near-Earth Object Population Research Articles

Main-belt comets as contributors to the near-Earth objects population

Main-belt comets as contributors to the near-Earth objects population

Tour of Asteroids for Characterization Observations (TACO): A Planetary Defense Asteroid Tour Concept

Asteroid impacts potentially represent a substantial threat to humanity, but one that we can plan for and mitigate. To design an effective asteroid mitigation mission, however, it is important to have as detailed knowledge of the asteroid threat as possible. Our understanding of a newly discovered object will generally derive from our understanding of the near-Earth object population, and in cases where there is no time for a reconnaissance mission prior to deflection or disruption, we may need to lean heavily on any existing data of similar objects. The Tour of Asteroids for Characterization Observations (TACO) mission concept would fill key gaps in the characterization knowledge needed to plan an effective response to an asteroid threat. A tour targeting potentially hazardous asteroids and focused on reconnaissance objectives specifically relevant for planetary defense would also test instruments and technologies (e.g., autonomous navigation, high-rate gimbals) ahead of when they are actually required in response to a threat. Testing these capabilities is identified as a need in the National Near-Earth Object Preparedness Strategy and Action Plan. The TACO tour concept is specifically designed to measure the most important asteroid properties for planetary defense, including mass, size/shape, surface and near-surface structure, presence of satellites, and composition. These measurements can be obtained using a nominal payload, including a narrow-angle camera, a thermal infrared imager, and deployed test masses for gravity science.

The Population of Small Near-Earth Objects: Composition, Source Regions, and Rotational Properties

The study of small (<300 m) near-Earth objects (NEOs) is important because they are more closely related than larger objects to the precursors of meteorites that fall on Earth. Collisions of these bodies with Earth are also more frequent. Although such collisions cannot produce massive extinction events, they can still produce significant local damage. Here we present the results of a photometric and spectroscopic survey of small NEOs that include near-infrared spectra of 84 objects with a mean diameter of 126 m and photometric data of 59 objects with a mean diameter of 87 m. We found that S-complex asteroids are the most abundant among the NEOs, comprising ∼66% of the sample. Most asteroids in the S-complex were found to have compositions consistent with LL-chondrites. Our study revealed the existence of NEOs with spectral characteristics similar to those in the S-complex but that could be hidden within the C- or X-complex due to their weak absorption bands. We suggest that the presence of metal or shock darkening could be responsible for the attenuation of the absorption bands. These objects have been grouped into a new subclass within the S-complex called Sx-types. The dynamical modeling showed that 83% of the NEOs escaped from the ν 6 resonance, 16% from the 3:1, and just 1% from the 5:2 resonance. Lightcurves and rotational periods were derived from the photometric data. No clear trend between the axis ratio and the absolute magnitude or rotational period of the NEOs was found.

Challenges in Identifying Artificial Objects in the Near-Earth Object Population: Spectral Characterization of 2020 SO

Since the dawn of the Space Age, hundreds of payloads have been launched into heliocentric space. As near-Earth object (NEO) surveys search deeper for small asteroids, more artificial objects in heliocentric orbits are being discovered. We now face a challenge to identify the true nature of these objects and avoid contaminating the NEO catalog. Here, we present the methods used to characterize one such object. 2020 SO was discovered by the Pan-STARRS1 survey on 2020 September 17. Originally classified as a NEO, the object’s artificial nature became evident due to its low velocity relative to Earth and solar radiation pressure affecting its orbit about the Sun. Based on a backward propagation of its orbit, 2020 SO is thought to be a Centaur rocket body (R/B) from the launch of the Surveyor 2 mission to the Moon. We characterized 2020 SO using a range of ground-based optical and near-infrared telescopes to constrain its true nature. We find that its reflectance spectrum is consistent with that of other Centaur R/B launched during a similar time frame, and we identify 1.4, 1.7, and 2.3 μm absorption bands consistent with polyvinyl fluoride used on the aft bulkhead radiation shield exterior of Centaur-D R/B at the time.

