The visualization starts with an overview of the MMS orbit.
This visualization starts with the viewer camera just outside earth's magnetosphere (the faint grey mesh) looking down on the orbit of the four MMS spacecraft. During this portion of the mission, the apogee of the orbit takes the spacecraft just outside the magnetopause. The lower orbit speed at this location maximizes the time spent there and increases chances of catching a reconnection event which is the goal of the mission.
The camera zooms in to a chase of the four spacraft, simultaneously altering the timescale so each movie frame has a smaller time between them. We catch up with the four spacecraft and see the tetrahedral flying formation.
The MMS spacecraft are not always collecting data. Due to telemetry limitations, the data is collected in segments, at different sampling rates, and then downloaded to ground-stations on Earth. In this close-up view, we see two segments of data collection, with a short gap of no data between them.
The arrows represent the data collected by the spacecraft. To better comprehend changes as the spacecraft moves along, the data are allowed to 'echo' along the spacecraft trail. The length of the vectors represent the relative magnitude of the vector. However, the electron and proton vectors are scaled so equal velocities correspond to vectors of equal magnitude.
Magenta represents the direction and magnitude of the magnetic field at the spacecraft position.
Yellow represents the direction and magnitude of the bulk motion (total average) velocity of the electrons measured at the spacecraft position.
Blue represents the direction and magnitude of the bulk motion (total average) velocity of the protons measured at the spacecraft position.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 22.214.171.124.0