Observations Of near-Earth Objects Research Articles

Taxonomy of Subkilometer Near-Earth Objects from Multiwavelength Photometry with RATIR

We present results from observations of 238 near-Earth objects (NEOs) obtained with the RATIR instrument on the 1.5 m robotic telescope at San Pedro Martir’s National Observatory in Mexico, in the frame of our multiobservatory, multifilter campaign. Our project is focused on rapid response photometric observations of NEOs with absolute magnitudes in the range 18.1–27.1 (diameter ≈ 600 and 10 m, respectively). Data with coverage in the near-infrared and visible range were analyzed with a nonparametric classification algorithm, while visible-only data were independently analyzed via Monte Carlo simulations and a 1-Nearest Neighbor method. The rapid response and the use of spectrophotometry allows us to obtain taxonomic classifications of subkilometer objects with small telescopes, representing a convenient characterization strategy. We present taxonomic classifications of the 87 objects observed in the visible and near-infrared. We also present the taxonomic distribution of an additional 151 objects observed in the visible. Our most accurate method suggests a nonfeatured-to-featured ratio of ≈0.75, which is consistent with the value found by the Mission Accessible Near-Earth Object Survey, which conducted a similar study using a spectral analysis. The results from the Monte Carlo method suggest a ratio of ≈0.8, although this method has some limitations. The 1-Nearest Neighbor method showed to be not suitable for NEO classifications.

Near-Earth Object Observations using Synthetic Tracking

Synthetic tracking (ST) has emerged as a potent technique for observing fast-moving near-Earth objects (NEOs), offering enhanced detection sensitivity and astrometric accuracy by avoiding trailing loss. This approach also empowers small telescopes to use prolonged integration times to achieve high sensitivity for NEO surveys and follow-up observations. In this study, we present the outcomes of ST observations conducted with Pomona College’s 1 m telescope at the Table Mountain Facility and JPL’s robotic telescopes at the Sierra Remote Observatory. The results showcase astrometric accuracy statistics comparable to stellar astrometry, irrespective of an object’s rate of motion, and the capability to detect faint asteroids beyond 20.5th magnitude using 11 inch telescopes. Furthermore, we detail the technical aspects of data processing, including the correction of differential chromatic refraction in the atmosphere and accurate timing for image stacking, which contribute to achieving precise astrometry. We also provide compelling examples that showcase the robustness of ST even when asteroids closely approach stars or bright satellites cause disturbances. Moreover, we illustrate the proficiency of ST in recovering NEO candidates with highly uncertain ephemerides. As a glimpse of the potential of NEO surveys utilizing small robotic telescopes with ST, we present significant statistics from our NEO survey conducted for testing purposes. These findings underscore the promise and effectiveness of ST as a powerful tool for observing fast-moving NEOs, offering valuable insights into their trajectories and characteristics. Overall, the adoption of ST stands to revolutionize fast-moving NEO observations for planetary defense and studying these celestial bodies.

Toward a European Facility for Ground-Based Radar Observations of Near-Earth Objects

In this work, we present the preliminary results of radar observations of Near-Earth Objects (NEOs) carried out by European radio telescopes in the framework of the European Space Agency (ESA) project “NEO observation concepts for radar systems”, aimed at deriving the functional requirements of a planetary radar system, evaluating the available European assets to perform NEO radar observations, and carrying out test radar campaigns. In the first part of the project, we executed the performance analysis of a possible European planetary radar system. Instrumental features, as much as issues like the impact of weather conditions on signal propagation at different radio frequencies, were considered. This paper focused on the test campaigns, performed in the years 2021–2022 in collaboration with the Jet Propulsion Laboratory (JPL), which led to the observation of several asteroids including 2021 AF8, (4660) Nereus, and 2005 LW3, which allowed us to derive astrometric measurements, as well as to measure physical properties, such as rotation periods, and observe how one of the targets is actually a binary asteroid. The obtained results demonstrated that European radio astronomical dishes, although employed only as receivers (in bistatic or multistatic configurations) and for a limited amount of time, are able to provide a significant contribution to the constitution of a European network to increase the opportunities for NEO monitoring and studies, if a transmitting antenna—equipped with a suitable high-power transmitter—were made available.

