Dangerous Asteroids Research Articles

Astrometry and Photometry of Potentially Dangerous Asteroid 65690 (1991 DG)

Astrometry and Photometry of Potentially Dangerous Asteroid 65690 (1991 DG)

Linking Sky-plane Observations of Moving Objects

The Asteroid Terrestrial-impact Last Alert System (ATLAS) observes the visible sky every night in search of dangerous asteroids. With four (soon five) sites ATLAS is facing new challenges for scheduling observations and linking detections to identify moving asteroids. Flexibility in coping with diverse observation sites and times of detections that can be linked is critical, as is optimization of observing time for coverage versus depth. We present new algorithms to fit orbits rapidly to sky-plane observations, and to test and link sets of detections to find the ones which belong to moving objects. The PUMA algorithm for fitting orbits to angular positions on the sky executes in about a millisecond, orders of magnitude faster than the methods currently in use by the community, without sacrifice in accuracy. The PUMA software should be generally useful to anyone who needs to test many sets of detections for consistency with a real orbit. The PUMALINK algorithm to find linkages among sets of detections has similarities to other approaches, notably HelioLinC, but it functions well at asteroid ranges of a small fraction of an astronomical unit. PUMALINK is fast enough to test 10 million possible tracklets against one another in a half hour of computer time. Candidate linkages are checked by the PUMA library to test that the detections correspond to a real orbit, even at close range, and the false alarm rate is manageable. Sky surveys that produce large numbers of detections from large numbers of exposures may find the PUMALINK software helpful. We present the results of tests of PUMALINK on three data sets which illustrate PUMALINK’s effectiveness and economy: 2 weeks of all ATLAS detections over the sky, 2 weeks of special ATLAS opposition observations with long exposure time, and 2 weeks of simulated LSST asteroid observations. Detection probabilities of linkages must be traded against false alarm rate, but a representative choice for PUMALINK might be 90% detection probability for real objects while keeping the false alarm rate below 10% for a 100:1 population of false:real. Although optimization of the tradeoffs between detection probability, execution time, and false alarm rate is application specific and beyond the scope of this paper, we provide guidance on methods to distinguish false alarms from correct linkages of real objects.

Machine learning techniques for classifying dangerous asteroids

There is an infinite number of objects in outer space, and these objects and asteroids might be harmful. Hence, it is wise to know what is surrounding us and what can harm us amongst those.Therefore, in this article, with the hyperparameters tuning of Extra Tree, Random Forest, Light Gradient Boosting Machine, Gradient Boosting, and Ada Boost, the hazards of asteroids around the Earth were classified, and the results of ROC Curves for these algorithms were compared.•Reviewing the list of NASA-certified asteroids classified as the nearest Earth object•Investigating the risk of asteroids with the help of Extra Tree, Random Forest, Light Gradient Boosting Machine, Gradient Boosting, and Ada Boost•Comparing the performance of machine learning algorithms in the classification of high-risk asteroids

Investigating Possible Correlations between Gamma-Ray and Optical Lightcurves for TeV-Detected Northern Blazars over 8 Years of Observations

Blazars are a subclass of active galactic nuclei (AGN) having relativistic jets aligned within a few degrees of our line-of-sight and form the majority of the AGN detected in the TeV regime. The Fermi-Large Area Telescope (LAT) is a pair-conversion telescope, sensitive to photons having energies between 20 MeV and 2 TeV, and is capable of scanning the entire gamma-ray sky every three hours. Despite the remarkable success of the Fermi mission, many questions still remain unanswered, such as the site of gamma-ray production and the emission mechanisms involved. The Asteroid Terrestrial-impact Last Alert System (ATLAS) is a high cadence all sky survey system optimized to be efficient for finding potentially dangerous asteroids, as well as in tracking and searching for highly variable and transient sources, such as AGN. In this study, we investigate possible correlations between the Fermi-LAT observations in the 100 MeV–300 GeV energy band and the ATLAS optical data in the R-band, centered at 679 nm, for a sample of 18 TeV-detected northern blazars over 8 years of observations between 2015 and 2022. Under the assumption that the optical and gamma-ray flares are produced by the same outburst propagating down the jet, the strong correlations found for some sources suggest a single-zone leptonic model of emission.