Recalibration of the lunar chronology due to spatial cratering-rate variability

Cratering chronologies are used to derive the history of planetary bodies and assume an isotropic flux of impactors over the entire surface of the Moon. The impactor population is largely dominated by near-Earth-objects (NEOs) since ∼3.5 billion years ago. However, lunar impact probabilities from the currently known NEO population show an excess of impacts close to the poles compared to the equator as well as a latitudinal dependency of the approach angle of impactors. This is accompanied by a variation of the impact flux and speed with the distance from the apex due to the synchronicity of the lunar orbit around the Earth. Here, we compute the spatial dependency of the cratering rate produced by such variabilities and recalibrate the lunar chronology. We show that it allows to reconcile the crater density measured at mid-latitudes around the Chang'e-5 landing site with the age of the samples collected by this mission. Our updated chronology leads to differences in model ages of up to 30% compared to other chronology systems. The modeled cratering rate variability is then compared with the distribution of lunar craters younger than ∼1 Ma, 1 Ga and 4 Ga. The general trend of the cratering distribution is consistent with the one obtained from dynamical models of NEOs, thus potentially reflecting a nonuniform distribution of orbital parameters of ancient impactor populations, beyond 3.5 Ga ago, i.e., planetary leftovers and cometary bodies. If the nonuniformity of the cratering rate could be tested elsewhere in the Solar System, the recalibrated lunar chronology, corrected from spatial variations of the impact flux and approach conditions of impactors, could be extrapolated on other terrestrial bodies such as Mercury and Mars, at least over the last 3.5 billion years. The modeled cratering rate presented here has strong implications for interpreting results of the Artemis program, aiming to explore the South Pole of our satellite, in particular when it will come to link the radiometric age of the samples collected in this region and the crater density of the sampled units.

NEOMOD 2: An updated model of Near-Earth Objects from a decade of Catalina Sky Survey observations

Catalina Sky Survey (CSS) is a major survey of Near-Earth Objects (NEOs). In a recent work, we used CSS observations from 2005–2012 to develop a new population model of NEOs (NEOMOD). CSS’s G96 telescope was upgraded in 2016 and detected over 10,000 unique NEOs since then. Here we characterize the NEO detection efficiency of G96 and use G96’s NEO detections from 2013–2022 to update NEOMOD. This resolves previous model inconsistencies related to the population of large NEOs. We estimate there are 936±29 NEOs with absolute magnitude H<17.75 (diameter D>1 km for the reference albedo pV=0.14) and semimajor axis a<4.2 au. The slope of the NEO size distribution for H=25–28 is found to be relatively shallow (cumulative index ≃2.6) and the number of H<28 NEOs (D>9 m for pV=0.14) is determined to be (1.20±0.04)×107, about 3 times lower than in Harris & Chodas (2021). Small NEOs have a different orbital distribution and higher impact probabilities than large NEOs. We estimate 0.034±0.002 impacts of H<28 NEOs on the Earth per year, which is near the low end of the impact flux range inferred from atmospheric bolide observations. Relative to a model where all NEOs are delivered directly from the main belt, the population of small NEOs detected by G96 shows an excess of low-eccentricity orbits with a≃1–1.6 au that appears to increase with H (≃30% excess for H=28). We suggest that the population of very small NEOs is boosted by tidal disruption of large NEOs during close encounters to the terrestrial planets. When the effect of tidal disruption is (approximately) accounted for in the model, we estimate 0.06±0.01 impacts of H<28 NEOs on the Earth per year, which is more in line with the bolide data. The impact probability of a H<22 (D>140 m for pV=0.14) object on the Earth in this millennium is estimated to be ≃4.5%.

