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The exploration of small bodies in our solar system is of great interest for the planetary science community due to their high scientific value. However, their generally weak and irregular gravity fields increase the difficulty associated with close proximity operations. Moreover, solar radiation pressure (SRP) can significantly perturb the motion of objects in their vicinity, particularly for bodies with high area-to-mass ratios. In this work, we adopt the polyhedral gravity model and identify natural dynamical structures that can be used for mission operations. Further, we study forced periodic motion in the body fixed frame while accounting for the effect of SRP with eclipses. Overall, our work seeks to identify suitable orbits and locations in the vicinity of small bodies that can be exploited for the design of science orbits. To obtain periodic orbits in the model accounting for SRP perturbations, we use a Melnikov function to find orbits that satisfy resonances with the asteroid spin and show no net change in energy over the orbit. We then use a differential correction scheme to find numerical solutions in the time-periodic model. Our test cases are potentially hazardous asteroid 101955 Bennu and main belt asteroid 16 Psyche. [ABSTRACT FROM AUTHOR]

7P/Pons–Winnecke is a near-Earth short-period comet of a moderate activity level. In this paper, we present the analysis of observations performed during a favorable apparition of the comet in 2021, indicating its status as a transitional ageing comet. The sublimation starts when the comet is close to the Sun, at a distance of RON = 1.76 ± 0.1 AU, and continues for ~13 months, which is apparently caused by residual reserves of water ice. The dust production rate of the comet is not high even at perihelion (<150 kg/s), and the 1.4-percent active portion of the nucleus area is sufficient to provide this mass loss. The photometric age of the comet is PAGE = 54.4 comet years; being combined with a light curve amplitude of ASEC(1;1) = 5.5m, this age corresponds to the state of a transitional middle-aged comet. [ABSTRACT FROM AUTHOR]

The paper discusses priority scientific tasks related to the study of small bodies in the Solar System, identifies the most promising objects for investigation from a spacecraft on a flyby trajectory and the sample return mission, and develops proposals for the preliminary composition of scientific instruments for remote asteroid research methods. A long-term and phased Russian scientific program for studying small Solar System bodies using spacecraft with electric propulsion has been proposed. The project is designed in such a way as to explore the largest number of scientifically interesting asteroids using a smaller number of spacecraft. A design concept for a small spacecraft to investigate near-Earth asteroids on a flyby trajectory and a main spacecraft for studying metallic asteroids in the Main Belt and sample sample return has been developed. A ballistic analysis of the flyby of five near-Earth asteroids and three metallic asteroids in the Main Belt is presented, as well as a ballistic analysis of the sample return mission from a Main Belt asteroid. The option of sample return using the nuclear tug Zevs is also considered. [ABSTRACT FROM AUTHOR]

In the last decades, we have seen a rapid increment in the use of finite-time chaos indicators in celestial mechanics. They have been used to analyze the complex dynamics of planetary systems, of minor planets and of space debris. In fact, theoretical studies on fundamental dynamical models have revealed that, computed on short time intervals, they allow to efficiently detect resonances, represent the phase portraits of complex dynamics, compute center-stable-unstable manifolds as well as Lagrangian coherent structures. In this paper, we focus on applications of the fast Lyapunov indicator (FLI) and review through examples why its computation is particularly powerful for those systems whose solutions may have an asymptotic behavior very different from the short-term one, as it is the case of sequences of close encounters in gravitational systems and the advection of particles in aperiodic flows. The main case study here considered is the computation of the manifold tubes and the related transit orbits in the restricted three-body problem. We also provide a new application of the FLI to a complex problem of planetary hydrodynamics, such as the detection of the stable and unstable manifolds guiding the motions of particles advected by the gas of a protoplanetary nebula. [ABSTRACT FROM AUTHOR]

The surface geology of Jupiter's Trojan asteroids is one of the scientific investigations of the NASA Lucy mission. A dedicated Geology Working Group will implement these studies using primarily panchromatic and color imaging data and complement the interpretation of these data with theoretical models, such as collisional evolution models. The Lucy Science Team will also rely on experience and lessons learned from prior space missions, such as NASA's NEAR, Dawn, OSIRIS-REx, and New Horizons. A chief goal of the Geology Working Group is to map craters and characterize their morphology across Lucy target's surfaces over a range of spatial resolutions. These data will be used to constrain the relative and absolute ages of terrains and their impactor size-frequency distributions. More broadly, impact-related processes such as excavation and mass wasting will inform other investigations, including geological unit mapping, stratigraphy and topography, surface composition, and internal structure. Lucy's cratering data and morphology will also be used to perform comparative analyses with similar data from other small bodies across the Solar System, from Main Belt asteroids to Kuiper Belt objects. The present article provides an overview of the planned activities and methodologies of the Geology Working Group. [ABSTRACT FROM AUTHOR]

