near-Earth Research Articles

Preatmospheric Detection of a Meter-sized Earth Impactor

On 2020 September 18 U.S. Government (USG) sensors detected a bolide with peak bolometric magnitude of −19 over the Western Pacific. The impact was also detected by the Geostationary Lightning Mapper instrument on the GOES-17 satellite and infrasound sensors in Hawaii. The USG measurements reported a steep entry angle of 67° from horizontal from a radiant 13° east of north and an impact speed of 11.7 km s−1. Interpretation of all energy yields produces a preferred energy estimate of 0.4 kt TNT, corresponding to a 23,000 kg, 3 m diameter meteoroid. A postimpact search of telescopic images found that the Asteroid Terrestrial-impact Last Alert System survey captured the object just 10 minutes prior to impact at an Earth-centered distance of nearly 11,900 km with apparent magnitude m = 12.5. The object appears as a 0.44° streak originating on the eastern edge of the image, extending one-third of the USG state-vector-based prediction of 1.26° over the 30 s exposure. The streak shows brightness variability consistent with small asteroid rotation. The position of Earth’s shadow, the object’s size, and its consistency with the reported USG state vector confirm the object is likely natural. This is the eighth preatmospheric detection of a near-Earth asteroid (NEA) impactor and the closest initial telescopic detection prior to impact. The high altitude of peak fireball brightness suggests it was a weak object comparable in many respects with 2008 TC3 (the Almahata Sitta meteorite), with an absolute magnitude H = 32.5 and likely low albedo. Therefore, we suggest the NEA was a C-complex asteroid.

Clustering the properties of near-Earth objects: physico-dynamical links among NEOs

Context. At present, near-Earth objects (NEOs) are being discovered at an ever-increasing rate. However, their physical characterisation is still significantly lagging behind. In particular, the taxonomic classification of newly discovered NEOs is of great importance with regard to improving our understanding of the population of NEOs. Aims. In this context, our goal is to probe potential links between orbital properties of NEOs and their composition. We investigate whether we can make a reasonable guess about the taxonomic class of an NEO upon its discovery with a decent orbital accuracy. Methods. We used a G-mode multivariate statistical clustering method to find homogeneous clusters in a dataset composed of orbital elements of NEOs. We adopted two approaches, using two sets of variables as inputs to the G-mode method. In each approach, we analysed the available taxonomic distribution of resulting clusters to find potential correlations with several unique parameters that distinctively characterise NEOs. We then applied a dynamical model on the same clusters to trace their escape regions. Results. Approach 1 (A1) led us to obtain NEO clusters that can be linked to a primitive composition. This result was further strengthened by the dynamical model, which mapped outer-belt sources as escape regions for these clusters. We remark on the finding of a cluster akin to S-type NEOs in highly eccentric orbits during the same approach (A1). Two clusters, one with small NEOs in terrestriallike orbits and one with relatively high inclinations, were found to be common to both approaches. Approach 2 (A2) revealed three clusters that are only separable by their arguments of perihelion. Taken altogether, they make up the majority of known Atira asteroids. Conclusions. For an NEO whose orbit is relatively well determined, we propose a model to determine whether the taxonomy of an NEO is siliceous or primitive if the orbital elements of the NEO fall within the presented combinations of inclination, eccentricity, and semi-major axis ranges.

The research on near-Earth objects(NEOs) and its possible protectionary methods

Recent year, as technologies and research have unprecedently grow in a fast speed, humans exploration toward outer space become enormous. Several private space exploration and aerospace manufacture corporations, such as SpaceX, have come into public which symbolize the development of human society and start to reshape the human civilization. Near Earth Objects(Neos) or Potential Hazard Asteroids(PHAs) have gradually focused by scientists. With the emerging of Neos observations, it has become vigilant that Neos impact to human civilization is obviously destructive refer to the distinction dinosaur. Neo impact technologies and strategies are tremendously vital in resort of continuing human civilization. This paper presents the time frame of launching of satellite and space station and their function of exploration and the information about near earth objects including its feature and propose several possible solutions toward Neos for short time scales and long times scales including nuclear explosive devices, kinetic impactor, asteroid gravity tractor and asteroid laser ablation. These methods have been list with their advantages and disadvantages and evaluation will be taken from the prospective of successful rate, time, efficiency and cost.

