A thermodynamic model of high temperature lava vaporization on Io

We modified the MAGMA chemical equilibrium code developed by Fegley and Cameron (1987, Earth Planet. Sci. Lett. 82, 207-222) and used it to model vaporization of high temperature silicate lavas on Io. The MAGMA code computes chemical equilibria in a melt, between melt and its equilibrium vapor, and in the gas phase. The good agreement of MAGMA code results with experimental data and with other computer codes is demonstrated. The temperature-dependent pressure and composition of vapor in equilibrium with lava is calculated from 1700 to 2400 K for 109 different silicate lavas in the ONaKFeSiMgCaAlTi system. Results for five lavas (tholeiitic basalt, alkali basalt, Barberton komatiite, dunite, and a molten type B1 Ca, Al-rich inclusion) are discussed in detail. The effects of continuous fractional vaporization on chemistry of these lavas and their equilibrium vapor are presented. The predicted abundances (relative to Na) of K, Fe, Si, Al, Ca, and Ti in the vapor equilibrated with lavas at 1900 K are lower than published upper limits for Io's atmosphere (which do not include Mg). We predict evaporative loss of alkalis, Fe, and Si during volcanic eruptions. Sodium is more volatile than K, and the Na/K ratio in the gas is decreased by fractional vaporization. This process can match Io's atmospheric Na/K ratio of 10±3 reported by Brown (2001, Icarus 151, 190-195). Silicon monoxide is an abundant species in the vapor above lavas. Spectroscopic searches are recommended for SiO at IR and mm wavelengths. Reactions of metallic vapors with S- and Cl-bearing volcanic gases may form other unusual gases including MgCl₂, MgS, MgCl, FeCl₂, FeS, FeCl, and SiS.     

Comparative planetology, climatology and biology of Venus, Earth and Mars

Spacecraft studies of the three terrestrial planets with atmospheres have made it possible to make meaningful comparisons that shed light on their common origin and divergent evolutionary paths. Early in their histories, all three apparently had oceans and extensive volcanism; Mars and Earth, at least, had magnetic fields, and Earth, at least, had life. All three currently have climates determined by energy balance relationships involving carbon dioxide, water and aerosols, regulated by solar energy deposition, atmospheric and ocean circulation, composition, and cloud physics and chemistry.This paper addresses the extent to which current knowledge allows us to explain the observed state of each planet, its planetology, climatology and biology, within a common framework. Areas of ignorance and mysteries are explored, and prospects for advances in resolving these with missions within the present planning horizon of the space agencies are considered and assessed.     

Preface: Workshop on matter,astrophysics, gravitation,ions and cosmology—MAGIC23

We outline our experience in organizing the first edition of the Workshop on Matter, Astrophysics, Gravitation, Ions and Cosmology, held in virtual and in-person format, denominated MAGIC23, held from 6 to 10 March, 2023, in Praia do Rosa, Santa Catarina, Brazil. The event aimed to bring together leading academic scientists, professors, students, and research scholars for exchanging experiences and discuss the most recent innovations, trends, practical challenges, and experimental and theoretical solutions adopted in the investigation fields within the scope of the meeting. The workshop offered to the participants a platform for scientific and academic projects, partnerships, and presentation of high-quality research contributions describing original and unpublished results on topics related to matter, astrophysics, gravitation, ions, and cosmology.     

时间频率量的特征及其对时频系统建设的影响

分析了物理量测量中时间频率量的特点，主要有：时间的流逝性；其基准是自然基准；时间和频率既密切相关又有区别；时间频率具有最高的测量精细度(分辨率)与准确度；其计量标准可通过电磁波发播；其测量精确度与测量时间有关。另外，从基准、守时、授时、时间频率设备的研制、生产和队伍建设等方面阐发了这些特点对时间频率系统建设的影响。     

