What is the difficult journey to Mars?

At the 20th anniversary of Apollo manned landing on the moon, US President George Bush confidently announced the trilogy of American expedition to Mars: the first step was to build the "Freedom" permanently manned space station in 1990s; The second step is to establish a lunar base for human habitation in the first year of 2 1 0 century; The third step is to start manned flight to Mars from the lunar base in 201year, and land on this red planet from 20 16 to 2020.

Of the nine planets, it is natural that people choose Mars as the first object to visit. Because Mars is a close neighbor of the earth, it is most similar to the earth. Although we haven't found any signs of life on Mars so far, it has enough sunshine, ice water and atmosphere, and it is obviously the most suitable celestial body for human habitation in the solar system.

Scientists have spent a whole generation investigating the secrets of this red planet, and the human and material resources invested are still escalating. In the past 20 years, all space agencies in the United States, Russia, Japan and Europe have been making unremitting efforts and competing to become the first country to land on Mars.

In the past 20 years, scientists all over the world have also accelerated the pace of exploration and research on Mars.

1976, the American Viking successfully landed on the side of Mars, and the era of in-depth exploration of planets began.

On July 20th, "Pirate 1" landed on the west slope of the Kexilishe Basin, where the terrain was undulating and rocks of different sizes were scattered. Viking 2 landed near the edge of the Arctic polar cap, about 4000 miles away from/kloc-0.

The main purpose of the planned Viking probe is to explore whether there is life on the surface of Mars, so a series of instruments for exploring life are installed in the lander. First of all, two TV cameras can shoot high-resolution and low-resolution images in stereoscopic, color, black and infrared modes to observe macro life forms or biological movement phenomena.

The lander is equipped with a mass spectrometer, which can directly sample from the air for sensitive analysis. The analysis results show that the Martian atmosphere is mainly composed of carbon dioxide, and oxygen only accounts for 0.3% ~ 0.4%. There are also three biological laboratories in the lander, which can analyze soil in three different ways. On July 28, the sampling arm of the lander collected the first batch of soil samples from the surface of Mars, and then sent them to the biological instrument for three experiments to observe whether there were primitive life forms of microorganisms or organic substances in the Martian soil.

The result was disappointing. There is no sign of any organic molecules in the first sample. Of course, this non-existence does not rule out the possibility of life on Mars, but only increases the difficulty of analysis. This at least makes it possible for those institutions that have witnessed "Martians" to become charlatans and fall into a rather embarrassing situation.

In order to expand the exploration area, NASA recently developed a Mars exploration program called Purple Bird. The so-called "Purple Bird Project" is to send four unmanned spacecraft to the surface of Mars. The only difference between this spacecraft and the Viking lander is that it is equipped with tracked wheels, looks like a large mobile office, and is equipped with nuclear-powered batteries at a speed of 3-4 kilometers per day. In a Mars year (about two Earth years), traveling thousands of miles can cover tens of thousands of times more distance than Viking.

The scientists who carried out this plan said with confidence: Through the "Purple Bird" plan, Mars will expose its secrets to the people of the earth naked like the moon. They believe that on Mars, it is likely to find lower organisms similar to the Earth or similar, or "Mars-like" lower organisms completely different from the Earth. If we are lucky, we may even find relics or remains of higher organisms.

The American "Mars Observer" is the pioneer of this plan. The $980 million spacecraft began to conduct an unprecedented detailed survey of the planet at a speed of 1 18 minutes per lap, which lasted for 2-6 years.

Water is of great significance for understanding the development of Mars, because as long as there is water, it means that there may have been life forms. M carr, a cosmologist of the American Mars Observation Team, said: "We have found many water erosion phenomena." In the southern hemisphere of Mars, which has a history of 3 billion years, some photos of bifurcated rivers have been taken, which are very similar to the dry riverbed on the earth. Carl said: "It is almost certain that when these rivers are formed, the climate on Mars will be warmer and the atmospheric density will be much higher." Some scientists speculate that there may have been oceans on Mars.

In addition to the smaller bifurcated rivers, there are some signs that floods have occurred in many areas of Mars. Carl said that these beast-like floods seem to have washed out a huge valley 90 miles wide in two or three weeks.

These floods seem to have occurred from time to time in the history of Mars for unknown reasons. However, Karl speculated that the water may be confined under the frozen crust because of great pressure. Once cracks appear or it is hit by a huge meteorite, the water will gush out under high pressure.

If there used to be running water on Mars, where are they now? Some scientists estimate that water may have been blown off the planet, but most scientists, such as Carl, think that it is still on the planet, confined to the surface of the ice or clay layer. One of the tasks of "Observer" and its follow-up flight is to find water to reproduce the historical features of Mars.

Although people may dream of visiting or even living on Mars one day, it is a forbidden area for human beings by the standards of the earth. In summer, the temperature in the equatorial region can reach a satisfactory 68 degrees Fahrenheit at noon, but because the carbon dioxide atmosphere of Mars is very thin, the temperature will drop by more than 200 degrees at night. At the poles of Mars, the average temperature in winter is about minus 220 degrees Fahrenheit. Researchers hope that through the "Mars Observer" and future flight plans, they can better understand the harsh climate of Mars, and may even master the method of forecasting its weather.

Is it harder to land on Mars than on the moon? Of course, and it is not a little difficult, but much more difficult. The average distance between the moon and us is only 380,000 kilometers, but the average distance between Mars and us is 22.8 billion kilometers, and the nearest time is more than 55 million to 654.38 billion kilometers. The gravity on Mars is almost three times that on the moon, and the spacecraft taking off from Mars must be much more powerful than the spacecraft taking off from the moon. The manned spacecraft flying to Mars must weigh hundreds of thousands of tons, and a flight will take 1.5 ~ 3 years. Therefore, it is necessary to reserve much more food, air and water for the spacecraft crew than to explore the moon. If you want to send such a monster into space, you must use the space shuttle to divide the prefabricated parts on the ground into many batches and send them to the space station, where they will be assembled into spacecraft, and then start the rocket and send it to Mars or the moon.

This is only a small part of many difficulties. As for establishing a base on Mars, building an artificial "biosphere", developing Mars travel business, and transforming the atmosphere, soil and climate of Mars, it will probably take several generations or even centuries of efforts to realize Mars immigration and let human beings live freely on another planet.

It is estimated that it will cost about $500 billion to complete the three mission to mars proposed by President Bush, which is a heavy burden for any country. However, if the world continues to advance along the track of peace and development and carries out extensive international cooperation, the pace of mankind's March to Mars will be much faster and the prospects will become more optimistic.