The NEO Surveyor Near-Earth Asteroid Known Object Model

The known near-Earth object (NEO) population consists of over 32,000 objects, with a yearly discovery rate of over 3000 NEOs per year. An essential component of the next generation of NEO surveys is an understanding of the population of known objects, including an accounting of the discovery rate per year as a function of size. Using a near-Earth asteroid (NEA) reference model developed for NASA’s NEO Surveyor (NEOS) mission and a model of the major current and historical ground-based surveys, an estimate of the current NEA survey completeness as a function of size and absolute magnitude has been determined (termed the Known Object Model; KOM). This allows for understanding of the intersection of the known catalog of NEAs and the objects expected to be observed by NEOS. The current NEA population is found to be ∼38% complete for objects larger than 140 m, consistent with estimates by Harris & Chodas. NEOS is expected to catalog more than two-thirds of the NEAs larger than 140 m, resulting in ∼76% of NEAs cataloged at the end of its 5 yr nominal survey, making significant progress toward the US Congressional mandate. The KOM estimates that ∼77% of the currently cataloged objects will be detected by NEOS, with those not detected contributing ∼9% to the final completeness at the end of its 5 yr mission. This model allows for placing the NEOS mission in the context of current surveys to more completely assess the progress toward the goal of cataloging the population of hazardous asteroids.

Size and Albedo Constraints for (152830) Dinkinesh Using WISE Data

Probing small main-belt asteroids provides insight into their formation and evolution through multiple dynamical and collisional processes. These asteroids also overlap in size with the potentially hazardous near-Earth object population and supply the majority of these objects. The Lucy mission will perform a flyby of the small main-belt asteroid, (152830) Dinkinesh, on 2023 November 1, in preparation for its mission to the Jupiter Trojan asteroids. In this Letter, we present data to support the planning of Lucy’s imminent encounter of Dinkinesh. We employed aperture photometry on stacked frames of Dinkinesh obtained by the Wide-field Infrared Survey Explorer and performed thermal modeling on a detection at 12 μm to compute diameter and albedo values. Through this method, we determined Dinkinesh has an effective spherical diameter of km and a visual geometric albedo of at the 16th and 84th percentiles. This albedo is consistent with typical stony (S-type) asteroids. These measurements will enable the Lucy team to optimize planning for the flyby of Dinkinesh, including refinement of exposure times and flyby geometry. The data obtained from this mission will, in turn, allow us to better understand the calibration of our thermal models by providing ground truth data. The Lucy flyby presents a rare opportunity to study the smallest main-belt asteroid ever observed in situ.

The ‘small’ asteroid population: a spectroscopic survey

ABSTRACT The study of near-Earth objects (NEOs) allow us to obtain information on the Solar system smallest bodies due to their closeness to Earth. In this work, we present the results of visible spectroscopic observations of 43 small and newly discovered NEOs, obtained during eighteen observing runs between October 2020 and December 2021, using the Goodman High Throughput Spectrograph at the 4.1-m Southern Astrophysical Research telescope (Cerro Pachón, Chile). We found a taxonomic distribution dominated by S-type asteroids but with an overabundance of A- and D-types. This result is in agreement with recent works on NEOs’ characterization and has implications for possible differences in the taxonomic distribution of ‘large’ and ‘small’ objects and emphasizes the idea of a non-homogeneous NEO population.

Close encounters of the interstellar kind: exploring the capture of interstellar objects in near-Earth orbit

ABSTRACT Recent observations and detections of interstellar objects (ISOs) passing through the Solar system have sparked a wave of interest into these objects. Although rare, these ISOs can be captured into bound orbits around the Sun. In this study, we investigate the novel idea of capture of ISOs into near-Earth orbits and find that a steady population of ISOs exists among the current population of near-Earth objects (NEOs). Using numerical simulations, we find that the capture of ISOs into near-Earth orbits is dominated by Jupiter that is 104 times more efficient in capturing ISOs compared to Earth. Captured ISOs are more likely to be in orbits with high eccentricities and low inclinations. We also investigate the stability of captured ISOs and find that they are generally unstable and have an average survival lifetime of ∼1 Myr, consistent with lifetime of NEOs originating from outer asteroid belt, and are ejected from the Solar system due to interactions with other planets or the Sun. Our results have important implications for understanding the population of ISOs in the Solar system and possible future detection. We find that about one to a few 50–70 m sized captured ISOs among NEOs would be detectable by Vera Rubin Observatory over its lifetime. By detecting and studying captured ISOs, we can learn about the properties and origins of such objects, and the formation and evolution of exoplanetary systems and even our Solar system.

