Main Belt Research Articles

Terrestrial planet formation during giant planet formation and giant planet migration. I. The first five million years

Terrestrial planet formation (TPF) is a difficult problem that has vexed researchers for decades. Numerical models are only partially successful at reproducing the orbital architecture of the inner planets, but have generally not considered the effect of the growth of the giant planets. Cosmochemical experiments suggest that the nucleosynthetic isotopic composition of bodies from beyond Jupiter is different from that of the inner Solar System. This difference could have implications for the composition of the terrestrial planets. I aim to compute how much material from the formation region of the gas giants ends up being implanted in the inner Solar System due to gas drag from the protoplanetary disc, how this implantation alters the feedstocks of the terrestrial planets, and whether this implantation scenario is consistent with predictions from cosmochemistry. I dynamically model TPF as the gas giants Jupiter and Saturn are growing using the Graphics Processing Unit (GPU) software Gravitational ENcounters with GPU Acceleration (GENGA). The evolution of the masses, radii, and orbital elements of the gas giants are precomputed and read and interpolated within GENGA. The terrestrial planets are formed by planetesimal accretion from tens of thousands of self-gravitating planetesimals spread between 0.5 au and 8.5 au. The total mass of the inner planetesimal disc and outer disc are typically 2 and 3 Earth masses (M_⊕) respectively, and the composition of the planetesimals changes from non-carbonaceous-like to carbonaceous-like at a prescribed distance, ranging from 2 au to 5 au. Here I report on the first five million years of evolution. At this time approximately 20% of the mass of planetesimals in the Jupiter--Saturn region is implanted in the inner Solar System, which could be more than the cosmochemical models predict; this amount can be reduced by reducing the total mass of the outer planetesimal disc, and the results suggest a mass of 1 M_⊕ could suffice. The mass-weighted fraction of outer Solar System material implanted in the inner Solar System shows a flat or bimodal distribution beyond 0.7 au, with an occasional peak near 0.9 au. The planetesimals that remain in the inner Solar System have a mixed composition, which could have implications for late accretion. The growing gas giants scattered the planetesimals in their vicinity into the inner Solar System, which changed the isotopic composition of the terrestrial planets. The inner planetesimal disc may not have extended much farther than 2 au, otherwise embryos do not grow fast enough to produce Mars analogues. This could mean that the region of the current asteroid belt never contained much mass to begin with. The implantation scenario could also explain the existence of active asteroids in the main belt.

Ceres: Organic‐Rich Sites of Exogenic Origin?

AbstractCeres, the largest object in the asteroid belt, is the only potential ocean world in the inner Solar System. Previous studies identified deposits of aliphatic organics in and around the Ernutet crater, and at small locations at Inamahari and Urvara craters. The origin of organics, either endogenic or exogenic, in these fresh exposures is still under debate. This study addresses the origin of the organics by analyzing their global distribution and geologic context. Our first step involved a global search for organic‐rich sites that might have escaped previous detections. We achieved this by using a deep neural network, utilizing spectral redness in the Dawn's Framing Camera multispectral data to identify potential organic‐rich sites. The identified sites were further studied by using IR spectrometer data to infer the compositions of materials showing spectral redness. Of the newly identified red‐sloped sites, only two can be considered certain to be organic‐rich. We also identified sites with spectral redness, but without any signature of organics in their infrared spectra. These sites could be attributed to the aqueous alteration of magnetite into ferric‐iron bearing phases. At Ernutet, Inamahari, and Urvara, the organic‐rich material is confined to the near surface only. Additionally, the absence of tectonic/volcanic features at these sites makes an endogenic origin questionable. The global rarity of detectable organics also supports this assessment. Consequently, we suggest that organics at these sites were originally delivered by low‐velocity, organic‐rich impactor(s) from the main belt and subsequently excavated, rather than originating from endogenous processes.

