FPMU conceptual instrument layout.
Histogram of the number of invalid checksums when recalculated over the received page on the ground station. A value of 0 means all seven checksums were valid and the page was received uncorrupted.
Noise in the data set of all four FPMU instruments due to telemetry errors. Median filtering mitigates most of the “spikes.”
Noise in the WLP and the NLP curves possibly due to interference from some other apparatus or activity onboard the ISS. Both curves are from when ISS was in eclipse conditions. The difference in floating potential observed in WLP curves is because of ISS charging due to VxB effect.
Four consecutive curves from the WLP and the NLP. There is no hysteresis in the internally heated WLP, while minimal hysteresis exists in the NLP indicating presence of some contamination.
Fits for and to the electron retardation region using Eq. (7). Both the WLP and the NLP curves are for the same second of data. The and fits for the WLP curve were and 2.12 V, while for the NLP curve were and 2.01 V, respectively.
Comparison of measured curves with the curves generated by analytical theory. The best match is acquired with a least-squares fit of Eq. (3) to and . It is important to note that the fit value of is different from that proposed by OML theory.
A single admittance vs frequency profile from the PIP data set.
Comparison of densities derived from different instruments.
Ground locations from where the data were assimilated into the USU-GAIM model run. The filled squares are GPS ground stations and empty squares are ionosondes.
The first row shows FPMU floating potential as measured by the FPP, the WLP, and the NLP. The second row compares the ion density derived from the WLP with density from USU-GAIM and IRI model runs. The third row compares the WLP and the NLP derived temperatures with IRI model results. The fourth row shows the ISS latitude and longitude.
The caption is the same as for Fig. 11.
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