2020 Vol. 7, No. 5
Patrol detection is an important form of deep space exploration. The planetary rover, which can move on the surface of solid-state planet and complete the tasks of exploration, sampling and transit, has many functions, such as expanding the scope of fine detection on planet surface, overcoming the impact of landing accuracy, reducing the workload of astronauts and so on. The technical development of lunar rover, Mars rover and others are reviewed focusing on the development of locomotion technology, navigation control technology, autonomous and intelligent technology, thermal control technology, ground test verification technology, remote operation technology, and the development trend of rover technology is analyzed.
Improving the environment perception ability is a prerequisite for improving the intelligence and autonomy of the rover. Non-geometric hazard perception is the key part of autonomous navigation. Reviewing the development of the non-geometric hazard perception of the rover, it shows that the key aspects of the non-geometric hazard perception are hazard estimation and hazard prediction. Non-geometric hazard estimation and prediction include wheel-soil model, wheel sinkage estimation, slip ratio estimation, identification of soil parameters and terrain classification, and the relevant research on theses aspects are introduced and analyzed. The future research on non-geometric hazard perception should focus on the optimization of wheel-soil interaction mechanics model, multi-source information fusion and the application of artificial intelligence technology. Finally, a slip ratio prediction method based on soil parameter identification is described.
In view of the fact that the Martian terrain environment cannot be realistically simulated on the ground, the functional performance of the rover is not fully verified on the ground, especially the Chinese rover adopts an active suspension mobile system, lacks experience in orbit. Establish a real dynamics model of the rover system, and comprehensively verify the rover's movement performance and strategy under different terrains through mathematical simulation methods. the simulation results show that the vehicle body lifting and wheel-lifting walking can effectively improve the passing performance and fault tolerance of the rover. Give the quantitative influence of terrain environment and walking gait on the performance of the rover, provide reference for Chinese Mars rover application in orbit and troubleshooting.
In view of a limited kind of drawout-expanded ramps, and in order to realize two transfer channels for Mars rover, considering all kinds of faults that could be occurred in orbit, and without changing the original mechanism, a two-way optional autonomous deployment strategy is carried out in this paper, . The whole process of the strategy is verified one by one in the joint test of transfer ramps and data management software, all telemetry parameters are normal, the system sequence is executed correct, the results show that the autonomous deployment strategy of transfer ramps is effective and reliable, which provides a strong guarantee for the successful transfer of Mars rover to the surface.
Spacecraft servo mechanisms are generally driven separately, and are controlled and monitored by ground tele-operation. The servo mechanisms of Mars rover have many functions such as movement, suspension adjustment, communication antenna pointing, solar wing orientation, mast rotation, etc. The Mars rover is equipped with numerous motors and sensors. The traditional design cannot meet the requirements of integration, autonomy and fault-tolerant control for the Mars rover. In this paper, the overall structure of the integrated control system for the Mars rover mechanism is optimized. The strategy of hardware resource reuse and computing resource reuse is adopted to achieve the goal of integration. Autonomous management functions are realized for motion planning, control operation, etc. The design requirements of fault-tolerant control are met through the functions of fault detection, emergency treatment and degraded control. For the application of the Mars rover mechanism control system, all specifications are optimized in compliance with many constraints. The validity and rationality of the method is verified, providing reference for the mechanism control systems of space explorer with complex functions and strict constraints.
Focused on the image data storage, compression and transmission of mars rover, system design and key hardware/software architecture design are carried out in this paper based on the analysis of function requirements and key design features. Image compression algorithm and transmission protocol are proposed, and the image storage and compression module in Mars rover is designed and implemented. The multi-camera partition parallel image file system based on FPGA（Field Programmable Gate Array）is realized. The adaptive first 1 run length coding algorithm for image compression based on DSP is realized on this module. Finally the function of multi-camera image data storage and management, flexible control of image compression ratio, quality progressive transmission, coding of region of interest, anti-error code diffusion and image thumbnail downward transmission are realized in the engineering development, meeting the reliable, efficient and flexible application requirements of China’s first Mars exploration mission.
