***Going on a date with Mars

Exploring Mars is not an easy task, but humankind’s enthusiasm for exploring Mars has never extinguished. Wu Weiren, chief designer of China's lunar exploration project, revealed that in 2020, our country will launch a probe to orbit, land and patrol Mars. Zhang Rongqiao, chief designer of China's Mars exploration mission, said that the first Mars exploration mission achieved "orbiting, landing and patrolling" in one step, which is unprecedented in the world and is extremely difficult. What magic power does Mars have that attracts humans to enjoy it? What results have humans achieved in exploring Mars? Are humans ready to face the difficult challenges?

Q&A

Do you know about Mars? ?

Mars is one of the eight planets in the solar system and the fourth planet from the inside to the outside. It is a terrestrial planet with a diameter of about 53% of the earth and a mass of 11% of the earth. The inclination of the rotation axis and the rotation period are similar to those of the Earth, and one revolution is about twice the time of the Earth. The orange-red appearance is hematite (iron oxide) on the surface. Mars is basically a desert planet, with sand dunes and gravel all over the surface. The atmosphere dominated by carbon dioxide is thin and cold, with sand and dust suspended in it, and dust storms often occur every year. Compared with the Earth, Mars is less geologically active, and most of its surface landforms were formed during a more active period in ancient times, with dense craters, volcanoes and canyons. Another unique topographic feature is the clear distinction between the northern and southern hemispheres: ancient, cratered highlands in the south and younger plains in the north.

Why do humans love Mars?

Mars is the planet closest to the Earth’s orbit. It is similar to the Earth in many aspects. Mars also has four seasons, and the temperature is lower than that of the Earth. Conditions are second only to Earth. Scientists believe that if there is life and water on Mars, it may be another planet suitable for human habitation, and humans may also immigrate to Mars and open up a new living space. Therefore, since the 1960s, the United States, the Soviet Union, Europe, and Japan have all raced to explore Mars.

Was Mars as habitable as Earth in the past?

During the period from 4.6 billion years ago to 3.7 billion years ago, the surface of Mars was warm and moist, and those on Mars were The landforms that look like they were washed out by water also show that there were a large number of rivers and lakes on the surface of Mars at that time. The latest research also shows that these rivers and lakes are connected through a groundwater system, that is, the water is all connected. These abundant water resources, combined with a dense atmosphere, make Mars as suitable for life as Earth is today. Why did the once warm and humid Mars turn into a desert today after hundreds of millions of years of evolution? One of the very important reasons is the solar wind from the sun. The sun itself has a very high temperature, and the plasma on the surface will break away from the constraints of the sun's gravity like water vapor, forming a high-speed plasma flow. These particles interact with Mars, causing the Martian atmosphere to escape from Mars, forming a stream of particles like a comet tail.

How far are we from Mars?

Discovering new knowledge

Organic matter found on Mars

June 7, 2018 , the National Aeronautics and Space Administration (NASA) held a press conference to announce a new discovery on Mars - the Curiosity Mars rover discovered organic molecules on Mars. In the Gale Crater on Mars where it landed, Curiosity drilled and sampled mudstone sedimentary rocks in four different areas that were gradually formed by the sedimentation of ancient lake bottoms billions of years ago. The samples were analyzed by Curiosity's Sample Analyzer (SAM). The sample analyzer heats a powdered rock sample to more than 500 degrees Celsius and detects the release of small organic molecules, fragments of larger organic molecules. Some of these fragments contain sulfur, which helps them survive Mars' harsh environment - just as sulfur-containing organic matter is more durable on Earth, such as hair, nails and car tires. Organic carbon was also found in the rock samples, with other identifiable molecules including thiophene, benzene, toluene and small carbon chains such as propane or butene.

Humans heard the sound of wind on Mars

On December 7, 2018, NASA announced that the "InSight" unmanned probe captured the sound of wind on Mars. For the first time, humans learned about the sound of Mars through a probe. NASA's Jet Propulsion Laboratory released a piece of about 20 seconds of Martian wind audio sent back by InSight that day, which sounded like a low "rumbling" sound. This was captured by the sensor on the "InSight" on the Ehrlich Plain on December 1. The wind was blowing from northwest to southeast with a wind speed of about 5 to 7 meters per second. This is consistent with the direction of the dust streaks observed in the landing zone from Mars orbit.

There is a large underground lake on Mars

In 2018, a study published in the American "Science" magazine showed that there is a lake about 20 kilometers below the surface of the Mars Antarctic ice sheet. A wide lake of liquid water. Scientists have long considered a stable source of liquid water, such as an underground lake or aquifer, rather than just trace amounts of water, vapor or ice, as key to life. The researchers also found that the temperature of the liquid lake was about minus 68 degrees Celsius.

