Space Probes Research Articles

A Kist o’ Whistles

A Kist o’ Whistles

The active weak-line T Tauri star LkCa 4 observed with SPIRou and TESS

ABSTRACTWe report results of a spectropolarimetric and photometric monitoring of the weak-line T Tauri star LkCa 4 within the SPIRou Legacy Survey large programme, based on data collected with SPIRou at the Canada–France–Hawaii Telescope and the TESS space probe between October 2021 and January 2022. We applied Zeeman–Doppler Imaging to our spectropolarimetric and photometric data to recover a surface brightness distribution compatible with TESS photometry, as well as the large-scale magnetic topology of the star. As expected from the difference in wavelength between near-infrared and optical data, the recovered surface brightness distribution is less contrasted than the previously published one based on ESPaDOnS data, but still features mid-latitude dark and bright spots. The large-scale magnetic field is consistent in shape and strength with the one derived previously, with a poloidal component resembling a 2.2 kG dipole and a toroidal component reaching 1.4 kG and encircling the star at the equator. Our new data confirm that the surface differential rotation of LkCa 4 is about 10 times weaker than that of the Sun, and significantly different from zero. Using our brightness reconstruction and Gaussian Process Regression, we were able to filter the radial velocity activity jitter down to a precision of 0.45 and 0.38 $\text{km}\, \text{s}^{-1}$ (from an amplitude of 6.10 $\text{km}\, \text{s}^{-1}$), respectively, yielding again no evidence for a close-in massive planet orbiting the star.

Rubble pile asteroids are forever

Rubble piles asteroids consist of reassembled fragments from shattered monolithic asteroids and are much more abundant than previously thought in the solar system. Although monolithic asteroids that are a kilometer in diameter have been predicted to have a lifespan of few 100 million years, it is currently not known how durable rubble pile asteroids are. Here, we show that rubble pile asteroids can survive ambient solar system bombardment processes for extremely long periods and potentially 10times longer than their monolith counterparts. We studied three regolith dust particles recovered by the Hayabusa space probe from the rubble pile asteroid 25143 Itokawa using electron backscatter diffraction, time-of-flight secondary ion mass spectrometry, atom probe tomography, and 40Ar/39Ar dating techniques. Our results show that the particles have only been affected by shock pressure of ca. 5 to 15 GPa. Two particles have 40Ar/39Ar ages of 4,219 ± 35 and 4,149 ± 41 My and when combined with thermal and diffusion models; these results constrain the formation age of the rubble pile structure to ≥4.2 billion years ago. Such a long survival time for an asteroid is attributed to the shock-absorbent nature of rubble pile material and suggests that rubble piles are hard to destroy once they are created. Our results suggest that rubble piles are probably more abundant in the asteroid belt than previously thought and provide constrain to help develop mitigation strategies to prevent asteroid collisions with Earth.

Space probe of the gravitational constant G

The empirical Gravitational constant G is of fundamental interest in metrology, Newtonian physics, and the field equations in General Relativity, particle physics, geophysics, and astrophysics. The precise value of G has yet to be known with the desired level of accuracy. In the 233 years since Cavendish, hundreds of experiments sought more accurate results but produced inconsistent results. Although they have had much more advanced supporting technology, past experiments have mostly stayed the same from the Cavendish approach. This paper shows that a different method is feasible to enhance the accuracy of G. A sphere made of metal with a large uniform mass density having a channel through the center with a bead oscillating back and forth in a simple-harmonic fashion. Monitoring the positions of the bead experimentally and comparing the predictions of the channel model will allow refining the value of G. The study develops a gravitational force function for the bead in a channeled sphere to provide more accuracy in the prediction of the bead's motion. This study determines that the best place to perform future gravitation constant experiments is in space far away from interfering effects. A near-perfect place is likely to be in outer space at the Sun-Earth Lagrange point L1, located about 1.5 million kilometers from the Earth on a line toward the Sun where other probes reside. It is estimated that three to six significant figures may be added to the current value of G.

