THEMIS (satellite)
THEMIS in Delta II fairing
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| Mission type | Magnetospheric research |
|---|---|
| Operator | NASA |
| COSPAR ID | 2007-004 (A, B, C, D, E) |
| SATCAT № | 30580, 30581, 30582, 30583, 30584 |
| Website | themis |
| Mission duration | elapsed: 9 years, 11 months and 9 days |
| Spacecraft properties | |
| Manufacturer | Swales Aerospace |
| Launch mass | 630 kilograms (1,390 lb) |
| Dry mass | 77 kilograms (170 lb) each |
| Power | 37.0 W each |
| Start of mission | |
| Launch date | 17 February 2007, 23:01:00 UTC |
| Rocket | Delta II 7925-10C |
| Launch site | Cape Canaveral SLC-17B |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Highly Elliptical |
| Eccentricity | 0.8637973070144653 |
| Perigee | 470 kilometres (290 mi) |
| Apogee | 87,330 kilometres (54,260 mi) |
| Inclination | 16.0° |
| Period | 1,870 minutes |
The Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission was originally a constellation of five NASA satellites (THEMIS A through THEMIS E) to study energy releases from Earth's magnetosphere known as substorms, magnetic phenomena that intensify auroras near Earth's poles. The name of the mission is an acronym alluding to the Titan, Themis.
Three of the satellites remain in the magnetosphere, while two have been moved into orbit near the Moon. Those have been renamed ARTEMIS for Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun. THEMIS B became ARTEMIS P1 and THEMIS C became ARTEMIS P2.
The THEMIS satellites were launched February 17, 2007 from Cape Canaveral Air Force Station Space Launch Complex 17 aboard a Delta II rocket. Each satellite carries identical instrumentation, including a fluxgate magnetometer (FGM), an electrostatic analyzer (ESA), a solid state telescope (SST), a search-coil magnetometer (SCM) and an electric field instrument (EFI). Each has a mass of 126 kg, including 49 kg of fuel.
THEMIS data can be accessed using the SPEDAS software.
THEMIS was originally scheduled to launch on October 19, 2006. Owing to delays caused by workmanship problems with Delta II second stages—an issue that also affected the previous mission, STEREO—the THEMIS launch was delayed to Thursday, February 15, 2007. Due to weather conditions occurring on Tuesday, February 13, fueling of the second stage was delayed, and the launch pushed back 24 hours. On February 16, the launch was scrubbed in a hold at the T-4 minute point in the countdown due to the final weather balloon reporting a red, or nogo condition for upper level winds. A 24-hour turnaround procedure was initiated, targeting a new launch window between 23:01 and 23:17 UTC on February 17.
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