Kinetic Impactor Research Articles

Centroiding method for small celestial bodies with unknown shape and small size

Focused on small celestial body deflection missions using a kinetic impactor spacecraft, we propose a method for estimating the center of small objects with unknown shape and small size, which relaxes the requirement for prior information of the object shape model and lowers the risk of missing the target. The impact center is inferred using the visible part of the object in a single image. In the first step, the illuminated part of the object’s true contour is segmented from the whole contour extracted from the image based on the prior information of the illumination direction. In the second step, the concave–convex characteristic of the illuminated contour is identified. In the third step, one of two modes, moment estimation or skeleton center estimation, is chosen based on the concave–convex characteristic to calculate the impact center. The proposed algorithm was verified by a simulation study under various conditions. Due to the problems of the unknown model shapes of small objects and complex illumination conditions in kinetic impact missions, the proposed centroiding algorithm will play an important role.

HERA Mission LIDAR Mechanical and Optical Design

Near-Earth Objects (NEO) are the topic of several research studies, with objects smaller than 1km in size posing the most threats and being the less understood of this scientific domain. The Asteroid Impact and Deflection Assessment (AIDA) mission involves NASA and ESA with the main mission goal to perform and analyze the asteroid deflection using the Kinetic Impactor technique. The mission target is Didymos-B, a moon of a binary asteroid called Didymos. NASA oversees the Double Asteroid Redirection Test (DART probe), and ESA is responsible for HERA probe, that will measure the Dydimos-B deflection caused by the impact. The Light Detection and Ranging (LIDAR), the Radar, the Satellite-to-Satellite Doppler tracking, the Seismometer, and the Gravimeter are instruments integrated into HERA spacecraft. Information synergy between the instruments allows the detailed characterization of the asteroid including internal structure. This experiment allows further understanding and will provide important information to improve the current NEO understanding and modelling. In this paper, scientific advances related to the LIDAR instrument are reported, including the innovative optomechanical design resulting from thermal and mechanical optimizations. The LIDAR has a compact design and needs to withstand extreme conditions, such as radiative and thermal conditions, without compromise its high accuracy measurements. The LIDAR is a time-of-flight altimeter instrument that will measure the distances from the HERA spacecraft to the target. It provides information for a 3D topographic mapping and calculates the asteroid reflectivity. The measurements are to be performed at a distance from 500 m to 14 km while operations such as fly byes or landings remain a possibility.

Influence of the projectile geometry on the momentum transfer from a kinetic impactor and implications for the DART mission

The DART spacecraft will impact Didymos’s secondary, Dimorphos, at the end of 2022 and cause a change in the orbital period of the secondary. For simplicity, most previous numerical simulations of the impact used a spherical projectile geometry to model the DART spacecraft. To investigate the effects of alternative, simple projectile geometries on the DART impact outcome we used the iSALE shock physics code in two and thee-dimensions to model vertical impacts of projectiles with a mass and speed equivalent to the nominal DART impact, into porous basalt targets. We found that the simple projectile geometries investigated here have minimal effects on the crater morphology and momentum enhancement. Projectile geometries modelled in two-dimensions that have similar surface areas at the point of impact, affect the crater radius and the crater volume by less than 5%. In the case of a more extreme projectile geometry (i.e., a rod, modelled in three-dimensions), the crater was elliptical and 50% shallower compared to the crater produced by a spherical projectile of the same momentum. The momentum enhancement factor in these test cases, commonly referred to as β, was within 7% for the 2D simulations and within 10% for the 3D simulations, of the value obtained for a uniform spherical projectile. The most prominent effects of projectile geometry are seen in the ejection velocity as a function of launch position and ejection angle of the fast ejecta that resides in the so-called ‘coupling zone’. These results will inform the LICIACube ejecta cone analysis.