Estimating the Asteroid’s Impact Risk under Significant Nonlinearity in the Orbit Determination Problem

A method has been developed for estimating the probability of an asteroid impact on the Earth. The method is based on the detection of impact orbit tubes in the initial confidence region, taking into account the nonlinearity in the problem of orbit determination. The method consists in sequential iteration of level surfaces of the minimized function and conditionally minimizing the distance from the asteroid to the Earth on them in some considered approach of the asteroid to the Earth. An approximate method has been developed for calculating the confidence level at any point in the initial region with a noticeable nonlinearity in the orbit determination problem. The impact risk is estimated by applying this method to the identified tube of impact orbits. The method has been tested for a number of potentially dangerous asteroids in their expected approaches to Earth.

Deflecting an Asteroid on a Collision Course with Earth Using a Powered Swing-By Maneuver

The deflection of potentially dangerous asteroids has been treated with great intensity and has gained more and more attention in scientific research. Different techniques are developed over the years. Among these techniques, we found the kinetic impact deflection technique to be the most viable at the moment. In this work we address the kinetic impact deflection technique, but in a scenario where we have a short time to deflect an asteroid that will collide with Earth. For this, we also use a maneuver similar to a powered gravity-assisted maneuver with Earth in a previous passage to change the trajectory of the asteroid to avoid the collision. We apply this technique in three scenarios: (i) impulse before the close encounter, (ii) impulse during the close encounter, and (iii) impulse after the close encounter. We observe that some trajectories are symmetric with respect to the line Sun–Earth, and others are asymmetric. We show that, using this technique, it is possible to change the trajectory of the asteroid, even in a short period, to avoid the collision without using a large variation of velocity in the orbit of the asteroid.

Photometric Observations of the Binary Near-Earth Asteroid (65803) Didymos in 2015–2021 Prior to DART Impact

We performed photometric observations of the binary near-Earth asteroid (65803) Didymos in support of the Double Asteroid Redirection Test (DART) mission that will test the Kinetic Impactor technology for diverting dangerous asteroids. It will hit the Didymos secondary, called Dimorphos, on 2022 September 26. We observed Didymos with 11 telescopes with diameters from 3.5 to 10.4 m during four apparitions in 2015–2021, obtaining data with rms residuals from 0.006 to 0.030 mag. We analyzed the light-curve data and decomposed them into the primary rotational and secondary orbital light curves. We detected 37 mutual eclipse/occultation events between the binary system components. The data presented here, in combination with 18 mutual events detected in 2003, provide the basis for modeling the Dimorphos orbit around the Didymos primary. The orbit modeling is discussed in detail by Scheirich & Pravec and Naidu et al. The primary light curves were complex, showing multiple extrema on some epochs. They suggest a presence of complex topography on the primary’s surface that is apparent in specific viewing/illumination geometries; the primary shape model by Naidu et al. (Icarus 348, 113777, 2020) needs to be refined. The secondary rotational light-curve data were limited and did not provide a clear solution for the rotation period and equatorial elongation of Dimorphos. We define the requirements for observations of the secondary light curve to provide the needed information on Dimorphos’s rotation and elongation when Didymos is bright in 2022 July–September before the DART impact.

Pulsed Control of a Dangerous Asteroid in the Domain of $$\mathbf{1:1}$$ Resonance

Pulsed Control of a Dangerous Asteroid in the Domain of $$\mathbf{1:1}$$ Resonance

Retrospective Analysis of the Orbits of Asteroids Colliding with Earth

In this paper, we consider the trajectories of real and model asteroids that lead to collisions with Earth. They highlight the close approaches to Earth that precede impact. The presence of such approaches allows us to detect a dangerous object in advance, clarify its orbit, and use the effect of a gravitational maneuver to economically prevent an asteroid from hitting Earth. In the paper we consider various families of collision trajectories: possible trajectories of real dangerous asteroids, as well as model trajectories that are not linked to a specific object. It is shown that in the first case, the approaches preceding the collision are noticeably greater.

