Macroscopic Bodies Research Articles

Orbital dynamics in the vicinity of asteroid 4660 Nereus

Spacecrafts operating in close proximity to small celestial bodies within our Solar System, such as asteroids, face dynamic environments that differ significantly from those encountered in the near-Earth space. Understanding the characteristics of orbital dynamics in the vicinity of asteroids is essential for the successful execution of asteroid exploration missions. Focusing on the asteroid 4660 Nereus, this paper studies the equilibrium points of it and the potentially natural, long-lifetime orbits subject to perturbations from both the asteroid's non-spherical gravitational field and the solar radiation pressure (SRP). Using the semi-analytical method based on averaged Lagrange planetary equations (LPEs), heliotropic and terminator orbits are found more likely to have long lifetimes. It is noteworthy that the conventional near-equatorial heliotropic orbits around Nereus struggle to maintain a long lifetime. In contrast, orbits characterized by a specific inclination and geometry where the apocenter approximately points toward the Sun tend to offer prolonged lifetimes. Moreover, the impact of variations in SRP, gravitational parameter, and pole direction on feasibility of long-term orbit solutions has been explored, resulting in an enhanced comprehension of the intricate orbital dynamics. This study contributes valuable insights for the design of exploration orbits in the vicinity of the Nereus asteroid.

Multipole Representation of the Gravitational Field for Asteroid (16) Psyche

An approach to calculating multipole approximations of the gravitational potential of small celestial bodies with an irregular mass distribution is demonstrated for the asteroid (16) Psyche as an example.

Phytochemical characterization and anti-arthritic potential of Croton bonplandianus leaves extract: In-vivo and in-silico approach

Croton bonplandianus, a natural source traditionally used for treating various illnesses, including rheumatoid arthritis, was evaluated in this study. The effects of ethanolic extracts (CBEE) and aqueous fractions (CBAF) of C. bonplandianus leaves on arthritis-induced inflammation were studied using an albino rat model of inflammation induced by Freund's complete adjuvant. Eight test groups (n = 5 per group) and one vehicle control were used to evaluate the antiarthritic effects of different doses of CBEE and CBAF (125 mg.kg−1, 250 mg.kg−1, and 500 mg.kg−1) on days 5, 10, 15, and 20 compared to arthritic and vehicle controls. Arthritis severity was assessed using macroscopic arthritis grading, histological analysis, body weights, and paw thickness. CBEE and CBAF were found to reduce the prevalence of arthritis, increase body weight, and decrease paw inflammation compared to the vehicle control group by the 23rd day. In addition, they showed no effect on biochemical parameters, but a significant difference (p < 0.05) in hematological parameters compared to the arthritic control group. The study identified Hentriacontane compound as a potential contributor to the anti-inflammatory effect of C. bonplandianus, as it showed the lowest dock score for IL-1β and IL-6. Palmitoylethanol amide was identified as a potential contributor to the anti-inflammatory effect of TNF-α. Gene expression of IL-6, IL-1β, and TNF-α was down-regulated significantly (p < 0.05) in a dose-dependent manner in all treatment groups compared to the arthritic control group. In conclusion, this study validated the anti-arthritic and anti-inflammatory properties of CBEE and CBAF in a time and dose-dependent manner.

Study of Small Bodies of the Solar System: Odyssey-Asteroids Project

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.

Shape models and spin states of Jupiter Trojans

The leading theory for the origin of Jupiter Trojans (JTs) assumes that JTs were captured to their orbits near the Lagrangian points of Jupiter during the early reconfiguration of the giant planets. The natural source region for the majority of JTs would then be the population of planetesimals born in a massive trans-Neptunian disk. If true, JTs represent the most accessible stable population of small Solar System bodies that formed in the outer regions of the Solar System. For this work, we compiled photometric datasets for about 1000 JTs and applied the convex inversion technique in order to assess their shapes and spin states. We obtained full solutions for 79 JTs, and partial solutions for an additional 31 JTs. We found that the observed distribution of the pole obliquities of JTs is broadly consistent with expectations from the streaming instability, which is the leading mechanism for the formation of planetesimals in the trans-Neptunian disk. The observed JTs’ pole distribution has a slightly smaller prograde vs. retrograde asymmetry (excess of obliquities &gt;130°) than what is expected from the existing streaming instability simulations. However, this discrepancy can be plausibly reconciled by the effects of the post-formation collisional activity. Our numerical simulations of the post-capture spin evolution indicate that the JTs’ pole distribution is not significantly affected by dynamical processes such as the eccentricity excitation in resonances, close encounters with planets, or the effects of nongravitational forces. However, a few JTs exhibit large latitude variations of the rotation pole and may even temporarily transition between prograde- and retrograde-rotating categories.

