The geostationary satellite has the characteristics of "standing high, seeing wide and staring long", and has the capability of large width imaging, continuous staring imaging and high timeliness imaging, which can realize the rapid response to various emergency observation tasks. The developments of high-orbit ocean remote sensing satellites and the array-gazing optical remote sensing system in ocean and coastal zones observation can fill the gap of dynamic monitoring on the marine environment in high orbit in China, and meet the urgent demand for observation and emergency monitoring of the surrounding sea areas, nearshore and islands of China. By analyzing the technical characteristics of the high-orbit optical remote sensing system for the ocean and coastal zone, a system design scheme has been put forward, in which many technologies are adopted, such as a large-aperture optical system with low stray light, low polarization and multi-spectral features, a high improvement in the signal-to-noise ratio, and an on-board calibration with high precision. Based on this, the prototype development and system testing have been completed, and combined with field tests, the feasibility of the core indicators has been effectively verified, laying a technical foundation for the implementation of the high-orbit optical remote sensing system project for the ocean and coastal zone.

To meet the demand of high-precision directional and detailed detection in a wide coastal zone, the new generation of ocean color observation satellites, the Coastal Zone Imager, employs the imaging technology featuring a front-mounted wide-range pointing mechanism. It utilizes a drive system consisting of "stepper motor rotation + harmonic gear reducer transmission" and a telemetry system incorporating "Hall effect digital switch circuit + absolute photoelectric encoder". Through successive approximation closed-loop control, it achieves a detection range of 1,000 km with an accuracy better than half a step angle, enabling accurate on-orbit line-of-sight positioning and precise surveying of hotspot areas. In ground laboratory tests, the Coastal Zone Imager achieved a control accuracy of better than 20 arcseconds and a measurement accuracy of better than 10 arcseconds for the line-of-sight pointing angle. The on-orbit tests fully verified the feasibility and robustness of this line-of-sight pointing system. This design is characterized by high positioning accuracy, high reliability, good safety, and compact scale, and is of great significance for directional and detailed detection in wide coastal zones.

To address the problem that the signal-to-noise ratio and stage linearity of the imaging circuit system under the horizontal uniform subdivision and summation timing do not meet the requirements of the camera specifications, based on the analysis of the characteristics and working principle of the ultra-large pixel TDICCD, this article proposes a design scheme for the horizontal non-uniform subdivision and summation timing. This scheme conducts timing optimization and software design from three aspects: extending the reset reference holding time of the analog signal, reducing the collection time of the intermediate charge packet, and extending the collection time of the last charge packet. As a result, the pre-sampling and post-sampling regions of the correlated double sampling are increased by more than 3 times and 1.7 times respectively, improving the sampling reliability. Moreover, the hardware design and performance test verification of the imaging circuit system are completed. The laboratory test results show that the signal-to-noise ratio in all spectral bands of the ultra-large pixel TDICCD is greater than 67 dB, and the stage linearity is better than 99%, meeting the requirements of the camera specifications. Meanwhile, the texture of the on-orbit images is clear, and the spectral bands have distinct layers, further verifying the application of this scheme.

The ocean color and temperature remote sensor is an important tool for monitoring the marine ecological environment, assessing primary productivity of the ocean, and studying global sea surface temperature changes. New generation ocean color and temperature scanner addresses the shortcomings of traditional ocean color remote sensors in terms of spatial resolution, spectral range setting, signal-to-noise ratio, and calibration accuracy. For the first time in China, a system design scheme for telescope overall rotation scanning and half angle mirror synchronous tracking is proposed. Firstly, an innovative rotating off-axis three mirror optical system was designed, combined with scanning imaging mode and a large pixel detector design, achieving system sweep width ≥3000 km, signal-to-noise ratio ≥1000, noise equivalent temperature difference of infrared band ≤0.1 K, system polarization sensitivity ≤1.5%, and stray light coefficient ≤1%. Secondly, in response to the demand for multi band and high-precision calibration on board, a full aperture and full path onboard calibration technology based on a rotating telescope has been proposed, which improves the solar calibration accuracy of the payload to within 2%. The performance test results indicate that the system surpasses comparable load-bearing systems both domestically and internationally in multiple metrics, the research results can provide technical support for the new generation of ocean color and temperature scanner in China.

To meet the user requirements for high resolution, high signal-to-noise ratio, wide dynamic range, and high revisit frequency in coastal zone observation, the coastal zone imager on the next-generation ocean color observation satellite employs an off-axis three-mirror main optical system and multi-spectral integrated high-sensitivity TDICCD detectors. This setup achieves high signal-to-noise ratio and wide dynamic range imaging across nine spectral bands under low water body radiance conditions, with a panchromatic spectral resolution of 5 meters and a multi-spectral resolution of 20 meters. The design of a large aperture pointing swing mirror, in combination with long-life mechanism design and high-precision closed-loop control, ensures the realization of high precision and reliability and the flexibility and maneuverability in orbit for the imager. The swath width, without the satellite side-to-side motion, reaches 1029 kilometers. Through ground testing and in-orbit operation verification, all performance indicators of the imager meet the design requirements and user needs. It has significant application prospects in enhancing coastal zone remote sensing observation capabilities, serving marine resource development and environmental protection.

The new-generation ocean color observation satellite is a key marine remote sensing research satellite under China's 13th Five-Year Plan. It carries three payloads: an ocean color and temperature scanner, a programable medium resolution imaging spectrometer, and a coastal zone imager. The satellite platform integrates 46 remote sensing spectral bands for ocean color and temperature detection, covering ultraviolet, visible, near-infrared, short-wave infrared, and mid-/long-wave infrared wavelengths. It achieves multiple spatial resolutions (5 m, 20 m, 100 m, and 500 m) and demonstrates improvements in radiation quality, system accuracy, operational efficiency, and service lifespan. These capabilities meet the requirements for multi-element, multi-scale, and multi-task ocean observation, with performance reaching or approaching that of international counterparts in ocean color remote sensing. This article introduces the technical features, development risk control, and on-orbit testing of the new-generation ocean color observation satellite, providing a comprehensive summary of its innovations.