Why can it remain liquid when it is well below freezing point? Scientists explained that the water may contain metal salts such as magnesium, calcium, and sodium dissolved in Martian rocks. These metal salts act like antifreeze, and combined with the pressure brought by the ice cap, the water The lake remains liquid below freezing point.

There are crater ice layers on Mars

At the end of 2018, the European Space Agency released several photos of Mars crater ice layers taken by the "Mars Express" probe. The brown craters are filled with The thick layer of ice looks like half a coconut filled with white ice cream. These images document the appearance of the Korolev crater in northern Mars. The crater is a well-preserved impact crater. The depressed area of ??the crater looks like it is filled with snow, but it is actually about 1.8 meters thick ice. Due to the "cold trap" phenomenon, that is, the air settles when it encounters cold in the mountain pass, the ice in the mountain pass does not melt all year round, with a total volume of about 2,200 cubic kilometers.

Interesting facts about Mars

1. Who discovered Mars

It is impossible to say who first discovered Mars, because for thousands of years , humans can see this planet with the naked eye. In 1609, Italian astronomer Galileo Galilei used a primitive telescope to observe Mars and became the "father of observational astronomy". In 1659, Dutch astronomer Christian Huygens used a more advanced telescope to observe and map Mars.

2. It will snow on Mars

It will snow on Mars just like Earth. NASA researchers observed this phenomenon at the South Pole of Mars, but it was dry ice, or solid carbon dioxide. This is also the only dry ice phenomenon observed so far in the entire solar system.

Researchers published a report in the "Journal of Geophysical Research" that they used relevant instruments on the Mars Reconnaissance Orbiter to observe the dry ice clouds in the South Pole of Mars and obtained information including temperature and dry ice particle size. and concentration data. After conducting analysis, the researchers found that dry ice falls in that area during the winter.

Dry ice needs to be formed at about minus 125 degrees Celsius, which is much lower than the temperature at which water freezes. Researchers said this shows that although the Martian environment has many similarities with the Earth, there are still big differences between the two. In 2008, space agency researchers observed real snow in the northern part of Mars, that is, ice and snow made of frozen water.

3. Mars has the largest mountain in the solar system

We all know that the highest mountain on Earth is Mount Everest, with an altitude of approximately 8844.43 meters. However, the highest mountain on Mars is Olin. Mount Olympus is 21,171 meters above the base level of Mars, more than twice as high as Mount Everest. Even if Mount Olympus were placed in the Mariana Trench, the deepest place on earth, it would still be exposed to more than 10,000 meters above sea level. Much higher than Mount Everest.

Olympus Mons is a shield volcano on Mars. It is the largest volcano known in the solar system, covering an area of ??300,000 square kilometers. The height difference from the foot of the mountain to the top of the mountain is 21.9 kilometers, which is equivalent to that of the Earth. The tallest mountain from base to summit is more than twice the size of Mauna Kea. If Olympus is compared to the plains 1,000 kilometers northwest of it, the mountain is nearly 27,000 meters higher.

4. You will feel thinner on Mars

If humans set foot on Mars, they will feel lighter. Mars is smaller than Earth and has less gravity than Earth, so you will experience gravity levels that are 62.5% smaller than on Earth. In other words, if you weigh 100 kilograms on Earth, you will only weigh 38 kilograms on Mars.

5. A year on Mars

A Martian year is equivalent to 687 Earth days, although a Martian day is only 40 minutes longer than an Earth day.

6. Another Mars Approach

In 2003, Mars reached the closest position to the Earth in the past 60,000 years - only 56 million kilometers away. According to NASA, we will have to wait until 2287 to see Mars so close again.

7. Ice Age

Radar detection pictures show that the current appearance of Mars was gradually formed after the end of an ice age 400,000 years ago.

8. Signs of life

In 2014, the Curiosity rover discovered methane bubbles. NASA scientists said that this discovery may indicate "evidence of ancient methane being sealed, which may mean the existence of ancient life."

A brief history of human exploration of Mars

So far, mankind has launched more than 40 probes to Mars, more than 60% of which failed and sank, while the successful ones are Humans have shown a strange and colorful picture of Mars.

In November 1962, the Soviet Union launched the "Mars 1" probe, which lost contact with the ground when it flew 100 million kilometers away from the earth, and has been missing ever since. It is seen as the beginning of human exploration of Mars.

In November 1964, the United States launched the "Mariner 4" spacecraft to Mars.

On July 15, 1965, "Mariner 4" flew close to Mars and took 21 photos from a distance of 10,000 kilometers from Mars. It was discovered that there are a large number of craters on Mars. The density of the Martian atmosphere is only 1% of that of the Earth. There is no melting on Mars. Iron cores also have no magnetic field.

In 1969, the American "Mariner 5" and "Mariner 6" spacecraft passed by Mars again. The more than 200 photos they took showed that the temperature on the surface of Mars is lower than expected. The carbon dioxide content in the Martian atmosphere is as high as 95%, and water vapor is almost difficult to find. That year, the U.S. Mariner 7 probe sent back 126 photos.

