Potentially Hazardous Asteroids Research Articles

A Review of quantum algorithms for prediction of hazardous asteroids

Quantum computing (QC) and quantum machine learning (QML), two emerging technologies, have the potential to completely change how we approach solving difficult problems in physics and astronomy, among other fields. Potentially Hazardous Asteroids (PHAs) can produce a variety of damaging phenomena that put biodiversity and human life at serious risk. Although PHAs have been identified through the use of machine learning (ML) techniques, the current approaches have reached a point of saturation, signaling the need for additional innovation. This paper provides an in-depth examination of various machine learning (ML) and QML techniques for precisely identifying potentially hazardous asteroids. The study attempts to provide information to improve the efficiency and accuracy of asteroid categorization by combining QML techniques like deep learning with a variety of machine learning (ML) algorithms, such as Random Forest and support vector machines. The study highlights weaknesses in existing approaches, including feature selection and model assessment, and suggests directions for further investigation. The results highlight the significance of developing QML techniques to increase the prediction of asteroid hazards, consequently supporting enhanced risk assessment and space exploration efforts. Paper reviews might not be related because the study only looks at generic paper reviews.

MARTIANS (MARs2020, TIANwen and So on) would see more potentially hazardous asteroids than Earthlings

Abstract Potentially Hazardous Asteroids (PHAs) are a special subset of Near-Earth Objects (NEOs) that can come close to the Earth and are large enough to cause significant damage in the event of an impact. Observations and researches of Earth-PHAs have been underway for decades. Here, we extend the concept of PHAs to Mars and study the feasibility of detecting Mars-PHAs in the near future. We focus on PHAs that truly undergo close approaches with a planet (dubbed CAPHAs) and aim to compare the actual quantities of Earth-CAPHAs and Mars-CAPHAs by conducting numerical simulations incorporating the Yarkovsky effect, based on observed data of the main asteroid belt. The estimated number of Earth-CAPHAs and Mars-CAPHAs are 4675 and 16910, respectively. The occurrence frequency of Mars-CAPHAs is about 52 per year, which is 2.6 times that of Earth-CAPHAs, indicating significant potential for future Mars-based observations. Furthermore, a few Mars-CAPHAs are predicted to be observable even from Earth around the time of next Mars opposition in 2025.

Mitigating potentially hazardous asteroid impacts revisited

Contact. Potentially hazardous asteroids (PHA) in Earth-crossing orbits pose a constant threat to life on Earth. Several mitigation methods have been proposed, and the most feasible technique appears to be the disintegration of the impactor and the generation of a fragment cloud by explosive penetrators at interception. However, mitigation analyses tend to neglect the effect of orbital dynamics on the trajectory of fragments. Aims. We aim to study the effect of orbital dynamics of the impactor’s cloud on the number of fragments that hit the Earth, assuming different interception dates. We investigate the effect of self-gravitational cohesion and the axial rotation of the impactor. Methods. We computed the orbits of 105 fragments with a high-precision direct N-body integrator of the eighth order, running on GPUs. We considered orbital perturbations from all large bodies in the Solar System and the self-gravity of the cloud fragments. Results. Using a series of numerical experiments, we show that orbital shear causes the fragment cloud to adopt the shape of a triaxial ellipsoid. The shape and alignment of the triaxial ellipsoid are strongly modulated by the cloud’s orbital trajectory and, hence, the impact cross-section of the cloud with respect to the Earth. Therefore, the number of fragments hitting the Earth is strongly influenced by the orbit of the impactor and the time of interception. A minimum number of impacts occur for a well-defined orientation of the impactor rotational axis, depending on the date of interception. Conclusions. To minimise the lethal consequences of an PHA’s impact, a well-constrained interception timing is necessary. A too-early interception may not be ideal for PHAs in the Apollo or Aten groups. Thus, we find that the best time to intercept PHA is when it is at the pericentre of its orbit.

