Effect of spacecraft attitude on radio wave polarization measurements for the radio Receiver instrument on Swarm-E

Kalafatoglu Eyiguler, E.C.; Pandey, K.; Howarth, A.D.; Holley, W.; Danskin, D.W.; Hussey, G.C.; Gillies, R.G.; Yau, A.W.

doi:10.1016/j.asr.2023.09.001

Cited by 3 publications

(4 citation statements)

References 33 publications

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“…Since the study lacked attitude and antenna pointing direction information, Kallio et al (2022) could not conclude the specific reasons for the signal loss. In addition, the diagnostic tools for the ionosphere can only be employed after accounting for the reception angles of the antenna boresight and the dipoles (Kalafatoglu Eyiguler et al, 2023c). cavsiopy computes the observation geometry and the reception angle throughout a spacecraft's trajectory to facilitate the interpretations of the observations made by the receivers onboard spacecraft.…”

Section: Discussionmentioning

confidence: 99%

“…Alternatively, the roll, pitch, and yaw angles and the spacecraft ephemerides are disseminated. Regardless, both methodologies produce equivalent outcomes (Kalafatoglu Eyiguler et al, 2023c). The choice of the method is influenced by user preference and data availability.…”

Section: Auxiliary Functionsmentioning

confidence: 99%

“…Figure 8 provides a quick-look plot for the RRI complex voltage observations (Figure 8A), the calculated powers (Figure 8B), SRA of the boresight and the CRAs of the dipoles (Figure 8C), the derived polarization characteristics: the orientation angle (Figure 8D), the ellipticity angle (Figure 8E), the aspect and the elevation angle during the course of the experiment, and the of observations (Figure 8F). The power at the dipoles (panel B), the orientation angle (panel D), and the ellipticity angle (panel E) were calculated using the Stokes module, which is not provided in cavsiopy since the derived parameters may not always represent the actual polarization state, and the interpretation requires careful consideration of the spacecraft attitude (Kalafatoglu Eyiguler et al, 2022;Kalafatoglu Eyiguler et al, 2023a;Kalafatoglu Eyiguler et al, 2023c). Stokes may be obtained separately as an auxiliary module by contacting the corresponding author.…”

Section: Auxiliary Functionsmentioning

confidence: 99%

“…For example, Cassini and Voyager missions had very high-pointing precision requirements to accomplish the scientific objectives (Heacock, 1980;Lee and Burk, 2019). Additionally, individual experiments may also necessitate different attitude modes for a spacecraft (Kalafatoglu Eyiguler et al, 2022;2023c). If multiple experiments on a spacecraft are operating simultaneously, the pointing of particular instruments and the observation geometry can increase in importance in the interpretation of the measurements.…”

Section: Introductionmentioning

confidence: 99%

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cavsiopy: a Python package to calculate and visualize spacecraft instrument orientation

Kalafatoglu Eyiguler,

Holley,

Howarth

et al. 2023

Front. Astron. Space Sci.

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Spacecraft attitude plays an important role in the observations of various atmospheric, planetary, and terrestrial parameters and phenomena that are of interest to the scientific community. Precise measurements from imagers, particle sensors, and antennas require accurate knowledge of instrument orientation. cavsiopy is an easy-to-install and use, light-weight open-source Python package for researchers who need to consider instrument pointing direction and observation geometry. cavsiopy contains the coordinate transformation routines and the corresponding rotation matrices from the spacecraft orbital reference frame (ORF) to any of the geocentric equatorial inertial for epoch J2000 (GEI J2K)/International Celestial Reference Frame (ICRF), Earth-centered, Earth-fixed (ECEF), International Terrestrial Reference Frame (ITRF), geodetic north-east-down, and geocentric north-east-center coordinate systems. Additionally, cavsiopy includes routines for importing Swarm-E ephemeris and generic two-line-element (TLE) data files; for the calculation of spacecraft azimuth, elevation, and orbital parameters; as well as for the 2D/3D visualization of the geometry between the instrument and the target. Functionality and utilization of cavsiopy for research problems are demonstrated with examples and visualizations for the Radio Receiver Instrument (RRI) and the Fast Auroral Imager (FAI) of e-POP/Swarm-E.