星载SAR干涉技术最新研究进展

简要介绍了SAR、InSAR、D-InSAR的发展概况,以及InSAR、D-InSAR的基本原理．重点讨论了InSAR、D-InSAR技术的最新理论及存在的问题,包括多基线SAR干涉技术、极化干涉技术、大气效应的削弱、永久散射体方法、InSAR与LIDAR和GPS等数据源的融合技术,以及InSAR并行算法等。详细论述InSAR、D-InSAR技术在地球科学及气象学等领域所取得的最新进展。最后对InSAR技术的发展前景作了展望。     

星系金属丰度的研究进展(Ⅰ):定标方法

金属丰度是表征星系特征的重要参量,对于理解星系的形成与演化具有重要意义。随着观测设备的不断完善与发展,已经获得越来越多的星系(包括近邻星系、中等红移及高红移星系)金属丰度的观测资料。在光致电离模型方面也取得了很大进展．这些对于理解星系中金属及恒星成分的累积历史有非常重要的作用。有多种方法可以用来估计星系的金属丰度(主要是星际介质中气相的O丰度),介绍和评述了估计星系的O丰度的多种方法,包括电子温度的方法、R23方法以及其他一些“强线”比值的方法,并给出了相应的解析公式,同时介绍了电离星云的物理本质及由光致电离模型估计星系金属丰度的方法,还给出了估计星系的C和N元素丰度的方法。     

Report of the IAU/IAG Working Group on cartographic coordinates and rotational elements: 2006

Every three years the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the directions of the poles of rotation and the prime meridians of the planets, satellites, minor planets, and comets. This report introduces improved values for the pole and rotation rate of Pluto, Charon, and Phoebe, the pole of Jupiter, the sizes and shapes of Saturn satellites and Charon, and the poles, rotation rates, and sizes of some minor planets and comets. A high precision realization for the pole and rotation rate of the Moon is provided. The expression for the Sun’s rotation has been changed to be consistent with the planets and to account for light travel time     

Review of measurements of dust movements on the Moon during Apollo

This is the first review of 3 Apollo experiments, which made the only direct measurements of dust on the lunar surface: (i) minimalist matchbox-sized 270 g Dust Detector Experiments (DDEs) of Apollo 11, 12, 14 and 15, produced 30 million Lunar Day measurements 21 July 1969–30 September, 1977; (ii) Thermal Degradation Samples (TDS) of Apollo 14, sprinkled with dust, photographed, taken back to Earth into quarantine and lost; and (iii) the 7.5 kg Lunar Ejecta and Meteoroids (LEAM) experiment of Apollo 17, whose original tapes and plots are lost. LEAM, designed to measure rare impacts of cosmic dust, registered scores of events each lunation most frequently around sunrise and sunset. LEAM data are accepted as caused by heavily-charged particles of lunar dust at speeds of <100 m/s, stimulating theoretical models of transporting lunar dust and adding significant motivation for returning to the Moon. New analyses here show some raw data are sporadic bursts of 1, 2, 3 or more events within time bubbles smaller than 0.6 s, not predicted by theoretical dust models but consistent with noise bits caused by electromagnetic interference (EMI) from switching of large currents in the Apollo 17 Lunar Surface Experiment Package (ALSEP), as occurred in pre-flight LEAM-acceptance tests. On the Moon switching is most common around sunrise and sunset in a dozen heavy-duty heaters essential for operational survival during 350 h of lunar night temperatures of minus 170 °C. Another four otherwise unexplained features of LEAM data are consistent with the “noise bits” hypothesis. Discoveries with DDE and TDS reported in 1970 and 1971, though overlooked, and extensive DDE discoveries in 2009 revealed strengths of adhesive and cohesive forces of lunar dust. Rocket exhaust gases during Lunar Module (LM) ascent caused dust and debris to (i) contaminate instruments 17 m distant (Apollo 11) as expected, and (ii) unexpectedly cleanse Apollo hardware 130 m (Apollo 12) and 180 m (Apollo 14) from LM. TDS photos uniquely document in situ cohesion of dust particles and their adhesion to 12 different test surfaces. This review finds the entire TDS experiment was contaminated, being inside the aura of outgassing from astronaut Alan Shepard's spacesuit, and applies an unprecedented caveat to all TDS discoveries. Published and further analyses of Apollo DDE, TDS and LEAM measurements can provide evidence-based guidance to theoretical analyses and to management and mitigation of major problems from sticky dust, and thus help optimise future lunar and asteroid missions, manned and robotic.     

