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Nature Geoscience, Published online: 02 September 2024; doi:10.1038/s41561-024-01533-y

This study investigates the history of graphitic carbon in two ancient North American mountain belts related to Nuna supercontinent assembly. Using rhenium–osmium and uranium–lead dating, the research reveals that biogenic graphite was hydrothermally remobilized in shear zones during late orogenesis, indicating periodic carbon cycling over 200 million years.

Nature Geoscience, Published online: 02 September 2024; doi:10.1038/s41561-024-01529-8

Deformation experiments and piezoelectric modelling show that the electric charge generated by quartz crystals is capable of depositing dissolved gold. These results suggest that the piezoelectric activity of quartz might drive gold nugget formation from hydrothermal solutions in earthquake settings.

Nature Geoscience, Published online: 02 September 2024; doi:10.1038/s41561-024-01522-1

Wildfires are a natural disturbance in Arctic and boreal regions, but unprecedented wildfire extremes over the past decade have been linked to climate warming. Tracking fires at high temporal resolution reveals a large spatial variability in Arctic–boreal fire regimes driven by environmental and anthropogenic factors, which also modulate the climate sensitivity of different regions.

Nature Geoscience, Published online: 02 September 2024; doi:10.1038/s41561-024-01514-1

Quartz emits a piezoelectric charge during deformation that may promote the formation of gold nuggets within veins in orogenic settings that experience earthquakes, according to a study using quartz deformation experiments and piezoelectric modelling.

Nature Geoscience, Published online: 02 September 2024; doi:10.1038/s41561-024-01505-2

Arctic–boreal biomes vary regionally in the sensitivity of their fire regime to climate, according to an analysis of properties of individual fires measured by satellite radiometry.

Abstract

There is ample evidence for magnetic reconnection in the solar system, but it is a nontrivial task to visualize, to determine the proper approaches and frames to study, and in turn to elucidate the physical processes at work in reconnection regions from in-situ measurements of plasma particles and electromagnetic fields. Here an overview is given of a variety of single- and multi-spacecraft data analysis techniques that are key to revealing the context of in-situ observations of magnetic reconnection in space and for detecting and analyzing the diffusion regions where ions and/or electrons are demagnetized. We focus on recent advances in the era of the Magnetospheric Multiscale mission, which has made electron-scale, multi-point measurements of magnetic reconnection in and around Earth’s magnetosphere.

Abstract

The JUpiter Icy Moon Explorer mission (JUICE) was designed to investigate Jupiter, its environment and its icy moons with at least one Europa flyby, a high inclination phase around Jupiter and a 280 days long near polar orbital phase around Ganymede, with 130 days on a low circular orbit. The goal of the JUICE mission analysis consisted in implementing these mission elements within a tight mass and radiation budget. A shift in the nominal launch date from June 2022 to September 2022 then April 2023 resulted in an arrival date at Jupiter in July 2031, close to equinox, so that the duration of eclipses by Jupiter became a major issue. A mission scheme meeting the requirements was designed using innovative approaches such as a double swing-by of the Moon and the Earth and a low energy endgame targeting a grazing Callisto flyby then grazing Ganymede encounters. Thanks to a near optimum launch date and launcher performance with full tanks, the post-launch Delta-V margins (150 m/s) made it possible to re-instate a 200 km circular orbital phase at the end of the nominal mission as planned in the mission proposal. The remaining Delta-V margin (55 m/s) and that expected from clean-up costs lower than allocated make it possible, while keeping adequate margins for contingencies, to consider significant improvements of the baseline mission scheme, in particular a higher maximum inclination during the tour and an inclination on the 200 km orbit close to Sun-synchronous, so that a long extended mission can be considered.