Comets are considered the most primitive planetary bodies in our Solar System. ESA's Rosetta mission to Jupiter family comet 67P/Churyumov-Gerasimenko (67P/CG) has provided a wealth of isotope data which expanded the existing data sets on isotopic compositions of comets considerably. In a previous paper (Hoppe et al. in Space Sci. Rev. 214:106, 2018) we reviewed the results for comet 67P/CG from the first four years of data reduction after arrival of Rosetta at the comet in August 2014 and discussed them in the context of respective meteorite data. Since then important new isotope data of several elements, among them the biogenic elements H, C, N, and O, for comet 67P/CG, the Tagish Lake meteorite, and C-type asteroid Ryugu became available which provide new insights into the formation conditions of small planetary bodies in the Solar System's earliest history. To complement the picture on comet 67P/CG and its context to other primitive Solar System materials, especially meteorites, that emerged from our previous paper, we review here the isotopic compositions of H, C, and N in various volatile molecules, of O in water and a suite of other molecules, of the halogens Cl and Br, and of the noble gas Kr in comet 67P/CG. Furthermore, we also review the H isotope data obtained in the refractory organics of the dust grains collected in the coma of 67P/CG. These data are compared with the respective meteoritic and Ryugu data and spectroscopic observations of other comets and extra-solar environments; Cl, Br, and Kr data are also evaluated in the context of a potential late supernova contribution, as suggested by the Si- and S-isotopic data of 67P/CG. [ABSTRACT FROM AUTHOR]

Photogeologic principles can be used to suggest possible sequences of events that result in the present planetary surface. The most common method of evaluating the absolute age of a planetary surface remotely is to count the number of impact craters that have occurred after the surface formed, with the assumption that the craters occur in a spatially random fashion over time. Using additional assumptions, craters that have been partially modified by later geologic activity can be used to assess the time frames for an interpreted sequence of events. The total number of craters on Venus is low and the spatial distribution taken by itself is nearly indistinguishable from random. The overall implication is that the Venusian surface is much closer to Earth in its youthfulness than the other, smaller inner solar system bodies. There are differing interpretations of the extent to which volcanism and tectonics have modified the craters and of the regional and global sequences of geologic events. Consequently, a spectrum of global resurfacing views has emerged. These range from a planet that has evolved to have limited current volcanism and tectonics concentrated in a few zones to a planet with Earth-like levels of activity occurring everywhere at similar rates but in different ways. Analyses of the geologic record have provided observations that are challenging to reconcile with either of the endmember views. The interpretation of a global evolution with time in the nature of geologic activity relies on assumptions that have been challenged, but there are other observations of areally extensive short-lived features such as canali that are challenging to reconcile with a view of different regions evolving independently. Future data, especially high-resolution imaging and topography, can provide the details to resolve some of the issues. These different global-evolution viewpoints must tie to assessments of present-day volcanic and tectonic activity levels that can be made with the data from upcoming missions. [ABSTRACT FROM AUTHOR]

Abstract—The formation of basalts is a global stage in the evolution of differentiated cosmic body (planet or asteroid) of the Solar System. The paper presents the main chemical and mineralogical features of basaltic meteorites of the SNC, HED group, angrites and lunar mare basalts based on literature data. Despite the differences in the products of basaltic volcanism on different cosmic bodies and significant compositional variations in major minerals of basaltic rocks, most of them belong to low-alkaline basalts, suggesting the prevalence of this type of rocks at least among small bodies of the Solar System. All of them are characterized by the presence of such rock-forming minerals as pyroxene, olivine, and plagioclase, and their spectral characteristics can be used to search for basalts on exoplanets. The main factors affecting the spectral characteristics of atmosphere-free bodies and larger planets with an atmosphere are shown, and the possibility of searching for products of basalt volcanism on exoplanets during future missions is considered. [ABSTRACT FROM AUTHOR]

The thermophysical properties of small Solar System bodies are essential to be determined, on which the thermal evolution of small bodies largely depends. The carbonaceous asteroid Ryugu is one of the small undifferentiated bodies formed in the early Solar System. Hayabusa2 explored the asteroid Ryugu and returned the surface samples in 2020 for detailed on-ground investigation, including measurements of thermal properties. Because the available sample amount was limited, this study developed a novel method to measure the thermal diffusivity of small and irregularly shaped samples of about 1 mm in diameter by combining lock-in thermography and periodic heating methods on the microscale. This method enables us to measure the thermal diffusivity of both flat-plate and granular shape samples by selecting the suitable detecting direction of the temperature response. Especially, when the sample has a flat-plate shape, the anisotropic distribution of the in-plane thermal diffusivity can be evaluated. This method was applied to six Ryugu samples, and the detailed anisotropic distribution of the thermal diffusivity was obtained. The measurement results showed that the samples show local thermal anisotropy caused by cracks and voids. The average thermal diffusivity among all samples was (2.8 to 5.8) × 10−7 m2·s. Based on the density and specific heat of the samples obtained independently, the thermal effusivity was estimated to be 791 J·(s1/2·m2·K) to 1253 J·(s1/2·m2·K), which is defined as the resistance of surface temperature to the change of thermal input. The determined thermal effusivity, often called thermal inertia in planetary science, is larger than the observed value of 225 ± 45 J· (s1/2·m2·K) of the asteroid Ryugu's surface, obtained from the diurnal temperature change of the rotating asteroid by a thermal infrared camera onboard Hayabuas2. This difference is likely to be attributed to the difference in the analytical scale between the sample and the surface boulders compared with the thermal diffusion length. Consequently, it was found that the present result is more representative of the thermal diffusivity and thermal inertia of local part of individual Ryugu particles. [ABSTRACT FROM AUTHOR]