ASTEROID POSITIONS BASED ON THE DUSHANBE PART OF THE FON PROJECT OBSERVATIONS

We present the results of asteroid images’ identification and creation of positional catalogs based on digitized photographic observations within the framework of the Northern Sky Survey (FON project). Namely, the cooperation between the Ukrainian Virtual Observatory and the Institute of Astrophysics of the Academy of Sciences of Tajikistan makes it possible to expand this work by involving numerous additional archives of digitized observations and processing services to obtain new original data about the small Solar system bodies. The Dushanbe part of the FON project is represented by about 1570 photographic plates obtained in 1985—1992 at the Gissar As- tronomical Observatory of the Institute of Astrophysics of the Academy of Sciences of Tajikistan. To the moment, their digitization and further scanning processing were completed, and a catalog of equatorial coordinates and stellar magnitudes for all registered objects on the plates was created. In parallel with solving the main task of the project to create a catalog of stars and galaxies, we analyzed the results of processing the plates to search for images of asteroids and comets and to create a catalog of their coordinates and magnitudes. More than 2200 positions of asteroids and comets were obtained with visual magnitudes from 7m to 16.5 m. All positions of the asteroids were compared with the ephemeris. A preliminary analysis of the O-C differences and their comparison with similar results obtained from the digitized observations of the Kyiv and Kitab parts of the FON project are conducted. The authors note some differences in the accuracy of the compared catalogs and also analyze the reasons for this and the possibilities of reducing their impact. In addition, the catalog includes several positions of Pluto and comets that were also identified in the negatives.

Small body harvest with the Antarctic Search for Transiting Exoplanets (ASTEP) project

ABSTRACT Small Solar system bodies serve as pristine records that have been minimally altered since their formation. Their observations provide valuable information regarding the formation and evolution of our Solar system. Interstellar objects can also provide insight on the formation of exoplanetary systems and planetary system evolution as a whole. In this work, we present the application of our framework to search for small Solar system bodies in exoplanet transit survey data collected by the Antarctic Search for Transiting ExoPlanets (ASTEP) project. We analysed data collected during the Austral winter of 2021 by the ASTEP 400 telescope located at the Concordia Station, at Dome C, Antarctica. We identified 20 known objects from dynamical classes ranging from Inner Main-belt asteroids to one comet. Our search recovered known objects down to a magnitude of V = 20.4 mag, with a retrieval rate of ∼80 per cent for objects with V ≤ 20 mag. Future work will apply the pipeline to archival ASTEP data that observed fields for periods of longer than a few hours to treat them as deep-drilling data sets and reach fainter limiting magnitudes for slow-moving objects, on the order of V ≈ 23–24 mag.

Photometry and Polarimetry of 2010 XC15: Observational Confirmation of E-type Near-Earth Asteroid Pair

Asteroid systems such as binaries and pairs are indicative of the physical properties and dynamical histories of small solar system bodies. Although numerous observational and theoretical studies have been carried out, the formation mechanism of asteroid pairs is still unclear, especially for near-Earth asteroid (NEA) pairs. We conducted a series of optical photometric and polarimetric observations of a small NEA 2010 XC15 in 2022 December to investigate its surface properties. The rotation period of 2010 XC15 is possibly a few to several dozen hours and the color indices of 2010 XC15 are derived as g − r = 0.435 ± 0.008, r − i = 0.158 ± 0.017, and r − z = 0.186 ± 0.009 in the Pan-STARRS system. The linear polarization degrees of 2010 XC15 are a few percent at the phase angle range of 58°–114°. We found that 2010 XC15 is a rare E-type NEA on the basis of its photometric and polarimetric properties. Taking the similarity of not only physical properties but also dynamical integrals and the rarity of E-type NEAs into account, we suppose that 2010 XC15 and 1998 WT24 are of common origin (i.e., an asteroid pair). These two NEAs are the sixth NEA pair and first E-type NEA pair ever confirmed, possibly formed by rotational fission. We conjecture that the parent body of 2010 XC15 and 1998 WT24 was transported from the main belt through the ν 6 resonance or Hungaria region.