Libration-induced Orbit Period Variations Following the DART Impact

Abstract The Double Asteroid Redirection Test (DART) mission will be the first test of a kinetic impactor as a means of planetary defense. In late 2022, DART will collide with Dimorphos, the secondary in the Didymos binary asteroid system. The impact will cause a momentum transfer from the spacecraft to the binary asteroid, changing the orbit period of Dimorphos and forcing it to librate in its orbit. Owing to the coupled dynamics in binary asteroid systems, the orbit and libration state of Dimorphos are intertwined. Thus, as the secondary librates, it also experiences fluctuations in its orbit period. These variations in the orbit period are dependent on the magnitude of the impact perturbation, as well as the system’s state at impact and the moments of inertia of the secondary. In general, any binary asteroid system whose secondary is librating will have a nonconstant orbit period on account of the secondary’s fluctuating spin rate. The orbit period variations are typically driven by two modes: a long period and a short period, each with significant amplitudes on the order of tens of seconds to several minutes. The fluctuating orbit period offers both a challenge and an opportunity in the context of the DART mission. Orbit period oscillations will make determining the post-impact orbit period more difficult but can also provide information about the system’s libration state and the DART impact.

Planetary defence systems – threat to survival?

ABSTRACT The article explains why Weaponisation of outer space may soon be inevitable and that development of space weapons is a serious issue, especially in regard to dealing with sensitive dual-use technology. At the same time, the Earth may be threatened by incoming asteroids and comets, which may endanger humankind’s existence. Hence, it is advisable to develop effective planetary defence systems. However, the article claims that discussed planetary defence technology – kinetic impactor, nuclear explosion, gravity tractor and space tug, laser, and solar collector – have far-reaching dual-use consequences with potential for their weaponisation. Thus, the article argues in favour of greater transparency and surveillance mechanisms for dual-use and arms control. Moreover, the private sector should be involved in discussion since it may be contributing to negotiation processes and can ensure secure research and development, as well as operability of sensitive planetary defence systems.

The Double Asteroid Redirection Test (DART): Planetary Defense Investigations and Requirements

Abstract The Double Asteroid Redirection Test (DART) is a Planetary Defense mission, designed to demonstrate the kinetic impactor technique on (65803) Didymos I Dimorphos, the secondary of the (65803) Didymos system. DART has four level 1 requirements to meet in order to declare mission success: (1) impact Dimorphos between 2022 September 25 and October 2, (2) cause at least a 73 s change in its binary orbit period via the impact, (3) measure the change in binary period to an uncertainty of 7.3 s or less, and (4) measure the momentum transfer efficiency (β) of the impact and characterize the resulting effects of the impact. The data necessary to achieve these requirements will be obtained and analyzed by the DART Investigation Team. We discuss the rationales for the data to be gathered, the analyses to be undertaken, and how mission success will be achieved.

The excited spin state of Dimorphos resulting from the DART impact

The NASA Double Asteroid Redirection Test (DART) mission is a planetary defense-driven test of a kinetic impactor on Dimorphos, the satellite of the binary asteroid 65803 Didymos. DART will intercept Dimorphos at a relative speed of ∼6.5km s−1, perturbing Dimorphos’s orbital velocity and changing the binary orbital period. We present three independent methods (one analytic and two numerical) to investigate the post-impact attitude stability of Dimorphos as a function of its axial ratios, a/b and b/c (a≥b≥c), and the momentum transfer efficiency β. The first method uses a novel analytic approach in which we assume a circular orbit and a point-mass primary that identifies four fundamental frequencies of motion corresponding to the secondary’s mean motion, libration, precession, and nutation frequencies. At resonance locations among these four frequencies, we find that attitude instabilities are possible. Using two independent numerical codes, we recover many of the resonances predicted by the analytic model and indeed show attitude instability. With one code, we use fast Lyapunov indicators to show that the secondary’s attitude can evolve chaotically near the resonance locations. Then, using a high-fidelity numerical model, we find that Dimorphos enters a chaotic tumbling state near the resonance locations and is especially prone to unstable rotation about its long axis, which can be confirmed by ESA’s Hera mission arriving at Didymos in late 2026. We also show that a fully coupled treatment of the spin and orbital evolution of both bodies is crucial to accurately model the long-term evolution of the secondary’s spin state and libration amplitude. Finally, we discuss the implications of a post-impact tumbling or rolling state, including the possibility of terminating BYORP evolution if Dimorphos is no longer in synchronous rotation.