Determination of the Motion Parameters of Near-Earth Objects from Position Measurements Performed at the Terskol Observatory

The paper presents a method for processing positional observations of near-Earth objects using a numerical model of satellite motion developed at the Research Institute of Applied Mathematics and Mechanics of Tomsk State University (NII PMM TSU). The root-mean-square error of orbit improvement without rejection of observations for such objects does not exceed 0.3″ over a seven-day time interval. The results of the presentation of observations for the next occurrence of the object are obtained, which makes it possible to find the object in a time interval of five months. The orbit has been refined in the joint processing of measurements on several occurrences of the object over a six-month time interval. All results were obtained from observations made on the equipment of the Terskol Observatory Shared Use Center.

New Tools for the Optimized Follow-Up of Imminent Impactors

The solar system is populated with, other than planets, a wide variety of minor bodies, the majority of which are represented by asteroids. Most of their orbits are comprised of those between Mars and Jupiter, thus forming a population named Main Belt. However, some asteroids can run on trajectories that come close to, or even intersect, the orbit of the Earth. These objects are known as Near Earth Asteroids (NEAs) or Near Earth Objects (NEOs) and may entail a risk of collision with our planet. Predicting the occurrence of such collisions as early as possible is the task of Impact Monitoring (IM). Dedicated algorithms are in charge of orbit determination and risk assessment for any detected NEO, but their efficiency is limited in cases in which the object has been observed for a short period of time, as is the case with newly discovered asteroids and, more worryingly, imminent impactors: objects due to hit the Earth, detected only a few days or hours in advance of impacts. This timespan might be too short to take any effective safety countermeasure. For this reason, a necessary improvement of current observation capabilities is underway through the construction of dedicated telescopes, e.g., the NEO Survey Telescope (NEOSTEL), also known as “Fly-Eye”. Thanks to these developments, the number of discovered NEOs and, consequently, imminent impactors detected per year, is expected to increase, thus requiring an improvement of the methods and algorithms used to handle such cases. In this paper we present two new tools, based on the Admissible Region (AR) concept, dedicated to the observers, aiming to facilitate the planning of follow-up observations of NEOs by rapidly assessing the possibility of them being imminent impactors and the remaining visibility time from any given station.

Asteroid Observations from the Transiting Exoplanet Survey Satellite: Detection Processing Pipeline and Results from Primary Mission Data

The Transiting Exoplanet Survey Satellite (TESS) is a NASA Explorer-class mission designed for finding exoplanets around nearby stars. TESS image data can also serve as a valuable resource for asteroid and comet detection, including near-Earth objects (NEOs). In order to exploit the TESS image data for moving object detection and potential object discovery, our team has developed an image processing pipeline as part of the Lincoln Near-Earth Asteroid Research (LINEAR) program, sponsored by the NASA NEO Observations Program. The LINEAR-TESS pipeline is currently in operation and reporting asteroid observations to the Minor Planet Center. In this paper we discuss the algorithms and methodology utilized to push the limits of the astrometric accuracy and photometric sensitivity of the TESS instrument for asteroid detection without a priori information on the ephemerides of the objects, and report on observation statistics from the first two years of TESS mission data.

A mission concept for the low-cost large-scale exploration and characterisation of near earth objects

This paper presents the preliminary mission and science analysis of a new mission concept for the large scale, low-cost exploration of Near Earth Objects (NEOs). The concept is to enable close range observations of NEOs by performing close flybys of a series of NEOs at one of their nodal points, with pairs of small spacecraft flying in formation. The paper presents a preliminary assessment of accessible asteroids and multi-target tour trajectories from data available in the JPL small-body database. The main instruments on board each spacecraft are a camera and a LIDAR which together can be used for orbit determination, surface imaging, direct asteroid ranging and asteroid mass estimation via intersatellite ranging. The paper provides a qualitative and quantitative assessment of the measurable quantities during each flyby. In particular, the feasibility of a novel method of NEO mass estimation is assessed.