Simultaneous Motion Replanning and Gravity Model Refinement near Small Solar System Bodies

Strategic missions to orbit celestial bodies have primarily considered spacecraft trajectories as a two-step process: capture of the spacecraft within the gravitational influence of the body, followed by in-orbit maneuvers. Moreover, a priori maneuver planning approaches using Earth-based measurements tend to generate motion plans that have little scope of replanning, especially when the spacecraft is in the body’s vicinity. Fine-grained motion plans that respond to mission conditions require a detailed understanding of the gravitational forces around the body, which can provide essential information about the body. Our research focuses on a problem variant where the orbital maneuvers are designed to continually refine the onboard gravitational model of the body while simultaneously using the model to perform increasingly smoother orbital maneuvers. We develop a receding horizon approach. Starting with a (low-fidelity) gravity model created from Earth-based observations, the gravity model is continually updated as the spacecraft experiences varying gravitational forces. The updated model is simultaneously and continually used to replan the craft’s trajectory, ensuring that successive maneuvers respect the most up-to-date gravity model. The motion plan eventually attains a near-stable orbital motion. Such an approach has the potential to expand to autonomous missions to improve the mapping and exploration of smaller bodies.

Macroscopic model for generalised Newtonian inertial two-phase flow in porous media

A closed macroscopic model for quasi-steady, inertial, incompressible, two-phase generalised Newtonian flow in rigid and homogeneous porous media is formally derived. The model consists of macroscopic equations for mass and momentum balance as well as an expression for the macroscopic pressure difference between the two fluid phases. The model is obtained by upscaling the pore-scale equations, employing a methodology based on volume averaging, the adjoint method and Green's formulation, only assuming the existence of a representative elementary volume and the separation of scales between the microscale and the macroscale. The average mass equations coincide with those for Newtonian flow. The macroscopic momentum balance equation in each phase expresses the seepage velocity in terms of a dominant and a coupling Darcy-like term, a contribution from interfacial tension effects and another one from interfacial inertia. Finally, the expression of the macroscopic pressure difference is obtained in terms of the macroscopic pressure gradient and body force in each phase, and interfacial terms that account for capillary effects and inertia, if present when the interface is not stationary. All terms involved in the macroscale equations are predicted from the solution of adjoint closure problems in periodic representative domains. Numerical predictions from the upscaled models are compared with direct numerical simulations for two-dimensional configurations, considering flow of a Newtonian non-wetting fluid and a Carreau wetting fluid. Excellent agreement between the two approaches confirms the pertinence of the macroscopic models derived here.

Adaptive Force-Control Augmentation for Small Celestial Body Sampling

An adaptive force-control augmentation for small celestial body sampling for a variety of surface properties is developed. The control algorithm consists of a nominal robust controller augmented with an adaptive controller combined with feedback linearization. When a spacecraft makes contact with the surface, it must maintain a desired contact force in order to capture a sample. The properties of the surface are unknown or uncertain before contact with the surface is made. Because the nominal robust controller may have poor performance in some surface property regimes, the goal is to improve performance using an adaptive controller. The adaptive controller performs system identification online to create an input–output model of the feedback-linearized system. From the input–output model, a block-observable canonical form is realized and the control input augmentation is determined by model predictive control. The resulting augmentation is added to the input of the robust controller to improve the closed-loop performance and maintain a desired contact force despite the unknown surface properties. The approach is applied to a variety of surface properties with linear and nonlinear contact models and multiple surface sampling maneuvers.

Correction to: The ice-organic-silicate contents of small Solar system bodies: indicators for a comet to asteroid evolutionary pathway

Correction to: The ice-organic-silicate contents of small Solar system bodies: indicators for a comet to asteroid evolutionary pathway

Trajectory design for landing on small celestial body with flexible lander

This paper investigates the trajectory design for landing on a small celestial body with a flexible lander. The flexible lander features a flexible structure that increases surface contact area and facilitates the dissipation of residual kinetic energy. Compared with rigid landing, flexible landing, which utilizes a flexible lander to execute the landing process, offers enhanced safety during the landing operation. However, the introduced nonlinear flexible force will degrade the convergence of landing trajectory optimization. To address this challenge, the homotopic approach is employed to smoothly connect the trajectory optimization problem from rigid landing to flexible landing. Then, the connection between the optimal solution of the rigid problem and the flexible problem is revealed in detail with the presented theorem. Based on this theorem, the flexible landing fuel optimal trajectory is generated by iteratively solving a sequence of convexified and discretized homotopic problems. The effectiveness of the proposed algorithm is demonstrated through 433 Eros flexible landing mission based numerical simulations.

