Fire. Star. Snow

Xinhua News: Scientists from NASA announced on the 2nd that the Mars rover "Opportunity" has found evidence that liquid water once existed on Mars. Therefore, I think it should exist. Since January, two American Mars rovers have landed on Mars, and they have been searching for traces of life on the planet. Experts say that "Opportunity" has found evidence related to the main purpose of Mars exploration, namely that liquid water once existed on Mars. According to the analysis of data on rock layers and other mineral conditions detected by the rover, scientists have found signs of water saturation on the surface of some rock layers in the area explored by the rover. These findings support the conclusion that when these rock layers were formed, the environment on Mars might have been suitable for the existence and reproduction of organic organisms. Professor Hitoshi Mizutani of the Japan Aerospace Exploration Agency believes that Venus also had water in the past, but because it is too close to the Sun and the high concentration of carbon dioxide in its atmosphere caused a greenhouse effect, the surface temperature of Venus became extremely high. As a result, all the water evaporated and disappeared into the vast universe, whereas the disappearance of water on Mars seems to be different from that on Venus. Professor Mizutani said that the destruction of the magnetic field played a significant role in the disappearance of water on Mars. On Earth, where humans live, the magnetic field acts like a shield, blocking high-energy particles from the Sun and preventing solar storms from directly reaching the atmosphere and surface. Although Mars still has a strong magnetic field today, it is no longer on the scale of Earth's. The Martian magnetic field was gradually destroyed about 3 billion years ago as the planet's interior cooled and solidified, making Mars incapable of avoiding the full brunt of solar storms. As a result, water vapor in the atmosphere was decomposed into hydrogen and oxygen and disappeared into the vast universe. In addition, Mars is only half the size of Earth, with gravity only about 40% of Earth's, making its ability to retain an atmosphere relatively weak, which also affected the disappearance of water to some extent. The former Soviet Union's Phobos 2 probe also found that a large amount of oxygen is still escaping into space from one side of Mars during its nighttime. Based on relevant data, scientists speculate that Mars' atmospheric pressure in the past was nearly three times that of Earth's current atmospheric pressure, but now it is only one-fiftieth of Earth's. Under such circumstances, if a small amount of water flows on the Martian surface, it will instantly vaporize. Perhaps not all water on Mars has disappeared into the universe.Associate Professor Yutaka Abe of the University of Tokyo said that as the amount of water and carbon dioxide in the atmosphere decreases, the greenhouse effect weakens, Mars gradually cools, and the water in the atmosphere falls to the surface after freezing. Therefore, the water on Mars may be hidden underground like glaciers.

New studies of the Martian polar caps by the U.S. Mars Global Surveyor and the Mars Odyssey spacecraft indicate that the Martian polar caps are almost entirely composed of ordinary frozen water, and there is very little dry ice (solid carbon dioxide).

Observations by the Viking spacecraft showed that beneath the dry ice layer of the Martian north polar cap, there is ordinary water ice. New photos of the Martian polar caps taken by the Mars Global Surveyor and Mars Odyssey at high resolution and in different spectral bands overturn the "dry ice" theory. Infrared photos of the polar regions show that the melting and freezing processes occurring on the Martian poles are fully consistent with the properties of water. These conclusions were drawn after carefully studying photos of flat circular crater areas with ice 8 meters deep and diameters ranging from 200 to 1000 meters. The top layer of ice there is indeed dry ice, but ordinary water ice exists at the bottom. Therefore, the composition of the Martian south polar cap is similar to that of the north polar cap. Each Martian summer, the north polar cap loses about 1 meter of dry ice layer through sublimation. In fact, the only difference between the Martian north and south poles is that the south polar cap's dry ice layer is about 8 meters thick, and during the entire summer, the dry ice layer does not have time to completely sublimate.