The Astrophysical Multimessenger Observatory Network (AMON)

We summarize the science opportunity, design elements, current and projected partner observatories, and anticipated science returns of the Astrophysical Multimessenger Observatory Network (AMON). AMON will link multiple current and future high-energy, multimessenger, and follow-up observatories together into a single network, enabling near real-time coincidence searches for multimessenger astrophysical transients and their electromagnetic counterparts. Candidate and high-confidence multimessenger transient events will be identified, characterized, and distributed as AMON alerts within the network and to interested external observers, leading to follow-up observations across the electromagnetic spectrum. In this way, AMON aims to evoke the discovery of multimessenger transients from within observatory subthreshold data streams and facilitate the exploitation of these transients for purposes of astronomy and fundamental physics. As a central hub of global multimessenger science, AMON will also enable cross-collaboration analyses of archival datasets in search of rare or exotic astrophysical phenomena.     

Crystallographic variety of magnetic spherules from Pleistocene and Holocene sediments in the Northern foreland of Morasko-Meteorite Reserve

The crystalline form of magnetic spherules, retrieved from the Pleistocene and Holocene mineral and organic surface sediments at the Northern foreland of Morasko meteorite-impact site, have been determined. While the magnetite (Fe₃O₄) composition of the spherules prevails, also hematite, maghemite and plagioclase crystalline inclusions have been observed. The magnetite form varies from amorphous, through fine powder, rough powder, holocrystalline to single crystals, as well as mixed forms, such as powder and holocrystalline, or amorphous and holocrystalline. The relieves on the surface of the spherules reflect the size and shape of the crystallites. The morphology of the spherules, their chemical composition and structure have been characterized and discussed in relation to the Morasko-Meteorite fall, and possible other cosmic, geological or anthropogenic origins.     

Recent geological and hydrological activity on Mars: The Tharsis/Elysium corridor

The paradigm of an ancient warm, wet, and dynamically active Mars, which transitioned into a cold, dry, and internally dead planet, has persisted up until recently despite published Viking-based geologic maps that indicate geologic and hydrologic activity extending into the Late Amazonian epoch. This paradigm is shifting to a water-enriched planet, which may still exhibit internal activity, based on a collection of geologic, hydrologic, topographic, chemical, and elemental evidences obtained by the Viking, Mars Global Surveyor (MGS), Mars Odyssey (MO), Mars Exploration Rovers (MER), and Mars Express (MEx) missions. The evidence includes: (1) stratigraphically young rock materials such as pristine lava flows with few, if any, superposed impact craters; (2) tectonic features that cut stratigraphically young materials; (3) features with possible aqueous origin such as structurally controlled channels that dissect stratigraphically young materials and anastomosing-patterned slope streaks on hillslopes; (4) spatially varying elemental abundances for such elements as hydrogen (H) and chlorine (Cl) recorded in rock materials up to 0.33 m depth; and (5) regions of elevated atmospheric methane. This evidence is pronounced in parts of Tharsis, Elysium, and the region that straddles the two volcanic provinces, collectively referred to here as the Tharsis/Elysium corridor. Based in part on field investigations of Solfatara Crater, Italy, recommended as a suitable terrestrial analog, the Tharsis/Elysium corridor should be considered a prime target for Mars Reconnaissance Orbiter (MRO) investigations and future science-driven exploration to investigate whether Mars is internally and hydrologically active at the present time, and whether the persistence of this activity has resulted in biologic activity.     

