It's urgent Information about life on mars.

Mars is one of the nine planets in the solar system. According to the order from near to far from the sun, Mars ranks fourth after the Earth. Its average diameter is 6790 kilometers, which is about half the diameter of the earth. Its density is also smaller than that of the earth, which is 3.933 g/cm3 (the earth is 5.52 g/cm3). The average distance between Mars and the sun is 228 million kilometers, and a circle around the sun is equivalent to about 687 days on earth. A day on Mars is equivalent to 24 hours, 37 minutes and 22.6 seconds on Earth, which is slightly longer than a day on Earth. Mars has two small satellites: Phobos and Phobos. Like the earth, the rotation axis of Mars is also inclined, and because it also has an atmosphere, it also has four seasons like the earth. The average temperature on the surface of Mars is minus 23 degrees Celsius. Mars has no detectable magnetic field, and with its low density, it can be concluded that it has no large metal core. Mars has a thin atmosphere, and its surface atmospheric pressure is 7.5 millibar, which is equivalent to the atmospheric pressure at a height of 30 ~ 40 kilometers on the earth. The main component of the Martian atmosphere (about 95%) is carbon dioxide, including about 3% nitrogen, 1 ~ 2% argon, plus about 0. 1% carbon monoxide and oxygen, and a very small amount of ozone and hydrogen. The amount of water vapor is very small, which varies with seasons and places, accounting for about 0.0 1% of the total atmospheric volume on average. If all the water in the Martian atmosphere condenses, only a water film with a thickness of 0.0 1% mm can be formed, covering the entire surface of Mars. Similar to the earth, there are clouds floating in the Martian atmosphere, but unlike the earth, the main components of clouds in the Martian atmosphere are carbon dioxide and water. In winter in the polar regions of Mars, the atmospheric temperature is lower than the freezing point of carbon dioxide, thus forming dense fog-like dry ice clouds covering the polar regions. It has been confirmed that there is also ice in polar clouds. In winter in mid-latitude areas, the temperature is also below freezing point, and water vapor condenses to form ice cloud.

Due to the large eccentricity of the orbit of Mars, the distance between the near and far days of Mars is 42 million kilometers. This has greatly changed the distance between Mars and the Earth. The distance between Mars and the Earth is related to the month when the sun is washed. The minimum distance is at the end of August, and the impact around this time is called perihelion impact or big impact. At this time, the distance between Mars and the Earth is only about 56 million kilometers. The period of revolution of Mars takes about 687 days, and it takes 780 days (at least 764 days and at most 806 days) for the Earth to collide with Mars. In this way, the collision point makes a circle in the orbit about 16 years. That is to say, Mars impacts occur about once every 15 years or 17 years. The last big impact on Mars occurred in July 1986. This year, Mars blocked the sun at 2 o'clock on August 29th, Beijing time, and the closest moment between Mars and the Earth was at August 27th 18. By then, Mars will be 55,758,005 kilometers away from the Earth, the latest time in more than 50,000 years.

Geomorphology of Mars

In the telescope, Mars presents a bright and fuzzy red round surface. The most striking thing is that the size of the white polar cap covering the polar regions changes with the seasons of Mars. In a larger telescope, at least hundreds of kilometers of linear bright or dark areas can be observed: bright and orange areas are called "continents", accounting for almost five-sixths of the total area of Mars; Dark areas are called "oceans" and their colors often change with the seasons.

There are striking differences between the northern and southern hemispheres of Mars. As far as the geological history of Mars is concerned, the southern half is relatively old, with rugged surface and dense craters. It is estimated that most of these craters were formed in the early history of Mars (probably the first billion years); The northern half is characterized by a large volcanic lava plain, which is very similar to the "sea" on the moon, and there are some extinct volcanoes. The terrain in the northern half is generally lower than that in the southern half, and there are many fewer craters than in the southern half. The height difference of the surface of Mars is generally about 5 ~ 10 km. The desert part of Mars is covered with red silicate, hematite and other iron oxides and other metal compounds, so it is bright orange-red. These covers are all young materials, which may have originated from volcanoes or weathering.

