The threat of near-Earth asteroid (NEA) impacts is inherently linked to humanity’s future, rendering the establishment of a global defense system an urgent priority. The successful implementation of NASA’s double asteroid redirection test (DART) mission and ESA’s Hera mission have verified the feasibility of active NEA defense technologies. In these missions, on-board space optical payloads played an irreplaceable role in critical processes including target detection, navigation control, and impact effect assessment. For China’s proposed first NEA defense mission, developing an independently controllable space optical payload system is not only essential for verifying the country’s own defense capabilities but also contributes to the global NEA defense network. Given the characteristics of target asteroids, China’s space- and ground-based deep-space monitoring resources, and platform capabilities, clarifying the requirements, technical features, and application outcomes of space optical payloads is of great significance for laying the foundation of China’s NEA defense system.

This study systematically reviews the technical characteristics and application outcomes of space optical payloads in NEA defense missions (e.g., DART and Hera) and analyzes the payload configuration requirements for China’s first NEA defense mission (Table 1 and Table 2). For NASA’s DART mission, the space optical payload inherits mature technologies from deep-space exploration and is optimized for defense-specific needs. The DART mission’s Didymos reconnaissance and asteroid camera for OpNav (DRACO) serves as a representative example: featuring a 208 mm aperture, 2.48 μrad angular resolution, and 14.5-magnitude detection capability, DRACO builds on the design of LORRI cameras from NASA’s New Horizons and Lucy missions while introducing key improvements—including the replacement of charge-coupled devices (CCDs) with complementary metal-oxide-semiconductor (CMOS) sensors, adoption of global/rolling shutter dual-mode operation, integration of the SMART Nav autonomous navigation algorithm, and improved adaptability to low-temperature environments [(-85±5) ℃] (Fig. 1). These upgrades enable DRACO to achieve cm-level impact point positioning (1σ error: ±68 cm) for the 160 m asteroid Dimorphos and capture high-resolution data on the size and distribution of boulders on its surface. For ESA’s subsequent Hera mission, payloads—including the asteroid framing camera (AFC), thermal infrared imager (TIRI), HyperScout H imaging spectrometer, and ASPECT hyperspectral imager—further enhance the mission’s multi-dimensional detection capabilities. Additionally, LICIACube (a NASA auxiliary CubeSat for the DART mission) carries LEIA (wide-field) and LUKE (narrow-field) cameras, which captures images of Dimorphos’ unimpacted hemisphere and dynamic videos of ejecta evolution processes, verifying the “primary mission+CubeSat” payload collaboration mode.

Three core technical challenges in space optical payload design are addressed during NASA’s DART mission. 1) Navigation-imaging multiplexing technology: DRACO employs rolling shutter mode (4.9 μrad angular resolution, 30× gain) for long-range navigation (resolving low signal-to-noise ratio problems) and global exposure mode (2.48 μrad angular resolution, 1× gain) for short-range high-precision detection (mitigating read noise and popcorn effects). Algorithm-based compensation was also implemented to correct rolling shutter distortion (up to 5 pixels) induced by rapid spacecraft attitude drift. 2) Autonomous high-precision guidance, navigation, and control: the SMART Nav algorithm assumes control of the spacecraft’s trajectory 4 h before impact, extracted Dimorphos’ centroid via surface feature detection, calculates real-time 3D coordinates of the impact point, and reduces the orbital error to the 10 m range 10 min prior to impact. In the final 30 s (when ground intervention was impossible due to signal delay), the algorithm completes image processing and decision-making within 200 ms. 3) Space environment adaptability: DRACO adopts a Ritchey-Chrétien optical system equipped with a lightweight microcrystalline glass primary mirror and Invar support (characterized by a low thermal expansion coefficient). It also eliminated the focusing mechanism to reduce weight and adopted a commercial CMOS detector integrated with overcurrent detection to mitigate single-event functional interruptions (SEFI), while exploring a low-cost technical approach.

For China’s first NEA defense mission, the target asteroid has a diameter of approximately 30 meters, with an unknown rotation period and surface properties. The mission requires its payloads to satisfy both engineering objectives (high-speed precision guidance and impact effect assessment) and scientific goals (research on orbital and intrinsic properties). Proposed payloads include: 1) a high-resolution camera (0.1 m resolution at 30 km, supporting both video and photography modes) for measuring asteroid shape and monitoring ejecta; 2) a multispectral camera (spectral range: 480?1000 nm, ≥8 bands) for surface topography and material research; 3) a visible-infrared spectrometer (spectral range: 400?1000 nm, ≥256 bands) for high-resolution spectral data acquisition; 4) a thermal radiation spectrometer (spectral range: 5?50 μm, temperature measurement accuracy: ±2 K) to invert thermophysical drivers of orbital evolution (e.g., the Yarkovsky effect) through multi-source data fusion. These payloads leverage China’s mature deep-space exploration technologies but require optimization to accommodate the smaller target asteroid and higher impact velocity.

For China’s NEA defense mission, the unique “flyby+impact+flyby” mode demands that payloads focus on dynamic monitoring, multi-dimensional comparison, and long-term stability. To achieve this, three key directions should be prioritized. 1) Strengthen scientific team-building, optimize parameters, and build a data platform for resource sharing. 2) Promote multi-payload collaboration and autonomy. 3) Optimize payload configuration and improve precision to compensate for limited ground-based observation data.By advancing these directions, China can build a space optical payload system with independent characteristics, providing technical support for its NEA defense mission and contributing a Chinese solution to global NEA defense.