The orbit of an active asteroid (457175) 2008 GO98/362P was obtained taking into account non-gravitational acceleration based on the Marsden model. The presence of systematic deviations was revealed in the 2016 observations prior to the cometary activity. The possibility of a collision with a minor body was considered. For this, the momenta of reaching the minimum distances (MOID, Minimum Orbit Intersection Distance) between the orbits of the asteroid (457175) and 585 961 numbered, and 536 561 unnumbered asteroids (according to the status in the Minor Planet Center catalogs of observations as of October 2021) were found. The maximum number of orbital rendezvouses falls on the time when the asteroid was passing in the vicinity of the ascending node, which suggests the possibility of a collision leading to the fragmentation of the main body. Two separation scenarios are considered and orbit variation of the main body and possible fragments are estimated. For the formed fragment, the heliocentric velocity variation amounted to m s and non-gravitational acceleration was AU day . The main body dynamics did not vary significantly. [ABSTRACT FROM AUTHOR]

The last thirty years of cosmochemistry and planetary science have shown that one major Solar System reservoir is vastly undersampled in the available suite of extra-terrestrial materials, namely small bodies that formed in the outer Solar System (>10 AU). Because various dynamical evolutionary processes have modified their initial orbits (e.g., giant planet migration, resonances), these objects can be found today across the entire Solar System as P/D near-Earth and main-belt asteroids, Jupiter and Neptune Trojans, comets, Centaurs, and small (diameter < 200 km) trans-Neptunian objects. This reservoir is of tremendous interest, as it is recognized as the least processed since the dawn of the Solar System and thus the closest to the starting materials from which the Solar System formed. Some of the next major breakthroughs in planetary science will come from studying outer Solar System samples (volatiles and refractory constituents) in the laboratory. Yet, this can only be achieved by an L-class mission that directly collects and returns to Earth materials from this reservoir. It is thus not surprising that two White Papers advocating a sample return mission of a primitive Solar System small body (ideally a comet) were submitted to ESA in response to its Voyage 2050 call for ideas for future L-class missions in the 2035-2050 time frame. One of these two White Papers is presented in this article. [ABSTRACT FROM AUTHOR]

Impacts by small solar system bodies (meteoroids, asteroids, comets and transitional objects) are characterized by a combination of energy dynamics and chemical modification on both terrestrial and small solar system bodies. In this context, the discovery of glycine amino acid in meteorites and comets has led to a hypothesis that impacts by astronomical bodies could contribute to delivery and polymerization of amino acids in the early Earth to generate proteins as essential molecules for life. Besides the possibility of abiotic polymerization of glycine, its decomposition by impacts could generate reactive groups to form other essential organic biomolecules. In this study, the high-pressure torsion (HPT) method, as a new platform for simulation of impacts by small solar system bodies, was applied to glycine. In comparison with high-pressure shock experiments, the HPT method simultaneously introduces high pressure and deformation strain. It was found that glycine was not polymerized in the experimental condition assayed, but partially decomposed to ethanol under pressures of 1 and 6 GPa and shear strains of < 120 m/m. The detection of ethanol implies the inherent availability of remaining nitrogen-containing groups, which can incorporate to the formation of other organic molecules at the impact site. In addition, this finding highlights a possibility of the origin of ethanol previously detected in comets. [ABSTRACT FROM AUTHOR]

The star β Pictoris harbors a young planetary system of about 20 million years old, which is characterized by the presence of a gaseous and dusty debris disk, at least two massive planets and many minor bodies. For more than thirty years, exocomets transiting the star have been detected using spectroscopy, probing the gaseous part of the cometary comas and tails. The detection of the dusty component of the tails can be performed through photometric observations of the transits. Since 2018, the Transiting Exoplanet Survey Satellite has observed β Pic for a total of 156 days. Here we report an analysis of the TESS photometric data set with the identification of a total of 30 transits of exocomets. Our statistical analysis shows that the number of transiting exocomet events (N) as a function of the absorption depth (AD) in the light curve follows a power law in the form d N (A D) ∝ A D - α , where α = 2.3 ± 0.4 . This distribution of absorption depth leads to a differential comet size distribution proportional to R - γ , where γ = 3.6 ± 0.8 , showing a striking similarity to the size distribution of comets in the Solar system and the distribution of a collisionally relaxed population ( γ D = 3.5 ). [ABSTRACT FROM AUTHOR]

Abstract—The mass of the asteroid () is determined by the dynamic method based on the analysis of gravitational perturbations in the motion of the asteroid (7562) Kagiroino–Oka caused by asteroid (7348). The choice of these asteroids is due to the fact that on March , they approached each other at a distance of about 1060 km. The diameter of the asteroid () is estimated at km. The coordinates of the major planets were calculated according to the DE440 ephemeris. Perturbations from dwarf planets and minor bodies included in the ephemeris model were also taken into account with the masses adopted in this ephemeris. Additionally, perturbations from asteroids () and () that had close encounters with () during the considered time interval were also taken into account. In the analysis of the orbit of (), Minor Planet Center catalog optical observations from the – interval were used. These observations were supplemented with observations from Gaia (DR2) space observatory obtained in – . As a result of solving the normal system with respect to the orbital parameter corrections for asteroid (7562) Kagiroino–Oka and the mass correction of (), the mass of () was derived as . Currently, it is the smallest asteroid the mass of which was determined by the dynamic method. [ABSTRACT FROM AUTHOR]