Abstract

The sampling of extraterrestrial bodies is a critical technology in deep space exploration. Analyzing these samples allows researchers to uncover valuable information about the composition, structure, and evolutionary history of these celestial bodies. Compared to alternative sampling methods such as shoveling and grinding, drilling offers the advantage of obtaining larger sample volumes while preserving sample integrity. Furthermore, it enables sampling at various depths and terrains, making it an essential approach for acquiring samples from extraterrestrial environments. However, drill-based sampling devices are versatile, and their working principles and methods vary across different exploration missions and celestial bodies’ environments. This paper provides a comprehensive investigation into the progress made in drill-based sampling devices for extraterrestrial bodies. It begins by introducing the environmental and geological characteristics of the target celestial bodies, analyzing how these factors impact the structural design and operational parameters of sampling devices. The research then reviews drill-based sampling devices used in previous extraterrestrial exploration missions and examines the latest advancements in drill-based sampling technology. Based on different drilling depths, this study categorizes drill-based sampling devices into seven groups: small drills, pneumatic surface drills, single-rod drills, multi-rod drills, pneumatic deep probes, cable-based drills, and terrestrial ice penetration drills. It also provides an analysis of the operational characteristics, advantages and disadvantages of these seven types of drill-based sampling devices. The paper further outlines the technical difficulties and challenges encountered during the sampling of extraterrestrial bodies and concludes by presenting prospects for the future development of drill-based sampling technology for extraterrestrial bodies.

Publication date: Available online 19 August 2024

Source: Advances in Space Research

Author(s): Rosemary M. Killen, Benjamin T. Sprague, William M. Farrell

Publication date: Available online 19 August 2024

Source: Advances in Space Research

Author(s): Di Chen, Qiuzhi Peng, Jiating Lu, Peiyi Huang, Yaxuan Liu, Fengcan Peng

Publication date: Available online 19 August 2024

Source: Advances in Space Research

Author(s): Xiongchuan Chen, Shuangcheng Zhang, Yong Fang, Bin Wang, Ning Liu, Ningkang An, Jun Li, Zhijie Feng, Sijiezi Li

Abstract

Hot Flow anomalies (HFAs), one of the most well-analyzed transient phenomena in the Earth's foreshock, are known as kinetic structures driven by tangential discontinuities (TDs). Recently, a 2-dimensional (2D) magnetohydrodynamics (MHD) model reproduced HFAs with either a high- or low-density core. Further investigation of an HFA with two cores observed by the Magnetospheric Multiscale (MMS) mission is reported. The observation via the Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) mission suggests this MHD HFA is associated with a foreshock density hole-like structure. The trailing flux tube in simulation may propagate with a TD in the foreshock. Our work suggests that HFAs with two low-density cores can also be achieved in MHD process. Results show the total ram pressure can be an excellent diagnostic for the presence of transient structures, such as HFAs, at the bow shock.

Abstract

The impact of the Madden-Julian oscillation (MJO) on the intraseasonal PNA (ISPNA) was investigated and was found to be modulated by the El Niño-Southern Oscillation (ENSO), which reasonably explains the skewness of the ISPNA during El Niño and La Niña winters. It was shown that the intensity and periodicity of the ISPNA was much stronger and slightly longer in La Niña winters than in the El Niño winters. The phase-locked association between the ISPNA and MJO indicate that this skewness was controlled by the MJO. The northward Rossby wave activities derived from the tropics associated with the MJO to the subtropical Pacific sector of the ISPNA clarified that the stronger intensity of the MJO convection in the western Pacific during the La Niña winters, as well as the slower eastward propagation of the MJO, led to the asymmetric intensity and period of the ISPNA in the two ENSO phases.

What would happen if humans dried out the Mediterranean sea, turning it into a giant salt lake? Would its wildlife survive, and if so, how long would it take to recover?

Abstract

Precise orbit, clock and observable-specific phase bias products play a pivotal role in facilitating precise point positioning (PPP) with ambiguity resolution (AR). The model and strategy used to generate Wuhan University Multi-GNSS (WUM) hourly updated ultra-rapid products is summarized in this study. A refined iteration of the block-to-block operation method is introduced, which demonstrates a substantial increase in efficiency, achieving enhancements of 13-fold and 29-fold for Central Processing Unit and Graphics Processing Unit platforms, respectively. Subsequently, a pre-integration approach is introduced for numerical orbit integration, resulting in a noticeable improvement of efficiency ranging from 6 to 28 times. To enhance the solution strength and precision, a single-differenced-based ambiguity fixing method is explored in our routine processing, which improves for all the satellites, except for GLONASS, and multi-GNSS products are released with a 1-h latency. The orbit assessment is conducted through a comparative analysis with International GNSS Service (IGS) and the Wuhan University Multi-GNSS Combined orbits. The three-dimensional precision of the near real-time orbits reaches 2.4 cm, 4.6 cm, 3.8 cm, and 4.9 cm for GPS, GLONASS, Galileo, and BDS3 MEO satellites, respectively. Regarding IGSO satellites of BDS and QZSS, the corresponding values range between 11.4 cm and 15.7 cm. In contrast, the GEOs of BDS and QZSS exhibit comparatively inferior performance, demonstrating consistencies of 234.7 cm and 70.9 cm, respectively. The validation of the near real-time products is performed utilizing PPP-AR. The statistical analysis across a global network of 340 stations with 20 days reveals a wide-lane fixing rate exceeding 91.1% for multi-GNSS, accompanied by a narrow-lane fixing rate of approximately 97.0%. The PPP-AR solution demonstrates the accuracy of 1.6 mm, 1.7 mm, and 5.0 mm in the east, north, and up directions for IGS weekly solutions, respectively. The results are promising and further confirm that the products are effective.