Lidar and the mobile Scene Modeler (mSM) as scientific tools for planetary exploration

With the continued success of the Mars Exploration Rovers and the return of humans to the Moon within the next decade, a considerable amount of research is being done on the technologies required to provide surface mobility and the tools required to provide scientific capability. Here, we explore the utility of lidar and the mobile Scene Modeler (mSM) - which is based on a stereo camera system - as scientific tools. Both of these technologies have been, or are being considered for, technological applications such as autonomous satellite rendezvous and rover navigation. We carried out a series of field tests at the 23 km diameter, 39 Ma, Haughton impact structure located on Devon Island in the Canadian Arctic. Several sites of geological interest were investigated, including polygonal terrain, gullies and channels, slump/collapse features, impact melt breccia hills, and a site of impact-associated hydrothermal mineralization. These field tests show that lidar and mSM provide a superior visual record of the terrain, from the regional (km) to outcrop (m to cm) scale and in 3-D, as compared to standard digital photography. Thus, a key strength of these technologies is in situ reconnaissance and documentation. Lidar scans also provide a wealth of geometric and structural information about a site, accomplishing the equivalent of weeks to months of manual surveying and with much greater accuracy than traditional tools, making this extremely useful for planetary exploration missions. An unexpected result of these field tests is the potential for lidar and mSM to provide qualitative, and potentially quantitative, composition information about a site. Given the high probability of lidar and mSM being used on future lunar missions, we suggest that it would be beneficial to further investigate the potential for these technologies to be used as science tools.     

Fe Mössbauer spectroscopy as a tool in astrobiology

The element Fe and Fe-bearing minerals occur ubiquitously throughout the field of astrobiology. Cycling between the various oxidation states of Fe provides a source of energy available for life. Banded iron formations may record the rise of oxygenic photosynthesis. The distribution of Fe between Fe-bearing minerals and its oxidation states can help to characterize and understand ancient environments with respect to the suitability for life by constraining the primary rock type and the redox conditions under which it crystallized, the extent of alteration and weathering, the type of alteration and weathering products, and the processes and environmental conditions for alteration and weathering. Fe Mössbauer spectroscopy is a powerful tool to investigate Fe-bearing compounds. It can identify Fe-bearing minerals, determine Fe oxidation states with high accuracy, quantify the distribution of Fe between mineralogical phases, and provide clues about crystallinity and particle sizes. Two miniaturized Mössbauer spectrometers are on board of the NASA Mars Exploration Rovers Spirit and Opportunity. The Fe-bearing minerals goethite, an iron oxide-hydroxide, and jarosite, an iron hydroxide sulfate, were identified by Mössbauer spectroscopy in Gusev Crater and at Meridiani Planum, respectively, providing in situ proof of an aqueous history of the two landing sites and constraints on their habitability. Hematite identified by Mössbauer spectroscopy at both landing sites adds further evidence for an aqueous history. On Earth, Mössbauer spectroscopy was used to monitor possibly microbially-induced changes of Fe-oxidation states in basaltic glass samples exposed at the Loihi Seamount, a deep sea hydrothermal vent system, which might be analogous to possible extraterrestrial habitats on ancient Mars or the Jovian moon Europa today.     

Mercury's sodium exosphere

Mercury's neutral sodium exosphere is simulated using a comprehensive 3D Monte Carlo model following sodium atoms ejected from Mercury's surface by thermal desorption, photon stimulated desorption, micro-meteoroid vaporization and solar wind sputtering. The evolution of the sodium surface density with respect to Mercury's rotation and its motion around the Sun is taken into account by considering enrichment processes due to surface trapping of neutrals and ions and depletion of the sodium available for ejection from the surfaces of grains. The change in the sodium exosphere is calculated during one Mercury year taking into account the variations in the solar radiation pressure, the photo-ionization frequency, the solar wind density, the photon and meteoroid flux intensities, and the surface temperature. Line-of-sight column densities at different phase angles, the supply rate of new sodium, average neutral and ion losses over a Mercury year, surface density distribution and the importance of the different processes of ejection are discussed in this paper. The sodium surface density distribution is found to become significantly nonuniform from day to night sides, from low to high latitudes and from morning to afternoon because of rapid depletion of sodium atoms in the surfaces of grains mainly driven by thermal depletion. The shape of the exosphere, as it would be seen from the Earth, changes drastically with respect to Mercury's heliocentric position. High latitude column density maxima are related to maxima in the sodium surface concentration at high latitudes in Mercury's surface and are not necessarily due to solar wind sputtering. The ratio between the sodium column density on the morning side of Mercury's exosphere and the sodium column density on the afternoon side is consistent with the conclusions of Sprague et al. (1997, Icarus 129, 506-527). The model, which has no fitting parameters, shows surprisingly good agreement with recent observations of Potter et al. (2002, Meteor. Planet. Sci. 8, 3357-3374) successfully explaining their velocity and column density profiles vs. heliocentric distance. Comparison with this data allows us to constrain the supply rate of new sodium atoms to the surface. We also discuss the possible origins of the strong high latitude emissions (Potter and Morgan, 1990, Science 248, 835-838; 1997a, Adv. Space Res. 19, 1571-1576; 1997b, Planet. Space Sci. 45, 95-100; Sprague et al., 1998, Icarus 135, 60-68) and the strong variations of the total content of the sodium exosphere on short (Potter et al., 1999, Planet. Space Sci. 47, 1441-1449) and long time scales (Sprague et al., 1997, Icarus 129, 506-527).     