Identifying meteorite droppers among the population of bright ‘sporadic’ bolides imaged by the Spanish Meteor Network during the spring of 2022

ABSTRACTThe extraordinary weather conditions available between February and March 2022 over Spain have allowed us to analyse the brightest fireballs recorded by the monitoring stations of the Spanish Meteor Network (SPMN). We study the atmospheric flight of 15 large meteoroids to determine if they are meteorite dropper events to prepare campaigns to search for freshly fallen extraterrestrial material. We investigate their origins in the Solar system and their dynamic association with parent bodies and meteoroid streams. Employing our python pipeline 3d-firetoc, we reconstruct the atmospheric trajectory utilizing ground-based multistation observations and compute the heliocentric orbit. In addition, we apply an ablation model to estimate the initial and terminal mass of each event. Using a dissimilarity criterion and propagating backward in time, we check the connection of these meteoroids with known complexes and near-Earth objects. We also calculate if the orbits are compatible with recent meteoroid ejections. We find that ∼27 per cent of these fireballs are dynamically associated with minor meteoroid streams and exhibit physical properties of cometary bodies, as well as one associated with a near-Earth asteroid. We identify two meteorite-producing events; however, the on-site search was unsuccessful. By considering that these fireballs are mostly produced by cm-sized rocks that might be the fragmentation product of much larger meteoroids, our findings emphasize the idea that the population of near-Earth objects is a source of near-term impact hazards, existing large Earth-colliding meteoroids in the known complexes.

A Deep and Wide Twilight Survey for Asteroids Interior to Earth and Venus

We are conducting a survey using twilight time on the Dark Energy Camera with the Blanco 4 m telescope in Chile to look for objects interior to Earth’s and Venus’ orbits. To date we have discovered two rare Atira/Apohele asteroids, 2021 LJ4 and 2021 PH27, which have orbits completely interior to Earth’s orbit. We also discovered one new Apollo-type Near Earth Object (NEO) that crosses Earth’s orbit, 2022 AP7. Two of the discoveries have diameters ≳1 km. 2022 AP7 is likely the largest Potentially Hazardous Asteroid (PHA) discovered in about eight years. To date we have covered 624 square degrees of sky near to and interior to the orbit of Venus. The average images go to 21.3 mag in the r band, with the best images near 22nd mag. Our new discovery 2021 PH27 has the smallest semimajor axis known for an asteroid, 0.4617 au, and the largest general relativistic effects (53 arcsec/century) known for any body in the solar system. The survey has detected ∼15% of all known Atira NEOs. We put strong constraints on any stable population of Venus co-orbital resonance objects existing, as well as the Atira and Vatira asteroid classes. These interior asteroid populations are important to complete the census of asteroids near Earth, including some of the most likely Earth impactors that cannot easily be discovered in other surveys. Comparing the actual population of asteroids found interior to Earth and Venus with those predicted to exist by extrapolating from the known population exterior to Earth is important to better understand the origin, composition, and structure of the NEO population.