Study of the effects of projectile strength and density in the asteroid deflection by hypervelocity impact

In recent years, potentially hazardous asteroids (PHAs), which have orbits approaching the Earth and are a threat to humankind, have been attracting attention. It is necessary to prevent them from impacting the Earth, and asteroid deflection by hypervelocity impact is one of the best impact avoidance. This asteroid deflection needs to be greater, but momentum enhancement factor β, which represents deflection efficiency, is affected by various factors. This study focused on projectile strength and density, and experiments for small-scale impacts and numerical simulations for large-scale impacts were conducted to clarify these effects on β. In experiments, six types of projectiles with different strengths and densities and the same shape and size were impacted into brick targets at 1-3.5 km/s using a Two-Stage Light Gas Gun to investigate the effects in actual impacts. In simulations, three types of projectiles with different densities and the same shape and mass were impacted into granite targets at 3-10 km/s using AUTODTN to investigate the effects in asteroid-deflection-scale impacts, which are difficult for experiments. In conclusion, the effect of projectile strength on β is less, and the one of projectile density on β is high. It is demonstrated that projectiles whose density is close to the target density increase β, namely, are suitable for asteroid deflection regardless of impact scale. Additionally, a crater formed by hypervelocity impact is a preferably flat shape for asteroid deflection, and the effect of crater shape on β is higher at large-scale impact. Further study of this effect and the scaling one could be expected.

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.

Heuristic Technique for the Search of Interception Trajectories to Asteroids with the Use of Solar Sails

With the advances of space-exploration technologies, a long-lasting concern is finally being addressed: the deflection of potentially hazardous objects (PHOs). Most recently, the first mission of this kind was launched by NASA—the Double Asteroid Redirection Test (DART). Nevertheless, it is estimated that a great number of these PHOs are unattainable by means of current chemical propulsion systems. With that in mind, this study proposes the development of a heuristic technique for the search of interception trajectories with the use of solar sails and its application in determining a set of possible trajectories to intercept hazardous asteroids. As a case study, a hybrid mission inspired by the DART mission is proposed by using a solar sail as means of propulsion after the initial chemical combustion. The dynamics consider a model of the solar radiation pressure acceleration as a function of the orientation of the sail. In turn, the orientation is defined by the application of the developed heuristic technique with the goal of defining alternative trajectories compared to the original mission. These trajectories result in different impact conditions and mission durations. Although the use of solar sails breaks the symmetry in the solutions, the results obtained offer the possibility of fuel economy or even better deflection results by the achievement of greater impact energy with the hazardous objects.

Hazard assessment method for underwater potentially hazardous objects

The article describes a method for assessing the danger of Underwater Potentially Hazardous Objects (PHUOs). The method based on data on the maximum permissible concentrations of hazardous substances in marine areas. For using the proposed method, accurate information of type of hazardous substances contained in the protective shells of the PHUO, and their quantity are required. To assess the scale of pollution of water areas, data on the depth of the object and the hydrological characteristics of the water area are required. A salvo release is considered as a mechanism for the release of hazardous substances from the PHUO, as the most destructive for the water area where underwater potentially dangerous object is located. The concepts of "shallow sea" and "deep sea" are introduced. For these concepts, the features of the distribution of hazardous substances from PHUO are determined. A criterion is given that allows making the right choice of the algorithm for calculating the spread of hazardous substances in the water area of the PHUO. Algorithms for estimating the parameters of the distribution of hazardous substances in the conditions of "shallow" and "deep" sea, in the presence and in the absence of underwater currents, are given.

