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The Mission

Orbits

The five THEMIS spacecraft (probes) were placed in highly elliptical orbits where the spacecraft line up at apogee every four days. The apogee rotates slowly around the Earth to cover the dayside, dawnside, nightside, and duskside of the magnetosphere. Initially, right after launch, the 5 THEMIS spacecraft were lined up in the same orbit. Since 2011, P1 and P2 have become ARTEMIS and orbit the moon, while the 3 remaining Earth-orbiting probes are able to synergize observations with other heliophysics missions such as Van Allen Probes (VAP) and Magnetospheric Multiscale (MMS). The current phase is in green, future phases are in yellow.


Stage 33:  Dayside Science Phase, HSO Optimization with MMS and VAP
04/09/16 - 07/27/16

In the dayside science phase the apogee of P3, P4, and P5 are approximately 12 Re. The probes are separated by 1000 km to a few Earth radii at apogee. MMS is at opposition in the tail, and VAP is in the dawn sector.

Stage 32:  Dusk Science Phase, HSO Optimization with MMS and VAP
12/20/15 - 04/08/16

In the dusk science phase the apogee of P3, P4, and P5 are approximately 12 Re. The probes are separated by 1000 km to a few Earth radii at apogee. MMS is at opposition in dawn, and VAP is in the dayside sector.

Stage 31:  Tail Science Phase, Heliophysics System Observatory (HSO) Optimization with MMS and VAP
08/31/15 - 12/19/15

In the tail science phase the apogee of P3, P4, and P5 are approximately 12 Re. The probes are separated by 1000 km to a few Earth radii at apogee. MMS is at opposition in dayside, and VAP is in the dusk sector.

Stage 30:  Dawn Phase, VAP Conjunctions
05/13/15 - 08/30/15

In the dawn science phase the apogee of the P3, P4, and P5 orbits are on the dawnside of the magnetosphere. Probes 3 and 4 have apogees at 12 Re, and Probe 5 has an apogee at 13 Re. MMS preliminary orbital maneuvers to coordinate with THEMIS observations.

Stage 29:  Dayside Science Phase, VAP Conjunctions
01/22/15 - 05/12/15

In the dayside science phase the apogees of the P3, P4, and P5 orbits are approximately 12 Re. The probes are separated by approximately 500 km to 3000 km. Projected MMS launch and preliminary orbital maneuvers, systems checkout.


Click here to see past orbital configurations.