The dynamical environment in the close-proximity of small celestial bodies is characterized by a very weak and irregular gravity field. In this low-acceleration deep-space environment, small dynamical perturbations might affect significantly the dynamics of a spacecraft hovering near the surface of such objects. This poses a challenge to the efficient design of trajectories of space probes for space missions aimed at the exploration of small Solar System bodies. This applies especially to CubeSats, small spacecraft with limited autonomy and maneuvering capabilities. In this case, a careful and efficient design of the operational trajectory is mandatory to accomplish the objective of the mission. As a representative and timely case study, we investigate the dynamics around binary asteroid (65803) Didymos, the target of NASA's Double Asteroid Redirection Test (DART) and ESA's Hera missions. We analyze all the relevant dynamical contributions concurring to the acceleration environment near Didymos and provide a subdivision of it into subregions, each identified by a different dynamical regime. With reference to the Hera Milani CubeSat mission scenario, we describe the methodology and design approach to find trajectories in the dayside of Didymos system. Finally, we provide examples of suitable trajectory options to host the operational phase of the Hera Milani CubeSat. [ABSTRACT FROM AUTHOR]

A numerical-analytical method for analyzing the orbital evolution of a planetary satellite under the influence of a perturbing body moving in an elliptical orbit is described. In the averaged Gaussian scheme used this influence is replaced by the attraction of a material elliptical ring with the corresponding mass. Based on the closed analytical expression for the force function of such a ring derived by B.P. Kondrat'ev, we present formulas for the component of the attractive force acting on the planetary satellite. The method of numerical integration of the averaged equations in Keplerian elements is used to analyze the orbital evolution. We consider two methodological illustrative examples: Mercury as the main body, the Sun as the perturbing body, and an artificial Messenger-type satellite of Mercury; the Earth as the main body, the Moon and the Sun as the perturbing bodies, and a hypothetical artificial Earth satellite with its apogee outside the sphere with the radius of the lunar orbit. The described method can be used in evolution problems of celestial mechanics to study the perturbed motion of small Solar System bodies. [ABSTRACT FROM AUTHOR]

Chaotic motion affecting small bodies in the Solar system can be caused by close encounters or collisions or by resonance overlapping. Chaotic motion can be detected using approaches that measure the separation rate of trajectories that starts infinitesimally close or changes in the frequency power spectrum of time series, among others. In this work, we introduce an approach based on the autocorrelation function of time series, the ACF index (ACFI ). Autocorrelation coefficients measure the correlation of a time series with a lagged copy of itself. By measuring the fraction of autocorrelation coefficients obtained after a given time lag that are higher than the 5% null hypothesis threshold, we can determine how the time series autocorrelates with itself. This allows identifying unpredictable time series, characterized by low values of ACFI . Applications of ACFI to orbital regions affected by both types of chaos show that this method can correctly identify chaotic motion caused by resonance overlapping, but it is mostly blind to close encounters induced chaos. ACFI could be used in these regions to select the effects of resonance overlapping. [ABSTRACT FROM AUTHOR]

Early evolution of Solar System small bodies proceeded through interactions of mineral and water. Melting of water ice accreted with mineral particles to the parent body results in the formation of secondary minerals, the so-called aqueous alteration. Formation of phyllosilicates from anhydrous silicates is a typical alteration effect recorded in primitive meteorites. In addition to mineral and water, organic matter could have been also a significant component in meteorite parent bodies. However, the role of organic matter in the alteration of silicates is not well understood. We conducted a heating experiment of anhydrous silicate (olivine) with a mixture of organic compounds which simulated primordial organic matter in the Solar System. Dissolution and precipitation features were confirmed on the olivine surface after heating at 300 °C for 10 days, and proto-phyllosilicates were formed in the precipitation area. Magnesite was also detected as concomitant mineral phase. These minerals could be the evidence of aqueous alteration and carbonation of olivine induced by water generated through decomposition of the organic compounds with hydroxy groups. Our result showed that the in situ formation of hydrated silicates through a mineral–organic interaction without the initial presence of water. It further implies that formation of phyllosilicates on the olivine surface in contact with organic matter can occur in meteorite parent bodies which formed inside the H2O snow line but accreted with organic matter, initially without water. Water formed through decomposition of organic matter could be one candidate for hydrous silicate formation, for example, in ordinary chondrites from S-type asteroids inside the H2O snow line. Although the origin of water in ordinary chondrites is under debate, water generation from organic matter may also explain the D-rich water in ordinary chondrites because primordial organic matter is known to be D rich. [ABSTRACT FROM AUTHOR]

The "Bumerang" space mission to the satellites of Mars is discussed. The purpose of the mission is to study the satellites and return of soil samples from Phobos to the Earth. The previous such missions to Mars are revisited. To increase the chances of success of the "Bumerang" mission, it is proposed to carry out a preemptive demo flight to a small asteroid, ahead of the mission. The goal of this flight is to test the technological version of the mission's space complex while simultaneously obtaining scientific and applied information of independent and significant value. Results are presented of the studies on the outlook of the demo flight to the asteroid. [ABSTRACT FROM AUTHOR]