Abstract

Existing approaches for predicting total water storage (TWS) rely on land surface or hydrological models using meteorological forcing data. Yet, such models are more adept at predicting specific water compartments, such as soil moisture, rather than others, which consequently impedes accurately forecasting of TWS. Here we show that machine learning can be used to uncover relations between nonseasonal terms of Gravity Recovery and Climate Experiment (GRACE) derived total water storage and the preceding hydrometeorological drivers, and these relations can subsequently be used to predict water storage up to 12 months ahead, and even exceptional droughts on the basis of near real-time observational forcing data. Validation by actual GRACE observations suggests that the method developed here has the capability to forecast trends in global land water storage for the following year. If applied in early warning systems, these predictions would better inform decision-makers to improve current drought and water resource management.

Abstract

Dust records extracted from ice cores can facilitate the reconstruction of historical atmospheric dust levels and climate change. However, interpreting dust variations in ice cores is intricate because of the compounded influence of emission, transport, and deposition processes. This study investigated dust records retrieved from the Guliya ice cap drilled in 2015 on the West Tibetan Plateau using a mean trajectory transport and deposition model. Results showed that the Guliya dust concentration has exhibited a declining trend since the 1960s (−751 μg kg−1 yr−1). Applying an attribution approach, we discovered that low dust emission (80.3%) was the main cause of the drop in dust concentration, with changes related to transportation (5.2%) and deposition (14.5%) making only minor contributions. The weakening of surface wind speed in the desert and increasing precipitation in both the desert and glacier were the primary factors driving the decrease in Guliya dust concentration.

Abstract

The mid-latitude extreme weather disasters are often associated with explosively developing cyclones (ECs). Based on different vertical development characteristics, 4,608 ECs identified over the North Pacific in the cold season of 44 years of NCEP-CFSR reanalyzes are divided into four types of upward development and four types of downward development categories. ECs with vertical upward (downward) development follow a northeastward (nearly eastward) path, mainly explosively developing over the Northwest Pacific (Asia continent and Pacific). Furthermore, utilizing the piecewise potential vorticity inversion method reveals the synergetic forcing of the turbulent heat transport and baroclinicity in the lower troposphere, the latent heat release in the middle levels, the upper-level jet stream, and the downward intrusion of stratospheric potential vorticity on the ECs. Different configurations of these influences from the troposphere to the stratosphere result in the occurrences of eight types of ECs in the cold season over the North Pacific.

Abstract

We compare Fourier Amplitude Spectra of Fault Normal (FN) and Fault Parallel (FP) seismograms at near-fault sites for seven strike-slip earthquakes with moment magnitudes M w ≥ 6. For all events we find large FN/FP ratios at low frequencies consistent with near-fault S-wave radiation patterns for strike-slip earthquakes. However, the difference diminishes with increasing frequency and FN/FP is about 1 above a transition frequency. The results may reflect small tensile/isotropic components in the earthquake rupture zones that homogenize the high-frequency radiation in different directions at near-fault sites. The FN/FP ratios at low frequencies and transition frequencies above which FN ∼ FP vary among the analyzed earthquakes and have no clear correlation with the magnitudes. The lack of correlation may signify a characteristic scale (e.g., process zone size, duration of source time function) controlling the isotropic radiation, and/or wave propagation and other effects that mask the source effects.