The opportune location for a kinetic impactor to disrupt potentially hazardous asteroids

Several studies have proposed a way to mitigate a possible threat given by an asteroid approach to the Earth. However, the possibility to deviate or break such bodies depends mainly on their physical characteristics. Our work aims to determine the best region for human interference in the object's trajectory. It means that we will search for the region of minimal internal forces that keep the body as a single unit, which is the best point for the asteroid breakup. We report that the consideration of the body resistance, while it belongs to the strength regime size, shall be the key to find the best location for an interception. We use the Johnson-Kendall-Roberts (JKR) theory to add adhesive contact forces between the target body's micro-sized particle constituents. We also solve the balanced equation for tidal due to Earth for the body, and we consider it with and without adhesion forces. We see that the best approach region happens while the self-gravity is minimized by the Earth's gravity, which occurs when the body is still held in one piece by the inter-particles forces. It means that we do not expect a natural breakup. Nevertheless, these minimum adhesion forces points are the best options to target a spacecraft for a collision that breaks the asteroids if it is necessary to do so.

Assembled kinetic impactor for deflecting asteroids by combining the spacecraft with the launch vehicle upper stage

Asteroid impacts pose a major threat to all life on Earth. Deflecting an asteroid on an impact trajectory is critical to mitigating this threat. A kinetic impactor remains the most feasible asteroid deflection method. However, due to launch capability constraints, an impactor with a limited mass can only minimally change the velocity of an asteroid. To improve the deflection efficiency of the kinetic impactor strategy, this paper proposes the Assembled Kinetic Impactor (AKI), which combines the spacecraft with the launch vehicle upper stage. After the launch vehicle upper stage sends the spacecraft into an Earth-escaping trajectory, the spacecraft-rocket separation is not performed, and the spacecraft controls the AKI to impact the asteroid. By retaining the mass of the launch vehicle upper stage, the mass of the impactor is increased, thereby enhancing the deflection efficiency. According to the technical data of the Long March 5 (CZ-5) launch vehicle, missions to deflect Bennu are designed to demonstrate the power of the AKI concept. Simulation results of the AKI compared with the Classical Kinetic Impactor (CKI, with spacecraft-rocket separation) show that the addition of the mass of the upper stage increases the deflection distance by >3 times. To achieve a given deflection distance, the addition of the upper stage mass reduces the number of launches to 1/3 that of the number of CKI launches. The AKI concept makes it possible to deflect large Bennu-like asteroids with a nuclear-free technique with a 10-year launch lead time. Additionally, with a single CZ-5, the deflection distance of a 140-m-diameter asteroid with a 10-year launch lead time increases from less than 1 to more than 1 Earth radius, representing an improvement in the reliability and efficiency of asteroid deflection missions.

Assessment of Near-Earth Asteroid Deflection Techniques via Spherical Fuzzy Sets

Extensions of fuzzy sets to broader contexts constitute one of the leading areas of research in the context of problems in artificial intelligence. Their aim is to address decision-making problems in the real world whenever obtaining accurate and sufficient data is not a straightforward task. In this way, spherical fuzzy sets were recently introduced as a step beyond to modelize such problems more precisely on the basis of the human nature, thus expanding the space of membership levels, which are defined under imprecise circumstances. The main goal in this study is to apply the spherical fuzzy set version of Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), a well-established multicriteria decision-making approach, in the context of planetary defense. As of the extraction of knowledge from a group of experts in the field of near-Earth asteroids, they rated four deflection technologies of asteroids (kinetic impactor, ion beam deflection, enhanced gravity tractor, and laser ablation) that had been previously assessed by means of the classical theory of fuzzy series. This way, a comparative study was carried out whose most significant results are the kinetic impactor being the most suitable alternative and the spherical fuzzy set version of the TOPSIS approach behaves more sensitively than the TOPSIS procedure for triangular fuzzy sets with regard to the information provided by our group of experts.