НАЗЕМНА ПІДТРИМКА КОСМІЧНОЇ МІСІЇ PARKER УКРАЇНСЬКИМИ НИЗЬКОЧАСТОТНИМИ РАДІОТЕЛЕСКОПАМИ

Subject and Purpose. The sporadic radio emissions coming from the Sun in a broad frequency range contain a lot of important information concerning the solar corona, parameters of the radio frequency sources therein, and the parameter variations resulting from active processes on and about the Sun. These have been the reasons for recent launches of the space missions intended for stud- ying the Sun and its corona, such as the Parker Solar Probe (PSP) and the Solar Orbiter. The present work is aimed at demonstrating effectiveness of the ground-based support for the space missions, the PSP before all, which is provided by the large Ukrainian radio telescopes of the decameter wavelength range. Another purpose has been cross-calibration of the space-borne radiometer against calibrated data from a ground-based instrument. Methods and Methodology. One of the remote diagnosis techniques widely used with respect to the solar corona is to analyze parameters of the radio frequency emissions from sources lying at a variety of altitudes within the corona. The methodology of such joint, space-borne/terrestrial investigations suggests simultaneous observations of certain individual events during closest approach of the space probe PSP to the Sun, with analysis over a widest possible frequency range. The data obtainable within overlapping fre- quency bands are proposed for calibrating the on-board radio receivers of the space probe. Results. The methodology proposed for joint, space-based / terrestrial observations has been substantiated. Data from the UTR-2 and URAN-2 radio telescopes and the space probe PSP have been used to plot the dynamic and the polarization spectra of the June 9, 2020 solar bursts, with identification and comparison of the relevant individual events. A joint dynamic spectrum of these bursts has been obtained for the frequency band of 0.5 to 32 MHz. The calibrated data from the ground-based radio telescopes have allowed performing cross-calibration of the HF receiver in the FIELDS-PSP data taking module within the frequency band of 10 to 18 MHz. Conclusions. The paper has provided evidence of an effective ground-based support for the space mission PSP on the part of large Ukrainian radio telescopes. Examples of joint observations have been given, and a methodology described which is employed for cross-calibrating the HF receivers of the FIELD-PSP module. Prospects are outlined of further ground-based support for solar space research missions.

Potential scientific synergies in weak lensing studies between the CSST andEuclidspace probes

Aims.With the next generation of large surveys poised to join the ranks of observational cosmology in the near future, it is important to explore their potential synergies and to maximize their scientific outcomes. In this study, we aim to investigate the complementarity of two upcoming space missions:Euclidand the China Space Station Telescope (CSST), both of which will be focused on weak gravitational lensing for cosmology. In particular, we analyze the photometric redshift (photo-z) measurements by combining NUV,u, g, r, i, z, ybands from CSST with the VIS,Y, J, Hbands fromEuclid, and other optical bands from the ground-basedVera C. RubinObservatory Legacy Survey of Space and Time (LSST) and Dark Energy Survey. We also consider the advantages of combining the two space observational data in simplifying image deblending. ForEuclid, weak lensing measurements use the broad optical wavelength range of 550−900 nm, for which chromatic point-spread function (PSF) effects are significant. For this purpose, the CSST narrow-band data in the optical can provide valuable information forEuclidto obtain more accurate PSF measurements and to calibrate the color and color-gradient biases for galaxy shear measurements.Methods.We created image simulations, using theHubbleDeep UV data as the input catalog, for different surveys and quantified the photo-zperformance using theEAZYtemplate fitting code. For the blending analyses, we employed high-resolution HST-ACS CANDELSF606WandF814Wdata to synthesize mock simulated data forEuclid, CSST, and an LSST-like survey. We analyzed the blending fraction for different cases as well as the blending effects on galaxy photometric measurements. Furthermore, we demonstrated that CSST can provide a large enough number of high signal-to-noise ratio multi-band galaxy images to calibrate the color-gradient biases forEuclid.Results.The sky coverage ofEuclidlies entirely within the CSST footprint. The combination ofEuclidwith the CSST data can thus be done more uniformly than with the various ground-based data that are part of theEuclidsurvey. Our studies show that by combiningEuclidand CSST, we can reach a photo-zprecision ofσNMAD ≈ 0.04 and an outlier fraction ofη ≈ 2.4% at the nominal depth of theEuclidWide Survey (VIS < 24.5 AB mag). For CSST, including theEuclidY, J, Hbands reduces the overall photo-zoutlier fraction from ∼8.5% to 2.4%. Forz > 1, the improvements are even more significant. Because of the similarly high resolutions, the data combination ofEuclidand CSST can be relatively straightforward for photometry measurements. On the other hand, to include ground-based data, sophisticated deblending utilizing priors from high-resolution space observations are required. The multi-band data from CSST are very helpful in controlling the chromatic PSF effect forEuclidVIS shear measurements. The color-gradient bias forEuclidgalaxies with different bulge-to-total flux ratio at different redshifts can be well calibrated to the level of 0.1% using galaxies from the CSST deep survey.