Kinetic impactor for a short warning asteroid deflection

In this paper, GMV as a major AOCS (Attitude Orbit Control System)/GNC (Guidance, Navigation and Control) system provider presents its work on the development of a GNC system for a Kinetic Impact mission. Asteroid impacts on Earth are a known source of extinction and played an important role in the evolution of life on Earth. This comes as no surprise given the high number of objects orbiting in Earth’s vicinity—asteroid impacts become a question of “when” rather than “if”.This comes as no surprise given the high number of objects orbiting in Earth’s vicinity—asteroid impacts become a question of “when” rather than “if”. Under this motivation, thousands of potentially hazardous asteroids (PHAs) are monitored around the globe and naturally the question on the next step rose: What can we do when an incoming asteroid is identified as being on collision course with Earth? This is the motivation behind the field of Planetary Defence. Several mitigation strategies are being studied, but most of these have technology readiness levels still far off from the required. The one that comes closest is the kinetic impactor concept, which is the focus of this work. The concept is simple from a theoretical standpoint - a spacecraft (impactor) is sent into a collision course against the hazard NEO transferring enough momentum through kinetic energy to slightly change the NEO’s trajectory and causes it to miss the Earth.The main component of kinetic impactors is the GNC, due to the necessity of a fully autonomous system. The major elements are the camera and the guidance, since they will allow detecting the target and modifying its trajectory to have a successful impact, respectively. This study includes the implementation of the required algorithms as well as an analysis of their performance in the impact scenario.The main variables that control the simulations have been examined in order to determine the design limits. The sensitivity analysis illustrates that the errors introduced in the model were chosen conservatively, inasmuch as the impact could be reached introducing higher uncertainties and errors in the systems considered. In general, even with the not excessively complex algorithms employed, the performance of the GNC is good. This study opens the door for the development of a kinetic impactor mission.

Lightcurve analysis of near-Earth objects from the IMPACTON project: Evidence of binary systems and cohesion strength

Rotations of asteroids have been set and altered by several processes since their formation. In the case of the near-Earth objects (NEOs), the rotational states are significantly affected by non-gravitational effects. In addition, an abundant population of binary systems has been found among NEOs with rotational periods very close to the spin barrier and in the size range from 0.2 to 10 km. In this paper we report photometric observations of about 80 NEAs carried out with the 1-m telescope of the Observatório Astronômico do Sertão de Itaparica (OASI, Brazil) from 2016 October to 2020 December. Reliable rotational periods and lightcurve amplitudes were determined for 46 objects, of which 15 are Potentially Hazardous Asteroids (PHAs). A minimum period value was also derived for other 11 NEOs. Then, asteroids with rotation periods between 2 and 3 h had their lightcurves analyzed for binarity signatures. We analyzed 21 binary candidates and for 8 of them we found the signature of a possible satellite. These suspected binaries showed a single possible mutual event or a secondary period superimposed on the lightcurve. Primary lightcurves for 6 confirmed binary NEOs were also obtained and for some of them the orbital period was also determined. Finally, we show that binary candidates require some internal cohesion strength to avoid structural failure by centrifugal forces.

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.

NEOWISE Observations of the Potentially Hazardous Asteroid (99942) Apophis

Large potentially hazardous asteroids (PHAs) are capable of causing a global catastrophe in the event of a planetary collision. Thus, rapid assessment of such an object’s physical characteristics is crucial for determining its potential risk scale. We treated the near-Earth asteroid (99942) Apophis as a newly discovered object during its 2020–2021 close approach as part of a mock planetary defense exercise. The object was detected by the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE), and data collected by the two active bands (3.4 and 4.6 μm) were analyzed using thermal and thermophysical modeling. Our results indicate that Apophis is an elongated object with an effective spherical diameter D eff = 340 ± 70 m, a geometric visual albedo p V =0.31 ± 0.09, and a thermal inertia Γ ∼ 150–2850 J m−2 K−1 with a best-fit value of 550 J m−2 K−1. NEOWISE “discovery” observations reveal that (99942) Apophis is a PHA that would likely cause damage at a regional level and not a global one.

Hydrocode Investigations of Terminal Astroballistics Problems during the Hypothetical Future Planetary Defense System's Space Mission.

The article is devoted to the preliminary concept of the Future Planetary Defense System (FPDS) emphasizing astroballistics. This paper is intended to support international efforts to improve the planetary security of Earth. The work covers three areas of knowledge: astronautics, astrodynamics, and astroballistics. The most important part of the presented article is dynamic, contact combat modeling against small, deformable celestial bodies. For these purposes, the original, proprietary hydrocode of the free particle method (HEFPM-G) with gravity was used. The main aim of combat is to redirect potentially hazardous objects (PHOs) to orbits safe for Earth or destroy them. This concept’s first task is to find, prepare, and use dynamic three-dimensional models of the motion of celestial bodies and spacecraft or human-crewed spaceships in the solar system’s relativistic frame. The second task is to prepare the FPDS’ architecture and computer simulation space missions’ initial concepts in the internal part of the solar system. The third and main task covers simulating, using hydrocodes, and selected methods of fighting 100 m diameter rock material asteroids.