The Arecibo Observatory's legacy and future radar capabilities

Ground-based radar systems are critical for physical and dynamical characterization of near-Earth objects (NEOs) and space debris. The operational aspect and applications of radar for planetary defense and space situational/domain awareness (SSA/SDA) are similar, but there are some factors that should be taken into account for an instrument to support both areas: planetary defense is focused on asteroids and comets in heliocentric orbit with perihelion distance <1.3 au. Special attention is given to potentially hazardous objects (PHOs), which are NEOs larger than 140 m that can come within 0.05 au (∼20 lunar distances) of Earth. Radar can quickly and accurately determine NEOs' future trajectory, therefore, the sooner an object can be observed, the safer it is to assess any possible threat. Radar is also useful to help obtaining information about the objects’ properties to plan for an impact mitigation mission if needed. For SSA, the focus is artificial objects orbiting Earth. This document presents the radar capabilities of the legacy Arecibo telescope, and explores synergistic future concepts for planetary defense and SSA.

The spatial distribution of soluble organic matter and their relationship to minerals in the asteroid (162173) Ryugu

We performed in-situ analysis on a ~ 1 mm-sized grain A0080 returned by the Hayabusa2 spacecraft from near-Earth asteroid (162173) Ryugu to investigate the relationship of soluble organic matter (SOM) to minerals. Desorption electrospray ionization-high resolution mass spectrometry (DESI-HRMS) imaging mapped more than 200 CHN, CHO, CHO–Na (sodium adducted), and CHNO soluble organic compounds. A heterogeneous spatial distribution was observed for different compound classes of SOM as well as among alkylated homologues on the sample surface. The A0080 sample showed mineralogy more like an Ivuna-type (CI) carbonaceous chondrite than other meteorites. It contained two different lithologies, which are either rich (lithology 1) or poor (lithology 2) in magnetite, pyrrhotite, and dolomite. CHN compounds were more concentrated in lithology 1 than in lithology 2; on the other hand, CHO, CHO–Na, and CHNO compounds were distributed in both lithologies. Such different spatial distribution of SOM is likely the result of interaction of the SOM with minerals, during precipitation of the SOM via fluid activity, or could be due to difference in transportation efficiencies of SOMs in aqueous fluid. Organic-related ions measured by time-of-flight secondary ion mass spectrometry (ToF–SIMS) did not coincide with the spatial distribution revealed by DESI-HRMS imaging. This result may be because the different ionization mechanism between DESI and SIMS, or indicate that the ToF–SIMS data would be mainly derived from methanol-insoluble organic matter in A0080. In the Orgueil meteorite, such relationship between altered minerals and SOM distributions was not observed by DESI-HRMS analysis and field-emission scanning electron microscopy, which would result from differences of SOM formation processes and sequent alteration process on the parent bodies or even on the Earth. Alkylated homologues of CHN compounds were identified in A0080 by DESI-HRMS imaging as observed in the Murchison meteorite, but not from the Orgueil meteorite. These compounds with a large C number were enriched in Murchison fragments with abundant carbonate grains. In contrast, such relationship was not observed in A0080, implying different formation or growth mechanisms for the alkylated CHN compounds by interaction with fluid and minerals on the Murchison parent body and asteroid Ryugu.Graphical

Mineralogical Characterization and Phase Angle Study of Two Binary Near-Earth Asteroids, Potential Targets for NASA’s Janus Mission

Ground-based characterization of spacecraft targets prior to mission operations is critical to properly plan and execute measurements. Understanding surface properties, such as mineralogical composition and phase curves (expected brightness at different viewing geometries), informs data acquisition during the flybys. Binary near-Earth asteroids (NEAs) (35107) 1991 VH and (175706) 1996 FG3 were selected as potential targets of the National Aeronautics and Space Administration’s (NASA) dual spacecraft Janus mission. We observed 1991 VH using the 3 m NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, on 2008 July 26. 1996 FG3 was observed with the IRTF for seven nights during the spring of 2022. Compositional analysis of 1991 VH revealed that this NEA is classified as an Sq-type in the Bus–DeMeo taxonomy classification, with a composition consistent with LL ordinary chondrites. Using thermal modeling, we computed the thermally corrected spectra for 1996 FG3 and the corresponding best-fit albedo of about 2%–3% for the best spectra averaged for each night. Our spectral analysis indicates that this NEA is a Ch-type. The best possible meteorite analogs for 1996 FG3, based on curve matching, are two carbonaceous chondrites, Y-86789 and Murchison. No rotational variation was detected in the spectra of 1996 FG3, which means there may not be any heterogeneities on the surface of the primary. However, a clear phase reddening effect was observed in our data, confirming findings from previous ground-based studies.