Generalized manev potential in the perturbed circular restricted four interacting bodies hill problem with asteroids belt

This paper starts with the determination of equations of motion and Jacobian integral of the fourth smallest body in the perturbed circular restricted four interacting bodies configuration. Then by the use of proper scale and transformations in the obtained equations of motion, we develop the equations of motion and Jacobian integral for the perturbed hill four-body configuration. Further, we analyze numerically the motion properties such as potential surfaces, equilibrium points, zero-velocity curves, Poincaré surfaces of sections with trajectories allocation, basins of attracting domain and stability of the equilibrium points of the fourth smallest body in both the above said cases.

On the Lunar Origin of Near-Earth Asteroid 2024 PT5

Abstract The near-Earth asteroid (NEA) 2024 PT5 is on an Earth-like orbit that remained in Earth's immediate vicinity for several months at the end of 2024. PT5's orbit is challenging to populate with asteroids originating from the main belt and is more commonly associated with rocket bodies mistakenly identified as natural objects or with debris ejected from impacts on the Moon. We obtained visible and near-infrared reflectance spectra of PT5 with the Lowell Discovery Telescope and NASA Infrared Telescope Facility on 2024 August 16. The combined reflectance spectrum matches lunar samples but does not match any known asteroid types—it is pyroxene-rich, while asteroids of comparable spectral redness are olivine-rich. Moreover, the amount of solar radiation pressure observed on the PT5 trajectory is orders of magnitude lower than what would be expected for an artificial object. We therefore conclude that 2024 PT5 is ejecta from an impact on the Moon, thus making PT5 the second NEA suggested to be sourced from the surface of the Moon. While one object might be an outlier, two suggest that there is an underlying population to be characterized. Long-term predictions of the position of 2024 PT5 are challenging due to the slow Earth encounters characteristic of objects in these orbits. A population of near-Earth objects that are sourced by the Moon would be important to characterize for understanding how impacts work on our nearest neighbor and for identifying the source regions of asteroids and meteorites from this understudied population of objects on very Earth-like orbits.

The James Webb Space Telescope Absolute Flux Calibration. III. Mid-infrared Instrument Medium Resolution Integral Field Unit Spectrometer

Abstract We describe the spectrophotometric calibration of the Mid-Infrared Instrument’s (MIRI) Medium Resolution Spectrometer (MRS) aboard the James Webb Space Telescope. This calibration is complicated by a time-dependent evolution in the effective throughput of the MRS; this evolution is strongest at long wavelengths, approximately a factor of 2 at 25 μm over the first 2 yr of the mission. We model and correct for this evolution through regular observations of internal calibration lamps. Pixel flat fields are constructed from observations of the infrared-bright planetary nebula NGC 7027, and photometric aperture corrections from a combination of theoretical models and observations of bright standard stars. We tie the 5–18 μm flux calibration to high signal-to-noise ratio (S/N; ∼600–1000) observations of the O9 V star 10 Lacertae, scaled to the average calibration factor of nine other spectrophotometric standards. We calibrate the 18–28 μm spectral range using a combination of observations of main belt asteroid 515 Athalia and the circumstellar disk around young stellar object SAO 206462. The photometric repeatability is stable to better than 1% in the wavelength range 5–18 μm, and the S/N ratio of the delivered spectra is consistent between bootstrapped measurements, pipeline estimates, and theoretical predictions. The MRS point-source calibration agrees with that of the MIRI imager to within 1% from 7 to 21 μm and is approximately 1% fainter than prior Spitzer observations, while the extended source calibration agrees well with prior Cassini Composite Infrared Spectrometer and Voyager Infrared Interferometer Spectrometer and Radiometer observations.