Asteroids and other Small Solar System Bodies (SSSBs) are of high general and scientific interest in many aspects. The origin, formation, and evolution of our Solar System (and other planetary systems) can be better understood by analysing the constitution and physical properties of small bodies in the Solar System. Currently, two space missions (Hayabusa2, OSIRIS-REx) have recently arrived at their respective targets and will bring a sample of the asteroids back to Earth. Other small body missions have also been selected by, or proposed to, space agencies. The threat posed to our planet by near-Earth objects (NEOs) is also considered at the international level, and this has prompted dedicated research on possible mitigation techniques. The DART mission, for example, will test the kinetic impact technique. Even ideas for industrial exploitation have risen during the last years. Lastly, the origin of water and life on Earth appears to be connected to asteroids. Hence, future space mission projects will undoubtedly target some asteroids or other SSSBs. In all these cases and research topics, specific knowledge of the structure and mechanical behaviour of the surface as well as the bulk of those celestial bodies is crucial. In contrast to large telluric planets and dwarf planets, a large proportion of such small bodies is believed to consist of gravitational aggregates ('rubble piles') with no—or low—internal cohesion, with varying macro-porosity and surface properties (from smooth regolith covered terrain, to very rough collection of boulders), and varying topography (craters, depressions, ridges). Bodies with such structure can sustain some plastic deformation without being disrupted in contrast to the classical visco-elastic models that are generally valid for planets, dwarf planets, and large satellites. These SSSBs are hence better described through granular mechanics theories, which have been a subject of intense theoretical, experimental, and numerical research over the last four decades. This being the case, it has been necessary to use the theoretical, numerical and experimental tools developed within soil mechanics, granular dynamics, celestial mechanics, chemistry, condensed matter physics, planetary and computer sciences, to name the main ones, in order to understand the data collected and analysed by observational astronomy (visible, thermal, and radio), and different space missions. In this paper, we present a review of the multi-disciplinary research carried out by these different scientific communities in an effort to study SSSBs. [ABSTRACT FROM AUTHOR]

At the beginning of this century, the SOHO space observatory discovered near-Sun comets with perihelion distances q ≈ 0.05 AU, which remained observable over several close encounters with the Sun. This became one of the surprises in studying the small bodies of the Solar System. Currently, there are objects that have already been observed in four (342P) and five (321P, 322P, and 323P) apparitions. In the present work, the estimates of nongravitational effects are obtained for these objects based on the pair-wise linkage of the apparitions. The calculations show that the observations of these objects are poorly represented if solely the gravitational forces are considered. The magnitude of nongravitational effects in the semimajor axis noticeably changes with time. The motion of all comets is significantly affected by the components of nongravitational forces that are perpendicular to the orbital plane. [ABSTRACT FROM AUTHOR]

A systematic analysis ofmethods for computing the trajectories of solid-phase particles applied in modern astrophysics codes designed for modeling gas-dust circumstellar disks has been carried out for the first time. Themotion of grains whose velocities are determinedmainly by the gas drag, that is, for which the stopping time or relaxation time for the velocity of the dust to the velocity of the gas t is less than or comparable to the rotation period, are considered. The methods are analyzed from the point of view of their suitability for computing the motions of small bodies, including dust grains less than 1 μm in size, which are strongly coupled to the gas. Two test problems are with analytical solutions. Fast first order accurate methods that make it possible to avoid additional restrictions on the time step size τ due to gas drag in computations of the motion of grains of any size are presented. For the conditions of a circumstellar disk, the error in the velocity computations obtained when using some stable methods becomes unacceptably large when the time step size is τ > t . For the radial migration of bodies that exhibit drifts along nearly Keplerian orbits, an asymptotic approximation, sometimes called the short friction time approximation or drift flux model, gives a relative error for the radial-velocity computations equals to St , where St is the Stokes number, the ratio of the stopping time of the body to some fraction of the rotation period (dynamical time scale) in the disk. [ABSTRACT FROM AUTHOR]

On June 12 1996 UT, three 11-12 R magnitude stars were occulted by comet Hale-Bopp. The passage of these stars through the cometary atmosphere was monitored at the Observatorio do Pico dos Dias (Brazil) using a 0.6 m telescope. We detected an absorption of starlight by the comet dust implying in a drop of $$(6\pm 1) \times 10^{-2}$$ magnitude of occulted star XPM 152-0898466 at a minimum distance of ( $$4.3 \pm 0.2)\times 10^{4}$$ km from the central condensation. This result, combined with magnitude variations of other stars, suggests the detection of a jet in the coma. From our measurement of extinction, we infer that the opacity of the nucleus surface was $$\tau \sim 3$$ . The mean geometric albedo p of dust grains is $$(4.5 \pm 0.7) \times 10^{-3}$$ . This low albedo may suggest a difference in the grain population associated to coma and jets. [ABSTRACT FROM AUTHOR]

