Accurate detection of non-cooperative spacecraft based on optical sensor data is essential for critical space tasks, such as on-orbit servicing, rendezvous and docking, and debris removal. Traditional object detection methods struggle in the challenging space environment, which includes extreme variations in lighting, occlusions, differences in image scale. To address this problem, this paper proposes a high-precision, deep-learning-based, domain-adaptive detection method specifically tailored for non-cooperative spacecraft. The proposed algorithm focuses on two key elements: dataset creation and network structure design. First, we develop a spacecraft image generation algorithm using CycleGAN, facilitating seamless conversion between synthetic and real spacecraft images to bridge domain differences. Second, we combine a domain-adversarial neural network with YOLOv5 to create a robust detection model based on multi-scale domain adaptation. This approach enhances the YOLOv5 network’s ability to learn domain-invariant features from both synthetic and real spacecraft images. The effectiveness of our high-precision domain-adaptive detection method is verified through extensive experimentation. This method enables several novel and significant space applications, such as space rendezvous and docking and on-orbit servicing.

Owing to its low cost and ease of manufacture, integrated monocular space camera and laser rangefinders are commonly used in many space applications (i.e., pose measurement of non-cooperative targets). This and other composite systems estimate poses with high precision using a combination of high-resolution lateral visual and high-precision distance information. Notably, any system that is tested on ground must again receive precise on-orbit calibration because the accompanying spaceborne turntables and arms must be frequently manipulated to meet field-of-view and distance measurement requirements and require complicated realignments. To accommodate flexible multiple target calibration, this study proposed an on-orbit model that obtains accurate pose relationships jointly using the monocular camera and laser rangefinder. First, we invented a robust calibration model and derive its pose transformation matrix based on the given component positions. We then provided an improved (simplified) orthogonal iteration algorithm that optimizes the given matrix for calibration. The influences of different factors on calibration accuracy are quantitatively analyzed via simulations, and the new method’s performance is verified with real-world experiments. This system enables several novel and significant space and military applications.

In order to capture true-color information of distant targets under extremely low light, a large-format low-light imaging system is designed based on an RGB filter wheel. By decomposing the system indicators, this study proposes a method for acquiring low-light true-color images using a large-aperture, low-distortion optical lens combined with an RGB filter wheel capable of multi-line sequential exposure. The optical field segmentation is achieved using a four-panel optical reflective prism, and the images from four high-sensitivity SCOMS detectors are stitched together to form a composite image. The working principle of the system is explained, and the low-light imaging capability is thoroughly evaluated. The dimensions and rotation speed of the filter wheel are then calculated in detail, ensuring accurate synchronization of the filter wheel’s speed and exposure time. The calculation method for the parameters of the four-panel reflective prism structure is investigated, mathematical expressions for the geometric parameters of the prism assembly are provided, and a prism assembly suitable for four-way spectral separation is designed. Based on the research and design results, a large-swath-width, low-light true-color imaging system is developed that is suitable for an environmental illuminance of 0.01 lux. The system achieves a ground pixel resolution of 0.5 m (at an altitude of 5 km) and an effective image resolution of 4 K × 4 K, and is capable of accurately reproducing target color information. Laboratory and field flight tests verified that the large-swath-width images obtained by the imaging system are clear, with high contrast and resolution. After image fusion and spectral registration, the color images exhibit full saturation and high fidelity, meeting the requirements of low-light true-color imaging under airborne conditions. The design methodology of this low-light imaging system can serve as a reference for the development of airborne low-light imaging equipment.

In the athermal and apochromatic design of optical systems, the distribution of lens’ optical powers and the selection of optical glass and structural materials are crucial. In this paper, an athermal and apochromatic design method is proposed for optical systems with a long focal length, large relative aperture, and wide spectrum. Firstly, a complex optical system composed of multiple lenses is equivalent to a two-component, single-lens system consisting of a replacement and an equivalent lens group. The optical glass for the replacement lens group is selected based on weight and the principle of material replacement in the 3D glass diagram, thus achieving an athermal and apochromatic design. Secondly, an athermal and apochromatic optical system with a focal length of 130 mm, an F-number of 2.0, a spectral range of 480 nm~800 nm, a field of view angle of 22°, and an operating temperature of −40 °C~+60 °C is designed. The modulation transfer function (MTF) at each field of view is greater than 0.6 at 50 lp/mm in the −40 °C~+60 °C temperature range, and the secondary spectrum aberration is 0.0056 mm, which is within the focal depth range of the optical system.

Weakly-supervised object detection (WSOD) methods that trains an object detection network using image-level labels has attracted much attention due to its cost-effective annotation and broad applied requirement. However, applying such weak label to detect targets in infrared images is not trivial due to the less discriminative target information and interference of complex backgrounds. This paper proposes a Multi-grained and Confidence-aware Multiple Instance Network (MCMIN) to detect infrared targets given the imprecise labels. The multi-scale multi-grained feature extraction module is designed to capture discriminative features from different receptive fields for dim-small targets. The hierarchical multiple instance target detection module firstly applies L1-sparsity regularization to encourage the model generate reliable pseudo ground truth, and then leverages the confidence-aware instance adaptive weighting strategy to refine proposals with particular emphasis, achieving more accurate target detection. The experimental results on two infrared target detection datasets illustrate that the proposed MCMIN outperforms other state-of-the-art WSOD methods with higher AP. The proposed approach decreases the false alarms.

In order to meet the needs of scientific research in space medicine and biology, a new multifunctional automated cell sample culture device for a Chinese space station has been designed. The temperature and carbon dioxide concentration are adjustable, making it convenient for cell culture in microgravity environments of the space station. A centrifuge is used to simulate the microgravity environment, allowing for synchronous gravity and microgravity comparison during cell culture. An automated focusing visible light microscope has been designed, capable of real-time photography of cultured cells, which can receive ground commands to complete automatic focusing and image transmission. The thermal design of the cell sample culture device uses an air heating method, and the rationality of the thermal control measures has been verified through thermal simulation analysis. The designed cell sample preparation device can monitor and display the cell growth environment parameters and device performance parameters in real time on orbit. It can also control the internal temperature within the temperature range required for cell culture. Thus, it can meet the urgent needs of various cell cultures, experiments, and scientific research on a Chinese space station.