An Automated Occultation Network for Gravitational Mapping of the Trans-Neptunian Solar System

Abstract We explore the potential of an array of O ( 100 ) small fixed telescopes, aligned along a meridian and automated to measure millions of occultations of Gaia stars by minor planets, to constrain gravitational signatures from a “Planet X” mass in the outer solar system. The accuracy of center-of-mass tracking of occulters is limited by photon noise, uncertainties in asteroid shapes, and Gaia’s astrometry of the occulted stars. Using both parametric calculations and survey simulations, we assess the total information obtainable from occultation measurements of main-belt asteroids (MBAs), Jovian Trojans, and trans-Neptunian objects (TNOs). We find that MBAs are the optimal target population due to their higher occultation rates and abundance of objects above Legacy Survey of Space and Time detection thresholds. A 10 yr survey of occultations by MBAs and Trojans using an array of 200 40 cm telescopes at 5 km separation would achieve 5σ sensitivity to the gravitational tidal field of a 5M ⊕ Planet X at 800 au for >90% of potential sky locations. This configuration corresponds to an initial cost of ≈$15 million. While the survey's sensitivity to tidal forces improves rapidly with increasing number of telescopes, sensitivity to a Planet X becomes limited by degeneracy with the uncertain masses of large moonless TNOs. The 200-telescope survey would additionally detect ≈1800 TNO occultations, providing detailed shape, size, and albedo information. It would also measure the Yarkovsky effect on many individual MBAs, measure masses of many asteroids involved in mutual gravitational deflections, and enable better searches for primordial black holes and departures from general relativity.

Physical properties of newly active asteroid 2010 LH15

The main-belt asteroid 2010 LH15 has been classified as an active asteroid, based on the recent discovery of dust activity from the archival images observed in 2010 and 2019. In this study, we perform measurements and dynamical modeling of the dust tail of the active asteroid 2010 LH15 using ZTF archival data from July 26 to August 31, 2019, with the derived physical properties from these relatively independent methods being compatible. The photometric results show that the radius of the nucleus is 1.11 ± 0.02 km, with an assumed geometric albedo of pr = 0.05, and the color index of the nucleus is relatively close to that of the ejecta around the nucleus, with a value of Hg − Hr = 0.44 ± 0.07. The effective scattering cross section increases at an average rate of 0.28 ± 0.02 km2 day−1 throughout the observation period, indicating that the activity of LH15 is likely driven by mechanisms capable of causing a sustained process like sublimation. Further dust dynamics modeling indicates that the dust activity initiates as early as about June 26, 2019, with the ejected dust particles having a radius ranging from 0.03 mm to 3 mm. The dependence of the terminal velocity on dust size is consistent with a sublimation-driven mechanism. If the orbit of LH15 is stable, its sublimation origin will extend the inner boundary of the water-ice-bearing region in the main asteroid belt inward by approximately 0.1 AU.

Observations and Quantitative Compositional Analysis of Ceres, Pallas, and Hygiea Using JWST/NIRSpec

Abstract We present JWST Near Infrared Spectrograph (NIRSpec) measurements of the three largest low-albedo main-belt asteroids: (1) Ceres, (2) Pallas, and (10) Hygiea. Their reflectance spectra all have very similar absorptions centered near 2.72 μm attributed to Mg–OH in minerals. Within this band, Pallas also shows evidence of a sharper, deeper band, also centered near 2.72 μm. These band positions are similar to those seen in the most aqueously altered carbonaceous chondrites and samples from Ryugu and Bennu. Absorptions in the 2.7–2.9 μm region due to other cation–OH combinations are weak, if present. The NIRSpec spectrum of Ceres is consistent with the global average spectrum of Dawn, and the similarity between Ceres and Hygiea seen in other wavelength regions continues into the 2.5–2.8 μm region. This similarity in spectral properties, and thus in interpretations of surface composition, implies that the two bodies may have had similar processes occur and similar histories. This suggests that Hygiea, similar to Ceres, may be associated with the “ocean worlds” despite its relatively small mass. Quantitative estimates of the hydrogen concentrations on the surfaces suggest hydrogen concentrations of roughly 0.5–1 wt%, consistent with CM chondrites. Additional absorptions attributed to ammoniated minerals are seen in Ceres’s and Hygiea’s spectra, as has been reported by others, but are not seen in Pallas’s spectrum. Absorptions are also seen in the 2.5–2.7 μm region in all three asteroids, likely due to OH combination bands, and from roughly 3.9 to 4.3 μm in Hygiea, which could be due to carbonates plus an unidentified constituent.