Video observations of tiny near-Earth objects with Tomo-e Gozen

Abstract We report the results of video observations of tiny (diameter less than 100 m) near-Earth objects (NEOs) with Tomo-e Gozen on the Kiso 105 cm Schmidt telescope. The rotational period of a tiny asteroid reflects its dynamical history and physical properties since smaller objects are sensitive to the Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect. We carried out video observations of 60 tiny NEOs at 2 fps from 2018 to 2021 and successfully derived the rotational periods and axial ratios of 32 NEOs including 13 fast rotators with rotational periods less than 60 s. The fastest rotator found during our survey is 2020 HS$_\mathsf {7}$ with a rotational period of 2.99 s. We statistically confirmed that there is a certain number of tiny fast rotators in the NEO population, which have been missed with all previous surveys. We have discovered that the distribution of the tiny NEOs in a diameter and rotational period (D–P) diagram is truncated around a period of 10 s. The truncation with a flat-top shape is not explained well by either a realistic tensile strength of NEOs or the suppression of YORP by meteoroid impacts. We propose that the dependence of the tangential YORP effect on the rotational period potentially explains the observed pattern in the D–P diagram.

The Debiased Compositional Distribution of MITHNEOS: Global Match between the Near-Earth and Main-belt Asteroid Populations, and Excess of D-type Near-Earth Objects

Abstract We report 491 new near-infrared spectroscopic measurements of 420 near-Earth objects (NEOs) collected on the NASA InfraRed Telescope Facility as part of the MIT-Hawaii NEO Spectroscopic Survey. These measurements were combined with previously published data from Binzel et al. and bias-corrected to derive the intrinsic compositional distribution of the overall NEO population, as well as of subpopulations coming from various escape routes (ERs) in the asteroid belt and beyond. The resulting distributions reflect well the overall compositional gradient of the asteroid belt, with decreasing fractions of silicate-rich (S- and Q-type) bodies and increasing fractions of carbonaceous (B-, C-, D- and P-type) bodies as a function of increasing ER distance from the Sun. The close compositional match between NEOs and their predicted source populations validates dynamical models used to identify ERs and argues against any strong composition change with size in the asteroid belt between ∼5 km and ∼100 m. A notable exception comes from the overabundance of D-type NEOs from the 5:2J and, to a lesser extend, the 3:1J and ν 6 ERs, hinting at the presence of a large population of small D-type asteroids in the main belt. Alternatively, this excess may indicate preferential spectral evolution from D-type surfaces to C and P types as a consequence of space weathering, or point to the fact that D-type objects fragment more often than other spectral types in the NEO space. No further evidence for the existence of collisional families in the main belt, below the detection limit of current main-belt surveys, was found in this work.

Optimized continuous-thrust round-trip trajectories to ultra-low Δv ISRU targets

We present the results and implications of our optimized round-trip trajectories to thousands of synthetic but realistic ultra-low Δv (≲ 8 ​km ​s−1) asteroids for the purpose of in-space resource utilization (ISRU) of water extracted from the targets. We show that our carpe diem mission scenario works — ISRU missions utilizing ‘hibernating’ spacecraft on loosely-bound orbits in cis-lunar space can begin soon after targets are discovered if the asteroids are rapidly characterized with accurate and precise orbits. Our algorithm identified ultra-low Δv round-trip mission trajectories for 100% of the ISRU targets that approach to within 0.05 au of Earth. The median minimum distance between the targets and Earth during the rendezvous/mining phase is ∼ 0.23 au (∼ 115 light-seconds) while the maximum one-way communication time is ​≲ ​4 ​min. The return-trip missions have a median Δv ∼ 2.9 ​km ​s−1 so that the typical mission returns about 50% of the extracted H2O to cis-lunar space. We estimate a steady-state rate of about 2 water-mining missions per year returning about 100 tonne yr−1 to the Earth-Moon system. Converting the water to LOX/LH2 is ∼ 93% efficient, suggesting that asteroid H2O mining could provide ∼ 93 tonne of bipropellant to cis-lunar space on an annual basis. We applied our mission optimization algorithm to 168 known near-Earth objects (NEO) with orbital elements similar to our synthetic ultra-low Δv population and estimate that almost 95% of the population of ultra-low Δv NEOs remain to be discovered.