Paths not taken – The Gossamer roadmap’s other options

Highly efficient low-thrust propulsion is increasingly applied beyond commercial use, also in mainstream and flagship science missions, in combination with gravity assist propulsion. Another recent development is the growth of small spacecraft solutions, not in size but in numbers and individual capabilities.Just over ten years ago, the DLR-ESTEC Gossamer Roadmap to Solar Sailing was set up to guide technology developments towards a propellant-less and highly efficient class of spacecraft for solar system exploration and applications missions: small spacecraft solar sails designed for carefree handling and equipped with carried application modules.Soon, in three dedicated Gossamer Roadmap Science Working Groups it initiated studies of missions uniquely feasible with solar sails such as Displaced L1 (DL1) space weather advance warning and monitoring, Solar Polar Orbiter (SPO) delivery to very high inclination heliocentric orbit, and multiple Near-Earth Asteroid (NEA) rendezvous (MNR). Together, they demonstrate the capability of near-term solar sails to achieve at least in the inner solar system almost any kind of heliocentric orbit within 10 years, from the Earth-co-orbital to the extremely inclined, eccentric and even retrograde. Noted as part of the MNR study, sail-propelled head-on retrograde kinetic impactors (RKI) go to this extreme to achieve the highest possible specific kinetic energy for the deflection of hazardous asteroids.At DLR, the experience gained in the development of deployable membrane structures leading up to the successful ground deployment test of a (20 m)2, i.e., 20 m by 20 m square solar sail at DLR Cologne in 1999 was revitalized and directed towards a 3-step small spacecraft development line from as-soon-as-possible sail deployment demonstration (Gossamer-1) via in-flight evaluation of sail attitude control actuators (Gossamer-2) to an envisaged proving-the-principle flight in the Earth-Moon system (Gossamer-3). First, it turned the concept of solar sail deployment on its head by introducing four separable Boom Sail Deployment Units (BSDU) to be discarded after deployment, enabling lightweight 3-axis stabilized sailcraft. By 2015, this effort culminated in the ground-qualified technology of the DLR Gossamer-1 deployment demonstrator Engineering Qualification Model (EQM). For mission types using separable payloads, such as SPO, MNR and RKI, design concepts can be derived from the BSDU characteristic of DLR Gossamer solar sail technology which share elements with the separation systems of asteroid nanolanders like MASCOT. These nano-spacecraft are an ideal match for solar sails in micro-spacecraft format whose launch configurations are compatible with ESPA and ASAP secondary payload platforms.Like any roadmap, this one contained much more than the planned route from departure to destination and the much shorter distance actually travelled. It is full of lanes, narrow and wide, detours and shortcuts, options and decision branches. Some became the path taken on which we previously reported. More were explored along the originally planned path or as new sidings in search of better options when circumstance changed and the project had to take another turn. But none were dead ends, they just faced the inevitable changes when roadmaps face realities and they were no longer part of the road ahead. To us, they were valuable lessons learned or options up our sleeves. But for future sailors they may be on their road ahead.

Study on ballistic kinetic impactor mission design and evaluation using impact-geometry maps

This paper aims to investigate the ballistic kinetic impactor (B-KI) in order to mitigate the risks posed by a potential asteroid collision on Earth in the future. The B-KI is a spacecraft that employs a single impulsive thrust to put the spacecraft into an orbit, which, in turn, impacts the target asteroid to deflect it from the collision route of Earth. To evaluate the effectiveness of the B-KI, we introduce impact-geometry maps (IGMs), which visualize the achievable change in the orbital energy of the asteroid as a function of the spacecraft’s semi-major axis and eccentricity. The achievable performance of the B-KI is investigated in the form of its mobility capability on the IGM. In addition, parameters that govern the mission’s feasibility, such as the spacecraft’s relative impact speed and phase angle, are discussed. We conducted a parametric study on the asteroid’s orbital elements and found that the B-KI is, in fact, a better option for deflecting asteroids belonging to the Aten family at the intersection point where the radial velocity component is positive. We also designed several fictional B-KI missions to achieve a more realistic asteroid mitigation campaign scenario. The obtained results are compared with those of previous kinetic impactor studies that employ low-continuous-propulsion systems. The study finally highlights that the B-KI can efficiently increase the impact efficiency and deflection distance for a part of the target asteroids.