Distribution of the creepex-magnitude correlation parameter for big-depth seismicity in the context of global tectonics

In a number of the author’s papers, the successful application of creepex-parameter of seismicity in the problems of geodynamic research of preparation areas of large events by time-changing both the creepex value in the vicinity of their sources and the pair correlation coefficient of creepex Cr(t) and magnitude MS(t) graphs (the creepex-magnitude correlation KCOR) in accompanying earthquakes swarms or during the preparation of a large shock was demonstrated. With the transition to regional and global levels of research on the KCOR change, the influence of big-depth seismicity (H≥50 km), distributed along the regional and global deep faults closest to the focal zone on the processes of source preparation was discovered. In this paper, the dynamics of KCOR parameter for the entire period covered by the CMT global catalog along the main Earth’s seismic belts is considered. The “main belts” are the global lineaments detected by the GIS-ENDDB system, in the 10% confidence band of which the 100% of all Globe earthquakes with MS≥7.5 are located. In KCOR dynamics a pattern of high correlation of MS(t) and Cr(t) sets was revealed on the eve of several major earthquakes (called “key ones”). This can indicate the creation of a special organized environment state during their preparation, possibly associated with the environment consolidation along the seismic belts (in the case of inverse correlation of MS(t) and Cr(t)), or with increased environmental variability (in the case of direct correlation). The periodic nature of KCOR time-change on a global scale is shown (in the case of its calculation with a fixed size of a time-sliding series), possibly associated with periodic fluctuations in the Earth’s rotation speed.

Precise Orbit Determination of Mars-crossing Asteroids

This study investigates the orbit determination of the Mars-crossing asteroids (MCAs) with a focus on the possibility of detecting their Yarkovsky signals. We analyze the influences of force model uncertainties on MCA orbits, including the uncertainty of the main asteroid belt, and the uncertainty of the major planets’ ephemeris. The main asteroid belt is modeled using 343 asteroids and a ring structure. The Yarkovsky effect’s quadratic nature allows it to dominate over extended observation periods. To address dynamical errors and potential interactions with the main asteroid belt, we employ not only a traditional seven-dimensional differential corrector but also a nine-dimensional differential corrector that considers radial, vertical, and transversal forces. Comparison shows that the latter approach enhances the fit to observational data. However, the reliability of the Yarkovsky parameter is not enhanced because the estimation of the radial component is physically unacceptable. Despite incorporating precise Gaia data, our analysis does not conclusively detect a Yarkovsky effect on MCAs due to uncertainties in the force model. Nevertheless, our research advances our understanding of MCA dynamics, identifying five potential candidates whose Yarkovsky effect may be observable.

JWST sighting of decametre main-belt asteroids and view on meteorite sources.

Asteroid discoveries are essential for planetary-defence efforts aiming to prevent impacts with Earth1, including the more frequent2 megaton explosions from decametre impactors3-6. Although large asteroids (≥100 kilometres) have remained in the main belt since their formation7, small asteroids are commonly transported to the near-Earth object (NEO) population8,9. However, owing to the lack of direct observational constraints, their size-frequency distribution (SFD)-which informs our understanding of the NEOs and the delivery of meteorite samples to Earth-varies substantially among models10-14. Here we report 138 detections of some ofthe smallest asteroids (≳10 metres) ever observed in the main belt, which were enabled by JWST's infrared capabilities covering the emission peaks of the asteroids15 and synthetic tracking techniques16-18. Despite small orbital arcs, we constrain the distances and phase angles of the objects using known asteroids as proxies, allowing us to derive sizes through radiometric techniques. Their SFD shows a break at about100 metres (debiased cumulative slopes of q = -2.66 ± 0.60 and-0.97 ± 0.14 for diameters smaller and larger than roughly100 metres, respectively), suggestive of a population driven by collisional cascade. These asteroids were sampled from several asteroid families-most probably Nysa, Polana and Massalia-according to the geometry of pointings considered here. Through further long-stare infrared observations, JWST is poised to serendipitously detect thousands of decametre-scale asteroids across the sky, examining individual asteroid families19 and the source regions of meteorites13,14 'in situ'.