The geographical features of the surface of Mars mainly include craters and volcanoes. Compared with the surface of the moon, the number of craters on Mars is much less, and the edges of craters are gentle (the slopes are all less than 10), unlike the craters on the surface of the moon, which can cast sharp shadows, indicating that craters have been seriously eroded. There are two kinds of craters: volcanic craters and craters formed by meteorite impact. By the standards of the earth's surface, many surface structures on the surface of Mars are huge. For example, the giant shield volcano on Mars is much bigger than that on Earth. On earth, Mauna Loa volcano and Monaque Ya volcano have a combined diameter of about 200 kilometers, which is 9 kilometers higher than the seabed, while the largest Olympus volcano on Mars has a diameter of about 550 kilometers, which is 27 kilometers higher than the surrounding ground. There are also large volcanoes like this, which are located in the 2000km-long Tasis Highland, which is10km higher than the surrounding northern hemisphere plain. The shield volcano of Mars is similar in shape and structure to that of Hawaii. These craters used to be the outlet of lava. Lava flows down the side of the volcano, forming a radial terrain extending from the center in all directions. Many volcanoes with a diameter of about 100 km are in different preservation States, scattered on the surface of Mars, and most of them are located in the northern hemisphere. As for the crater formed by meteorite impact, the largest crater is Heiners Basin, with a width of1600km and a depth of at least 4km. In some parts of the southern hemisphere, the density of craters is similar to that of the bright highland ring mountains on the moon, and it is speculated that they were formed at the same time, ranging from 4 billion to 4.5 billion years. These areas still retain the ancient surface. Due to the continuous coverage of lava flows in most parts of the northern hemisphere, the ancient surface no longer exists. Several craters on the plain are records of meteorite impacts after the formation of the plain.

The most striking feature on the surface of Mars is the huge canyon in the equatorial region. The largest is Mariner Valley, which is located south of the equator. It is actually a series of canyons, extending more than 4000 kilometers in the equatorial region, 6 kilometers lower than the surrounding ground. Canyon walls are usually very steep, with obvious boundaries, and show signs of collapse and landslide activity. Some intricate canyons may be formed during the melting and evaporation of underground ice, or may be caused by wind or water erosion. The origin of the Grand Canyon is still unknown.

Today, Mars is a desolate world. There is no liquid water on the surface, but there are some wide and curved riverbeds on the surface of Mars. These riverbeds are completely different from the sensational "canal". These dry river beds are about 1 1,500 km long and more than 60 km wide. The main river beds are distributed in the equatorial region. Satellite images show that the large river bed and its tributary system are combined to form a well-defined waterway system. At the same time, it has teardrop-shaped islands, sandbars and woven patterns. Almost all the tributaries flow downstream. These riverbeds are different from the lava riverbeds on the earth and the moon, and must be caused by liquids less viscous than lava flows. This liquid is probably water. Today, the surface temperature of Mars is very low, and most of the water is preserved in the form of underground ice, and some of it is imprisoned in the permanent polar cap. The extremely thin atmosphere makes ice sublimate directly into water vapor when the temperature is high enough. Free-flowing water seems impossible. Some people think that in the early history of Mars, frequent volcanic activities discharged a large number of volcanic gases such as ammonia and methane, and this thick primitive atmosphere would have a strong greenhouse effect, thus warming the surface of Mars and creating conditions for river flow. Later, volcanic activity decreased, volcanic gas gradually decomposed, light element atoms escaped to interstellar space, and heavy element atoms combined with other components, making the atmosphere of Mars thin, dry and cold, and the surface of Mars became what it is now. Some people think that in the early history of Mars, the inclination of the rotation axis was larger than it is now, so the polar caps of the two poles melted, a large amount of carbon dioxide entered the atmosphere, and a large amount of water evaporated and condensed into raindrops and landed in the equatorial region, forming rivers. As for some large river beds, it is estimated that volcanic activity and geothermal energy melted the underground ice, and a large amount of water washed the surface of Mars. In addition, there are many gullies obviously washed by water, which seems to prove that there was water on Mars at least before.