Approaches and collisions of asteroids with the Moon and planets

In this paper we discuss the characteristics of possible collisions of the asteroid Apophis with the Earth. We use the initial conditions published in mid-January 2021 (the nominal orbit NASA), i.e. new observations for Apophis. Estimates of the probability of collisions of dangerous asteroids with planets and the Moon were obtained using the Monte Carlo method.

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.

Retrospective analysis of the orbits of asteroids colliding with the Earth

In this paper, we consider the trajectories of real and model asteroids that lead to collisions with the Earth. They highlight the close approaches to the Earth that precede the impact. The presence of such approaches allows you to detect a dangerous object in advance, clarify its orbit, and also use the effect of a gravitational maneuver to economically prevent an asteroid from hitting the Earth. The article considers various families of collision trajectories: possible trajectories of real dangerous asteroids, as well as model ones trajectories that are not linked to a specific object. It is shown that in the first case, the approaches preceding the collision are noticeably greater.

Магнитное буксирование астероидов с помощью космического аппарата, приводимого в движение солнечным парусом

The paper considers the possibility of changing the orbit of potentially dangerous asteroids using the concept of a spacecraft — a magnetic tractor. The described concept is based on the use of a superconducting electromagnet mounted on a spacecraft and a permanent neodymium magnet attached to the surface of an asteroid. The principle of operation of this type of vehicle is similar to the concept of a spacecraft — a gravitational tractor, however, the considered vehicle, in addition to the force of mutual gravitational interaction, uses the force of magnetic attraction as a tug. A solar sail is used as a propulsion system for the type of vehicles under consideration. Within the framework of the work, the analysis of the effectiveness of the use of spacecraft of this type was carried out by modeling the joint motion of the asteroid — spacecraft system for a long time using the example of the change in the orbit of the asteroid Apophis.

Possible Collisions and Approaches of Some Dangerous Asteroids with the Earth

Possible Collisions and Approaches of Some Dangerous Asteroids with the Earth

Deflecting an Asteroid with a Low-Thrust Tangential Engine to the Orbit

In order to solve the problem of deflecting a dangerous asteroid from a collision orbit with the Earth, using a low-thrust engine directed tangentially to the trajectory is considered. The engine can be mounted on the asteroid or on a “gravity tractor.” The purpose of this study is to establish the fundamental possibility of steering away an asteroid to a safe distance over times of approximately a month and a year. This is acceptable since an asteroid with about a 100-m diameter is unlikely to strike immediately after its discovery. We limited ourselves to a model statement of the problem: the engine provides constant tangential acceleration. Previously, we transformed the respective Euler equations using the averaging method. Here, we solve them by the method of series in powers of “slow time” and demonstrate the adequacy of the solution on the time intervals of decades. It turns out that asteroids up to 55 m in diameter can be deflected in a year with an engine thrust of 1 N. With a thrust of 20 N, asteroids up to 50 m in diameter can be deflected in a month, and asteroids with a diameter of up to 150 m, in a year. Diverting larger asteroids requires more time or more powerful engines. The results are compared with the previously obtained similar data for the case of the transversal perturbing acceleration. The tangential traction leads to better results in all cases; however, both variants nearly coincide for orbits with eccentricities up to 0.4. The difference becomes significant at $$e > 0.5$$ .

