Arnold, D.

Grombein, T.

Jäggi, A.

Kobel, C.

Lasser, M.

English

Bern Open Repository and Information System (BORIS)

source: https://doi.org/10.48350/185556 | downloaded: 29.9.2023www.kit.eduKIT – The Research University in the Helmholtz AssociationGravity field recovery based on GPS data of CubeSats from the Spire constellationT. Grombein1,2, D. Arnold2, C. Kobel2, M. Lasser2, A. Jäggi21 Geodetic Institute, Karlsruhe Institute of Technology 2 Astronomical Institute, University of BernT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 2IntroductionCan CubeSats serve as gravity field sensors? • A huge number of (commercial) CubeSats is collecting GPS data• Tracking data allows to recover large-scale gravity field information• Big potential to increase the spatial-temporal coverage• However: dual-frequency GPS receivers are neededSpire Global constellation• More than 100 CubeSats in low Earth orbit (LEO)• High-quality dual-frequency GPS receivers• Different orbital characteristics© Spire Global10 x 10 x 34 cm, 4.7 kgT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 3IntroductionCan CubeSats serve as gravity field sensors? • A huge number of (commercial) CubeSats is collecting GPS data• Tracking data allows to recover large-scale gravity field information• Big potential to increase the spatial-temporal coverage• However: dual-frequency GPS receivers are neededSpire Global constellation• More than 100 CubeSats in low Earth orbit (LEO)• High-quality dual-frequency GPS receivers• Different orbital characteristics➢ Case study based on 6 months of GPS data from 9 Spire CubeSats© Spire Global10 x 10 x 34 cm, 4.7 kgT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 4MethodOrbit and gravity field recovery• Celestial Mechanics Approach (Beutler et al., 2010)• Two-step procedure1) GPS tracking data → Kinematic orbit positions2) Kinematic orbit positions → Gravity field recoveryProcessing with the Bernese GNSS software• GNSS products of the CODE analysis center• In-flight calibrated phase center variation (PCV) maps• Unmodeled forces are absorbed by empirical parametersT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 5Selected Spire CubeSats Altitude Inclination Sampling~ 505 km ~ 97.5° 1s~ 530 km ~ 97.5° 1s~ 570 km ~ 37.0° 1sData overview (May – Oct 2020)FM099 FM101 FM102FM103 FM104 FM106 FM107 FM108FM115T. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 6Carrier phase residuals of kinematic orbit determinationSpire GPS data qualitySpire GPS data have frequent gapsT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 7Carrier phase residuals of kinematic orbit determinationHigher noise level compared to scientific LEO missionsSpire GPS data qualityT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 8Spire kinematic orbit positionsDaily availability of derived kinematic positionsFM099 FM101 FM10264 % 73 % 69 %FM11539 %FM103 FM104 FM106 FM107 FM10866 % 74 % 81 % 79 % 82 %Total availability over 6 monthsT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 9Monthly Spire-based gravity fieldsCombinations at normal equation level using variance component estimation (VCE)T. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 10Difference degree amplitudesSpire gravity fieldsDifferences w.r.t. monthly ITSG-Grace2018 solutions (Mayer-Gürr et al., 2018) FM099T. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 11Difference degree amplitudes Geoid height differences700 km Gauss filteredSpire gravity fieldsFM099T. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 12Difference degree amplitudes Geoid height differencesSpire gravity fieldsFM099Artifacts in Est/West-direction are correlated with locations of yaw flips (under investigation)T. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 13Difference degree amplitudes Geoid height differencesSpire gravity fieldsFM099 FM101 FM102T. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 14Difference degree amplitudes Geoid height differencesSpire gravity fieldsFM099 FM101 FM102 FM103 FM104 FM106 FM107 FM108T. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 15Difference degree amplitudes Geoid height differencesSpire gravity fieldsFM099 FM101 FM102 FM103 FM104 FM106 FM107 FM108 FM115T. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 16Difference degree amplitudesSpire gravity fieldsFM099 FM101 FM102 FM103 FM104 FM106 FM107 FM108 FM115Solutions based on 9 CubeSats can reach a quality level comparable to Swarm-BT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 17Weighted RMS values of geoid height differencesQuality of Spire gravity field solutions700 km Gauss filteredT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 18Weighted RMS values of geoid height differences700 km Gauss filteredQuality of Spire gravity field solutionsT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 19Swarm−Spire combinationsT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 20Difference degree amplitudes Geoid height differencesCombination of Swarm with Spire solutionsT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 21Difference degree amplitudes Geoid height differencesRMS improvement: ~ 10%Combination of Swarm with Spire solutionsT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 22Combination of Swarm with Spire solutionsDifference degree amplitudes Geoid height differencesT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 23Summary and outlookMain findings• GPS data of Spire CubeSats allow to recover monthly gravity field solutions• Individual CubeSat solutions cannot compete with scientific LEO missions• Accumulation of CubeSat solutions significantly increases the quality• Solutions based on 9 CubeSats can improve selected coefficients of a Swarm modelNext steps• Process Spire data of further CubeSats and longer time spans• Analysis on the impact of low-inclined CubeSats• Feasibility to increase the temporal resolution (< 1 month)T. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 24Thank you for your attentionWe acknowledge the support from Spire Global and the provision of Spire data by ESAContact: grombein@kit.eduT. Grombein et al. ‒ Gravity field recovery based on GPS data of CubeSats from the Spire constellation Geodetic Institute (GIK)Slide 25ReferencesBeutler G, Jäggi A, Mervart L et al. (2010): The celestial mechanics approach: theoretical foundations, Journal of Geodesy 84(10):605–624, DOI: 10.1007/s00190-010-0401-7Mayer-Gürr T, Behzadpur S, Ellmer M et al. (2018): ITSG-Grace2018 - Monthly, Daily and Static Gravity Field Solutions from GRACE. GFZ Data Services, DOI: 10.5880/ICGEM.2018.003

Gravity field recovery based on GPS data of CubeSats from the Spire constellation

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Gravity field recovery based on GPS data of CubeSats from the Spire constellation

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