As the world major national space projects advance from near-Earth orbit to the deep space, spacecraft have some challenges to operate reliably in extreme environments. It is thus necessary for the development of spacecraft to solve the problems (i.e., From the deterioration of the space irradiated environment to the constraints of energy problems far from the sun, from the difficulties of high heat flow and heat dissipation of highly integrated devices to the development trend of highly sensitive sensors for spacecraft health monitoring). Diamond has five characteristics like "hard, high, transparent, wide and fast" due to its unique crystal structure, determining its high temperature resistance, high frequency resistance, high pressure resistance and irradiation resistance in extreme environments. Deep space exploration plays a role in space environment sensing and pulsar-based navigation by detecting X-ray, ultraviolet and particles from solar radiation. Diamond detectors are fabricated based on photovoltaic effect and/or interaction between particle and diamond. Electrode structure, device structure, and diamond quality have an impact on the detector performance. The detector arrays with large area and excellent performance with the heteroepitaxial diamond size of 1.0-3.5 inches are developed. In addition, a portable power supply based on isotope batteries is also an effective option to solve the problem of insufficient solar radiation during deep space exploration. A radio-voltaic effect isotope battery mainly utilizes the photovoltaic effect generated by the high-energy particle radiation released during isotope decay inside the semiconductor energy transfer junction to generate output current. Compared with other wide-bandgap semiconductors including SiC, GaN, AlGaAs and diamond, diamond has a higher electron-hole pair generation efficiency of 44.2%. The existing transducer junction structure focuses on metal/diamond Schottky junction and diamond/other semiconductors P-N junction, on account of the lack of efficient N-doping. A open circuit voltage of 5 V and a rectification ratio of 107 are obtained for diamond/β-Ga2O3 hetero-junction battery while a theoretical value of energy conversion efficiency of 26.8% is predicted for diamond P-N junction. As the thermal environment inside and outside the spacecraft changes, thermal management and control are crucial for the spacecraft in-orbit work. Diamond as a semiconductor with a high thermal conductivity can enhance the heat conduction as a heat spread or heat radiation as a near-field thermal radiation device. Space active phased array antenna typically features a high performance and a high heat flux due to the high device integration of transmit/receive (T/R) module. The T/R module generates a significant amount of heat in a very small space, leading to a challenge for the thermal management and dissipation from the “hotspot” of devices. When diamond is applied in four launched satellites, the temperature gradients of the T/R modules less than 2.2?℃ is recorded from the flight data, further verifing the rationality and effectiveness of using high-thermal-conductivity diamonds in the thermal design and implementation of active phased array antenna. Near-field thermal radiation device can be used as the heat dissipation surface of a satellite or other spacecraft. As an intelligent thermal control method, the emissivity can be adjusted upon the application of the electric field in the P-N junction and MIS junction. This technology is in the theoretical research stage, but this device based on diamond heterojunction has prospects. In the bargain, in addition to solar irradiation and cosmic rays, spacecraft operating in the space environment also faces many threats such as space debris and high/low temperature alternating environment, leading to the failure of spacecraft structure and bring great hidden dangers to space flight. It is thus important to monitor spacecraft temperature, pressure/strain, acceleration and other parameters in real time. The basic principle of diamond quantum sensing is to use the NV-spin energy level to be sensitive to physical signals such as electromagnetic field, strain, temperature, etc., via measuring the change in the intensity of the output fluorescence signal caused by the NV- change in the external field. Comparing the sensitivity of diamond quantum sensors and other types of sensors in detecting magnetic fields indicates that the sensitivity of diamond quantum sensors is still relatively high. Space optical sensors are known as the "eyes" of spacecraft, providing the positioning information for space missions such as deep space exploration and remote sensing mapping. Diamond has a high transmittance in the deep ultraviolet band, which can well meet the application requirements of the sensor optical system window, and has intense anti-irradiation characteristics and good stability in extreme space environments. With the development of large-scale curved diamond preparation technology, diamond could be used as an excellent optical alternative material in the future.Summary and prospects In this review, the application of diamond materials in deep space exploration (detectors), portable power supplies (isotope batteries), spacecraft thermal control (heat conduction and near-field thermal radiation devices), spacecraft health monitoring (quantum sensors), and optical windows (optical sensor windows were proposed). To represent the application advantages of diamond in the extreme field of aerospace, it is necessary to continue efforts in at least the following aspects. First, 2-inch large-area array polycrystalline diamond arrays are reported to have a good ultraviolet detection performance, and it is possible to effectively synthesize large-area heteroepitaxial single crystal diamond for diamond detectors with better electrical properties. Second, diamond isotope cells and near-field thermal radiation devices both are based on the construction of diamond semiconductor heterojunctions, but the effective diamond N-type doping technology has not yet been broken through. It is thus necessary to further develop the effective diamond doping technology based on new principles. Finally, diamond quantum sensing technology has the advantages of multi-parameter sensing, but how to distinguish the output signal under different field signal excitations and reduce the interference in the face of multi-source targets needs to be further investigated.