Overview of Hayabusa2 Asteroid Proximity Operation Planning and Preliminary Results

Hayabusa2 is a Japanese asteroid explorer launched by the H-IIA rocket on Dec. 3, 2014. After the long cruising with the ion engine system, the spacecraft approached its target body, Ryugu, using optical navigation. It arrived at Home Position (HP), 20 km above the sub-Earth point, on Jun. 27, 2018. The spacecraft is now on its way back to Earth. It will reach the Earth by the end of 2020. During the 1.5-year asteroid proximity phase, we performed many kinds of science observations using the remote sensing instruments. We performed several numbers of descent operations to deploy and lander/rovers, to collect the surface samples, and to create an artificial crater using a new small kinetic impactor. Detailed operation planning of the asteroid proximity phase started after the launch, and lots of training for the proximity phase were conducted from one year before the arrival. This paper summarizes the overview of the asteroid proximity operation plan of Hayabusa2 and its preliminary results.

Challenges in LICIA Cubesat trajectory design to support DART mission science

In 2021, the DART spacecraft will be launched by NASA to intercept the binary system Didymos and impact the moonlet (Dimorphos), to test the effectiveness of kinetic impactors for the deviation of hazardous asteroids’ trajectories. The impact is expected to generate a cloud of particles, whose study could provide valuable data about asteroid’s properties and impact models. Observations from ground to characterize ejecta and plume evolution after impact would be possible, but the resulting quality would be significantly lower than a short-range imaging. In this framework, ASI (Italian Space Agency) and NASA started a collaboration to embark on the US DART vehicle the LICIA (Light Italian CubeSat for Imaging Asteroid) 6U CubeSat as a piggyback payload. LICIA is devoted to grasp science data by imaging the ejecta plume after the impact, and observe Dimorphos surface while flying by the binary system. The Italian consortium involved in the mission sees ARGOTEC for the platform development, and INAF, Politecnico di Milano and Università di Bologna to cover the mission science, trajectory design and orbit de-termination tasks, respectively. The paper focuses on the mission analysis and maneuvers design, strongly driven by the science return, under the tight constraints enforced by the platform. In particular, it describes the preliminary procedure followed to derive trajectory constraints and to select the best option for the flyby. Despite the mission is still under development, and subjected to frequent updates of several parameters, the final performances derived in this paper maintain their validity as they represent the desired target values for the mission.

Evaluation of NEA deflection techniques. A fuzzy Multi-Criteria Decision Making analysis for planetary defense

Current statistics on the flux of impactors on the Earth reveal that asteroids with a diameter larger than few hundreds of meters are unlikely to reach the Earth’s orbit, although their potential effects on the life of our planet could be quite catastrophic. The present article assesses a set consisting of four deflection approaches, namely: kinetic impactor, ion beam deflection, enhanced gravity tractor, and laser ablation to be applied to mitigate a hypothetic impact with an asteroid smaller than 250 meters in diameter. This size range corresponds to the most common impactors that occur in timescales of less than 100.000 years. With the current discovery rate for small asteroids, such a range of diameters could be of interest to assess a future impact forecast, and quantify our capacity to react in time. To achieve this, a set of eight criteria are used: build time; active deflection duration; asteroid rotation; asteroid composition; asteroid structure; asteroid shape; level of maturity of a NEA deflection technique; and mission risk. This assessment is carried out with a combination of Multi-Criteria Decision Making tools and fuzzy logic, which enables proper management of imprecise criteria. The valuable knowledge provided by a group of experts enabled the importance of each attribute and the evaluation of these NEA deflection techniques to be quantified. Our results suggest that the kinetic impactor is the best option to deflect mid-size NEAs, whereas for larger asteroids, enhanced gravity tractor, and laser ablation become to be more appropriate.