Mining archival data from wide-field astronomical surveys in search of near-Earth objects

Mining archival data from wide-field astronomical surveys in search of near-Earth objects

Alternative approach to the DART mission by the use of gravity assist maneuvers with the Moon and solar sails

The formation of our Solar System and planetary defense strategies are among the priorities to be investigated in the next years by the space science community. As in-situ missions to small bodies (as comets and asteroids) are options to conduct these investigations, this paper proposes a combination of methodologies to produce low-cost transfers to near-earth asteroids (NEAs). Low-cost trajectories derived from retrograde periodic orbits around {L}_{1} are taken as a starting point for the escape of the Earth-Moon system and, as the vehicle exits the sphere of influence of Earth, the deployment of an adjustable solar sail guarantees the interception of the target in a predetermined position and time of flight. Different sail loadings (164, 61 and 30 g/m2) are tested and a case study to the NEA 65,803 Didymos is presented. The results show economies in the velocity increments required by the mission up to 8.48%, although a longer time of flight might be needed depending on the sail loading.

Detection system of near Earth objects based on the axial orbit in the Sun–Earth circular restricted three-body problem

L4 and L5 axial orbits provide special locations to monitor and search for near Earth objects (NEOs) due to their offset locations. In this paper, we propose a detection system of NEOs on the axial orbit in the Sun–Earth circular restricted three-body problem. Taking the Sun exclusion zone into consideration, we design an observation strategy for space-based telescopes on axial orbits. Then, an observation accessibility measure for the motionless point is presented to evaluate the performances of the different axial orbits and formations. In addition, the detection performance of axial orbits is compared with the distant retrograde orbits (DROs) and Earth-displaced heliocentric orbits (EDHOs). Numerical simulations indicate that the detection performance of axial orbits for the motionless point is better than that of DROs but is inferior to EDHOs. On the other hand, the axial orbit is dynamical stable, but EDHOs are unstable and their fuel costs for maintenance cannot be ignored with the increase of service time. Furthermore, the detection system on axial orbits is applied to moving objects. For example, the detection system of the EDHOs cannot predict the Chelyabinsk asteroid impact, but it is possible for the DRO and axial orbits. Numerical simulations for 4000 virtual NEOs indicate that due to a better observation geometry, the detection system of axial orbits can find more NEOs than those of the DRO and EDHOs.

Low-thrust trajectory design for near-Earth asteroid supply delivery and resource transportation mission using high-power solar electric propulsion

This paper presents the low-thrust (LT) trajectory design for near-Earth asteroid (NEA) supply delivery and resource transportation mission using high-power Solar Electric Propulsion (SEP). NEA low-thrust roundtrip accessibility is investigated through a numerical approach and new knowledge of the mass transportation capability of SEP systems in NEA missions is provided. A number of powerful deep neural networks (DNNs) were trained and optimized for 60 kW, 150 kW, 300 kW and 500 kW SEP-based LT trajectory design. DNNs are used as the surrogate of the conventional optimization process. A new low thrust trajectory roundtrip opportunity search algorithm is developed, which integrates the DNN models and allows an efficient roundtrip search process. Compared to the conventional approach, the DNN-based search algorithm reduces the search time by 99.96%. The SEP mass transportation capabilities were numerically studied. It was found the 60 kW SEP can deliver 5 tons of supply to up to 40% of NEAs. Considering refueling on NEAs, the accessible NEAs can be further increased by 16.2%. It is suggested that the 150 kW, 300 kW, 500 kW SEP to be used to transport 10–30 tons, 30–70 tons, 70–120 tons resources from NEAs respectively. These mass ranges ensure about 4,000 or more targets to be accessible. In all the case studies, the roundtrip accessible boundaries were constructed using polynomial regression. These boundaries were numerically obtained, which could be useful for mission designers to rapidly determine the LT roundtrip accessibility of newly found NEAs.