The climate of Mars

The average temperature on the surface of Mars is more than 30 degrees Celsius lower than that on Earth. The thin and dry atmosphere of Mars makes the temperature difference between day and night on its surface often exceed 100 degrees Celsius, which is much larger than that on the earth. Near the equator of Mars, the highest temperature can reach about 20 degrees Celsius (about one hour in the afternoon). At night, due to the poor thermal insulation of the Martian atmosphere, the surface temperature drops rapidly, and the lowest temperature (before dawn) is below MINUS 80 degrees Celsius. The temperature in the polar regions of Mars is even lower. In the long polar nights, the minimum temperature can drop to minus 139 degrees Celsius.

Clouds stretching for hundreds of kilometers can often be observed near some large shield volcanoes. It is estimated that this is because the airflow in the Martian atmosphere is disturbed, rising when it meets the towering crater terrain, and cooling when it expands, forming a solidified cloud. These clouds all appear when the water vapor in the atmosphere increases in summer. Sandstorm is a unique phenomenon in the atmosphere of Mars, and its shape is like a yellow "cloud". It is composed of wind with dust particles in the lower atmosphere of Mars. Large sandstorms can be observed with large telescopes on the ground. Local dust storms often occur on Mars. Because the atmospheric density of Mars is less than 1% of that of the earth, the wind speed must be greater than 40-50 meters per second to move the dust particles on the surface, but once it is blown up, even if the wind speed is very small, it can carry the dust particles to the high altitude. In a typical sandstorm, the diameter of most dust particles is estimated to be about 10 micron. The smallest dust particles will be carried to an altitude of 50 kilometers by the wind. Most large dust storms occur in late spring in the southern hemisphere, when Mars is close to perihelion. The origin of sandstorm lies in the latitude line of direct sunlight, which often occurs in the Noachis area hundreds of kilometers west of Heines Basin. The central dust cloud spread slowly in the first few days, and then spread rapidly, covering the southern hemisphere completely in a few weeks. Particularly large sandstorms can also spread to the northern hemisphere, thus covering the whole earth. The cause of sandstorm seems to be related to the thermal effect of the sun. When Mars passes the perihelion, the heating effect of the sun is great, which causes the instability of atmospheric temperature, thus causing the initial disturbance of raising dust. However, once the dust particles reach the air and absorb more solar energy, the air filled with dust particles will be hotter than the surrounding atmosphere, thus rising rapidly. The air from other places rushed to fill the original position, causing stronger ground wind and forming a bigger sandstorm. The scope and intensity of sandstorms are increasing. When the sandstorm finally spread to the whole area of Mars, the temperature difference on Mars decreased, the wind gradually subsided, and dust particles slowly settled down from the atmosphere. The settlement process takes at least a few weeks, and it can last for several months when the sandstorm is fierce. This kind of large-scale sandstorm happens almost every Mars year. There are often sandstorms on Mars.

Mars exploration

Humans have known about Mars for a long time, and many people even believe that there are rivers and forests on Mars. This is not only because Mars is close to the earth, but also because it is very close to the earth from the angle of axial inclination, which dominates the seasonal variation. Although one year there is equivalent to two years on the earth, one day is similar to the earth. In the past, people found many criss-crossing shadows on Mars through simple telescopes, and thought it was a canal dug by intelligent creatures. As a result, the mystery of Mars has increased, and human expectations for it have also increased.

From June 1962 to June/1,the former Soviet Union launched a series of Mars probes, and from June 1964 to June 1977, the United States launched two series of probes, Mariner and Pirate. 1 The true face of Mars Viking1in July and September, 976 is a world as desolate as the moon and full of craters.

Nevertheless, the similarity between the surface of Mars and the earth still makes people want to believe that there was life on Mars. The main reason is that there are signs of water on Mars, which is the source of life. Even if there is no life on Mars, as long as there is water there, human beings will feel more cordial. After all, in the solar system, except Mars, the earth can talk about it, and there is no partner who can help her breed life. To this end, mankind will make unremitting efforts to open up an oasis on Mars. Maybe one day, humans will sit on Mars.