Gas Dynamic Models of the Interaction between the Solar Wind

Gas dynamic models of the interaction between the solar wind and cometary atmospheresare considered. Interest in the development of such models arose sharply after the beginning of the investigations of comets with the use of spacecraft launched at distances close to their surfaces. The instruments on this spacecraft gave the possibility to investigate experimentally the parameters of gas flow out from the cometary surfaces when the comets approach the Sun and its interaction with the solar wind plasma flow, which could not be made using only the spectral photometry. The beginning of such studies was started by almost instantaneous approaching of several space probes to Halley’s Comet on March 1986. Only after 28 years, the Rosetta spacecraft launched by the European Space Agency (ESA) along a complex trajectory have approached comet Churyumov–Gerasimenko and, maneuvering in the neighborhood of this comet during more than two years, it, in particular, have investigated the interaction of the cometary atmosphere and the solar wind

Sunvoyager: Interstellar Precursor Probe Mission Concept Driven by Inertial Confinement Fusion Propulsion

The Sunvoyager is a concept mission for a space probe that can be sent outside of the solar heliosphere to a distance of 1000 AU in a trip time of only 3.4 years traveling at speeds of 1500 km/s or 325 AU/year. It is an advanced Voyager flyby probe, but the concept design is unique in that it would utilize an inertial confinement fusion propulsion engine driving a gram-scale capsule mass at 10 Hz pulse frequency using 5 MJ laser driver energy reaching the capsule. Such a design may be possible in the latter part of the 21st century. The probe would carry a 100-ton scientific payload for the purpose of observations from the location of gravitational focal point, a dwarf planet flypast, and imaging of interstellar asteroids. Secondary science objectives would include measurements of the interstellar medium, measurements of astrometry, and the search for extraterrestrial power and propulsion emission signatures. The propulsion engine is characterized by 23 kN thrust, 54 GW jet power, and 147 kW/kg specific power. This paper outlines the science goals in addition to calculations that scope out the design space using a recently constructed propulsion performance and mission analysis numerical tool called HeliosX.

Redefining low Earth orbit as a parking orbit for flexible and economical Earth departure in deep space missions