The telescope SBG ( D = 0.42 m, F = 0.76 m) at the Kourovka Astronomical Observatory of the Ural Federal University has undergone an upgrade in 2005-2006. A CCD camera (Apogee Alta U32) and a new drive system were installed, and a new system for telescope and observation control was implemented. This upgrade required verifying the astrometric quality of the telescope. The data processing approaches tested when searching for the optimum CCD image processing technique combined TYCHO2 and UCAC2 catalogues with various reduction models and methods for choosing reference stars. Lorentzian and Moffat profiles were used in the measurement of pixel coordinates. It was demonstrated that the accuracy of SBG observations of main-belt asteroids with precisely determined orbits depends on their brightness and varies from 0.06' (11.5) to 0.4' (18.5). Regular SBG observations of comets and asteroids (mostly near-Earth and potentially hazardous ones) have been performed since 2007. Coordinates of 8515 positions of 720 asteroids and more than 1000 positions of 40 comets were obtained. The RMS deviations of observed coordinates from their calculated values are typically smaller than 1': the average deviations for asteroids are 0.33' (in right ascension) and 0.34' (in declination); the corresponding values for comets are 0.37' (in α) and 0.38' (in δ). The results of observations are sent to the Minor Planet Center and are used to determine orbits more accurately and solve other fundamental and applied problems. [ABSTRACT FROM AUTHOR]

The most relevant tasks associated with the problem of asteroid-comet hazard are discussed. A review is given of the respective research at the Institute of Applied Astronomy. The institute is currently implementing a project to create an information center whose tasks include the collection and processing of optical and radar observations of small solar system bodies, determination of their orbits, and assessment of the impact hazard of the newly discovered small bodies with respect to the earth, moon, and the other major planets and their satellites. [ABSTRACT FROM AUTHOR]

Orbital dynamics around small bodies are as varied as the shapes and dynamical states of these bodies. While various classes of orbits have been analyzed in detail, the global overview of relevant ballistic orbits at particular bodies is not easily computed or organized. Yet, correctly categorizing these orbits will ease their future use in the overall trajectory design process. This paper overviews methods that have been used to organize orbits, focusing on periodic orbits in particular, and introduces new methods based on clustering approaches. [ABSTRACT FROM AUTHOR]

It is expected that a non-trivial percentage of small bodies that future missions may visit are in non-principal axis rotation (i.e. 'tumbling'). The primary contribution of this paper is the application of the Extended Kalman Filter (EKF) Simultaneous Localization and Mapping (SLAM) method to estimate the small body spin state, mass, and moments of inertia; the spacecraft position and velocity; and the surface landmark locations. The method uses optical landmark measurements, and an example scenario based on the Rosetta mission is used. The SLAM method proves effective, with order of magnitude decreases in the spacecraft and small body spin state errors after less than a quarter of the comet characterization phase. The SLAM method converges nicely for initial small body angular velocity errors several times larger than the true rates (effectively having no a priori knowledge of the angular velocity). Surface landmark generation and identification are not treated in this work, but significant errors in the initial body-fixed landmark positions are effectively estimated. The algorithm remains effective for a range of different truth spin states, masses, and center of mass offsets that correspond to expected tumbling small bodies throughout the solar system. [ABSTRACT FROM AUTHOR]

A geometric approach to select small bodies as the candidates for low-speed encounters with planets is developed. On the plane 'semimajor axis-eccentricity' of initial conditions the areas have been found for the orbits of small bodies where they may experience low-speed encounters with planets. The values of the Tisserand constant of a small body relative to a planet which admits the low-speed encounters have been determined. [ABSTRACT FROM AUTHOR]

A kinematic approach is developed to qualitative analysis of characteristics of a low-speed encounter of a small body with a planet. A classification of encounters of small bodies with planets based on the magnitude of planetocentric speed is proposed. The concept of the points of low-speed quasi-tangency of orbits of small bodies and planets is introduced. Based on this concept, the definitions of the point of minimum planetocentric speed, a quasi-tangent low-velocity segment on the orbit of a small body, low-velocity and high-velocity encounters are formulated. A classification of encounters of small bodies with planets according to the global minimum of the function of planetocentric distance is also proposed. The classification is based on the concepts of the gravity sphere of action and the Hill sphere of the planet. The definitions of an area and duration of low-speed and high-speed encounters are given. [ABSTRACT FROM AUTHOR]

The CoLiTec software for the automated search for small celestial objects of the solar system on a series of CCD frames has been developed within the Ukrainian virtual observatory project. Four comets and more than a thousand asteroids were discovered using the software. It was also used to send approximately 700000 positional CCD measurements to the Minor Planet Center. In this paper, accuracy factors of positional CCD measurements using the CoLiTec software are analyzed according to data from the Minor Planet Center. The comparative analysis of these factors according to the results of the processing of the same frames using CoLiTec and Astrometrica software is also conducted. In the case of low signal to noise ratios, the standard deviation of positional CCD measurements using the Astrometrica software is 30-50% greater than that of the CoLiTec software. [ABSTRACT FROM AUTHOR]

