Univertity of California, Berkeley   Austrian Academy of Sciences   Centre d'étude des Environnements Terrestre et Planétaires  

Johns Hopkins University Applied Physics Laboratory NASA Goddard Space Flight Center  Swales Aerospace


Technical University Carolo-Wilhelmina at Brunswick University of Alberta University of Calgary

University of California, Los Angeles THEMIS E/PO Site University of Colorado, Boulder


THEMIS answers fundamental outstanding questions regarding the magnetospheric substorm instability, a dominant mechanism of transport and explosive release of solar wind energy within Geospace.  THEMIS will elucidate which magnetotail process is responsible for substorm onset at the region where substorm auroras map (~10Re): (i) a local disruption of the plasma sheet current or (ii) that current's interaction with the rapid influx of plasma emanating from lobe flux annihilation at ~25Re. Correlative observations from long-baseline (2-25 Re) probe conjunctions, will delineate the causal relationship and macroscale interaction between the substorm components. THEMIS's five identical probes measure particles and fields on orbits which optimize tail-aligned conjunctions over North America.  Ground observatories time auroral breakup onset. Three inner probes at ~10Re monitor current disruption onset, while two outer probes, at 20 and 30Re respectively, remotely monitor plasma acceleration due to lobe flux dissipation. In addition to addressing its primary objective, THEMIS answers critical questions in radiation belt physics and solar wind - magnetosphere energy coupling. THEMIS's probes use flight-proven instruments and subsystems, yet demonstrate spacecraft design strategies ideal for Constellation class missions. THEMIS is complementary to MMS and a science and a technology pathfinder for future STP missions. THEMIS will be launched February, 2007.
THEMIS was successfully launched at 6:01 pm  EST, February 17, 2007.

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Vassilis Angelopoulos, THEMIS Principal Investigator, explains how the 5 probes will interact with the influences on the magnetic field generated by Coronal Mass Ejections (CME). Final assembly of the THEMIS carrier with it's 5 probes is evaluated by the technicians prior to fueling and spin testing. Pictured are 100 gram counter weights used to balance the spacecraft during spin testing.


Shown is the unique release mechanism on the central probe (typical). THEMIS will deploy 5 probes at once, the first time this has ever been attempted. THEMIS, shown on it's unique carrier, is prepped for spin testing at Astrotech in Titusville Florida. THEMIS awaits launch at pad 17B.


Main engine start At T-2 seconds the main engine is coming up to full power. Booster ignition and liftoff of the Delta II 7925-10 launch vehicle and the five THEMIS probes