Insights on the Rotational State and Shape of Asteroid (203) Pompeja from TESS Photometry

The Main Belt asteroid (203) Pompeja shows evidence of extreme variability in visible and near-infrared spectral slope with time. The observed spectral variability has been hypothesized to be attributed to spatial variations across Pompeja’s surface. In this scenario, the observed spectrum of Pompeja is dependent on the geometry of the Sun and the observer relative to the asteroid’s spin-pole and surface features. Knowledge of the rotational spin pole and shape can be gleaned from light curves and photometric measurements. However, dense light curves of Pompeja are only available from two apparitions. Further, previous estimates of Pompeja’s sidereal period are close to being Earth commensurate, making ground-based light curves difficult to obtain. To overcome these difficulties, we implement a pipeline to extract a dense light curve of Pompeja from cutouts of Transiting Exoplanet Survey Satellite (TESS) full-frame images. We succeeded in obtaining a dense light curve of Pompeja covering ∼22 complete rotations. We measure a synodic period of P syn = 24.092 ± 0.005 hr and amplitude of 0.073 ± 0.002 mag during Pompeja’s 2021 apparition in the TESS field of view. We use this light curve to refine models of Pompeja’s shape and spin-pole orientation, yielding two spin-pole solutions with sidereal periods and spin-pole ecliptic coordinates of P sid,1 = 24.0485 ± 0.0001 hr, λ 1 = 132°, and β 1 = +41° and P sid,2 = 24.0484 ± 0.0001 hr, λ 2 = 307°, and β 2 = +34°. Finally, we discuss the implications of the derived shape and spin models for spectral variability on Pompeja.

Possible origin of Mars-crossing asteroids and related dynamical properties of inner main-belt asteroids

Context. The orbital element distribution of the inner main belt (IMB) provides clues to the origin of the main-belt asteroids. Mars-crossing asteroids (MCAs) and near-Earth objects (NEOs) can provide some references to validate and improve theoretical models of the IMB evolution. Aims. With the updated Asteroid Families Portal database, we analyzed the distribution of orbital elements and the dynamic completeness limit of IMB asteroids. By incorporating larger and more diverse datasets, the study seeks to provide a more comprehensive understanding of the IMB and MCAs origin and evolution. Methods. We fitted the completeness-limit magnitude for the IMB. The size frequency and albedo distribution were used to analyze the family characteristics. The role of chaotic effects in the dynamic evolution of IMB and MCAs is further quantified by simulations. Results. An albedo analysis showed that some halo asteroids may have originated from family asteroids, whereas the remaining non-family asteroids (14%) are likely to be members of a potential ghost family. We estimated the chaotic diffusion of asteroid orbits considering 1M/2A mean motion resonance. The eccentricity diffusion rate is estimated to be 0.45 and the inclination diffusion rate is 0.4 for resonant asteroids. The loss rate of MCAs IIMC(17.6) = 24.13 Myr−1, while the loss rate of the IMB asteroids due to the chaotic diffusion is 0.2648 Myr−1, which represents only 1.1% of MCAs. This indicates that chaotic diffusion has a limited capacity to replenish MCAs. However, for the large MCAs, a loss rate of IIMC(12) = 0.2646 Myr−1 was observed. This suggests that the large MCAs (H < 12) are in the dynamic equilibrium, primarily evolving through chaotic diffusion.

322P/SOHO: The counterpart of a historical comet in 254 CE?