Geomorphic knobs of Candor Chasma, Mars: New Mars Reconnaissance Orbiter data and comparisons to terrestrial analogs

High Resolution Imaging Science Experiment (HiRISE) imagery and digital elevation models of the Candor Chasma region of Valles Marineris, Mars, reveal prominent and distinctive positive-relief knobs amidst light-toned layers. Three classifications of knobs, Types 1, 2, and 3, are distinguished from a combination of HiRISE and Thermal Emission Imaging System (THEMIS) images based on physical expressions (geometries, spatial relationships), and spectral data from Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Type 1 knobs are abundant, concentrated, topographically resistant features with their highest frequency in West Candor, which have consistent stratigraphic correlations of the peak altitude (height). These Type 1 knobs could be erosional remnants of a simple dissected terrain, possibly derived from a more continuous, resistant, capping layer of pre-existing material diagenetically altered through recrystallization or cementation. Types 2 and 3 knobs are not linked to a single stratigraphic layer and are generally solitary to isolated, with variable heights. Type 3 are the largest knobs at nearly an order of magnitude larger than Type 1 knobs. The variable sizes and occasional pits on the tops of Type 2 and 3 knobs suggest a different origin, possibly related to more developed erosion, preferential cementation, or textural differences from sediment/water injection or intrusion, or from a buried impact crater. Enhanced color HiRISE images show a brown coloration of the knob peak crests that is attributable to processing and photometric effects; CRISM data do not show any detectable spectral differences between the knobs and the host rock layers, other than albedo. These intriguing knobs hold important clues to deducing relative rock properties, timing of events, and weathering conditions of Mars history.     

Significant science at Titan and Neptune from aerocaptured missions

In 2001, NASA began assembling the Aerocapture Systems Analysis Team, a team of scientists and engineers from multiple NASA centers. Their charter is to perform high-fidelity analyses of delivering scientifically compelling orbital missions that use aerocapture for orbit insertion at their destinations. After establishing scientific credibility, studies focus on aerocapture systems design and performance, including approach navigation, flight mechanics, aerothermodynamics, and thermal protection. The team's October 2001-September 2002 study examined a mission to explore the organic environment of Titan and its chemical, geological, and dynamical context. Its architecture includes a Titan polar orbiter that would complete and extend Cassini's soon-to-begin global mapping, aiding global extrapolation of findings from a mobile in situ element (rover, blimp, etc.). The in situ element would perform remote sensing and in situ investigations, for analysis and characterization of Titan's surface, shallow subsurface, atmosphere, processes occurring there, and energy sources driving it all. The study concentrated on the orbiter and orbit insertion, largely treating the in situ element as a black box with data relay requirements. October 2002-September 2003 the team studied a mission to perform Cassini/Huygens-level exploration of the Neptune system. Before aerocapture this mission would deploy and support multiple Neptune atmospheric entry probes. After aerocapture the orbiter uses Triton as a “tour engine”, in much the same manner as Cassini uses Titan, to provide many Triton flybys and orbit evolution for detailed investigation of Neptune's interior, atmosphere, magnetosphere, rings, and satellites.This presentation summarizes the missions’ science objectives, instrumentation, and data requirements that served as the foundations for the studies, and describes mission design requirements and constraints that affect the science investigations.     