Improving position accuracy for telescopes with small aperture and wide field of view utilizing point spread function modelling

ABSTRACT Telescopes with a small aperture and a wide field of view are widely used and play a significant role in large-scale state-of-the-art sky survey applications, such as transient detection and near-Earth object observations. However, owing to the specific defects caused by optical aberrations, the image quality and efficiency of source detection are affected. To achieve high-accuracy position measurements, an innovative technique is proposed. First, a large number of raw images are analysed using principal component analysis. Then, the effective point spread function is reconstructed, which reflects the state of the telescope and reveals the characteristics of the imaging process. Finally, based on the point spread function model, the centroids of star images are estimated iteratively. To test the efficiency and reliability of our algorithm, a large number of simulated images are produced, and a telescope with small aperture and wide field of view is utilized to acquire the raw images. The position measurement of sources is performed using our novel method and two other common methods on these data. Based on a comparison of the results, the improvement is investigated, and it is demonstrated that our proposed technique outperforms the others on position accuracy. We explore the limitations and potential gains that may be achieved by applying this technique to custom systems designed specifically for wide-field astronomical applications.

Noise estimation and probability of detection in non-resolved images: Application to space object observation

Charged Couple Device (CCD) technology is widely used in various scientific measurement contexts. CCD equipped cameras have revolutionized astronomy and space-related optical telescope measurements in recent years. They are also used in electroscopic measurements, e.g., in fields such as geology, biology, and medicine. The signal-to-noise ratio and the probability of detection are crucial to design experiments observation setups properly and to employ further mathematical methods for data exploitation such as, e.g. multi-target tracking methods. Previous attempts to correctly characterize the signal-to-noise ratio for star observations are revisited in this work and adapted for the application of near-Earth object observations and high precision measurements, leading to a modified CCD equation. Our formulation proposes a novel distribution of the signal noise that accurately accounts for the truncation noise and the presence of ambiguous pixels. These improvements are employed to derive the probability of detection and the SNR with significant improvements compared to existing formulations when ambiguous pixels are present.

HIGH-PRECISION FOLLOW-UP OBSERVATIONS OF NEAR-EARTH OBJECTS

Main objective of the study is orbit refinement of Near-Earth Objects (NEOs) as part of the global task of asteroid-cometary hazard. We present the latest results of ongoing high-precision astrometric follow-up observations of NEOs using the Mykolaiv Observatory KT-50 telescope of Mobitel Complex that equipped Alta U9000 CCD camera. Main feature of the objects of this study is the fast moving in the field of view. That circumstance makes impossible to observe NEOs as point images and to obtain their precise coordinates by the classical methods of observation. We used modified Rotating-drift-scan CCD mode for obtaining NEOs images and classical mode – for obtaining fields with reference stars to carry out astrometric reductions. The combination of classical and modified observational modes allows us to recover objects having V < 17 with high astrometric precision. The comparative statistics of Mykolaiv observations of NEOs for the period 2015-2018 and analysis of positional accuracy are presented. The results of the effect of new observational data on the residual differences (O-C) in both coordinates with respect to HORIZONS JPL ephemerides are shown on examples two potentially-hazard asteroids (2001KB67 and 2017YE5) during their close approaching to Earth in 2018. It is shown that adding new observations can significantly improve the accuracy of determining the orbital elements of such objects.CCD observations; asteroid-cometary hazard; near-earth asteroids; potentially hazard asteroids; ephemerids of small Solar system bodies

Infrared Light Curves of Near-Earth Objects

We present lightcurves and derive periods and amplitudes for a subset of 38 near earth objects (NEOs) observed at 4.5 microns with the IRAC camera on the the Spitzer Space Telescope, many of them having no previously reported rotation periods. This subset was chosen from about 1800 IRAC NEO observations as having obvious periodicity and significant amplitude. For objects where the period observed did not sample the full rotational period, we derived lower limits to these parameters based on sinusoidal fits. Lightcurve durations ranged from 42 to 544 minutes, with derived periods from 16 to 400 minutes. We discuss the effects of lightcurve variations on the thermal modeling used to derive diameters and albedos from Spitzer photometry. We find that both diameters and albedos derived from the lightcurve maxima and minima agree with our previously published results, even for extreme objects, showing the conservative nature of the thermal model uncertainties. We also evaluate the NEO rotation rates, sizes, and their cohesive strengths.