ONGOING FOLLOW-UP NEA OBSERVATIONS IN UKRAINE AND CHINA USING RDS CCD TECHNIQUE

The current state of near-Earth asteroids (NEAs) observations shows an annual increase in the number of newly discovered objects However, the frequency distribution of NEAs by size shows a sharp decrease in the number of objects with size less than 300 m, which contradicts the results of theoretical modeling of the NEA population. Considering definition of potentially hazardous asteroids (PHA), only objects with diameters more than 140 m could pose catastrophic consequences to the Earth and mankind in general. But in the same time, impacts of smaller size objects could lead to significant consequences on local level and their large predicted number increases this probability. Due to their small size which results in faint apparent magnitude, such NEAs are discovered in a short interval of their close approach (CA) to the Earth, when their apparent magnitude are tending to be as bright as possible for a given size. This is not only facilitates the detection of such new objects but also increases their observability by small ground-based telescopes. However, apparent rate of motion during this time might exceed 10 deg d −1 making the observations challenging. The used Rotating-drift-scan CCD (RDS CCD) technique allows to get images of fast-moving objects as a point, that in turn to determine the coordinates of their image centers with sufficient astrometric precision. Obtained in current research project positions show errors in the range ± (0.2″ − 0.3″) in both coordinates with comparison both to JPL's HORIZONS 1 system and NEODyS-2 2 service. The part of observations was obtained around time moment of minimal distance to the Earth during current CA for newly discovered NEAs. Such observations are important to extend observed orbital arc for reliable improvement of their orbit determinations and reducing orbital uncertainty, so it will be possible to recover them in next apparitions.

ON THE EFFECTS OF SOLAR RADIATION PRESSURE ON THE DEVIATION OF ASTEROIDS

In this work, we study the effects of solar radiation pressure (SRP) on the problem of changing the orbit of an asteroid to support planetary defense, scientific research, or exploitation of materials. This alternative considers a tethered reflective balloon (or a set of reflective balloons) attached to the asteroid, with a high area-to-mass ratio, to use the SRP to deflect a potentially hazardous asteroid (PHA) or to approximate the target asteroid to Earth. The tether is assumed to be inextensible and massless, and the motion is described only in the orbital plane of the asteroid around the Sun. The model is then used to study the effects that the tether length, the reflectivity coefficient, and the area-to-mass ratio have on the deviation of the trajectory of the asteroid.

The EURONEAR Lightcurve Survey of Near Earth Asteroids—Teide Observatory, Tenerife, 2015

One meter class telescopes could bring important contributions in the acquisition of lightcurves of near earth asteroids (NEAs), based on which rotations and other physical properties could be derived or constrained. Part of a collaboration between IAC, ESA and the EURONEAR during the semester 2015A, the IAC80 and OGS telescopes at Teide Observatory in Tenerife were allocated for a photometric project during 64 nights spread in a few observing runs. The main funding for this long observing mission was raised by the student observer Radu Cornea from private sponsors based in his natal city of Sibiu, Romania, mentioned in the Acknowledgements. We observed 33 lightcurves of NEAs not published before, including 10 potentially hazardous asteroids (PHAs). Based on the quality of the Fourier period fits, we sorted the results in four groups which include 7 secured periods, 9 candidate periods, 10 tentative periods and 7 objects not solved. We resolved periods or suggested constraints for 13 NEAs having no other rotation knowledge (including 3 PHAs), confirming periods for other 6 targets published by other authors (mainly by Brian Warner). We suggested tumbling or binary nature for 6 targets (probing one of them) recommended for future dedicated campaigns. We derived ellipsoid shape ratios for 21 NEAs (including 4 PHAs) not known before.