Porous Dust Particles in Protoplanetary Disks: Application to the HL Tau Disk

Dust particle sizes constrained from dust continuum and polarization observations by radio interferometry are inconsistent by at least an order of magnitude. Motivated by porous dust observed in small solar system bodies (e.g., from the Rosetta mission), we explore how the dust particle’s porosity affects the estimated particle sizes from these two methods. Porous particles have lower refractive indices, which affect both opacity and polarization fraction. With weaker Mie interference patterns, the porous particles have lower opacity at millimeter wavelengths than the compact particles if the particle size exceeds several hundred microns. Consequently, the inferred dust mass using porous particles can be up to a factor of six higher. The most significant difference between compact and porous particles is their scattering properties. The porous particles have a wider range of particle sizes with high linear polarization from dust self-scattering, allowing millimeter- to centimeter-sized particles to explain polarization observations. With a Bayesian approach, we use porous particles to fit HL Tau disk’s multiwavelength continuum and millimeter-polarization observations from the Atacama Large Millimeter/submillimeter Array (ALMA) and the Very Large Array (VLA). The moderately porous particles with sizes from 1 mm–1 m can explain both continuum and polarization observations, especially in the region between 20 and 60 au. If the particles in HL Tau are porous, the porosity should be from 70%–97% from current polarization observations. We also predict that future observations of the self-scattering linear polarization at longer wavelengths (e.g., ALMA B1 and ngVLA) have the potential to further constrain the particle’s porosity and size.

Second-order homogenization of 3-D lattice materials towards strain gradient media: numerical modelling and experimental verification

The literature in the field of higher-order homogenization is mainly focused on 2-D models aimed at composite materials, while it lacks a comprehensive model targeting 3-D lattice materials (with void being the inclusion) with complex cell topologies. For that, a computational homogenization scheme based on Mindlin (type II) strain gradient elasticity theory is developed here. The model is based on variational formulation with periodic boundary conditions, implemented in the open-source software FreeFEM to fully characterize the effective classical elastic, coupling, and gradient elastic matrices in lattice materials. Rigorous mathematical derivations based on equilibrium equations and Hill–Mandel lemma are provided, resulting in the introduction of macroscopic body forces and modifications in gradient elasticity tensors which eliminate the spurious gradient effects in the homogeneous material. The obtained homogenized classical and strain gradient elasticity matrices are positive definite, leading to a positive macroscopic strain energy density value—an important criterion that sometimes is overlooked. The model is employed to study the size effects in 2-D square and 3-D cubic lattice materials. For the case of 3-D cubic material, the model is verified using full-field simulations, isogeometric analysis, and experimental three-point bending tests. The results of computational homogenization scheme implemented through isogeometric simulations show a good agreement with full-field simulations and mechanical tests. The developed model is generic and can be used to derive the effective second-grade continuum for any 3-D architectured material with arbitrary geometry. However, the identification of the proper type of generalized continua for the mechanical analysis of different cell architectures is yet an open question.

Scalar-mediated quantum forces between macroscopic bodies and interferometry

We study the quantum force between classical objects mediated by massive scalar fields bilinearly coupled to matter. The existence of such fields is motivated by dark matter, dark energy, and by the possibility of a hidden sector beyond the Standard Model. We introduce the quantum work felt by an arbitrary (either rigid or deformable) classical body in the presence of the scalar and show that it is finite upon requiring conservation of matter. As an example, we explicitly show that the quantum pressure inside a Dirichlet sphere is finite — up to renormalizable divergences. With this method we compute the scalar-induced quantum force in simple planar geometries. In plane-point geometry we show how to compute the contribution of the quantum force to the phase shift observable in atom interferometers. We show that atom interferometry is likely to become a competitive search method for light particles bilinearly coupled to matter, provided that the interferometer arms have lengths below ∼10 cm.

Laboratory experiments on the sublimation of methane through ice dust layers and applications to cometary activity

Context. Comets are small celestial bodies made of ice, dust, and rock that orbit the Sun. Understanding their behavior as they warm up at perihelion unveils many pieces of information about the interior and general morphology of the ices hidden under the dust. Aims. The goal of this research is to study the sublimation of CH4 through amorphous solid water (ASW), with a focus on the structural changes in water and the influence of a layer of indene (as a proxy of the crust) during a period of thermal processing, which we use in a controlled laboratory setting to simulate cometary environments. Methods. Ices at a CH4/H2O abundance ratio of about 0.01 are deposited and layered, or co-deposited, at 30 K and are heated until 200 K (or 140 K) with a ramp of either 1 or 5 K min−1. We use mass spectrometry and infrared spectroscopy to analyze the results. Results. Depending on the heating ramp and type of deposition, the sublimation of methane through ASW varies, being lower in intensity and higher in temperature when the co-deposited structure is considered. When two temperature cycles are applied, the second one sees less intense CH4 desorptions. When indene is placed above the ice mixtures, we find that the thicker its layer, the later the methane desorption. However, this later desorption sees a greater quantity of methane released due to water reorganization and higher desorbed material pressure. Conclusions. The structural changes of water ice drive volatile and hyper-volatile desorption because of the transition from high to low intrinsic density and transformation from amorphous to crystalline. This desorption indicates that such material has been deposited at low temperatures in agreement with previous theories on cometary ices formed in the pre-stellar cloud. During the two temperature cycles of our experiments, most of the released material is seen to be pristine and the processed part, if any, is of a negligible quantity, in agreement with dust-rock cometary studies.

