space weather]]) in the Earth's magnetosphere.<ref>{{cite web |url=http://www.scientificamerican.com/article/nasa-probes-witness-powerful-magnetic-storms-near-earth/ |title=NASA Probes Witness Powerful Magnetic Storms near Earth |work=Scientific American |first=Charles Q. |last=Choi |date=13 May 2016 |accessdate=14 May 2016}}</ref>
==References==
{{reflist |refs=
<ref name="presskit">{{cite web |url=http://www.nasa.gov/sites/default/files/files/MMS_PressKit.pdf |title=Magnetospheric Multiscale: Using Earth’s magnetosphere as a laboratory to study the microphysics of magnetic reconnection |publisher=NASA |date=March 2015 |accessdate=12 March 2015}}</ref>

}}
{{refbegin}}
*{{cite book |title=An Introduction to Space Weather |publisher=Cambridge University Press |first=Mark |last=Moldwin |year=2008 |isbn=978-0-521-86149-6}}
*{{cite news |url=http://www.spacedaily.com/news/earth-magnetic-05f.html |title=SwRI To Lead NASA's Magnetospheric Multiscale Mission |work=Space Daily |date=12 May 2005}}
*{{cite book |chapter=Magnetospheric Multiscale Mission |title=Nonequilibrium Phenomena in Plasmas |publisher=Springer Netherlands |series=Astrophysics and Space Science Library |first1=A. Surjalal |last1=Sharma |first2=Steven A. |last2=Curtis |volume=321 |pages=179–195 |year=2005 |isbn=978-1-4020-3108-3 |doi=10.1007/1-4020-3109-2_8}}
*{{cite book |title=The Sun to the Earth - And Beyond |publisher=National Academies Press |author=National Research Council |year=2003 |isbn=978-0-309-08972-2}}
*{{cite book |url=http://purl.access.gpo.gov/GPO/LPS70969 |title=2006 NASA Strategic Plan |publisher=NASA |year=2006 |id=NP-2006-02-423-HQ |oclc=70110760}}
*{{cite book |url=http://science1.nasa.gov/media/medialibrary/2010/03/31/Science_Plan_07.pdf |title=Science Plan for NASA's Science Mission Directorate 2007–2016 |publisher=NASA |year=2007 |id=NP-2007-03-462-HQ}}
{{refend}}

==External links==
{{Commons|Category:Magnetospheric Multiscale Mission}}
*[http://mms.gsfc.nasa.gov/ Magnetospheric Multiscale Mission site] by NASA's Goddard Space Flight Center
*[http://www.nasa.gov/mms/ Magnetospheric Multiscale Mission site] by NASA's Mission Directorate
*[http://mms.space.swri.edu/ Magnetospheric Multiscale Mission site] by Southwest Research Institute
*[http://mms.rice.edu Magnetospheric Multiscale Mission site] by Rice University
*{{YouTube|user=nasamms|Magnetospheric Multiscale Mission}}

{{NASA space program}}

{{Wikipedia|Magnetospheric Multiscale Mission}}

[[Category:NASA space probes]]
[[Category:Geomagnetism]]
[[Category:Spacecraft launched in 2015]]
[[Category:Articles containing video clips]]