Finite element modeling to characterize the stress evolution in asteroid (99942) Apophis during the 2029 Earth encounter

The present study develops an approach combining a dynamics model and a finite element model (FEM) to characterize stress variations in Asteroid (99942) Apophis, a potentially hazardous asteroid (PHA) that approaches ∼6 Earth radii from the geocenter in 2029. Assuming that shape deformation is small, this approach simultaneously simulates the dynamic (rotation and translation) and structural (stress) evolution of an irregularly shaped body with time. We incorporate Apophis’ radar-driven shape model and trajectory to the FEM approach and analyze the stress evolution in this asteroid during the 2029 closest encounter. Considering the rotational uncertainties driven by optical and radar observations in 2012–2013, we investigate how the rotational condition affects the stress variations. The results from 216 rotational cases show that rotation contributes to changing stress variations; however, the predicted stress variations are up to 0.5 Pa, implying that the tidal effect on the structure is minimal. Statistically, the neck regions are more sensitive to stress variations than other areas. Our study suggests that the rotational and shape conditions are key to better constraining Apophis’ geophysical behavior during its 2029 closest encounter.

RISK ZONES FROM THE FILLING STATIONS MODELLING WITH APPLICATION OF GEOINFORMATION TECHNOLOGY

In this paper the questions of technogenic safety of the city Odesa with a population of over 1 million are considered on the example of the analysis of an emergency situation that may arise at filling stations (FS) of the city. The fire safety of theFSsnetwork becomes very important in the context of urban buildings and traffic flows compaction, a significant increase in the number of cars, as well as in the construction of new potentially hazardous objects (PHO) within the urban territory. To solve the problem ofanalysis ofthe risk zones of FSs, a conceptual digital model ofaFS was created, a numerical simulation of the scenario of an unfavourablesituation development at the FS was carried out according to the approved state methodology (an explosion of a vapour-air fuel mixture with a shock wave formation), as well as the obtained zones were visualized on a map of the city of Odessa using the geographic information system QGIS. The digital model of the FS was created taking into account the requirements for the presentation of attributive and spatial data of the relevant GIS. The components of the developed conceptual model are: universal digital identifier, spatial data in the form of type and coordinates of the object, attributive data, which consist of staticand dynamic features, as well as numerical models of emergency situation development. During the visualizing of the obtained calculated data by means of GIS, OSM Place Search, QuickOSM and Multi Ring Buffer plugins were used, as well as data from the OpenStreetMap server. The presented results of modellingand visualization indicate that, when the most unfavourabledevelopment scenarios are realized, the nature of accidents at FS can go beyond the local scale and move to the borders of the residential zone,as well as to nearby industrial buildings and FSs, which in turn can cause unfavourablesituations on them by the domino effect. In addition, the results of the analysis of the obtained heterogeneous modellingand visualization data to determine technogenic risk indicates the possibility of applying the studied principles to other PHOsand also allows to present the data in a visual and accessible form for decision-makers.

