Some people say that Venus’ past and Mars’ future are Earth’s present. How should humanity respond in the future?

I often hear that the past of Venus and the future of Mars are the present of Earth. Is there any basis for this statement? Let's discuss it together.

What was Venus like in the past and now?

There is a view that Venus had a suitable temperature, water, oceans and a suitable atmosphere in ancient times, but unfortunately, no life evolved. In other words, no signs of life have been found on Venus so far.

In the early days of the solar system, the temperature was not as high as it is now, and the planets were not as far away from the sun as they are now. Therefore, 4 billion years ago, Venus belonged to the so-called "habitable zone", which means that the temperature is suitable for the existence of liquid water. Water is the cradle of life, but the existence of water does not necessarily mean the existence of life.

As the temperature of the sun rose, the temperature of Venus became higher and higher. Two billion years ago, the liquid water on Venus evaporated completely, and it became a dry planet. As greenhouse gases increased, the temperature of the sun radiating to the surface could not be reflected back into space, and the temperature of Venus became higher and higher, and it became what it is today.

Venus is now surrounded by a thick atmosphere, with a concentration 90 times that of the Earth, which means that the surface atmospheric pressure is 90 times that of the Earth. The atmosphere is mainly composed of greenhouse gas carbon dioxide, which is like a thick quilt that wraps Venus and prevents the heat of Venus from dissipating into space. As a result, the surface temperature reaches 470°C.

The dense carbon dioxide clouds produced a large amount of sulfuric acid, which was like a torrential rain, and all that fell to the ground was concentrated sulfuric acid. In this way, the surface of Venus became a legendary hell, where life could not be nurtured or survived at all.

However, a study believes that the spectral characteristics of phosphine have been observed in the atmosphere of Venus. This compound is generally considered to be a metabolite of life, which has led some people to believe that there may be life on Venus. This research result was made by Professor Jane Greaves of Cardiff University in the UK and her colleagues, and was published in the journal Nature Astronomy on September 14, 2020.

Many scientists believe that phosphine is a "fingerprint of life". This highly toxic, flammable and extremely smelly gas is usually only produced by microorganisms on Earth, such as anaerobic bacteria. It is difficult to produce through geological or atmospheric effects. In addition, phosphine molecules are extremely unstable and need to be produced continuously to maintain their existence. Since this component is present in the atmosphere of Venus, it is not groundless for people to suspect that there is some form of life there.

Even if there is life on Venus, it cannot be advanced intelligent life such as "Venusians", but may be just some microorganisms. However, many scientists have expressed doubts about this study, believing that there is not enough evidence to show that there is a considerable amount of phosphine there, so the possibility of life on Venus is just one person's opinion and cannot be concluded.

What is the past and future of Mars?

People who hold this view believe that as the temperature of the sun rises, the temperature of the earth will become higher and higher, the sea water will evaporate, and the earth will become dry. As a result, the habitable zone of the solar system will gradually move outward, and Mars will become a place with a suitable temperature, just like the earth today. In fact, this is not the case. Rather than saying that Mars is like the earth, it is better to say that Mars was once like Venus in ancient times, which is more like the earth.

Research on the detection data sent back by numerous rovers and probes launched by NASA to Mars shows that there is already relatively conclusive evidence that there was a large amount of liquid water on the surface of Mars 4 billion years ago. This water formed oceans and lakes covering the entire planet of Mars, with a depth of 100 to 1,500 meters.

But this rippling blue water situation only lasted about 1 billion years, and Mars became a dry planet. So where did all the water go? In the past, scientists believed that due to the thin atmosphere of Mars and the lack of geomagnetic protection, the water on Mars evaporated and sublimated under the blowing of solar wind and escaped into space.

But a new study believes that the previous explanation can only explain that some water did escape from Mars, but cannot explain the disappearance of most of the water. In fact, 30% to 99% of the water on Mars is sealed in the minerals of the crust and has not been released. This study was published in the journal Science on March 16, 2021, and was conducted by the Jet Propulsion Laboratory of the California Institute of Technology. The first author of the paper is Eva Scheller of the California Institute of Technology.

Water interacts with rocks and forms clay and other water-containing minerals through weathering, thus forming a mineral structure containing water. In this respect, Mars and Earth should be similar. However, due to the strong plate movement on Earth, the water that enters the crust will be released again through plate movement, volcanic eruptions, etc., forming a large cycle; while most of the geology of Mars is inactive, and it is difficult for water that enters the crust to be released again. Once the surface dries up, it becomes a permanent phenomenon.