There are a number of deep space probes that are currently in operation with diverse destinations and objectives. For example, the Japanese Hayabusa2 and the U.S. OSIRIS-REx missions are both sample returns, targeting different near-Earth asteroids. Europe’s ExoMars and the U.S. Perseverance are orbiting and roving Mars as precursors of future manned explorations. Conventionally, deep space missions require dedicated launch vehicles for each mission. The interplanetary Earth departure trajectory from the low Earth orbit (LEO) usually lacks flexibility and efficiency. Furthermore, innovative and reusable launch systems have been researched and developed by multiple organizations including private sector organizations such as SpaceX and Blue Origin. It is expected that the unit cost per launch weight to LEO be significantly reduced by rideshare mass transportation executed by using reusable mega launchers in the near future. This study aims to fill the transportation gap between LEO and deep space by realizing a flexible and economical interplanetary Earth departure without sacrificing the arbitrariness of LEO, target V-infinity vector, and target Earth departure epoch. Thus, the one-revolution Earth free-return orbit (1rEFRO) and the consequent Earth gravity assist (EGA) are introduced to separate the velocity increment and direction adjustment. The planetary free-return and EGAs are common in interplanetary missions; however, a comprehensive study on the flexibility, economic efficiency, and arbitrariness of the sequence (1rEFRO + EGA) originating from LEO was not explicitly found. After describing the necessary coordinate frames, LEO’s orbital elements, 1rEFRO, and the terms ‘flexibility’ and ‘economic efficiency’ are defined in Section 2. Then in Section 3, the two-body-based preliminary orbit design method is proposed and formulated. Section 4 aims to reveal LEO’s comprehensiveness as efficient parking orbits when adopting the 1rEFRO + EGA sequence, using the newly proposed “ΣVEt LEO i-Ω diagram”. Section 5 describes a detailed orbit design constructed based on multi-body propagation and optimization to confirm the feasibility, flexibility, and economics of the solution and the usefulness of the initial solution given by the preliminary design method formulated in Section 3.

An Intelligent 2-D Chart Method With Autodetection for Weak Quasar Blind TDD Estimation in Deep Space △DOR Measurement

To achieve high accuracy navigation for deep space probes, the △differential one-way ranging (△DOR) measurement relies on the corrections from the time delay difference (TDD) estimation of reference weak Quasar signal, which is guided by the forecasting data compensation. However, disturbed by the interference, the forecasting data sometimes is unavailable, which directly leads to invalid compensation and Quasar TDD estimation failure. In this article, an intelligent 2-D chart method with autodetection is proposed for △DOR measurement without forecasting data support. Consisted of 2-D correlation chart generation, two stages autodetection and rough estimations iteration refining, the proposed scheme realizes the autodetection and TDD blind estimations of weak Quasar signal. The validation experiment is established with developed radio science software defined receiver systems, which are installed in ground stations for space △DOR navigation and positioning. Results show that the presented 2-D correlation chart extends the system weak Quasar signal detection ability with signal SNR can reach –23 dB. The overall accuracy of designed two stages autodetection for Quasar correlation spectral line search is 85.17%. The proposed scheme improves the utilization rate of Quasar data collected by the system by 24.01%. And the average P-F curve fitting residue error which reflects the TDD estimation accuracy is 0.1931/rad. It proves an equivalent precision to accurate forecasting data processing, which meets the △DOR measurement accuracy requirements.

Simulation Study of the Swirl Spray Atomization of a Bipropellant Thruster under Low Temperature Conditions

The spray atomization of an injector significantly influences the performance and working life span of a bipropellant thruster of a spacecraft. Deep space exploration requires the thruster to be able to operate reliably at a low temperature range from −40 °C to 0 °C, so the effect of low temperature conditions on the atomization characteristics of injector spray is motivated to be comprehensively investigated. To study the swirl atomization characteristics of MMH (methylhydrazine), which is more difficult to atomize than NTO (nitrogen tetroxide), numerical simulations were conducted, employing the methods of VOF (volume of fluid) and LES (large eddy simulation) under low temperature conditions. The physical model with a nozzle size of 0.5 mm and boundary conditions with a velocity inlet of 3.89 m/s both follow the actual operation of thrusters. The development of spray atomization at low temperatures was observed through parametric comparisons, such as spray velocity, liquid total surface area, droplet particle size distribution, spray cone angle and breakup distance. When the temperature decreased from 20 °C to −40 °C at the same condition of flowrate inlet, those atomization characteristics of MMH propellant vary following these rules: the spray ejection velocity of MMH is significantly reduced by 7.7%, and gas-liquid disturbance sequentially decreases; the liquid film development is more stable, with a negative influence on atomization quality, causing difficulties for primary and secondary breakup, so the total surface area of droplets also decreases by 6.4%; the spatial distribution characteristics, spray cone angle and breakup distance vary less than 5%. Therefore, the low temperature condition can directly lower the combustion efficiency of thrusters with obvious performance degradation, but there are no significant changes in the propellant mixing and liquid film cooling. It is concluded that the bipropellant thruster can reliably work at low temperatures around −40 °C for deep space probe operation.

