Physics Department Seminar | University of Alaska Fairbanks |
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J O U R N A L C L U B |
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Space Plasma Science
with Active Satellite Encounters |
by |
Paul Bernhardt |
Geophysical Institute, UAF |
ABSTRACT Satellites
in Low Earth Orbit, (LEO) can produce disturbances in the
ionosphere that are recorded with other satellites using plasma
wave and particle detectors. This process is useful for
determining the plasma wave excitation around a satellite and
determining the environmental impact of spacecraft rocket engine
burns in space. For the past 20 years, rocket engines have been
fired in the ionosphere with the specific purpose of making
neutral exhaust clouds for investigation with in situ diagnostic
instruments on satellites. For instance, in July 2009, the OMS
engines on the Space Shuttle Endeavour (STS-127) were ignited for
12 seconds to produce a water vapor and carbon dioxide cloud to
impact the AFLR C/NOFS satellite located at a range of 220 km
[Bernhardt et al., 2012]. This satellite to satellite encounter
produced a wide range of plasma waves that were recorded by the
VEFI instrument on C/NOFS. The plasma disturbances excited by the
STS-127 burn were (1) Compressional or Fast Alfven Wave Pulse, (2)
Whistlers, (3) Ion Acoustic Turbulence, and (4) Lower Hybrid
Turbulence. More recently, in July 2018, the BT-4 rocket motor on
the Cygnus Spacecraft was fired for 30 seconds to yield a
hypersonic exhaust cloud intersected 50 km away by the SWARM-E
satellite with the Radio Receiver Instrument (RRI). Measurements
of low frequency (10 Hz to 32 kHz) plasma waves [Bernhardt et al.
2021], show a frequency shift in the Strong Plasma Wave Emission
(SWPE) of lower-hybrid waves that lasted for 20 seconds of the
Cygnus burn. The next Cygnus burn experiment occurred in May 2020
when the BT-4 engine at 500 km altitude was fired over a ground
VLF transmitter when the SWARM-E RRI was above the burn at 1000 km
altitude on the same magnetic field line. This experiment produced
30 to 50 dB amplifications coherent VLF waves from ground sources
[Bernhardt, 2021]. Recently, on 4 March 2022, the SWARE-E
satellite passed by the Starlink-2521 satellite with a range of
400 meters. The RRI instrument detected a strong burst of waves
near the lower hybrid frequency with that “near collision”. The
implications of these measurements will be discussed. |
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Friday, 18 March 2022 |
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Globe Room, Elvey Building and on Zoom : https://zoom.us/j/796501820?pwd=R2xEcXNwZGVRbG0va29iN2REU241UT09 | ||
3:45PM |