The extension of Öpik's theory of close encounters developed in the last decades allows a fully analytical, quantitative treatment of the motion of a small body encountering a massive perturber on a circular orbit. In this paper we derive explicit expressions for the initial values of the angular elements of the small body orbit, of given semimajor axis, eccentricity and inclination, in order to obtain a post-encounter orbit with prescribed values of semimajor axis, eccentricity and inclination. We describe the geometrical aspects of the algorithm, and give two examples of application; the first of them concerns the geometry of the 2029 Earth encounter of Apophis, while the second illustrates a sequence of close encounters with Callisto of the JUICE probe, aimed at changing the inclination of the spacecraft orbit. In the planning of complex space missions involving multiple encounters with planets or satellites, the algorithm described in the paper could provide a reliable initial guess to start the computationally intensive optimization process. [ABSTRACT FROM AUTHOR]

This paper presents an automated algorithm to extract dynamical features, such as stability constraints, from phase space maps. The functional representation of these constraints allows their inclusion in optimization problems and thus expands the use of dynamical tools in space mission design. The challenge to autonomously detect the regions of interest in stability maps is discussed through utilizing image processing algorithms to cluster map data. Additionally, to use the detected regions, both discrete and smooth functional representations are studied. Based on similar clustering techniques that have been considered in extracting and representing features of phase space maps, we proposed an adaptively map generation algorithm. It creates a nonuniform grid of points on a map which is denser near the boundaries of the regions of interest. Both representation and map generation algorithms provide significant performance enhancements in phase space analysis. All these techniques are illustrated on examples of stability maps in small body dynamics. [ABSTRACT FROM AUTHOR]

The results of experimental and theoretical investigations of the operation and a two-stage light gas magnetoplasma launcher are presented. An optical method for measuring the velocity of small bodies (2-10 mm) has been developed and used in testing a combined gas discharger for micro- and macroparticle acceleration. The experimental results are in good agreement with the mathematical model of the two-stage light gas gun in the approximation of constancy of the accelerating pressure behind the striker. [ABSTRACT FROM AUTHOR]

The paper discusses two missions for studies of various typical Solar System small bodies. The first mission is intended to study the Martian satellites and will be completed by delivering soil samples to the Earth; the second will perform a comprehensive study of a small asteroid body and deliver a radio beacon to the latter. The similarity of the technological base for both missions that enables the use of a unified design baseline is analyzed. It is suggested that the missions be joined into an integrated program consisting of two stages and that their optimal sequence order be determined. [ABSTRACT FROM AUTHOR]

The D( a) distribution of asteroid sizes by their semimajor axes and the N( p) distribution of the number of asteroids by their albedo values for individual families are used to isolate the asteroid families more clearly. The families identified by Masiero et al. (2013) are analyzed with the use of these distributions, and correctly and incorrectly isolated families are found. A reduction in the mean albedo with increasing semimajor axis is observed for almost all correctly identified families that are not truncated by resonances. This reduction is statistically significant for the majority of these families. Not a single family exhibits a statistically significant increase in albedo. This confirms our previous conclusions that a nongravitational effect acting in the asteroid belt results in the spatial separation of asteroids with different albedos. [ABSTRACT FROM AUTHOR]

A universal method of determining the orbits of newly discovered small bodies in the Solar System using their positional observations has been developed. The proposed method suggests determining geocentric distances of a small body by means of an exhaustive search for heliocentric orbital planes and subsequent determination of the distance between the observer and the points at which the chosen plane intersects with the vectors pointing to the object. Further, the remaining orbital elements are determined using the classical Gauss method after eliminating those heliocentric distances that have a fortiori low probabilities. The obtained sets of elements are used to determine the rms between the observed and calculated positions. The sets of elements with the least rms are considered to be most probable for newly discovered small bodies. Afterwards, these elements are improved using the differential method. [ABSTRACT FROM AUTHOR]

The current concepts on the physical properties of the Jovian Trojans are reviewed in the paper. The distributions of rotation periods and light-curve amplitudes, the features of the phase dependencies of brightness, and the available data on the surface composition, density, diameters, and albedo of the Trojans are analyzed. The history of the discovery of Trojans, their dynamical properties, and the hypotheses on their origin are also briefly considered. A framework of the unsolved problems in the study of this population of small bodies is outlined. [ABSTRACT FROM AUTHOR]

This study continues our previous works on searching for the main source of the nuclei of Jupiter family comets (JFCs). Angular orbit element distributions are analyzed for comets and asteroids of different groups. The distributions of JFCs by argument of perihelion ω and longitude of perihelion π are studied. The distributions are shown not to have been formed during the evolution of JFCs in their current orbits. Similar distributions N(ω) and N(π) are not observed in bodies that have come into the JFC orbits from external sources. At the same time, the distributions of JFCs by all angular orbit elements are very similar to those of the Trojans. It is concluded that the latter are likely to be the main source of the JFC nuclei. [ABSTRACT FROM AUTHOR]