In May 1971, the Soviet Union launched the "Mars 3" probe. In December, the lander it launched lost contact with the Earth 22 seconds after it started taking photos and scans due to encountering a Martian dust storm.

In 1972, the American "Mariner 9" spacecraft flew along the outer space orbit of Mars and became the first artificial satellite of Mars, conducting long-term investigations around the Mars orbit. "Mariner 9" successfully photographed the entire landscape of Mars and sent back 7,329 photos, confirming that there are no canals on Mars. There are many ringed mountains on one hemisphere of Mars, which looks like the moon, while the other hemisphere is relatively flat.

In August 1975, the US "Viking 1" took off. The lander it released in July of the following year successfully landed on the surface of Mars and sent back color photos to the ground. The two worked together until the early 1980s.

In December 1996, the US "Mars Pathfinder" was launched. In July of the following year, the lander it carried successfully landed on Mars, and launched the "Sojourner" rover to conduct a roaming survey and discover ancient water traces.

In July 1998, Japan's "Kibo" probe flew to Mars, but malfunctions continued since then. In December 2003, Japan announced that the Mars exploration mission had failed.

In April 2001, the United States launched the "Odyssey" probe. The following year, the probe discovered that the surface of Mars may be rich in frozen water. The Russian high-energy neutron detector it carries is also trying to find water and detect neutron flows on the surface of Mars.

In 2003, the US "Spirit" and "Opportunity" Mars rovers were launched in June and July respectively. They all successfully landed on Mars and carried out seven or eight years of roaming investigation of Martian rocks and landforms. "Opportunity" landed on the surface of Mars at noon on January 25, 2004 (Beijing time). "Opportunity" and "Spirit" are twin brothers, affectionately called robot "geologists" by scientists. In 2010, "Spirit" lost contact with the Earth after six years of service, leaving only "Opportunity" on the surface of Mars.

In June 2003, the European Space Agency's "Mars Express" probe was launched. In December, its Beagle 2 lander was unable to contact Earth after landing on Mars. On January 23, 2004, the "Mars Express" probe discovered the existence of frozen water at the south pole of Mars. This frozen water was partially exposed on the surface of Mars and was not fully covered by dry ice formed by the solidification of carbon dioxide. This is the first time humans have discovered water directly on the surface of Mars.

On January 3, 2004, the American "Spirit" Mars rover successfully landed on the surface of Mars. A few hours after the successful landing, the probe sent back more than 10 high-definition pictures from near the landing area, making a good start for the detection work.

In August 2005, the US "Mars Reconnaissance Orbiter" was launched. The number of detectors it carried, its detection accuracy and data transmission capabilities all set historical records at the time.

In August 2007, the American "Phoenix" probe set off and landed at the North Pole of Mars in May of the following year. Two months after the probe's inspection, scientists confirmed that the "Phoenix" found water vapor when heating Martian soil samples, finding evidence that there is water on Mars. On November 10, 2008, NASA announced that the Phoenix Mars probe had lost contact and its more than five months of Mars exploration had come to an end.

On November 9, 2011, China's first "Yinghuo-1" probe was launched together with Russia's "Forbes-Soil" probe, and will separately go to Mars and Phobos for exploration and investigation. However, an accident occurred during the flight and they failed to change orbit as planned.

On November 26, 2011, the American "Curiosity" Mars rover was launched. On August 6, 2012, the "Curiosity" rover landed on the surface of Mars. It will explore whether there is an environment suitable for life on Mars in the past or present. This is the most sophisticated mobile science laboratory that humans have ever landed on other planets.

On November 5, 2013, India's first Mars probe "Mangalyan" was launched. On September 24, 2014, the "Mangalian" successfully entered Mars orbit. It is currently operating normally about 500 kilometers from the surface of Mars.

On March 14, 2016, the "Mars Biology-2016" jointly developed by Russia and the European Space Agency was successfully launched. The spacecraft was mainly used to detect the methane content in the Martian atmosphere and verify Mars landing. technology.

On May 5, 2018, the National Aeronautics and Space Administration (NASA) launched the unmanned probe "InSight", once again challenging the red planet.

After more than six months and a voyage of about 482 million kilometers, the "Insight" unmanned probe successfully arrived at the Mars landing site in the early morning of November 27, 2018, Beijing time, and successfully sent back its first photo, starting the first exploration in history. Exploration mission into the interior of Mars.

Space agencies of various countries are also preparing multiple plans to land on Mars. Around 2020, the United States plans to launch the next-generation Mars rover "Mars 2020"; Europe and Russia plan to jointly launch the "Mars Biology-2020" Mars rover; China plans to launch a Mars probe for the first time and implement its first Mars exploration mission.