Modified Gravity and a Space Probe–Venus Mission

A comparison of gravitational forces and a space probe’s trajectory parameters is made for two different models of the sun’s field, expressed in Schwarzschild and isotropic coordinates. It is shown that these two representations of a single Schwarzschild solution give, in the tangent space format, different deflections from classical finite trajectories and, hence, from one other; greatly amplified by a planet’s (Venus’) gravity assist, this effect renders it possible to experimentally specify the format of the gravity law that dominates the solar system.

Detection and characterization of wind-blown charged sand grains on Titan with the DraGMet/EFIELD experiment on Dragonfly

The EFIELD instrument is part of the geophysics and meteorology sensor package DraGMet on the Dragonfly mission, which will explore the surface of Titan in the mid-2030s. EFIELD consists of two electrodes designed to passively record the AC electric field at each Dragonfly landing site. The probes will be mounted at two different locations on the body of the rotorcraft lander.The exploration zone of the Dragonfly mission will mostly consist of dune fields, covered with sand grains. Little is known on the properties of these grains, although Cassini-Huygens observations suggest they are mostly made of organic material produced by Titan's atmospheric photochemistry and evolved at the surface. Little is known also about dune formation and, in general, about the transport of sediments by winds on Titan. The latter much depends on inter-particle forces and therefore on whether grains are charged (e.g. by friction) or not. In this paper, we demonstrate that the EFIELD experiment can bring new insights on these questions.We have developed a hydrodynamic-electrostatic model to simulate the trajectory of a wind-blown charged sand grain in the vicinity of an idealized EFIELD probe (an electronically insulated probe in a neutral open space) and to predict how such a grain flying close to the probe would affect its potential. We show that, in some conditions, the resulting perturbation will be strong enough to be detected by the EFIELD probe. More specifically, we find that the detection of typical charged wind-blown grains (200 μm in size) on Titan requires an instrument standard deviation noise inferior to 1 mV, though occasional larger grains flying close to one electrode could be detected with a higher noise level.Furthermore, we propose a method to retrieve information on the charge and velocity of wind-blown charged grains detected by the EFIELD experiment. This method well applies for cases where the particle trajectory can be regarded as quasi-linear. We validate our inversion approach on both synthetic and experimental data obtained with a laboratory prototype of the EFIELD experiment. Such approach was developed with assumptions on the accommodation and electronic design of the EFIELD experiment but can be adapted to account for the final architecture of the experiment.

Image Processing Robustness Assessment of Small-Body Shapes

Asteroids and comets are triggering interest due to the richness of precious materials, their scientific value as well as for their potential hazardousness. Owing to their significant diversity, minor bodies do not exhibit uniform shapes: they can range from spherical to irregularly shaped objects with rocky, uneven, and cratered surface. Nowadays, space probes rely more and more on optical navigation techniques, due to the increasing demand for autonomy. When dealing with minor bodies, the diversified range of shapes can significantly affect the performance of these techniques. In order to enable deep space probes to confidently deal with uncertainties, the need for robust image processing methods arises. Commonly, few image processing methods are designed and tested with limited shapes to meet mission requirements. In this work, we depart from this paradigm by developing a new framework, which includes extensive testing of the image processing algorithms with various shapes. The shapes are not randomly analyzed, yet they are arranged in a hierarchical structure called hyper-cube. The cube allows for a better understanding of the methods performance and to infer the way they shift from one shape to the other. The novelty of this approach lies both in the cube representation, which allows a better understanding of the link between the image processing algorithms and shape of the object, but also in the extensive number of shapes that have been tested, which has never been done before. In this analysis, four methods are considered, namely: center of brightness, intensity weighted centroiding, correlation with Lambertian spheres, and least-squares-based ellipse fitting. Results from this test allow us correlating the methods performances to the bodies shape, to suggest the best performing method for each shape family, and to assess their robustness.