Гравитационное буксирование астероидов космическими аппаратами с солнечным парусом в качестве движительной установки

The paper considers the possibility of changing the orbit of potentially dangerous aste-roids using a gravity tractor. The concept of using spacecrafts equipped with a solar sail for gravitational towing is described. The analysis of this type spacecraft effectiveness is carried out on the example of changing the orbit of the Apophis asteroid. Software and mathematical support for modeling the joint motion of the asteroid-spacecraft system has been developed. The model was used to assess the impact of spacecraft with design features on the asteroid’s orbit over a long period of time. Several variants of the spacecraft configuration with different weight and sail design are considered. A comparative analysis of the results of using solar sail vehicles with similar vehicles using low-thrust jet engines is carried out.

Сближения с Землей опасных астероидов

The paper considers the asteroids approach to the Earth, for which collisions with our planet in the XXI century are possible. Close encounters on trajectories leading to collisions can often be found more than on nominal trajectories. Close encounters provide an opportunity to use the effect of a gravitational maneuver to prevent an asteroid from collisions with the Earth. As a result, the deflection of the asteroid can be carried out by the impact which is by several decimal orders less. Such an impact can be basically implemented using modern space technology. The asteroids approach to the Earth also helps to detect these asteroids, to refine their orbits from observations and to predict the characteristics of their possible collisions with the Earth in the future. In this paper, we consider the approach on the trajectories leading to collisions with the Earth for dangerous asteroids 2008 EX5, 2015 RN35, Apophis, which we have studied in detail.

Elimination of the Potentially Dangerous Asteroid “Apophis” Using Electric Rocket

A project of elimination of potentially dangerous asteroid Apophis which April 13, 2029 year approaches to Earth at a distance of 36,000 km is considered. The elimination is carried out by means of asteroid disintegration into small fragments as a result of nuclear explosion, which is produced 133 days before the moment of maximal convergence of the asteroid Apophis with Earth. In the project, a method of phased timely delivery of nuclear charge on the surface of the asteroid is proposed. In the first stage, the nuclear charge using carrier rocket “Delta” is delivered into Earth orbit. In the second stage, the charge using electric rocket is transferred from Earth orbit into the orbit of asteroid Apophis and is descended onto its surface. For implementation of the project, the design of electric rocket ER-7, which uses electric rocket engines type MARS and solar panels based on gallium arsenide is developed. Design of landing capsule, which has a chemical rocket engine and the container in which located the nuclear charge of 6 megaton is developed.

The ATLAS All-Sky Stellar Reference Catalog

Abstract The Asteroid Terrestrial-impact Last Alert System (ATLAS) observes most of the sky every night in search of dangerous asteroids. Its data are also used to search for photometric variability, where sensitivity to variability is limited by photometric accuracy. Since each exposure spans 7.°6 corner to corner, variations in atmospheric transparency in excess of 0.01 mag are common, and 0.01 mag photometry cannot be achieved by using a constant flat-field calibration image. We therefore have assembled an all-sky reference catalog of approximately one billion stars to m ∼ 19 from a variety of sources to calibrate each exposure’s astrometry and photometry. Gaia DR2 is the source of astrometry for this ATLAS Refcat2. The sources of g, r, i, and z photometry include Pan-STARRS DR1, the ATLAS Pathfinder photometry project, ATLAS reflattened APASS data, SkyMapper DR1, APASS DR9, the Tycho-2 catalog, and the Yale Bright Star Catalog. We have attempted to make this catalog at least 99% complete to m < 19, including the brightest stars in the sky. We believe that the systematic errors are no larger than 5 mmag rms, although errors are as large as 20 mmag in small patches near the Galactic plane.

The Potentially Hazardous Asteroid 2000 SG344

AbstractWe computed impact solutions for the potentially dangerous asteroid 2000 SG344, based on 31 optical observations from 1999 May 15.20482 UTC to 2010 October 29 03.60723 UTC. Using the freely available OrbFit Software Package, we can follow its orbit forward in time searching for close approaches to the Earth, which can lead to possible impacts up to 2113. The asteroid 2000 SG344 belongs to the class of the so-called possible recovery Near Earth Asteroids and can be recovered in 2028. Its ephemerides for observational window in 2028 are presented.