Leveraging Spire CubeSats and ICGEM Models for Improved Gravity Field Solutions

Kurzfassung

In 2016, Spire Global Inc. began manufacturing commercial CubeSats to analyze Radio Occultation (RO) data from Global Navigation Satellite Systems (GNSS). While RO measurements have been used for various applications, including atmospheric research and ice sheet height estimation, the zenith-looking Precise Orbit Determination (POD) antenna introduces new possibilities for geodetic applications. Each Spire LEMUR CubeSat is equipped with a dual-frequency Global Positioning System (GPS) antenna and an Attitude Determination and Control System (ADCS). Leveraging the measurements provided by the POD antenna and the ADCS, Earth’s gravity field recovery emerges as a promising application, offering new opportunities for the geoscience community . The POD of Spire CubeSats constellation, performed using the raw observation approach, has been applied to model Earth’s gravity field through the short arc method. The Spire CubeSats, with different orbital characteristics, can be used individually or in combination to analyze the time-variable components of the Earth’s gravity field. However, cCombining individual gravity field solutions results in improved accuracy compared to standalone models. This framework provides the opportunity of combining Spire-based gravity field models with those obtained from low Earth orbit (LEO) dedicated or non-dedicated gravimetric missions that offer higher accuracy. In this contribution, monthly gravity field solutions from 10 Spire CubeSats constellation are combined with the ICGEM monthly solutions at the normal equations level (NEQs) using the variance component estimation (VCE). The quality of the combined Spire + SST-hl + SLR monthly gravity field solutions is then compared with the ITSG-GRACE gravity field model for 2020.