It is an atmospheric environment with an average pressure as 600 Pa of CO2 and a minimum temperature of -123 ℃ in Mars. Ultra-low quality and high efficient thermal insulation material is the key material for the thermal control system of Mars Rover to ensure the normal operation of electronic components. Aerogel is the solid material with the lowest thermal conductivity in the atmospheric environment. Therefore, it is the best insulation material choice for the thermal control of Mars Rover. To meet the need of Mars Rover, a low density nano-aerogel insulation material with density of less than 30 kg/m3 has been developed in this article. The preparation process of low density aerogel and composite materials, and the supercritical CO2 drying and ultra-low density aerogel composite’s being machined process are studied. The thermal physical properties, vacuum volatiles, the properties in the thermal cycling, thermal vacuum and other thermal environments are also characterized. The results show that the ultra-low density nano-aerogel insulation material has excellent structural and heat insulation stability in the Martian environment, which can meet the application requirement of space exploration. The material has good mechanical property and excellent thermal insulation property. The thermal conductivity of the low density aerogel composites is 0.0066 W/（m·K）at room temperature in Martian atmosphere which has been applied the Mars Rover in China.
The environments are very different between Martian Surface and near-earth space. To estimate the output power of the Solar Array on the Mars surface is not easy, which is affected by the solar radiation, temperature, dust and diffuse irradiance. A method to calculate the output power of Solar Array in Martian Surface Environment is proposed in this paper based on a survey to the results of research all over the world. Models about how the illumination, temperature and dust to affect the power generation of the Solar Array on Martian surface are established. Those numeric models and method are used to improve the power balance of the Mars Rover in the first Mars exploration mission of china and are a reference for the intending Mars and other deep-space exploration missions.
China’s Mars rover’s payloads consist of five devices, including multispectral camera, Mars rover penetrating radar, Mars surface composition detector, Mars rover magnetometer and Mars climate station. To ensure the validity of the scientific data obtained onboard, calibration should be carried out on the ground. Through calibration, the instruments’ performance can be determined and the calibration coefficients can be obtained, which are necessary for the quantitative analysis of scientific data. The calibration contents and results are introduced.The test results show that the performance of each instrument is stable and consistent, and lay a solid foundation for achieving scientific goals.
Bio-regenerative life support system （BLSS）, is one of key technologies for long-term and long-distance manned space missions such as manned Mars landing and the establishment of lunar and Mars bases. The theories and technologies of BLSS are summarized. Countries and organizations including Russia, USA, Europe, Japan and China have conducted a series of research in BLSS, from bio-unit test, systematic test to manned closed experiment and aquatic micro-ecosystem experiments in space. The development path of BLSS is proposed, and it points out that small-scale terrestrial ecosystem is the key part for the application of BLSS to space. The tendency and ground application prospect of technologies derived by BLSS are analyzed as well.
A short review of the available data on plant development, seed-to-seed, and next generations, and formation of generative and vegetative organs in real and simulated microgravity is presented. It is emphasized the timeliness of the emergence of plant space reproductive biology and its importance for progress in space agriculture that is necessary for future human exploration of space.
During long-term manned space flights, biological life support systems are required, so food becomes an instrument of paramount importance. Plants are an accessible source of biologically active compounds. Antioxidant deficiency decreases the body's functional activity. Vegetable foods, including non-traditional and medicinal crops, are the main and most affordable source of antioxidants for humans. Yacon （Polymnia sonchifolia Poepp. & Endl.） is one of the most promising introductory species for Ukraine, and has recently started growing as a vegetable crop in our country. The leaves of this plant contain high concentrations of flavonoids, chlorogenic, coffee acids, selenium, vitamins, minerals in, which gives it strong antioxidant properties. It is shown that Yacon root tubers have a high content of sugars, most of which are fructosans （over 60%）. Most of the fructosans and sugars are in root tubers grown in the Kyiv region. The amount of HCA based on chlorogenic acid is up to 4.5% DW in the tops of Yacon leaves in the Poltava region. Its content is the largest in root tubers （2.3%） of plants grown in Kyiv region （stem reproduction）. The biochemical composition of different parts of Yacon has proved that it is promising for the diverse and healthy nutrition of astronauts for their life support in long-term space missions.