The historical observations of East Asia provide a systematic and accurate record of bright periodic comets and could help us understand their past states. However, except for these comets, few other comets have been successfully associated with historical observations. Here we report that the sunskirter 322P/SOHO is probably associated with a historical comet in 254 CE, although it appeared no visible cometary activity in recent observations. By analyzing astrometric data from the IAU Minor Planet Center, we determine the orbit of 322P and suggest that its motion is affected by non-gravitational forces based on sodium sublimation, indicating its high devolatilization. The orbital integration shows that the position and perihelion date of 322P are highly corresponding to a historical comet in 254 CE. This comet had an extremely long tail that stretched across the sky, indicating the intense activity outburst. The dynamical properties of 322P and its similarity to dark comets suggests that it possibly originated from a volatile object in the main belt, but has undergone the rotational splitting and devolatilization. Previous studies have also suggested the possible splitting. Given that splitting is a common cause of activity outburst, we suggest that 322P might have experienced a fragmentation in 254 CE and released a large amount of material, which led to the spectacular tail and devolatilization. Only faint sodium-driven activity remained afterwards, which could explain the lack of historical observations after 254 CE.

Study of basaltic asteroids through their phase curves

ABSTRACT Characterized by a composition that highlights extensive geochemical differentiation processes, basaltic asteroids are considered fragments of differentiated bodies. To study the smallest bodies in this population, an important tool is the photometric phase curve that can exhibit different behaviours according to the surface properties of the body. We present here the phase curves obtained for 10 V-type asteroids, nine belonging to the main belt population and one a near-Earth object, with observations acquired at the Observatório Astronômico do Sertão de Itaparica (Brazil). Different behaviours of the phase curves were found, as already obtained by studies of polarimetric curves. Adding to our results in the phase curves of 20 V-types from the literature, we found behaviours not expected for objects of moderate to high albedo in the opposition effect region. We attribute this result to the way regoliths are distributed on the surface of small asteroids, which are different from those of larger objects, although the surface composition is the same.

Prospecting potential evaluation based on geological factor analysis-a case study of Jiaojiacheng ore belt

Mineral forecasting is of great significance for social development. As an important aspect of geological exploration, its importance lies not only in its direct contribution to economic growth but also in how it employs precise technical methods for mineral exploration. This study utilizes a geological factor analysis method that combines various complex geological observation factors into a few dominant comprehensive factors, followed by causal research and multivariate statistical analysis for classification. Based on this, the study applies principles and methods of elemental geochemistry to identify the dispersion and concentration patterns of associated elements from the distribution characteristics of ordered accompanying factors, providing a scientific basis for mineralization forecasting. Using geochemical experimental data, geological survey comprehensive profiles, and factor score contour maps, this paper analyzes the southern extension segment of the Jiaojia gold mine mineralization belt through geological factor analysis. It was found that the anomalous distribution of chemical elements F4 (Hg, Au, Pb) exhibits certain regularities, which significantly indicate mineralization information and suggest the presence of two main longitudinal mineralization belts.

An Objective Classification Scheme for Solar-System Bodies Based on Surface Gravity

We introduce succinct and objective definitions of the various classes of objects in the solar system. Unlike the formal definitions adopted by the International Astronomical Union in 2006, group separation is obtained from measured physical properties of the objects. Thus, this classification scheme does not rely on orbital/environmental factors that are subject to debate—the physical parameters are intrinsic properties of the objects themselves. Surface gravity g is the property that single-handedly differentiates (a) planets from all other objects (and it leaves no room for questioning the demotion of Pluto), and (b) the six largest (g>1 m s−2) of the large satellites from dwarf planets. Large satellites are separated from small satellites by their sizes and masses/densities, which may serve as higher-order qualifiers for class membership. Size considerations are also sufficient for the classification of (i) main-belt asteroids (except possibly Ceres) as small solar-system bodies similar in physical properties to the small satellites; and (ii) a group of large Kuiper-belt objects as dwarf planets similar in physical properties to the large (but not the largest) satellites in our solar system. The selection criteria are simple and clear and reinforce the argument that body shape and environmental factors need not be considered in stipulating class membership of solar as well as extrasolar bodies.