Spatiotemporal characteristics of near-earth object monitoring from a moon-based station: case from 1962 to 2020 in CNEOS

ABSTRACT Numerous discovered and undiscovered near-Earth objects (NEOs), celestial bodies from outer space with diverse physical properties, have ensued major potential impact threats to the Earth. For a timely and accurate response in monitoring NEOs entering Earth’s orbit, the future applied Moon-based monitoring platform (MBMP) will fully utilize the vast flat Moon’s surface, along with low thermal noise in the prospective permanent shadow area, low gravity and vacuum environment, and special space relation, among other advantages over the established ground-based monitoring platform (GBMP) and space-based monitoring platform (SBMP). Future single or clustered platforms might indeed survey space with limited solar influence involved. Through downloaded data from the Center for Near Earth Object Studies, this study analysed MBMP performance and studied the commonly visible ratio (VR) based on the overall geometry of Sun–Moon–Earth and NEOs. Results from the average near-side MBMP VR outperformed the far side GBMP, and other satellites even by 0.4. This provides locations with a high probability for monitoring platforms among the downloaded NEOs, while the rest of the Moon’s surface can serve as crucial underlying support for timely NEO monitoring and a valuable complement for GBMP and SBMP.

PHOTOMETRIC OBSERVATIONS OF MINOR PLANETS WITH THE TONANTZINTLA SCHMIDT CAMERA I. LIGHT CURVE ANALYSIS OF MAIN-BELT AND NEAR-EARTH ASTEROIDS

We report photometric observations of nine main-belt asteroids (MBAs), four near-Earth asteroids (NEAs), and one Mars-crossing asteroid (MCA) carried out with the historical Tonantzintla Schmidt Camera between 2015 and 2018, as part of a process of reactivation of this telescope for astrometric and photometric follow-up observations of MBAs and NEAs. This observational program is part of the commitment made by INAOE when requesting its inclusion in the International Asteroid Warning Network (IAWN). We present the light curves of these 14 asteroids and their corresponding Fourier analyses to determine the rotation period of the asteroids and the brightness amplitude of their light curves.

Novel constraints on fifth forces and ultralight dark sector with asteroidal data

We study for the first time the possibility of probing long-range fifth forces utilizing asteroid astrometric data, via the fifth force-induced orbital precession. We examine nine Near-Earth Object (NEO) asteroids whose orbital trajectories are accurately determined via optical and radar astrometry. Focusing on a Yukawa-type potential mediated by a new gauge field (dark photon) or a baryon-coupled scalar, we estimate the sensitivity reach for the fifth force coupling strength and mediator mass in the mass range m ≃ (10-21-10-15) eV, near the “fuzzy” dark matter region. Our estimated sensitivity is comparable to leading limits from equivalence principle tests, potentially exceeding these in a specific mass range. The fifth force-induced precession increases with the orbital semi-major axis in the small m limit, motivating the study of objects further away from the Sun. We also demonstrate that precession tests are particularly strong in probing long-range forces which approximately conserve the equivalence principle. We discuss future prospects for extending our study to more than a million asteroids, including NEOs, main-belt asteroids, Hildas, and Jupiter Trojans, as well as trans-Neptunian objects and exoplanets.

2022 Joint Barringer Medal for Kai Wünnemann and Gareth S. Collins

2022 Joint Barringer Medal for Kai Wünnemann and Gareth S. Collins

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.

Thermal Models of Asteroids with Two-band Combinations of Wide-field Infrared Survey Explorer Cryogenic Data

We used the reparameterized Near-Earth Asteroid Thermal Model to model observations of a curated set of over 4000 asteroids from the Wide-field Infrared Survey Explorer in two wavelength bands (W2–3 or W3–4) and compared the results to previous results from all four wavelength bands (W1–4). This comparison was done with the goal of elucidating unique aspects of modeling two-band observations so that any potential biases or shortcomings for planned two-band surveys (e.g., the NASA Near-Earth Object Surveyor Mission) can be anticipated and quantified. The W2–3 two-band fits usually yielded slightly smaller diameters than the four-band fits, with a median diameter difference of −10%, with the 5% and 95% quantiles of the distribution at −32% and −1.5%, respectively. We conducted similar comparisons for W3–4, in part because the longest wavelength bands are expected to provide the best two-band results. We found that the W3–4 two-band diameters are slightly larger than the four-band results, with a median diameter difference of 11% and the 5% and 95% quantiles of the distribution at −2.1% and 26%, respectively. The diameter uncertainty, obtained with bootstrap analysis, is larger by 30% and 35% (median values) for the W2–3 and W3–4 fits, respectively, than for the corresponding four-band fits. Using 23 high-quality stellar occultation diameters as a benchmark, we found that the median errors of W2–3 and W3–4 diameter estimates are −15% and +12%, respectively, whereas the median error of the four-band fits is 9.3%. Although the W2–3 and W3–4 diameters appear to have greater systematic errors and uncertainties than their four-band counterparts, two-band estimates remain useful because they improve upon diameter estimates obtained from visible photometry alone.

