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Polar Resurrects TIMAS, Immediately Detects New Terrestrial Ion Signature

On Oct 29, 1999, all telemetry reported from TIMAS became invalid (zeroes). Thereafter, collection of valid values was sporadic, ending on July 15, 2000. The fault appeared to be located at the interface between TIMAS and the GGS Telemetry Module 1 (GTM1) and was loosely temperature dependent. On Mar 27, 2001 the Polar spacecraft switched to its backup telemetry module and restored telemetry capture of the TIMAS mid-energy mass spectrometer. TIMAS immediately detected new terrestrial source ion signature at the dayside magnetosphere during magnetic storm period.

image of the  TIMAS mid-energy mass spectrometer

Polar's orbit has precessed so that it samples regions near the dayside equatorial magnetopause with high-temporal and spatial resolution the low-latitude boundary layer, turbulent boundary layer, magnetosphere, and magnetosheath.

Image of the 
TIMAS energy-time spectrogram

Other Polar Particle Detectors Report Similar Observations

TIDE low-energy ion data, from a similar orbit, clearly demonstrate the presence of the terrestrial source ions within the turbulent boundary layer.

Within this layer, circularly polarized waves accelerate the plasmaspheric-like ions to 30-40 km/s perpendicular to B.

New Dayside LLBL Observations Define Path for Circulation of Terrestrial Particles

Interpretation and Implications:

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NASA Official: Adam Szabo

Curators: Robert Candey, Alex Young, Tamara Kovalick

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