Thermal emission measurements of ordinary chondrite mineral analogs in a simulated asteroid environment: 1. Constituent mineral phases

Telescopic surveys suggest that S-type asteroids are the dominant small body type in the near-Earth object population and are among the most abundant in the inner main asteroid belt. Given the link between S-type asteroids and the ordinary chondrites, regoliths of ordinary chondrite mineralogy may represent the most common regolith type on small bodies in these populations, and therefore it is important to understand the thermal emission properties of ordinary chondrite mineral analogs radiating into asteroid-like environments. Thermal infrared spectra of particulate surfaces in airless environments are substantially modified due to near-surface thermal gradients formed between the immediate surface undergoing radiative cooling and underlying materials that are warmed by the absorption of solar radiation. To advance our understanding of how the thermal emission properties of materials relevant to ordinary chondrite composition may be modified in an airless environment, we analyze a suite of analogous single mineral phases in a simulated asteroid surface environment. A companion paper presents and discusses analyses of modal mixtures of these minerals designed to match modal abundances of ordinary chondrites as reported in the literature. We probe the thermal emission of these materials by investigating relationships between their sample temperatures, emissivity spectra, brightness temperatures, and the environmental and experimental conditions. We focus attention on the radiance spectra of the samples as derived by two data reduction methods and their corresponding brightness temperature spectra to infer the intensity of near-surface thermal gradients formed in the samples. We demonstrate that the Christiansen feature position is sensitive to the sample cup temperature with data collected in a simulated asteroid environment under constant illumination condition. Through the analysis of particulate samples of three particle size ranges (<25 μm, 25–125 μm, and 125–250 μm) at ambient and cold, vacuum conditions, we demonstrate that thermal gradients form as a result of the physical, environmental, and optical properties of the target surface. Using temperature variations observed in high spectral resolution brightness temperature spectra as a proxy for the near-surface thermal gradients, we observe relationships between the intensity of the thermal gradient and the sample particle size. Modifications of iron metal spectra due to the changing environmental conditions are examined and compared with the silicate data. Implications for the measurement of thermal infrared spectra of metal-bearing planetary materials, such as the ordinary chondrites, are discussed.

Dynamical evolution and thermal history of asteroids (3200) Phaethon and (155140) 2005 UD

The near-Earth objects (NEOs) (3200) Phaethon and (155140) 2005 UD are thought to share a common origin, with the former exhibiting dust activity at perihelion that is thought to directly supply the Geminid meteor stream. Both of these objects currently have very small perihelion distances (0.140au and 0.163au for Phaethon and 2005 UD, respectively), which results in them having perihelion temperatures around 1000K. A comparison between NEO population models to discovery statistics suggests that low-perihelion objects are destroyed over time by a, possibly temperature-dependent, mechanism that is efficient at heliocentric distances less than 0.3au. By implication, the current activity from Phaethon is linked to the destruction mechanism of NEOs close to the Sun.We model the past thermal characteristics of Phaethon and 2005 UD using a combination of a thermophysical model (TPM) and orbital integrations of each object. Temperature characteristics such as maximum daily temperature, maximum thermal gradient, and temperature at different depths are extracted from the model, which is run for a predefined set of semi-major axis and eccentricity values. Next, dynamical integrations of orbital clones of Phaethon and 2005 UD are used to estimate the past orbital elements of each object. These dynamical results are then combined with the temperature characteristics to model the past evolution of thermal characteristics such as maximum (and minimum) surface temperature and thermal gradient. The orbital histories of Phaethon and 2005 UD are characterized by cyclic changes in e, resulting in perihelia values periodically shifting between present-day values and 0.3au. Currently, Phaethon is experiencing relatively large degrees of heating when compared to the recent 20,000yr. We find that the subsurface temperatures are too large over this timescale for water ice to be stable, unless actively supplied somehow. The near-surface thermal gradients strongly suggest that thermal fracturing may be very effective at breaking down and ejecting dust particles. Observations by the DESTINY+ flyby mission will provide important constraints on the mechanics of dust-loss from Phaethon and, potentially, reveal signs of activity from 2005 UD.In addition to simulating the recent dynamical evolution of these objects, we use orbital integrations that start from the Main Belt to assess their early dynamical evolution (origin and delivery mechanism). We find that dwarf planet (2) Pallas is unlikely to be the parent body for Phaethon and 2005 UD, and it is more likely that the source is in the inner part of the asteroid belt in the families of, e.g., (329) Svea or (142) Polana.

