If you’re like most people, Mars isn’t the kind of place you want to live. From its thin atmosphere to its freezing temperatures, it’s an environment that’s incredibly hostile.
But the planet might have once been more like ours — with a thicker atmosphere and oceans of liquid water. In fact, a new study suggests that Mars could have been habitable billions of years ago.
The Origin of Life
The origin of life is a long-standing and controversial topic. There are several different mechanisms that have been proposed, including lightning in the early atmosphere and the consequent production of amino acids that, when combined in long polymer chains, provided the basic constituents of life. Another mechanism is chemical processes at submarine volcanic vents which are thought to have been common in the Archean period (4-2.5 BYA) and would have been shielded from ultraviolet radiation that then existed due to the absence of an ozone layer.
There are many theories as to how life began, but the prevailing scientific hypothesis is that it was a stepwise process. This involves the formation of a habitable planet, the prebiotic synthesis of organic molecules, molecular self-replication, self-assembly, autocatalysis and the emergence of cell membranes.
One of the earliest hypotheses is that simple inorganic molecules such as protons and electrons were able to undergo reactions within the primordial soup. These reactions could have lead to the formation of more complex molecules, which would then be able to replicate themselves and evolve into the molecules we see today.
But other researchers believe that this might not have happened. Instead, simpler molecules that performed a series of reactions better than the larger ones could have developed into proteins or DNA, scenarios known as “metabolism-first” models.
RNA is believed to have been one of these simpler molecules. It was able to store information like DNA and also perform other functions, such as acting as an enzyme and helping to create proteins and DNA.
These RNA molecules then evolved into proteins and DNA, which became the “genes” that we know today. Then they became enclosed in a membrane, which allowed them to grow into cells.
Scientists think the first cells were probably found in pools of water. These pools would have been a good place for life to start because they were easy to access and because they had the right environmental conditions, including the ability to deflect UV rays, which would have been harmful outside of water.
In addition, the first cells might have needed to be able to reproduce and this is why it is believed that the first cells had to be able to copy themselves. This was a crucial part of the origin of life as it allows for genetic material to pass on to the next generation and Darwinian evolution to occur.
The Atmosphere
The atmosphere is one of the most important features of a planet and plays an essential role in the formation of life. It is the barrier that protects life from ultraviolet radiation, and contains gases necessary for the vital processes of cellular respiration and photosynthesis. It also provides water, which is essential for the growth of plants and animals.
The air above Earth consists of five main layers: the troposphere, stratosphere, mesosphere, thermosphere and exosphere. The troposphere is where the air is closest to the surface. The mesosphere is between 50 and 80 km above Earth, and the thermosphere reaches a maximum of around 90 km from Earth’s surface.
Temperature is constant in the lower part of the troposphere (at -60 degC), but increases with altitude in the stratosphere and thermosphere. The stratosphere mainly contains strong zonal winds (east-west) and atmospheric tides, while the thermosphere mainly contains the ozone layer.
In the stratosphere, solar activity causes a large variety of changes to temperature. UV and X-rays from the sun are absorbed by the ozone layer, causing molecules to break apart into atoms. This heating can increase the temperature of the stratosphere to over 30 degC.
On the other hand, the atmosphere on Mars is very thin. The total volume of the Martian atmosphere is only 1% that of Earth’s, and it has a much different composition. It is largely carbon dioxide with some nitrogen and oxygen. This means that the greenhouse effect on Mars is essentially nonexistent, and that the temperature of Mars’ surface would be much colder than it is now.
Despite this difference in climate, the presence of liquid water on the surface has been found by several researchers. This is a unique feature in the Solar System, and it is believed to be an essential element in the formation of life.
Another critical point in the emergence of life on Mars is the occurrence of methane in its atmosphere. This is a gas that is chemically unstable and easily broken down by the sun’s UV radiation, so if methane is present on Mars, it must be replenished constantly.
The Surface
The surface is the part of Earth that people see when they look at a map. It includes land and water and is the part of the planet that we interact with the most. It provides everything needed for life to thrive, including food, shelter, and water.
It also includes a variety of different plants and animals. Some of these animals live on the ground, while others live in the air or in the sea.
Most of the surface of the planet is covered by water. It evaporates into water vapor, forms clouds, precipitates from the clouds to the ground, collects in lakes, flows in rivers, and returns to the sea.
As a result, it is shaped into many different landforms by tectonic activity and erosion. The land on the surface of the planet is made up of rocks and soil. It is a complex system that moves and changes over time as the planet’s crust shifts.
Our understanding of how the planet is shaped, including its surface, has improved dramatically over the last two decades. New spaceborne measurements are providing essential information about the state and ongoing dynamics of our planet–critical ingredients for forecasting, predicting, mitigating, and responding to hazardous processes and long-term trends that affect societal well-being.
The surface of the Earth is shaped by forces such as tectonic uplift, erosion, sediment transport, and climate. It is also shaped by human activities such as agricultural landscapes and mining.
These activities can change the shape of the land by moving soil, changing vegetation, and creating other effects that leave clear topographic signatures on the Earth’s morphology. These changes can be detected by remote sensing techniques, such as satellite imaging or airborne lidar (Haugerud et al., 2003; Figure 4.9).
While human activities have a major impact on the world’s surface, we still do not understand their full extent. In addition, we don’t know how these changes affect other vital systems, such as the atmosphere and hydrosphere. The growing complexity of the planet’s interactions with other vital systems has a profound impact on our ability to predict, prepare for, and mitigate the potential impacts of disruptive change.
The Future
Humans can’t escape the reality that the future is uncertain; ice caps melt, beaches are eroded and air and water pollution threaten life. The long-term effects of climate change, famine, war and nuclear fallout are increasingly frightening; yet it isn’t just the future itself that is grim. The images we hold of it, the ones that we use to plan, to feel secure and to invest in tomorrow, are fading.
We may not have much choice, but we can work to make the future a more positive one. By bringing the future to life, we can help to transform the world around us.
If we can do this, then we can create a brighter, biology-friendly future for all of us. It’s a big part of our mission at UNESCO.
To do this, we need to become more futures literate. This means putting our imaginations to good use, and learning how to make new images that can inspire hope.
This is especially important in light of the bleak reality that many people face now. Climate change, pandemics, economic crisis and social exclusion are all threatening our way of life. But without images of the future that we can build on and trust, we will lose all our confidence in ourselves and our ability to change the world.
The problem is that the future is a very difficult place to navigate, and many of us have a hard time distinguishing it from the past or from the present. This can lead to a sense of unease and disillusionment, which can be difficult to overcome.
That’s why we need to start building new images of the future, ones that inspire us and help to foster collaboration. By doing this, we can begin to create the kind of society that we want for ourselves and for our children.
There are many ways that we can go about doing this. For instance, we could develop technology that can convert carbon dioxide into oxygen. We could also use bioengineering to create organs and living cells. These technologies will give us an extended lifespan and allow us to perform tasks that we would otherwise be unable to do.