Earth's "sister star" Mars archives
Mars is the fourth closest planet to the sun, located between the earth and the moon, with an average equatorial radius of 3398km, which is about 1/2 of the earth and twice that of the moon. The orbit of Mars is obviously elliptical, and its period of revolution is 687 days, which is about 2 Earth years.
The inclination angle of Mars' axis and orbital eccentricity will change periodically. The change period from the shaft inclination angle is1.2000 years, and the change range is 14.9-35.3 (now 25). The variation period of eccentricity is about 2 million years, and the variation range is 0.004-0. 14 1 (.
Among the eight planets in the solar system, their physical and chemical properties are closest to those of the Earth. Mars has many kinds of landforms, such as mountains, plains and canyons. The south is full of highlands and canyons hit by meteorites, while the north is mostly plains full of lava. Because the axis inclination and rotation period are close to those of the earth, the length of day and night and the seasonal variation of Mars are almost the same as those of the earth.
Mars: Earth's Past or Future?
Mars exploration has achieved the most abundant results, especially the discovery of water, which greatly stimulated people's enthusiasm for finding life on Mars. Whether there are conditions for life on Mars and whether Mars is the past or the future of the earth have become major scientific issues in the study of Mars. Studying Mars is of great comparative significance for understanding the evolution of the earth.
At the same time, based on the existing space capabilities, the flight time can reach 8- 10 months, and the mission cycle is more suitable than more distant planets and satellites; Mars has the closest environment to the earth, which makes it possible for robots or humans to live on Mars. Therefore, after manned landing on the moon, Mars became the first choice for human beings to land on the planet.
Compared with lunar exploration, the task of Mars exploration is more arduous. Because Mars is far away from the earth, it puts forward high requirements for launch, orbit, control, communication, power supply and other technologies. Considering the risk, cost and other factors, the best route for the Earth spacecraft to Mars is the "Homan orbit" proposed by 1925. Because the orbit can only appear once every 26 months, and the latest "Homan orbit" was formed in the summer of 2020, the recent Mars exploration plans of all countries are concentrated in this time period.
The "Three Steps" to Mars!
Since 1996, almost every launch window has been launched by a Mars probe. According to the technical level and mission content, human exploration of Mars can be roughly divided into three stages.
The first stage: overflight detection in the initial stage of the study (1960- 1970).
At present, the exploration of international radiosonde is still in the primary stage of research. Relevant countries mainly focus on flying over Mars, transmitting pictures of Mars and detecting atmospheric parameters, but the success rate of the exploration mission is not high, and only one case has successfully completed the mission. 1962, the former Soviet Union launched the "Mars 1A" probe, which was considered as the starting point of international Mars exploration, but the probe lost contact with the ground on the way to Mars and eventually failed. Since then, Mars exploration missions such as "Mars 1" in the former Soviet Union and "Mariner 3" in the United States have also failed one after another. Until 1965, mariner 4 of the United States finally completed its first overflight of Mars, becoming the first artificial satellite to successfully explore Mars. By the middle and late 1960s, the enthusiasm of the United States and the former Soviet Union for Mars exploration had weakened, and they concentrated on Venus exploration.
The second stage: a preliminary understanding of the surface of Mars (1970- 1990)
In the early 1970s, the United States and the Soviet Union resumed Mars exploration activities, focusing on orbiting and landing. The main tasks include transmitting images, detecting the atmosphere, magnetic field and surface temperature.
At this stage, the success rate of the exploration mission was significantly improved, and many probes, including Mariner 6, successfully completed the mission, especially the Mars 3 probe launched by the former Soviet Union 197 1 successfully landed on Mars, becoming the first Mars lander. 1972, American mariner 9 arrived on Mars, becoming the first artificial satellite on Mars. In the late Cold War, the United States and the Soviet Union reduced their investment in deep space exploration. Only the former Soviet Union launched two Mars satellite probes, both of which failed. The main direction of Mars exploration has changed from launch detector to study the data obtained from previous launches.
The third stage: exploring the signs of life on Mars (1990- present)
After the Cold War, Mars exploration has once again become the focus of deep space exploration. Many countries and regions, led by the United States, carry out Mars exploration activities, mainly landing exploration, with the main goal of finding evidence and signs of life in Martian water. During this period, * * launched Mars Express, Spirit, Opportunity, Curiosity and other probes, and successfully found evidence of water on Mars.