What is the amount of baryonic dark matter in galaxies?

In this paper, we re-evaluate the estimates of dust mass in galaxies and demonstrate that current dust models are incomplete and based on a priori assumptions. These models suffer from a circularity problem and account for only a small portion of dust, specifically submicron-sized grains. They overlook larger dust particles and other macroscopic bodies, despite observational evidence supporting their existence. This evidence includes the observed (sub)millimetre excess in dust emission spectra and the power-law size distribution with a differential size index γ≈3.5−4.0, which has been measured for large particles and compact bodies across diverse environments. Examples of these large particles include large dust grains and meteoroids detected by satellites, near-Earth objects colliding with Earth, fragments in the Main Asteroid Belt and the Kuiper Belt, interstellar ’Oumuamua-like objects, and exoplanets. As a result, dust-type baryonic dark matter may be more abundant throughout the galaxy by one order of magnitude or even more than previously assumed, with a significant portion of its mass concentrated in large compact bodies. Additionally, black holes may contribute significantly to the total mass of baryonic dark matter. Consequently, current galaxy models do not provide reliable estimates of baryonic mass in galaxies. Clearly, a substantially larger amount of baryonic dark matter in galaxies would have major implications for theories of galaxy dynamics and evolution.

Detection of Hydration on Nominally Anhydrous S-complex Main Belt Asteroids

We present the results of a survey of nominally anhydrous main belt S-complex asteroids. Thirty-three observations of 29 unique asteroids were obtained using the IRTF+SpeX instrument in prism and LXD short modes. We report for the first time that S-complex main belt asteroids have 3 μm features. The majority of the observations (27 of 33) have a detectable 3 μm feature that has at least 1% band depth or greater (within error), indicating the presence of hydration. Most of the asteroids have bands of 1%–2.5% depth, but a notable fraction (nine of the observations) have band depths of >5%. These band depths are comparable to those of low albedo asteroids in the middle and outer belt that have experienced aqueous alteration. We investigate the origin of the hydration, searching for correlations with orbital, physical, and circumstantial parameters. However, we do not find any strong or moderate correlations with 3 μm band depth, indicating that multiple factors may be at play, including exogenic sources, primordial water, and/or solar wind implantation. Additionally, we report the mineralogies of the asteroids, derived from the prism observations.

Comparison of Propulsion Options for Interplanetary Missions

This paper investigates propulsion options and trajectory designs for a manned mission from Earth to Mars, followed by a mission to Ceres. It evaluates various propulsion technologies, including traditional chemical propulsion, nuclear thermal propulsion (NTP), and electric propulsion systems such as ion thrusters and Hall effect thrusters. The analysis highlights the limitations of chemical propulsion in terms of energy efficiency and payload capacity while underscoring the potential of NTP to reduce travel time and improve crew safety due to its higher specific impulse. The study also examines the feasibility of solar and nuclear electric propulsion, focusing on their high efficiency and suitability for extended missions, and considers innovative concepts like solar sails and fusion propulsion for their theoretical advantages in thrust and velocity. Low-thrust trajectories are analyzed for their ability to minimize overall delta-V requirements, which is essential for mission success. For the Mars mission, chemical propulsion systems currently under development are evaluated alongside electric propulsion powered by nuclear reactors, which could significantly reduce travel times and propellant needs. The additional challenges of propelling a spacecraft to Ceres, a more distant destination in the asteroid belt, shift the focus to electric propulsion options, particularly advanced nuclear-electric systems, which offer the potential to enable human exploration within a reasonable timeframe. The paper concludes that the optimal propulsion system for a manned mission to Mars and Ceres requires balancing travel time, technical feasibility, and crew safety, emphasizing the necessity for further development of advanced electric propulsion technologies to facilitate ambitious human deep-space exploration.