The knowledge of the physical and dynamical properties, distribution, formation, and evolution of small bodies is fundamental to understand how planet formation occurred and, even more importantly, if and how these objects have played a role in the apparition of life on Earth. In the last century, asteroids began to no longer appear as starlike points of light in our telescopes, but to be resolved worlds with distinctly measurable sizes, shapes, and surface morphologies. Only in the last 25 years, the exploration of small bodies by spacecraft has begun and revealed objects widely diverse in formation region, evolution and properties (e.g. shape, albedo density, gravity, regolith size distribution, and porosity). In this paper we will provide a chronological analysis of comet nuclei and asteroids as revealed by space missions. The real breakthrough began with the ESA Giotto mission in 1986 to the comet Halley, while the latest JAXA Hayabusa mission was devoted to hover above the small asteroid Itokawa with a touch-and-go for a sample return of asteroidal regolith. Comet and asteroid science stands at the threshold of a new exceptional era, with many new missions to be devoted to these widely diverse and still poorly known small bodies. [ABSTRACT FROM AUTHOR]

Comets are composed of dust and frozen gases. The ices are mixed with the refractory material either as an icy conglomerate, or as an aggregate of pre-solar grains (grains that existed prior to the formation of the Solar System), mantled by an ice layer. The presence of water-ice grains in periodic comets is now well established. Modelling of infrared spectra obtained about ten kilometres from the nucleus of comet Hartley 2 suggests that larger dust particles are being physically decoupled from fine-grained water-ice particles that may be aggregates, which supports the icy-conglomerate model. It is known that comets build up crusts of dust that are subsequently shed as they approach perihelion. Micrometre-sized interplanetary dust particles collected in the Earth's stratosphere and certain micrometeorites are assumed to be of cometary origin. Here we report that grains collected from the Jupiter-family comet 67P/Churyumov-Gerasimenko come from a dusty crust that quenches the material outflow activity at the comet surface. The larger grains (exceeding 50 micrometres across) are fluffy (with porosity over 50 per cent), and many shattered when collected on the target plate, suggesting that they are agglomerates of entities in the size range of interplanetary dust particles. Their surfaces are generally rich in sodium, which explains the high sodium abundance in cometary meteoroids. The particles collected to date therefore probably represent parent material of interplanetary dust particles. This argues against comet dust being composed of a silicate core mantled by organic refractory material and then by a mixture of water-dominated ices. At its previous recurrence (orbital period 6.5 years), the comet's dust production doubled when it was between 2.7 and 2.5 astronomical units from the Sun, indicating that this was when the nucleus shed its mantle. Once the mantle is shed, unprocessed material starts to supply the developing coma, radically changing its dust component, which then also contains icy grains, as detected during encounters with other comets closer to the Sun. [ABSTRACT FROM AUTHOR]

Over the course of the last decade, observations of highly inclined (orbital inclination i > 60 ∘ ) trans-Neptunian objects (TNOs) have posed an important challenge to current models of solar system formation (Levison et al. in Icarus 196(1):258–273, 2008; Nesvorný in Astron J 150:73, 2015). These remarkable minor planets necessitate the presence of a distant reservoir of strongly out-of-plane TNOs, which itself requires some dynamical production mechanism (Gladman et al. in Astron J Lett 697:L91–L94, 2009; Gomes et al. in Icarus 258:37–49, 2015; Batygin and Brown in Astrophys J 833(1):L3, 2016). A notable recent addition to the census of high-i minor bodies in the solar system is the retrograde asteroid 514107 Ka'epaoka'awela, which currently occupies a 1:-1 mean motion resonance with Jupiter at i = 163 ∘ (Wiegert et al. in Nature 543:687–689, 2017). In this work, we delineate a direct connection between retrograde Jupiter Trojans and high-i Centaurs. First, we backpropagate a large sample of clones of Ka'epaoka'awela for 100 Ma numerically and demonstrate that long-term stable clones tend to decrease their inclination steadily until it concentrates between 90 ∘ and 135 ∘ , while their eccentricity and semi-major axis increase, placing many of them firmly into the trans-Neptunian domain. Importantly, the clones show significant overlap with the synthetic high-i Centaurs generated in Planet 9 studies (Batygin et al. in Phys Rep 805:1–53, 2019), and hint at the existence of a relatively prominent, steady-state population of minor bodies occupying polar trans-Saturnian orbits. Second, through direct numerical forward modeling, we delineate the dynamical pathway through which conventional members of the Kuiper Belt's scattered disk population can become retrograde Jovian Trojan resonators in the presence of Planet 9. [ABSTRACT FROM AUTHOR]

Extreme-mass-ratio inspirals (EMRIs) are important gravitational-wave (GW) sources for future space-based detectors. The standard model consists of one stellar-mass black hole spiraling into a supermassive one, and such a process emits low-frequency (~10−3 Hz) GWs, which contain rich information about the space–time geometry around the central massive body. Here we show that the small bodies in EMRIs, in fact, could be binary black holes, which are captured by the massive black holes during earlier close encounters. About 30% of the captured binaries coalesce due to the perturbation by the massive bodies, resulting in a merger rate of 0.03 Gpc3 yr−1 in the most optimistic scenario. The coalescence generates also high-frequency (~102 Hz) GWs detectable by ground-based observatories, making these binary-EMRIs ideal targets for future multi-band GW observations. An extreme-mass-ratio inspiral, generally consists of a stellar-mass black hole and a supermassive black hole. The authors propose an alternative scenario where the small black hole is replaced by a binary black hole, and show how likely their gravitation wave signal can be detected, simultaneously, by LISA and LIGO. [ABSTRACT FROM AUTHOR]