Apophis 2029: Decadal Opportunity for the Science of Planetary Defense

Many advancements in planetary science are achieved by seizing upon the opportunity created by rare natural events (e.g. comet Shoemaker-Levy 9 Jupiter impact; 1994) and by planned physical interactions (e.g. Deep Impact into comet Tempel 1; 2005). A forthcoming opportunity to seize upon a natural physical “experiment” occurs on April 13, 2029 with the unprecedentedly close Earth encounter by the large 340m asteroid (99942) Apophis. On that date, nature is performing the “experiment” of subjecting the physical body of Apophis to Earth’s tidal torques as it approaches to within 31,000 km of Earth’s surface, a distance that is closer than orbiting geosynchronous satellites. A potentially hazardous asteroid (PHA) as large as Apophis encountering Earth this closely (within 0.1 lunar distances) is, on average, a once-per-thousand year event. (In context, Apophis is 7 times larger and 350 times more massive than the Tunguska 1908 impactor; 5000 times more massive than Chelyabinsk 2013.) Because of this event’s incredible rarity, knowledge gained through measurements and outcomes of the Apophis 2029 “natural experiment” are clearly a decadal, if not millennial, opportunity for planetary science. Most specifically, this knowledge opportunity is for the science supporting planetary defense. Further, on April 13, 2029 all of Earth will be watching: Apophis will be visible to the naked eye speeding across the evening sky for an estimated 2 billion people spanning western Europe and northern Africa. In this White Paper we outline our current best understanding, and uncertainties, for scientific advances in the physical study of potentially hazardous asteroids that may be achievable by measuring physical changes of Apophis’ spin, surface structure, and/or shape configuration in response to Earth’s tidal torques. If tidal torques themselves, or surface configuration changes induce any measurable seismic vibration signal inside Apophis, a new field of asteroid seismology has the potential to be born. Over six decades of planetary science, seismology has been achieved beyond Earth for only two planetary worlds: Moon and Mars. With this White Paper, we take no position on how to implement specific investigations capable of achieving the science advances offered by the Apophis 2029 opportunity. Instead we advocate that competitive selection of investigations, be they theoretical or observational (ground-based, space-based, or in situ), be executed under the direction of NASA’s Planetary Defense Coordination Office, with a projected and perhaps necessarily augmented budget capable of supporting them. International collaboration is strongly encouraged. Thus, summarizing in four specific points, we urge the framers of the Decadal Survey to: • Recognize the decadal, if not millennial, opportunity for the science of planetary defense presented by the Apophis 2029 once-per-thousand-year “natural experiment.” • Prioritize as a top-level planetary defense science goal modeling and measuring the physical outcome on Apophis exerted by Earth’s tidal torques so as to achieve the greatest possible new insights into the physical nature, including the internal structure, of PHAs. • Recognize that time is of the essence for defining and implementing investigations of physical effects on Apophis, particularly if in situ measurements are to be considered. An Apophis 2029 Science Definition Team may be prescribed. • Recognize that the achievable knowledge of PHAs presented by the Apophis 2029 opportunity could have immeasurable benefits to the future of humanity, in the highly unlikely, but not impossible necessity to mitigate a future impact threat

Conceptual Design for Deflecting a Potentially Hazardous Asteroid with a Space Duster

The deflecting asteroid by dusting (DAD) mission addresses the challenges of deflecting a potentially hazardous asteroid (PHA) that has a large probability of impacting Earth. It is an innovative and mass-minimalist approach to exploit PHAs by using the dusting deflection method. This conceptual design is developed based on an asteroid space duster, which is a space miner that is equipped with dust mining equipment, path-finding systems, and robotic capabilities, that converts available materials into mining prospects. It also stores energy to power the space miner and produces thrust to deflect the asteroid. The primary goals of DAD are to use the dust-to-thrust dusting technique on a PHA and to characterize and measure the deflection caused by the dusting. The 99942 Apophis is used as the reference asteroid in the dust-to-thrust study to test the feasibility of using the approach for deflecting PHAs. There are currently no methods that continuously use the dust-to-thrust approach from an asteroid mining perspective in comparison to the existing deflecting asteroid concepts. This unsolved problem is the focus of the DAD-related study.

Enhanced Kinetic Impactor for Deflecting Large Potentially Hazardous Asteroids via Maneuvering Space Rocks

Asteroid impacts pose a major threat to all life on Earth. The age of the dinosaurs was abruptly ended by a 10-km-diameter asteroid. Currently, a nuclear device is the only means of deflecting large Potentially Hazardous Asteroids (PHAs) away from an Earth-impacting trajectory. The Enhanced Kinetic Impactor (EKI) concept is proposed to deflect large PHAs via maneuvering space rocks. First, an unmanned spacecraft is launched to rendezvous with an intermediate Near-Earth Asteroid (NEA). Then, more than one hundred tons of rocks are collected from the NEA as the EKI. The NEA can also be captured as the EKI if the NEA is very small. Finally, the EKI is maneuvered to impact the PHA at a high speed, resulting in a significant deflection of the PHA. For example, to deflect Apophis, as much as 200 t of rocks could be collected from a NEA as the EKI based on existing engineering capabilities. The EKI can produce a velocity increment (∆v) of 39.81 mm/s in Apophis, thereby increasing the minimum geocentric distance during the close encounter in 2029 by 1,866.93 km. This mission can be completed in 3.96 years with a propellant cost of 2.98 t. Compared with a classic kinetic impactor, the deflection distance can be increased one order of magnitude. The EKI concept breaks through the limitation of the ground-based launch capability, which can significantly increase the mass of the impactor. We anticipate that our research will be a starting point for efficient planetary defense against large PHAs.