Maps of secular resonances in the NEO region

Context. From numerical simulations, it is known that some secular resonances may affect the motion of near-Earth objects (NEOs). However, the specific location of the secular resonance inside the NEO region is not fully known because the methods previously used to predict their location cannot be applied to highly eccentric orbits or the time when the NEOs cross the orbits of the planets. Aims. In this paper, we aim to map the secular resonances with the planets from Venus to Saturn in the NEO region, while including high eccentricity values as well. Methods. We used an averaged semi-analytical model that can deal with orbit-crossing singularities for the computation of the secular dynamics of NEOs, from which we were able to obtain suitable proper elements and proper frequencies. Then, we computed the proper frequencies over a uniform grid in the proper elements space. Secular resonances can thus be located by the level curves corresponding to the proper frequencies of the planets. Results. We determined the location of the secular resonances with the planets from Venus to Saturn, showing that they appear well within the NEO region. By using full numerical N-body simulations, we also showed that the location predicted by our method is fairly accurate. Finally, we provided some indications about possible dynamical paths inside the NEO region due to the presence of secular resonances.

Homogeneity and heterogeneity in near-infrared FTIR spectra of Ryugu returned samples

Surface and subsurface materials of C-type near-Earth asteroid 162173 Ryugu were collected and successfully returned to the Earth in the Hayabusa2 mission. Fourier Transform Infrared Spectroscopy (FTIR) has been conducted to characterize these returned samples as one of the initial descriptions in a non-destructive manner under a purified nitrogen condition without terrestrial contamination. We selected the individual grains and aggregate samples that were not severely influenced by the reflection of incident beam at the sapphire dish and analyzed their reflectance spectra using the primary component analysis (PCA). The result indicates that Ryugu returned samples are highly homogeneous with only a little heterogeneity. The average spectrum of the main PCA group is represented by four absorption bands at 2.7, 3.05, 3.4, and 3.95 μm. The spectral feature is consistent with that obtained from bulk FTIR measurements, indicating potential presence of hydroxyl, organics, and carbonates. Rarely observed types of grains with unique spectra are categorized into three groups: significantly high reflectance, carbonates, and hydroxyl compounds with broad OH absorption.Graphical

Long-term capture of asteroids to the Sun-Earth L1/L2 using a lunar flyby and station-keeping maneuvers

Long-term capture of near-Earth asteroids to Sun-Earth L1/L2 libration point orbits using a lunar flyby and station-keeping maneuvers is investigated in this paper. The model of the circular restricted three-body problem (CR3BP) provides reference L1/L2 libration point orbits and stable manifolds to capture asteroids. A station-keeping method using target points is employed to maintain the final periodic orbits under the Moon’s perturbation. Then the stable manifold with the Moon’s perturbation is applied to achieve transfers for capturing candidate asteroids. After candidate asteroids are selected using the non-planar Hohmann transfer, optimizations of capturing asteroids are carried out by minimizing the sum of transfer costs and station-keeping maneuvers. Simulation results show that the lunar flyby can reduce the fuel consumption of capturing asteroids, even when the station-keeping maneuvers are taken into account.

Influence of the dynamic classification of asteroids on observation astrometric errors: a statistical analysis

ABSTRACT The ephemerides of minor planets are computed on the basis of astrometric observations. The asteroid orbit determination process requires these observations to be properly weighted to take into account the expected accuracy of the data. If not directly provided by the observers, the weights are, in general, computed after a station-specific statistical analysis on the observation residuals, where the influence of external factors such as epoch of observation, magnitude, and employed catalogue has been proven. In this paper, we perform a statistical analysis on observation residuals of the major surveys taking into account a new factor, i.e. the dynamical classification of asteroids, to understand whether the observation quality may have a dependence on the different type of observed object. If an influence is actually found, then it will be possible to develop a new weighting system based on these results. The weights will be easily applicable once one knows the asteroid orbit. In particular, four stations have been found having different qualities depending on whether they are observing near-Earth asteroids or main-belt asteroids. Moreover, the cross-correlation between the dynamic classification and epoch, magnitude, and catalogue is investigated, as well as the influence of these factors on observations’ quality.