A Complex for Carrying Out Radar Observations of Near-Earth Objects

The Institute of Applied Astronomy of the Russian Academy of Sciences and the Goldstone Deep Space Communications Complex regularly conduct intercontinental radar observations of near-Earth objects using a 70-m DSS-14 antenna as a transmitter and the 32-m RT-32 radio telescopes of the Quasar VLBI network as receivers. To carry out the observations, the existing complex for reception, conversion, and recording of signals from the RT-32 radio telescopes has been adapted and special software for scheduling observations and processing echo signals has been developed. Since 2015, echoes from the 2011 UW158, 2003 TL4, 2003 YT1, 2003 BD44, and 2014 JO25 asteroids have been recorded. The power spectra of the echoes from these asteroids have been obtained and analyzed.

Advances in planetary defense in the United States

The National Aeronautics and Space Administration (NASA) recently established an office to manage the Agency's planetary defense-related projects and coordinate activities across multiple U.S. agencies as well as with international efforts to plan appropriate responses to the potential asteroid impact hazard. The creation of the Planetary Defense Coordination Office (PDCO) is a logical and formal step forward with NASA's NEO Observations program which began nearly two decades ago. Since the program's inception in 1998, NASA-funded efforts have discovered more than 98% of the more than 16,000 NEOs currently known.As important as it is to mitigate a potential impact event, the essential first step is to find these near-Earth objects as early as possible. To that end, NASA's PDCO leads national and international efforts to:•detect any potential for significant impact of the Earth by natural objects;•appraise the range of potential effects by any possible object; and•develop strategies to mitigate impact effects on human welfare.Since commencing the program in 1998, NASA has provided funding to upgrade and operate existing 1-m class telescopes to conduct the search for NEOs. Today, NASA funds three primary ground-based survey capabilities: the Lincoln Near-Earth Asteroid Research (LINEAR) project, the Catalina Sky Survey (CSS), and the Panoramic Survey Telescope and Rapid Reporting System (Pan-STARRS). Recent enhancements to NASA's Near-Earth Object (NEO) Observations Program have led to ∼83% increase in the discovery rate of near-Earth asteroids (NEAs) over the past three years.These survey efforts are increasingly detecting close encounter events (i.e., <0.001 AU; recent examples include 2012 DA14, 2017 EA, and 2017 GM) and have enabled the prediction of some small object impact events (e.g., 2008 TC3 and 2014 AA). Such encounters provide opportunities for NASA's Infrared Telescope Facility (IRTF) to make spectral measurements; or observation by planetary radars at Arecibo and Goldstone to refine the orbit of the object with great precision and even “image” the small primitive body.Of critical importance is the Minor Planet Center (MPC), where automated systems process observations made by the search teams to determine orbits and what are NEOs. The Center for NEO Studies at the Jet Propulsion Laboratory (JPL) determines more precise orbits for the objects. Both JPL and the MPC utilize processes and procedures for NEO orbit determination and prediction that are sanctioned and monitored by the International Astronomical Union (IAU) and produce data catalogues on small bodies in the Solar System that are utilized world-wide by the astronomical community.The Wide-field Infrared Survey Explorer (WISE) was reactivated for the purpose detecting NEOs and will continue to operate well into 2018. It is in Sun-synchronous, near-polar inclination (97.5°) orbit around the Earth. The NEOWISE project uses WISE in ‘warm mode’ (at 3.4 and 4.6 μm), and in conjunction with ground-based follow-up, this unique dataset has set limits on population statistics, orbital parameters, approximate sizes, and initial compositional knowledge of the asteroid population.Further follow-up observations with visible and infrared telescopes (e.g., NASA's Infrared Telescope Facility, Spitzer Space Telescope, other NASA-funded NEO observer teams) refine the astrometric positions of an NEO, photometric observations obtain detailed light curve information [thereby constraining NEO shapes and spin state], and collect albedo and spectral data on basic physical properties and mineralogy.Planetary defense demonstration missions also fall within the purview of the PDCO. The Double Asteroid Redirection Test (DART) mission is directed by NASA to the Johns Hopkins University Applied Physics Laboratory (JHU/APL). The target is the binary near-Earth asteroid (65803) Didymos, which consists of a primary body ∼800 m across, and a secondary body (or “moonlet”) whose 150-m size is more typical of the size of asteroids that could pose a more common hazard to Earth.However, the first step in planetary defense is the overarching goal to complete the NEO survey down to a 100 m-sized objects. The asteroid hunter mission – NEOCam – is a single scientific instrument: 0.5-m aperture infrared telescope that would survey the solar system for NEOs from Sun-Earth L1 Lagrange point (SEL1). NEOCam is also in an extended Phase A study under the auspices of NASA's PDCO.

