Star tracker derived rotations and accelerometer analysis Peter

1 Star tracker data Level 1 A Version 3 products: • SW_OPER_STRASCI_1 A_yyyymmdd. T

2 Star tracker derived rotations SWARM Data Quality Workshop – Potsdam / Germany 3

2 Star tracker derived rotations SWARM Data Quality Workshop – Potsdam / Germany 4

2 Star tracker derived rotations - STR processed data record: MDR_STR_PRC SWARM Data Quality

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2 Star tracker derived rotations SWARM Data Quality Workshop – Potsdam / Germany 7

2 Star tracker derived rotations SWARM Data Quality Workshop – Potsdam / Germany 8

2 Star tracker derived rotations SWARM Data Quality Workshop – Potsdam / Germany 9

3 Accelerometer analysis Figure 2‑ 23: Radial acceleration of Swarm A. Left: S/C is

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3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 12 02. –

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3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 14 02. –

3 Accelerometer analysis Courtesy to Eelco Doornbos SWARM Data Quality Workshop – Potsdam /

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 16 02. –

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 17 02. –

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3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 21 02. –

3 Accelerometer analysis a = amplitude = width = center (time) ζ = asymmetry

3 Accelerometer analysis heater torquer twangs SWARM Data Quality Workshop – Potsdam / Germany

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 24 02. –

3 Accelerometer analysis Charging and discharging of satellite surfaces SWARM Data Quality Workshop –

4 Summary STR: - STR processed data record: MDR_STR_PRC ICRF quaternions in overlapping time

Thank you for your attention SWARM Data Quality Workshop – Potsdam / Germany 27

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Star tracker derived rotations and accelerometer analysis Peter Schack, Anja Schlicht, Nadja Peterseim, Roland Pail, Thomas Gruber Institut für Astronomische und Physikalische Geodäsie (IAPG), TU München Forschungseinrichtung Satellitengeodäsie (FESG), TU München Centre of Geodetic Earth System Research (CGE) SWARM Data Quality Workshop – Potsdam / Germany 02. – 05. December 2014

1 Star tracker data Level 1 A Version 3 products: • SW_OPER_STRASCI_1 A_yyyymmdd. T 235500_yyyymmdd. T 000459_0301 • SW_RPRO_STRASCI_1 A_yyyymmdd. T 235500_yyyymmdd. T 000459_0301 Attitude of CHUs data record: MDR_STR_SCI STR processed data record: MDR_STR_PRC Abbreviations: ICRF: Inertial Reference Frame CRF: Common Reference Frame MRF: Measurement Reference Frame SWARM Data Quality Workshop – Potsdam / Germany 2 02. – 05. December 2014

2 Star tracker derived rotations SWARM Data Quality Workshop – Potsdam / Germany 3 02. – 05. December 2014

2 Star tracker derived rotations SWARM Data Quality Workshop – Potsdam / Germany 4 02. – 05. December 2014

2 Star tracker derived rotations - STR processed data record: MDR_STR_PRC SWARM Data Quality Workshop – Potsdam / Germany 5 02. – 05. December 2014

2 Star tracker derived rotations SWARM Data Quality Workshop – Potsdam / Germany 6 02. – 05. December 2014

2 Star tracker derived rotations SWARM Data Quality Workshop – Potsdam / Germany 7 02. – 05. December 2014

2 Star tracker derived rotations SWARM Data Quality Workshop – Potsdam / Germany 8 02. – 05. December 2014

2 Star tracker derived rotations SWARM Data Quality Workshop – Potsdam / Germany 9 02. – 05. December 2014

3 Accelerometer analysis Figure 2‑ 23: Radial acceleration of Swarm A. Left: S/C is in full sun. Right: S/C passes through the eclipse (indicated by grey background). (Swarm Accelerometer Anomaly Report) SWARM Data Quality Workshop – Potsdam / Germany 10 02. – 05. December 2014

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 11 02. – 05. December 2014

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 12 02. – 05. December 2014

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 13 02. – 05. December 2014

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 14 02. – 05. December 2014

3 Accelerometer analysis Courtesy to Eelco Doornbos SWARM Data Quality Workshop – Potsdam / Germany 15 02. – 05. December 2014

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 16 02. – 05. December 2014

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 17 02. – 05. December 2014

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 18 02. – 05. December 2014

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 19 02. – 05. December 2014

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 20 02. – 05. December 2014

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 21 02. – 05. December 2014

3 Accelerometer analysis a = amplitude = width = center (time) ζ = asymmetry factor bi = polynomial coefficents a 2 = amplitude, depends on a s = scaling of damping d 1, d 2 = damping factors ω = ang. frequency SWARM Data Quality Workshop – Potsdam / Germany 22 02. – 05. December 2014

3 Accelerometer analysis heater torquer twangs SWARM Data Quality Workshop – Potsdam / Germany 23 02. – 05. December 2014

3 Accelerometer analysis SWARM Data Quality Workshop – Potsdam / Germany 24 02. – 05. December 2014

3 Accelerometer analysis Charging and discharging of satellite surfaces SWARM Data Quality Workshop – Potsdam / Germany 25 02. – 05. December 2014

4 Summary STR: - STR processed data record: MDR_STR_PRC ICRF quaternions in overlapping time periods at beginning and end of a file do not contain identical values - Attitude of CHUs data record: MDR_STR_SCI Time tags are not ‘equidistant’ (sometimes 2 values in 1 second) - Star tracker derived angular accelerations are dominated by noise. Comparison to temperature reduced angular accelerations from VZLU on the basis of angular rates can be considered (after compensating STR temperature dependence) ACC: - High amplitude peaks seem to be comparable to GRACE twangs - With support from TU Delft it would be possible to correlate these peaks with solar impact on different satellite surfaces SWARM Data Quality Workshop – Potsdam / Germany 26 02. – 05. December 2014

Thank you for your attention SWARM Data Quality Workshop – Potsdam / Germany 27 02. – 05. December 2014