Magnetospheric Multiscale Mission

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Magnetospheric Multiscale Mission
Atlas V MMS 2015-03-15 NASA.jpg
Mission type Magnetosphere research
Operator NASA
Mission duration Planned: 2 years, 5.5 months[1]
Elapsed: 1 month and 6 days
Spacecraft properties
Manufacturer Goddard Space Flight Center
Launch mass 1,360 kg (2,998 lb)[1]
Dimensions Stowed: 3.4 × 1.2 m (11 × 4 ft)[1]
Deployed: 112 × 29 m (369 × 94 ft)[1]
Start of mission
Launch date 13 March 2015, 02:44 (2015-03-13UTC02:44Z) UTC
Rocket Atlas V 421
Launch site CCAFS SLC-41, Cape Canaveral, FL
Contractor United Launch Alliance
Orbital parameters
Reference system Geocentric
Regime Highly elliptical
Perigee 2,550 km (1,580 mi)[1]
Apogee Day phase: 70,080 km (43,550 mi)[1]
Night phase: 152,900 km (95,000 mi)[1]
Inclination 28.0°
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 tetrahedral formation.[2] The spacecraft were launched on 13 March 2015 at 02:44 UTC.[3] It is designed to gather information about the microphysics of magnetic reconnection, energetic particle acceleration, and turbulence, processes that occur in many astrophysical plasmas.[4]


MMS mission overview video

The mission builds upon the successes of the ESA 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. The study of turbulence in outer space involves the measurement of motions of matter in stellar atmospheres, like that of the Sun, and magnetic reconnection is a phenomenon in which energy is efficiently transferred from a magnetic field to charged particles.[5]


The MMS mission consists of four spacecraft. Each has a launch mass of 1,360 kg (2,998 lb).[1] In their stowed launch configuration, each are approximately 3.4 by 1.2 m (11 by 4 ft), and when stacked together they have a total height of 4.9 m (16 ft).[1] After being deployed in orbit, a total of eight axial and wire booms are deployed, increasing vehicle size to 112 by 29 m (369 by 94 ft).[1]

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 trackers, two accelerometers, and two sun sensors.[1]

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 2,550 by 70,080 km (1,580 by 43,550 mi). The second science phase will study reconnection in Earth's magnetic tail (night side operations) for half a year, increasing the orbit to 2,550 by 152,900 km (1,580 by 95,010 mi).[1]

Personnel and purpose[edit]

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.[6] The Project Scientist is Thomas E. Moore of Goddard Space Flight Center.[7] 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 and Cassini missions. In June 2009, MMS was allowed to proceed to Phase C, since they passed their Preliminary Design Review. The mission passed its Critical Design Review in September 2010.[8] The spacecraft launched on an Atlas V 421 rocket,[9] in March of 2015.[3][10]

Formation flying[edit]

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 formation maintenance maneuvers.


  1. ^ a b c d e f g h i j k l "Magnetospheric Multiscale: Using Earth’s magnetosphere as a laboratory to study the microphysics of magnetic reconnection" (PDF). NASA. March 2015. Retrieved 12 March 2015. 
  2. ^ "MMS Spacecraft and Instruments". NASA. 
  3. ^ a b "MMS Launch". NASA. 
  4. ^ Lewis, W. S. "MMS-SMART: Quick Facts". Southwest Research Institute. Retrieved 5 August 2009. 
  5. ^ Vaivads, Andris; Retinò, Alessandro; André, Mats (February 2006). "Microphysics of Magnetic Reconnection". Space Science Reviews (Kluwer Academic Publishers) 122 (1-4): 19–27. doi:10.1007/s11214-006-7019-3. 
  6. ^ "The SMART Team". Southwest Research Institute. Retrieved 28 September 2012. 
  7. ^ Fox, Karen C.; Moore, Tom (1 October 2010). "Q&A: Missions, Meetings, and the Radial Tire Model of the Magnetosphere". Retrieved 28 September 2012. 
  8. ^ Hendrix, Susan (3 September 2010). "NASA's Magnetospheric Mission Passes Major Milestone". Retrieved 28 September 2012. 
  9. ^ "United Launch Alliance Atlas V Awarded Four NASA Rocket Launch Missions" (Press release). United Launch Alliance. 16 March 2009. Retrieved 5 August 2009. 
  10. ^ Werner, Debra (19 December 2011). "Spending Lags Growing Recognition of Heliophysics' Contribution". Space News. Retrieved 6 March 2014. 

External links[edit]