TY - JOUR
T1 - Indirect Observations of Electric Fields at Comet 67P
AU - Moeslinger, Anja
AU - Nilsson, Hans
AU - Stenberg Wieser, Gabriella
AU - Gunell, Herbert
AU - Goetz, Charlotte
N1 - Funding information: Rosetta is a European Space Agency (ESA) mission with contributions from its member states and the National Aeronautics and Space Administration (NASA). Work at the Swedish Institute of Space Physics in Kiruna (IRF) was funded by the Swedish National Space Agency (SNSA) Grant 132/19. Work at Umeå University was supported by the SNSA Grant 108/18.
PY - 2023/9/20
Y1 - 2023/9/20
N2 - No spacecraft visiting a comet has been equipped with instruments to directly measure the static electric field. However, the electric field can occasionally be estimated indirectly by observing its effects on the ion velocity distribution. We present such observations made by the Rosetta spacecraft on 19 April 2016, 35 km from the nucleus. At this time comet 67P was at a low outgassing rate and the plasma environment was relatively stable. The ion velocity distributions show the cometary ions on the first half of their gyration. We estimate the bulk drift velocity and the gyration speed from the distributions. By using the local measured magnetic field and assuming an E × B drift of the gyrocentre, we get an estimate for the average electric field driving this ion motion. We analyze a period of 13 hr, during which the plasma environment does not change drastically. We find that the average strength of the perpendicular electric field component is 0.21 mV/m. The direction of the electric field is mostly anti-sunward. This is in agreement with previous results based on different methods.
AB - No spacecraft visiting a comet has been equipped with instruments to directly measure the static electric field. However, the electric field can occasionally be estimated indirectly by observing its effects on the ion velocity distribution. We present such observations made by the Rosetta spacecraft on 19 April 2016, 35 km from the nucleus. At this time comet 67P was at a low outgassing rate and the plasma environment was relatively stable. The ion velocity distributions show the cometary ions on the first half of their gyration. We estimate the bulk drift velocity and the gyration speed from the distributions. By using the local measured magnetic field and assuming an E × B drift of the gyrocentre, we get an estimate for the average electric field driving this ion motion. We analyze a period of 13 hr, during which the plasma environment does not change drastically. We find that the average strength of the perpendicular electric field component is 0.21 mV/m. The direction of the electric field is mostly anti-sunward. This is in agreement with previous results based on different methods.
UR - http://www.scopus.com/inward/record.url?scp=85171655091&partnerID=8YFLogxK
U2 - 10.1029/2023ja031746
DO - 10.1029/2023ja031746
M3 - Article
SN - 2169-9380
VL - 128
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
IS - 9
M1 - e2023JA031746
ER -