Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) was launched on May 22, 2018. It carries the Laser Ranging Interferometer (LRI) as a technology demonstrator that measures the inter-satellite range with nanometer precision using a laser-link between satellites. To maintain the laser-link between satellites, the LRI uses the beam steering method: a Fast Steering Mirror (FSM) is actuated to correct for misalignment between the incoming and outgoing laser beams. From the FSM commands, we can compute the inter-satellite pitch and yaw angles. These angles provide information about the spacecraft's relative orientation with respect to line-of-sight (LOS). We analyze LRI derived inter-satellite pointing angles for 2019 and 2020. Further, we present its comparison with the pointing angles derived from GRACE-FO SCA1B data, which represents the spacecraft attitude computed from star cameras and Inertial Measurement Unit (IMU) data using a Kalman filter. We discuss the correlations seen between the laser based attitude data and the spacecraft temperature variations. This analysis serves as the basis to explore the potential of this new attitude product obtained from the Differential Wavefront Sensing (DWS) control of a FSM.

Introduction: Heat therapy may help in reducing pain during labor as it blocks the receptors of pain, according to gate control theory. This systematic review and metaanalysis study aims to evaluate the effect of heat therapy (HT) systematically and critically on pain intensity, duration of...

For missions such as GRACE, precise knowledge of the satellite's attitude is a fundamental requirement for the realization of the intersatellite ranging principle. It is not only essential for the realization of the precise in-orbit intersatellite pointing but also for the recovery of accurate temporal gravity field models. Here, we present a comparative study of two attitude datasets. One of them is the standard SCA1B RL02 datasets provided by JPL NASA, and another is a fused attitude dataset computed at TU Graz, based on the combination of ACC1B angular accelerations and SCA1B quaternions. Furthermore, we also present the impact of the attitude datasets on the intersatellite range measurements by analyzing their residuals. Our analysis reveals the significant improvement in the attitude due to the reprocessed product and reduced value of residuals computed from the reprocessed attitude.

For further improvements of gravity field models based on Gravity Recovery and Climate Experiment (GRACE) observations, it is necessary to identify the error sources within the recovery process. Observation residuals obtained during the gravity field recovery contain most of the measurement and modeling errors and thus can be considered a realization of actual errors. In this work, we investigate the ability of wavelets to help in identifying specific error sources in GRACE range-rate residuals. The multiresolution analysis (MRA) using discrete wavelet transform (DWT) is applied to decompose the residual signal into different scales with corresponding frequency bands. Temporal, spatial, and orbit-related features of each scale are then extracted for further investigations. The wavelet analysis has proven to be a practical tool to find the main error contributors. Besides the previously known sources such as K-band ranging (KBR) system noise and systematic attitude variations, this method clearly shows effects which the classic spectral analysis is hardly able or unable to represent. These effects include long-term signatures due to satellite eclipse crossings and dominant ocean tide errors.

For further improvements of gravity field models based on Gravity Recovery and Climate Experiment (GRACE) observations, it is necessary to identify the error sources within the recovery process. Observation residuals obtained during the gravity field recovery contain most of the measurement and modeling errors and thus can be considered as a realization of actual errors. In this work, we investigate the ability of wavelets to help in identifying specific error sources in GRACE range rate residuals. The Multi-Resolution Analysis (MRA) using Discrete Wavelet Transform (DWT) is applied to decompose the residual signal into different scales with corresponding frequency bands. Temporal, spatial, and orbit-related features of each scale are then extracted for further investigations. The wavelet analysis has proved to be a practical tool to find the main error contributors. Beside the previously known sources such as K-Band Ranging (KBR) system noise and systematic attitude variations, this method clearly shows effects which the classic spectral analysis is hardly able or unable to represent. These effects include long-term signatures due to satellite eclipse crossings and dominant ocean tide errors.

The Tigris and Euphrates river basin is among the most water stressed transboundary systems on Earth, yet observationally grounded, basin-resolved assessments of its groundwater have not kept pace with the deepening crisis of the 2020s. Here, we combine mascon solutions of total water storage anomalies from GRACE and GRACE-FO (CSR RL06.3, 0.25° grid) with GLDAS Noah v2.1 land surface storage to isolate groundwater storage anomalies, computed separately for each basin over 2002 to 2026. Anomalies are referenced to a 2004 to 2009 baseline and composited into hydrologic-year seasons. Both basins show sustained and highly significant decline. Total water storage fell at 0.95 and 0.75 cm per year in the Tigris and Euphrates, and groundwater was reduced by 0.83 and 0.65 cm per year (Mann–Kendall p < 0.001, robust to serial correlation). The groundwater residual accounts for about 87% of the total loss. Because it also contains unmodelled surface water, this is an upper estimate, but groundwater remains about two-thirds of the loss under a surface-water sensitivity analysis. The record contains two depletion phases, the 2007 to 2009 drought and a deeper decline after 2021, separated by a transient recovery in 2019 to 2021, with the Tigris depleting faster throughout. Groundwater loss in the Tigris accelerated from 0.88 cm per year over 2002 to 2020 to 2.83 cm per year over 2021 to 2025. Net wet season groundwater storage gain in the Tigris fell from 11.7 cm in 2005 to zero in 2025; across all years from 2003 to 2025, however, the gain shows no significant trend and closely tracks wet season precipitation (r = 0.83), so the 2025 minimum reflects the driest winter of the record rather than a loss of recharge capacity. Spatially, the deficits expanded from near neutral in 2005 to region-wide and severe by 2025 and were deepest along the northeastern Zagros margin. These results extend the established GRACE record of Middle Eastern depletion by more than a decade and show that depletion proceeds through a lowering of the whole seasonal cycle, with dry season losses exceeding wet season gains, which has direct consequences for transboundary water governance.