NASA's Asteroid Grand Challenge: Strategy, Results, and Lessons Learned

Beginning in 2012, NASA used a strategic process to identify broad societal questions, or grand challenges, that are well suited to the aerospace sector and align with national priorities. This effort generated NASA's first grand challenge, the Asteroid Grand Challenge (AGC), a large-scale effort using multidisciplinary collaborations and innovative engagement mechanisms, that focused on finding and addressing asteroid threats to human populations. In April 2010, President Barack Obama announced a mission to send humans to an asteroid by 2025. This resulted in the agency's Asteroid Redirect Mission (ARM) to leverage and maximize existing robotic and human efforts to capture and reroute an asteroid, with the goal of eventual human exploration. The AGC, initiated in 2013, complemented ARM by expanding public participation, partnerships, and other approaches to find, understand, and overcome these potentially harmful asteroids. This article describes a selection of AGC activities implemented from 2013 to 2017 and their results, excluding those conducted by NASA's Near-Earth Object Observations Program and other organizations. The strategic development of the initiative is outlined as well as initial successes, strengths, and weaknesses resulting from the first 4 years of AGC activities and approaches. Finally, we describe lesson learned and areas for continued work and study. The AGC lessons learned and strategies could inform the work of other agencies and organizations seeking to conduct a global scientific investigation with matrixed organizational support, multiple strategic partners, and numerous internal and external open innovation approaches and audiences.

An Investigation of the Ranges of Validity of Asteroid Thermal Models for Near-Earth Asteroid Observations

Abstract The majority of known asteroid diameters are derived from thermal-infrared observations. Diameters are derived using asteroid thermal models that approximate their surface temperature distributions and compare the measured thermal-infrared flux with model-dependent predictions. The most commonly used thermal model is the Near-Earth Asteroid Thermal Model (NEATM), which is usually perceived as superior to other models like the Fast-Rotating Model (FRM). We investigate the applicability of the NEATM and the FRM to thermal-infrared observations of Near-Earth Objects using synthetic asteroids with properties based on the real Near-Earth Asteroid (NEA) population. We find the NEATM to provide more accurate diameters and albedos than the FRM in most cases, with a few exceptions. The modeling results are barely affected by the physical properties of the objects, but we find a large impact of the solar phase angle on the modeling results. We conclude that the NEATM provides statistically more robust diameter estimates for NEAs observed at solar phase angles less than ∼65°, while the FRM provides more robust diameter estimates for solar phase angles greater than ∼65°. We estimate that &lt;5% of all NEA diameters and albedos derived up to date are affected by systematic effects that are of the same order of magnitude as the typical thermal model uncertainties. We provide statistical correction functions for diameters and albedos derived using the NEATM and FRM as a function of solar phase angle.

Observing Near-Earth Objects with the James Webb Space Telescope

The James Webb Space Telescope (JWST) has the potential to enhance our understanding of near-Earth objects (NEOs). We present results of investigations into the observability of NEOs given the nominal observing requirements of JWST on elongation (85°–135°) and non-sidereal rates (<30 mas s−1). We find that approximately 75% of NEOs can be observed in a given year. However, observers will need to wait for appropriate observing windows. We find that JWST can easily execute photometric observations of meter-sized NEOs that will enhance our understanding of the small NEO population.

