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Hi, I'm John Dorelli. I'm a space scientist at NASA's Goddard Space Flight Center.

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I'd like to tell you a little bit about NASA's MMS mission.

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MMS was designed to study a phenomenon known as magnetic reconnection,

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which is kind of a magnetic explosion in space. You can think of

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Earth as a giant bar magnet with magnetic lines of force emanating out into

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space in a dipole pattern. Under just the right conditions, energy

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in this magnetic field is explosively converted into plasma energy, creating

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spectacular space weather phenomenon like the aurora and magnetic storms.

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To catch these explosions in action, the MMS orbits were designed

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in two phases: a day-side phase, and a night-side phase.

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MMS is actually four identical spacecraft flying in a geometrical formation

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known as a tetrahedron. Scientists hope to capture the magnetic explosions

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somewhere inside this tetrahedron. At closest approach to Earth, the

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tetrahedron is highly stretched, and not suitable for capturing the magnetic explosions.

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But by the time we get out to 76,000 kilometers, MMS will be

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in nearly perfect formation, the four spacecraft separated by only

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ten kilometers. The Sun is constantly blowing out its atmosphere

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into space, and this solar wind meets Earth's magnetic field at the magnetopause.

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Here, at the magnetopause, scientists expect to catch magnetic reconnection in action.

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So the apogee of the orbit is designed so that the tetrahedron

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cuts across the boundary twice per orbit while in perfect formation.

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As it crosses the magnetopause, MMS will take

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high-speed snapshots of the magnetic explosions as they unfold.

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[  whoosh  ] [beep beep... beep beep... beep beep...]

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[ beep beep... beep beep... beep beep... ]

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