A Sliding Window Adaptive Filtering Algorithm for Autonomous Navigation of the Approach Phase of Deep Space Probe

A Sliding Window Adaptive Filtering Algorithm for Autonomous Navigation of the Approach Phase of Deep Space Probe

Intelligent architecture of space unmanned system with learning and reasoning capabilities

Spacecraft represented by satellites, manned spaceships, and deep space probes are typical unmanned systems that are developing from automation to autonomy. To improve the adaptability and intelligent autonomy level of spacecraft to unknown space environments and complex space tasks, an intelligent architecture of space unmanned system with learning and reasoning capabilities is designed and the architectural components and functions are proposed. Then, the operating mechanism of learning and reasoning capabilities in the architecture are analyzed, and the solutions for key technologies, such as the construction, update, and expansion methods of the action and knowledge libraries, are proposed. Finally, through an example of the extraterrestrial surveying and sampling task, the process of new knowledge generation, knowledge-based reasoning, and autonomous task execution under this intelligent architecture, as well as the interaction between the knowledge library, environment, task, and action library, are explained.

ELCD: Efficient Lunar Crater Detection Based on Attention Mechanisms and Multiscale Feature Fusion Networks from Digital Elevation Models

The detection and counting of lunar impact craters are crucial for the selection of detector landing sites and the estimation of the age of the Moon. However, traditional crater detection methods are based on machine learning and image processing technologies. These are inefficient for situations with different distributions, overlaps, and crater sizes, and most of them mainly focus on the accuracy of detection and ignore the efficiency. In this paper, we propose an efficient lunar crater detection (ELCD) algorithm based on a novel crater edge segmentation network (AFNet) to detect lunar craters from digital elevation model (DEM) data. First, in AFNet, a lightweight attention mechanism module is introduced to enhance the feature extract capabilities of networks, and a new multiscale feature fusion module is designed by fusing different multi-level feature maps to reduce the information loss of the output map. Then, considering the imbalance in the classification and the distributions of the crater data, an efficient crater edge segmentation loss function (CESL) is designed to improve the network optimization performance. Lastly, the crater positions are obtained from the network output map by the crater edge extraction (CEA) algorithm. The experiment was conducted on the PyTorch platform using two lunar crater catalogs to evaluate the ELCD. The experimental results show that ELCD has a superior detection accuracy and inference speed compared with other state-of-the-art crater detection algorithms. As with most crater detection models that use DEM data, some small craters may be considered to be noise that cannot be detected. The proposed algorithm can be used to improve the accuracy and speed of deep space probes in detecting candidate landing sites, and the discovery of new craters can increase the size of the original data set.