Hayabusa2's kinetic impact experiment: Operational planning and results

Hayabusa2 is a Japanese interplanetary probe launched on December 3, 2014, which arrived at asteroid Ryugu on June 27, 2018. During its stay around Ryugu, it completed several challenging operations, including deploying two rovers and a lander, conducting two sample collections, and performing a kinetic impact experiment. The kinetic impact experiment was one of the biggest challenges of the Hayabusa2 mission. Investigating the physical and chemical properties of asteroid internal materials and structures is an important scientific objective for small body exploration. We developed a small kinetic impactor called the SCI (Small Carry-on Impactor) to achieve this objective. The SCI is a compact kinetic impactor designed to remove a small region of Ryugu's uppermost surface regolith layer and create an artificial crater. The spacecraft deployed the SCI on April 5, 2019, successfully creating an artificial crater with a diameter of 15 m. This paper describes the operational planning of the kinetic impact experiment and summarizes the operation results.

Deflection driven evolution of asteroid impact risk under large uncertainties

The threat of asteroid impacts on the Earth can be mitigated through deflection missions. The deflection capability has previously been omitted in asteroid impact risk analysis work that quantifies impact damage on the Earth. Here we investigate the effect of pre-designed deflection missions on the risk profile of the fictitious impact scenario 2019 PDC. The impact risk analysis is based on a statistical approach. We sample orbital and physical property distributions that provide a complete representation of possible impact scenarios. Three pre-designed kinetic impactor deflection missions are considered in separate simulations. The deflection mission imposes a deflection ΔV on the asteroid and the impulse enhancement factor β is calculated as part of the analysis. The post-deflection impact risk is compared to the undeflected risk situation. Variations in physical and orbital properties make the outcome of deflection missions uncertain. It can therefore be inadequate to label deflection mission outcomes in binary terms of success and failure. Instead, defining a satisfactory risk reduction goal and scaling the deflection mission capability to deliver this risk reduction is more accurate. In addition, the results highlight dilemmas that decision-makers would face in an asteroid threat scenario. By implementing a deflection mission, the potential impact point of the asteroid is moved, threatening new populations and potentially increasing damage in case of an impact.

A benchmarking and sensitivity study of the full two-body gravitational dynamics of the DART mission target, binary asteroid 65803 Didymos

NASA's Double Asteroid Redirection Test (DART) is designed to be the first demonstration of a kinetic impactor for planetary defense against a small-body impact hazard. The target is the smaller component of the binary asteroid 65,803 Didymos. We have conducted high-fidelity rigid full two-body simulations of the mutual dynamics of this system in a broad benchmarking exercise to find the best simulation methodologies, and to understand the sensitivity of the system to initial conditions. Due to the non-spherical shapes of the components and their close proximity, the components cannot be treated as point masses and so the dynamics differ significantly from a simple Keplerian orbit, necessitating the use of numerical simulations to fully capture the system's dynamics. We find that the orbit phase (angular position or true anomaly) of the secondary is highly sensitive to the initial rotation phase of the primary, making prediction of the secondary's location from numerical simulation challenging. Finally, we show that the DART impact should induce significant free and forced librations on the secondary. If this libration can be measured by ESA's recently approved follow-up spacecraft, Hera, it may be possible to constrain properties of the secondary's interior structure.

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.

Highly Effective Kinetic Impact Design for Asteroid Deflection Missions Exploiting Impact-Geometry Maps

The kinetic impactor, which is a spacecraft that impacts against an Earth-threatening asteroid, is one of the potential methods for deflecting an asteroid from the Earth collision route. To improve the effectiveness of the impact, an impact-geometry map is used that visualizes the kinetic impact effectiveness as a form of impact geometry, which is the inner product of the asteroid velocity vector and the spacecraft velocity vector relative to the asteroid velocity. A locally optimal thrust control law is proposed that maximizes the change rate of the impact geometry, and it achieves a monotonic increment in it. The law is combined with a global optimization method, and a trajectory design system is developed for kinetic impactor missions. Trajectory optimizations are numerically demonstrated for fictional asteroid deflection scenarios. The results show that the proposed system achieves a larger deflection distance despite the reduction in the projectile’s impact velocity relative to the asteroid as compared to a previous method. Besides, as the proposed method focuses not on the spacecraft impact velocity but on the impact geometry, the merit to improve the mobility capability on the impact-geometry map by increasing the available thrust at the expense of increasing the fuel consumption is also indicated.