This paper describes the preliminary study results of developing a hypervelocity terminal intercept guidance system of a multiple kinetic-energy impactor vehicle (MKIV). The proposed MKIV system is intended to fragment or pulverize an asteroid of smaller than approximately 150 m in diameter that is detected with a mission lead time of shorter than 10 years, without using nuclear explosive devices. This paper focuses on the development of a new image processing algorithm based on Otsu’s method for the coordinated terminal intercept guidance and control of multiple kinetic-energy impactors employing visual and/or infrared sensors. A scaled polyhedron shape model of asteroid (216) Kleopatra is used as a fictional target asteroid. GPU-based simulation results demonstrate the feasibility of impacting a small irregular-shaped asteroid by using the proposed new image processing algorithm and a classical pulsed TPN (true proportional navigation) terminal guidance law.

In this paper, the performance of two distinct classes of feedback guidance algorithms is evaluated for a spacecraft rendezvous problem utilizing a continuous low-thrust propulsion system. They are the DG (Differential Geometric) and ZEM/ZEV (Zero-Effort-Miss/Zero-Effort-Velocity) feedback guidance algorithms. Even though these two guidance algorithms do not attempt to minimize the onboard fuel consumption or $\mathrm{\Delta }V$ directly, the $\mathrm{\Delta }V$ requirement is used as a measure of their orbital rendezvous performance for various initial conditions and a wide range of the rendezvous time (within less than one orbital period of the target vehicle). For the DG guidance, the effects of its guidance parameter and terminal time on the closed-loop performance are evaluated by numerical simulations. For the ZEM/ZEV guidance, its near- fuel-optimality is further demonstrated for a rapid, short-range orbital rendezvous, in comparison with the corresponding open-loop optimal solutions. Furthermore, the poor $\mathrm{\Delta }V$ performance of the ZEM/ZEV guidance for a slow, long-range orbital rendezvous is remedied by simply adding an initial drift phase. The ZEM/ZEV feedback guidance algorithm and its appropriate variants are then shown to be a simple practical solution to a non-impulsive rendezvous problem, in comparison with the DG guidance as well as the open-loop optimal guidance.

This paper presents an overview of space mission concepts for disrupting or pulverizing hazardous asteroids, especially with warning time shorter than approximately 10 years. An innovative mission concept, referred to as a nuclear hypervelocity asteroid intercept vehicle (HAIV) system, employs both a kinetic-energy impactor and nuclear explosive devices. A new mission concept of exploiting a multiple kinetic-energy impactor vehicle (MKIV) system that doesn’t employ nuclear explosives is proposed in this paper, especially for asteroids smaller than approximately 150 m in diameter. The multiple shock wave interaction effect on disrupting or pulverizing a small asteroid is discussed using hydrodynamic simulation results. A multi-target terminal guidance problem and a planetary defense mission design employing a heavy-lift launch vehicle are also briefly discussed in support of the new non-nuclear MKIV mission concept. The nuclear HAIV and non-nuclear MKIV systems complement to each other to effectively mitigate the various asteroid impact threats with short warning time.