A Grand Challenge International Infrastructure for Earthquake Science

Editorial| September 22, 2022 A Grand Challenge International Infrastructure for Earthquake Science Yehuda Ben‐Zion; Yehuda Ben‐Zion * 1Department of Earth Sciences and Southern California Earthquake Center, University of Southern California, Los Angeles, California, U.S.A. *Corresponding author: benzion@usc.edu https://orcid.org/0000-0002-9602-2014 Search for other works by this author on: GSW Google Scholar Gregory C. Beroza; Gregory C. Beroza 2Department of Geophysics, Stanford University, Palo Alto, California, U.S.A. https://orcid.org/0000-0002-8667-1838 Search for other works by this author on: GSW Google Scholar Marco Bohnhoff; Marco Bohnhoff 3Helmholtz Centre Potsdam German Research Centre for Geosciences GFZ, Potsdam, Germany4Department of Earth Sciences, Free University Berlin, Berlin, Germany https://orcid.org/0000-0001-7383-635X Search for other works by this author on: GSW Google Scholar Alice‐Agnes Gabriel; Alice‐Agnes Gabriel 5Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, U.S.A.6Department of Earth and Environmental Sciences, Ludwig‐Maximilians‐Universität München, Munich, Germany https://orcid.org/0000-0003-0112-8412 Search for other works by this author on: GSW Google Scholar Paul Martin Mai Paul Martin Mai 7Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia https://orcid.org/0000-0002-9744-4964 Search for other works by this author on: GSW Google Scholar Seismological Research Letters (2022) 93 (6): 2967–2968. https://doi.org/10.1785/0220220266 Article history first online: 22 Sep 2022 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Yehuda Ben‐Zion, Gregory C. Beroza, Marco Bohnhoff, Alice‐Agnes Gabriel, Paul Martin Mai; A Grand Challenge International Infrastructure for Earthquake Science. Seismological Research Letters 2022;; 93 (6): 2967–2968. doi: https://doi.org/10.1785/0220220266 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySeismological Research Letters Search Advanced Search Scientific communities need cutting‐edge collaborative observational facilities to test models and to enable ground‐breaking discoveries. The acquisition of fundamental new data often leads to transformative advances in research that have significant societal and economic benefits. Grand challenges in physical sciences often require grand facilities. Several scientific communities, not including Earthquake Science so far, have realized grand‐challenge facilities. Particle physicists use very large accelerators to study properties of elementary particles. Astronomers send state‐of‐the‐art telescopes to space to improve their observations. Space missions deploy rovers and other instrumentation on nearby planets and space probes to advance planetary sciences. Such efforts involve infrastructure... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

COHERENT constraint on leptophobic dark matter using CsI data

We use data from the COHERENT CsI[Na] scintillation detector to constrain sub-GeV leptophobic dark matter models. This detector was built to observe low-energy nuclear recoils from coherent elastic neutrino-nucleus scattering. These capabilities enable searches for dark matter particles produced at the Spallation Neutron Source mediated by a vector portal particle with masses between 2 and 400 MeV/c2. No evidence for dark matter is observed and a limit on the mediator coupling to quarks is placed. This constraint improves upon previous results by two orders of magnitude. This newly explored parameter space probes the region where the dark matter relic abundance is explained by leptophobic dark matter when the mediator mass is roughly twice the dark matter mass. COHERENT sets the best constraint on leptophobic dark matter at these masses.Received 26 May 2022Accepted 30 August 2022DOI:https://doi.org/10.1103/PhysRevD.106.052004Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle dark matterParticles & Fields

Dual-target Signal Simulation of Very Long baseline Interferometry for Chang’E-5

Very long baseline interferometry (VLBI) is an important deep-space tracking technology from radio astronomy. A mission that uses VLBI, China’s lunar sample-return mission Chang’E-5 (CE-5) collects soil samples on the lunar surface, arrives at a rendezvous point, and docks in the lunar orbit through cooperation of the Orbiter and the Ascender. During rendezvous and docking, the Chinese VLBI network (CVN) used same beam VLBI (SBI) to observe two high-velocity probes simultaneously. However, before the launching of the CE-5, CVN lacked the capability to examine dynamic dual-target tracking ability of SBI mode because there were no similar space probes can be used in tests of upgraded VLBI data-processing system. This study proposes a method to simulate VLBI signals and acquire relevant data from the dual-target probe and calibration quasar signals recorded by each station according to the orbits and beacons of probes, station coordinates, etc. The real-time data-processing capability of the system is verified by processing the simulated data during rendezvous and docking. The consistency between simulation and VLBI data-processing was consistent to better than 0.05 ns. This method is universal and can also be used in VLBI simulation and orbital analysis of other deep-space probes.