One of the evidences for this theory is that there is not enough "deuterium" in the atmosphere of Mars. Water is composed of hydrogen and oxygen, and most of the hydrogen atoms are "protium", one of the isotopes of hydrogen, and only about 0.02% are "deuterium". The nucleus of protium has only one proton and no neutrons, while the nucleus of deuterium has one proton and one neutron, so deuterium is heavier than protium, which is the so-called "heavy hydrogen".

When water sublimates and escapes, the lighter "hydrogen" is more likely to escape the planet's gravity and enter space, so after escaping, it will leave an excessive amount of "deuterium" in the upper atmosphere of a planet, which is called the "deuterium" mark. The study did not find this "deuterium" mark in the Martian atmosphere, so the study believes that the loss of water on Mars is the result of a combination of two mechanisms: absorption by crustal minerals and loss in the atmosphere. Only in this way can the "deuterium" content observed in the Martian atmosphere be explained.

Since most of the water is still preserved in the Martian crust, will Mars become a habitable place with beautiful weather and rippling blue water in the future? It is difficult. The presence of water on Mars only provides a condition for the formation of surface water in the future, but it is difficult and far away in the natural state.

The main reason is that Mars has no geomagnetic field and dense atmosphere, so it is impossible for the temperature to dissolve the underground water ice in the short term under natural conditions. However, humans are planning to transform Mars: in the next few hundred years, by creating greenhouse gases there, raising the temperature of Mars, and dissolving the underground frozen water; then, seeds that have been genetically modified to adapt to the Martian environment will be spread on Mars to form forests and grasslands, and oxygen will be produced by plants, transforming the Martian atmosphere into an ideal atmosphere.

This plan seems to be just a fantasy, but the ambitious Musk's 120-meter-high large starship has been successfully tested, and it has completely changed the past mode of launching spacecraft with a carrier rocket. The starship can take off directly from the earth and land directly on Mars. Musk is planning to build 1,000 such starships to gradually send humans to Mars. In the next few decades, the number of humans sent to Mars will reach 1 million. Can this dream plan be realized? Young people can wait and see.

What is the future of the Earth?

The Earth is currently the only home for mankind. Many people are puzzled by scientists' obsession with exploring and developing Mars, believing that mankind already has such a good home on Earth, and that transforming the deserts on Earth is far less expensive than developing Mars. Therefore, those self-righteous scientists, entrepreneurs, and politicians who spend huge amounts of money on Mars are simply putting on a show, wasting human wealth, and having nothing better to do.

This statement may be agreed by most people, because there are very few people in this world who have foresight and basic scientific literacy. Those who are working hard and spending huge amounts of money to explore and develop Mars may seem foolish, but in fact they are smarter than anyone else and are pioneers of human beings who dare to sacrifice themselves. They think of things that ordinary people will think of 100 or even 1,000 years later.

But by that time, it was too late. Don't look at the thousands of years of recorded human history. Although humans have killed many people, nature has generally been good, which has nurtured and raised more and more humans. But this is a kind of luck and fluke. In fact, the earth is a very fragile planet.

If the sun gets a little angry, if a large asteroid hits the earth, humanity will probably be finished. Moreover, the environmental problems caused by the modern way of life are getting worse, and the climate change caused by greenhouse gases is getting worse. If it is not curbed, it is likely to cause a mass extinction disaster by the end of this century.

These problems are always hitting those scientists, politicians, and entrepreneurs who have a "worrying about the future" complex. They worry that if all the eggs of mankind are placed in one basket on Earth, it will be easy for all of them to be broken. Only by finding another home quickly can the danger of human extinction be avoided. This is the most important reason why they continue to explore and develop Mars.

Even if it is not destroyed by natural disasters, the Earth will eventually become uninhabitable, and all humans will eventually have to move out of the Earth and find a new habitat. Developing Mars and exploring the universe is to prepare for this day.

Now human aerospace technology is just in its infancy, and it is just a dream for human aircraft to fly out of the solar system. Future interstellar immigrants must fly out of the solar system. Therefore, it is necessary to constantly solve the energy and speed bottlenecks of long-distance spaceflight and solve the problem of ensuring long-term survival of mankind in space.

Aerospace is a manifestation of comprehensive scientific and technological strength. Only through long-term gradual development and improvement can it move from low-level to high-level. If you don't work hard now, you will regret it in the future. Why don't many people understand this truth?

Therefore, no matter whether Venus and Mars are the past and future of the Earth, there is no need to worry more about it. Development is the hard truth, and leaving the Earth and colonizing other planets is a goal that must be pursued for human survival.

What do you think? Welcome to discuss, thanks for reading.

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