Оценка координат близких астероидов на пзс изображении

The development of computational methods for highly precise estimation of near-Earth objects coordinates on a sampled image is of current importance nowadays due to a significant increase of penetrating power of optical systems. In this regard, it becomes much more difficult to achieve the required accuracy of observations of near-Earth objects with statistically dependent images. The paper proposes a method that allows potentially accurate estimation of coordinates of several near-Earth celestial objects on the CCD-frame. The developed method is based on the OLS assessment of parameters of statistically dependent objects images. The optimization problem of minimizing the sum of squared residuals (between theoretical and experimental brightness of the CCD matrix pixels) can be solved by the Levenberg-Marquardt algorithm. The developed method can be used in the systems of concurrent automatic detection of asteroids, for example, in the program CoLiTec, for estimating the coordinates of several near-Earth statistically dependent objects

ExploreNEOs. II. THE ACCURACY OF THE WARMSPITZERNEAR-EARTH OBJECT SURVEY

We report on results of observations of near-Earth objects (NEOs) performed with the NASA Spitzer Space Telescope as part of our ongoing (2009–2011) Warm Spitzer NEO survey ("ExploreNEOs"), the primary aim of which is to provide sizes and albedos of some 700 NEOs. The emphasis of the work described here is an assessment of the overall accuracy of our survey results, which are based on a semi-empirical generalized model of asteroid thermal emission. The NASA Spitzer Space Telescope has been operated in the so-called Warm Spitzer mission phase since the cryogen was depleted in 2009 May, with the two shortest-wavelength channels, centered at 3.6 μm and 4.5 μm, of the Infrared Array Camera continuing to provide valuable data. The set of some 170 NEOs in our current Warm Spitzer results catalog contains 28 for which published taxonomic classifications are available, and 14 for which relatively reliable published diameters and albedos are available. A comparison of the Warm Spitzer results with previously published results ("ground truth"), complemented by a Monte Carlo error analysis, indicates that the rms Warm Spitzer diameter and albedo errors are ±20% and ±50%, respectively. Cases in which agreement with results from the literature is worse than expected are highlighted and discussed; these include the potential spacecraft target 138911 2001 AE2. We confirm that 1.4 appears to be an appropriate overall default value for the relative reflectance between the V band and the Warm Spitzer wavelengths, for use in correction of the Warm Spitzer fluxes for reflected solar radiation.

The observations of Near Earth Objects by the automatic mirror astrograph ZA–320M at Pulkovo observatory

AbstractAt Pulkovo Observatory, we conduct observations of various Solar System bodies: major planets, their satellites, comets, and asteroids, including Near Earth Objects. For these purposes, a robotic telescope was constructed on the base of the ZA–320 Mirror Astrograph (D=320 mm, F=3200 mm). It can perform CCD observations of Solar System bodies with the limiting magnitude of up to 19.0.Independent ephemeris support is provided by the EPOS software package developed at Pulkovo Observatory; it includes tracing of catalogues of comets and asteroids, regular ephemeris calculations, and control of observations. CCD frame processing is done by the Apex automatic data reduction package developed at Pulkovo Observatory.In 2001-2006, more than 12000 observations of minor Solar System bodies were collected, including more than 6000 positions of 656 NEAs, about 1200 observations of 27 comets, and about 2000 observations of major planets satellites. The mean accuracy of obtained positions is 0″.09−0″.40. Results of observations are regularly submitted to the Minor Planet Center.Currently, ZA–320M is the 16-th of more than 680 telescopes in the worldwide rating of those that observe NEAs (by the number of observations).In the near future, our group is planning to start observations with another two robotic telescopes: MTM–500 (D=500 mm, F=4000 mm Maksutov) and 1-meter telescope (D=1000 mm, F=1200 mm) of the Pulkovo mountain station at Northern Caucasus (Kislovodsk, 2100 m above sea level). These two instruments will allow to increase the number of observations, their accuracy, and limiting magnitude (up to 20.5 mag).

Astrometry of small Solar System bodies at the Molėtai observatory

AbstractWe describe an observational project devoted to astrometric observations of Near-Earth Objects (NEO), main belt asteroids and comets at the Molėtai Observatory, Lithuania. Exposures are obtained with the two telescopes of the observatory: 0.35/0.50 m f/3.5 Maksutov telescope and the 1.65 m reflector with focal reductor f/3.1 and CCD camera. The results of more than 10,000 positions of asteroids and comets have been published in the Minor Planet Circulars and Minor Planet Electronic Circulars. During the 2001–2006 period 130 new asteroids were discovered. The latest discovery is the high-inclination asteroid 2006 SF77 belonging to the NEO Aten group.