NEO Population, Velocity Bias, and Impact Risk from an ATLAS Analysis

Abstract We estimate the total population of near-Earth objects (NEOs) in the solar system using an extensive, “solar-system-to-pixels” fake-asteroid simulation to debias detections of real NEOs by the ATLAS survey. Down to absolute magnitudes H = 25 and 27.6 (diameters of ∼34 and 10 m, respectively, for 15% albedo), we find total populations of (3.72 ± 0.49) × 105 and (1.59 ± 0.45) × 107 NEOs, respectively. Most of the plausible sources of error tend toward underestimation, so the true populations are likely larger. We find the distribution of H magnitudes steepens for NEOs fainter than H ∼ 22.5, making small asteroids more common than extrapolation from brighter H mags would predict. Our simulation indicates a strong bias against detecting small but dangerous asteroids that encounter Earth with high relative velocities—i.e., asteroids in highly inclined and/or eccentric orbits. Worldwide NEO discovery statistics indicate this bias affects global NEO detection capability to the point that an observational census of small asteroids in such orbits is probably not currently feasible. Prompt and aggressive followup of NEO candidates, combined with closer collaborations between segments of the global NEO community, can increase detection rates for these dangerous objects.

Geoinformation modeling of near-Earth space: current tasks and future prospects

The history of space exploration and current near-Earth space objects population are described in this paper. Moreover, the necessity of GIS technologies application to solve space industry tasks and the development of corresponding GIS are explained. The legal and regulatory issues of the near-Earth space GIS project development are touched upon, as well as the classification and options for the target purpose of the system. The stages of technological search and development are presented, as a result of which the Cesium library was chosen. Based on the results of discussions, a decision is made to expand the limits of the modeling space to the outer boundaries of the Hill sphere. In addition, it is noted that the objects of geoinformation modeling of near-Earth space should be not only space objects, considered as three-dimensional, but also the physical fields of the Earth. The results of performance evaluation experiments on SGP4/SDP4 based software tool for predicting space objects position are shown, and the accuracy of this model itself is assessed by reference GPS coordinates. Possible ways of industry tasks that could be solved using the developed near-Earth space GIS are presented; promising routes of the future development including DISCOS data are indicated.

Extended photometric survey of near-Earth objects

Context. The near-Earth objects (NEOs), whose proximity makes them the most accessible bodies in the Solar System, allow us to sample asteroids from tens of kilometers down to objects of a few meters in size. However, while the physical properties for the largest bodies are mostly known, we have very little physical information regarding the small NEOs. These objects today represent the overall majority among the ~2500 new discoveries each year, but they are usually only bright enough to be observable during their close approaches. Aims. Our aim was to extend our survey that started in 2015 on the NEO population, using ground-based observations to characterize the fainter (and typically smaller) NEOs observable each night. Methods. We performed BVRIz photometry of NEOs, making use of the DOLORES instrument at the Telescopio Nazionale Galileo (TNG, La Palma, Spain) and the Asiago Schmidt telescope (Italy), in order to derive visible color indexes and the taxonomic classification for each target in our sample. Results. We taxonomically classified 51 new NEOs for the first time. Together with data obtained in our previous work and collected by other surveys available online, we analyzed an extended sample of 1081 individual NEOs. While the overall majority of them belong to the S-complex, our analysis of the taxonomic distribution found a larger contribution for dark bodies going toward larger H, suggesting that they could be more abundant among the fainter NEOs. Moreover, we find an interesting correlation between semi-major axis and diameter, which could be in part related to the Yarkovsky effect. Rapid characterization of the fainter NEO population shortly after their discovery will be crucial in the future, before those bodies become too faint to be observed, or lost forever.