Constraints on the Gamma-Ray Emission from Small Solar System Bodies with the Fermi Large Area Telescope Data

All known small solar system bodies have diameters between a few meters and a few thousands of kilometers. Based on the collisional evolution of solar system bodies, a larger number of asteroids with diameters down to ∼2 m is thought to exist. As all solar system bodies, small bodies can be passive sources of high-energy gamma-rays, produced by the interaction of energetic cosmic rays impinging on their surfaces. Since the majority of known asteroids are in orbits between Mars and Jupiter (in a region known as the Main Belt), we expect them to produce a diffuse emission close to the ecliptic plane. In this work, we have studied the gamma-ray emission coming from the ecliptic using the data collected by the Large Area Telescope (LAT) onboard the Fermi satellite. We have fit the results with simulations of the gamma-ray intensity at the source level (calculated with the software FLUKA) to constrain the small solar system bodies population. Finally, we have proposed a model describing the distribution of asteroid sizes and we have used the LAT data to constrain the gamma-ray emission expected from this model and, in turn, on the model itself.

The behaviors of the wave functions of small molecules with negative kinetic energies

According to relativistic quantum mechanics, particles can be of negative kinetic energies (NKE). The author asserts in his previous works that the NKE substances are dark matters. Some NKE particles, say a pair of NKE electrons, can constitute a stable system by means of the repulsive interaction between them. In the present work, two simplest three-particle systems are investigated. One consists of two NKE positrons and one NKE proton, called dark hydrogen anion. The other is composed of two NKE protons and one NKE positron, called dark hydrogen molecule cation. They are so named because the Hamiltonians of them can correspond to those of the hydrogen anion and hydrogen molecule cation. In evaluating the dark hydrogen molecule cation, the famous Born‐Oppenheimer approximation does not apply, i.e., the NKE of the protons cannot be neglected. Without the NKE, the system cannot be stable. Our study reveals that in a NKE system, the particles with the same kind of electric charge combine tightly. This is to enhance the repulsive Coulomb potential so as to raise the total energy as far as possible. A great amount of NKE particles can compose a dense and dark macroscopic NKE body. Thus, it is conjectured that some remote dark celestial bodies may be NKE ones other than the well-known black holes. The discrepancies between the black holes and macroscopic NKE bodies are pointed out.

Analysis of CN emission as a marker of organic compounds in meteoroids using laboratory simulated meteors

Fragments of small solar system bodies entering Earth’s atmosphere have possibly been important contributors of organic compounds to the early Earth. The cyano radical (CN) emission from meteors is considered as potentially one of the most suitable markers of organic compounds in meteoroids, however, its detection in meteor spectra has been thus far unsuccessful. With the aim to improve our abilities to identify CN emission in meteor observations and use its spectral features to characterize the composition of incoming asteroidal meteoroids, we present a detailed analysis of CN emission from high-resolution spectra of 22 laboratory simulated meteors including ordinary, carbonaceous, and enstatite chondrites, as well as a large diversity of achondrites (i.e., ureilite, aubrite, lunar, martian, howardite, eucrite, and diogenite), mesosiderite, and iron meteorites. We describe the variations of CN emission from different classes of asteroidal meteor analogues, its correlation and time evolution relative to other major meteoroid components. We demonstrate that CN can be used as a diagnostic spectral feature of carbonaceous and carbon-rich meteoroids, while most ordinary chondrites show no signs of CN. Our results point out strong correlation between CN and H emission and suggest both volatile features are suitable to trace contents of organic matter and water molecules present within meteoroids. For the application in lower resolution meteor observations, we demonstrate that CN can be best recognized in the early stages of ablation and for carbon-rich materials by measuring relative intensity ratio of CN band peak to the nearby Fe I-4 lines.