太阳表面磁场的分布与演化研究进展

太阳磁场、较差自转和内部对流使得日面磁场与磁活动在很大的时间尺度和空间尺度范围均表现得相当复杂.其中最有名的是太阳活动的11年周期,或22年磁周期.在较小时间尺度上,从几秒到几小时,有时太阳大气中会发生一些壮观的爆发事件,如耀斑、日珥爆发、日冕物质抛射等.所有这些形式的事件都与太阳磁场紧密关联.简单评述了太阳磁场起源与观测方法,重点论述了不同尺度太阳磁场的空间分布与演化,介绍了从太阳磁活动现象统计得到的有关太阳磁场的几个典型特征,同时讨论了进一步研究的方向.     

实验室X射线天体物理

正在进行的实验室天体物理测量解决了X射线天文学的一些问题，这些实验产生了大量可靠的原子数据，它们既可用于电荷分布中电离与复合截面的计算，又可用于对X射线谱线形成的线表、激发截面及双电子复合系数的理解。另有一部分实验注重于解决天体观测的难题，以及验证现有的和寻找新的X射线谱线诊断。讨论了上述实验产生的数据类型，并展示了实验室测量如何为卫星（ASCA、EUVE、Chandra、XMM和ASTRO-E2）观测提供实验依据．     

The High Resolution Imaging Science Experiment (HiRISE) during MRO’s Primary Science Phase (PSP)

The High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO) acquired 8 terapixels of data in 9137 images of Mars between October 2006 and December 2008, covering ∼0.55% of the surface. Images are typically 5-6 km wide with 3-color coverage over the central 20% of the swath, and their scales usually range from 25 to 60 cm/pixel. Nine hundred and sixty stereo pairs were acquired and more than 50 digital terrain models (DTMs) completed; these data have led to some of the most significant science results. New methods to measure and correct distortions due to pointing jitter facilitate topographic and change-detection studies at sub-meter scales. Recent results address Noachian bedrock stratigraphy, fluvially deposited fans in craters and in or near Valles Marineris, groundwater flow in fractures and porous media, quasi-periodic layering in polar and non-polar deposits, tectonic history of west Candor Chasma, geometry of clay-rich deposits near and within Mawrth Vallis, dynamics of flood lavas in the Cerberus Palus region, evidence for pyroclastic deposits, columnar jointing in lava flows, recent collapse pits, evidence for water in well-preserved impact craters, newly discovered large rayed craters, and glacial and periglacial processes. Of particular interest are ongoing processes such as those driven by the wind, impact cratering, avalanches of dust and/or frost, relatively bright deposits on steep gullied slopes, and the dynamic seasonal processes over polar regions. HiRISE has acquired hundreds of large images of past, present and potential future landing sites and has contributed to scientific and engineering studies of those sites. Warming the focal-plane electronics prior to imaging has mitigated an instrument anomaly that produces bad data under cold operating conditions.     

Algorithm Analysis of Autonomous Navigation of Spacecraft Based on X-ray Pulsars

A pulsar has the very stable rotation and can be used as the time standard. The astrometric parameters and astrophysical parameters of many pulsars, such as the spatial position, proper motion, distance, rotation period and its derivative, etc., can be all accurately determined. Since the pulsar can provide the time signal and the coordinates of its spatial position simultaneously, the pulsar navigation system installed on a spacecraft enables the autonomous navigation of the spacecraft to be realized. Firstly, the position of the spacecraft is predicted based on the equation of orbit dynamics of the spacecraft and then the Kalman filtering is applied to calculating the estimation error of the spacecraft position through the difference between the pulse arrival time observed on the spacecraft and the predicted pulse arrival time, thereby modifying the position of the spacecraft. Finally, the effects of the initial error, measuring accuracy of the pulse arrival time and number of pulsars on the navigation accuracy are analyzed.