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Section: Discussionmentioning

confidence: 99%

Section: Auxiliary Functionsmentioning

confidence: 99%

Section: Auxiliary Functionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

cavsiopy: a Python package to calculate and visualize spacecraft instrument orientation

Kalafatoglu Eyiguler,

Holley,

Howarth

et al. 2023

Front. Astron. Space Sci.

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The Ellipticity of High Frequency Transionospheric Radio Waves

Pandey,

Kalafatoglu Eyiguler,

Hussey

et al. 2024

JGR Space Physics

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The polarization state of transionospheric high frequency (HF) radio waves can be determined using the crossed‐dipole antennas of the Radio Receiver Instrument (RRI) onboard Enhanced Polar Outflow Probe (e‐POP) on the CAScade, Smallsat, and IOnospheric Polar Explorer/Swarm‐E satellite. Coordinated experiments between ground radars and RRI showed that the radio waves have high ellipticity angles (elliptical or circular polarization) for propagation direction 6°–25° from the perpendicular direction to the local geomagnetic field. However, from magnetoionic theory and a typical assumption of roughly equal power in the O‐ and X‐modes, radio waves can have high ellipticity angles only when the propagation direction is within 10° of perpendicularity. This investigation uses coordinated experiments between the Saskatoon SuperDARN radar and RRI. Magnetoionic modeling reveals that the relative strengths of the O‐ and X‐modes for the HF radio waves transmitted from the Saskatoon SuperDARN change significantly poleward of the radar. Differences in the relative power between the two wave modes were found to significantly modify the polarization state of radio waves, and govern the sense of rotation of the wave. Even a relatively modest 2–5 dB power difference in the X‐mode over the O‐mode was found to result in unexpected observations of circularly polarized radio waves at aspect angles 6°–10° from perpendicular, and unexpected elliptically polarized waves observed at aspect angles more than 10° from perpendicular. Therefore, a combination of RRI observations and modeling, which accounts for relative differences in the O‐ and X‐mode powers, was used here to better understand the unexpected observations of polarization states of transionospheric radio waves.

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Differential Delay of Ordinary and Extraordinary Modes of Transionospheric Radio Waves

Pandey,

Kalafatoglu Eyiguler,

Gillies

et al. 2024

JGR Space Physics

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The terrestrial ionosphere is a birefringent medium that allows radio waves to propagate in two modes: the ordinary (O‐mode) and the extraordinary (X‐mode). A difference in the index of refraction of the two modes results in differential delay (mode delay) between the O‐ and X‐modes of radio waves propagating through the ionosphere. Mode delays of transionospheric high frequency radio waves are determined using the Radio Receiver Instrument (RRI) onboard the Enhanced Polar Outflow Probe (e‐POP) on the CASSIOPE/Swarm‐E satellite. Experiments between RRI and the SuperDARN radar at Saskatoon, Canada show large variabilities in mode delays. The mode delays are nearly constant in some experiments but other experiments have large variations. The mode delay observations could not be explained by the distance between the e‐POP satellite and the radar, the foF2 values along the satellite track, nor whether the satellite track was across or along a SuperDARN radar beam. A combination of RRI observations and ray‐trace modeling are used to investigate the mode delay of transionospheric radio waves.

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Effect of spacecraft attitude on radio wave polarization measurements for the radio Receiver instrument on Swarm-E

Cited by 3 publications

References 33 publications

cavsiopy: a Python package to calculate and visualize spacecraft instrument orientation

cavsiopy: a Python package to calculate and visualize spacecraft instrument orientation

The Ellipticity of High Frequency Transionospheric Radio Waves

Differential Delay of Ordinary and Extraordinary Modes of Transionospheric Radio Waves

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