Is there Life on Mars?
A question that people have asked for all eternity is "Are we alone?" This is because Earth is the only place in the entire universe known to support life. This doesn't mean that life can't and doesn't exist elsewhere. It's just that it hasn't been found yet! The solar system contains a number of worlds which might have the potential to support life in some form. Jupiter's moon Europa possibly has deep oceans of water under its icy surface, and Saturn's moon Titan is believed to share chemical similarities with the young Earth. But it is Earth's neighbour, Mars, that is the most likely place that evidence of life may be found. The search for life on Mars is the main reason why many space craft are sent to the planet.
Against
- Mars' thin atmosphere is made up mainly of Carbon Dioxide (95.32%). This is the poisonous gas that also makes up most of
Venus' atmosphere. It is deadly to breathe in. Although the surface temperature on Mars can reach up to 27
° C (80 °F) , the average surface temperature there is -63 °C (-81 °F) and it reaches as low as -133 °C
(-207 °F). Temperatures on Earth do go below freezing, and people can survive in them, but -133 °C
(-207 °F) is probably too cold for even the most cold-resistant eskimos!
- There is very little water on Mars. Only 0.03% of its atmosphere contains droplets of water. On
Earth, 70% of the planet's surface is made up of water. Even with this small amount of Martian water, high clouds, frost and fog can form on Mars. The ice in its ice-caps is frozen Carbon Dioxide (also known as 'Dry Ice'). Water is one of the most important elements for life to exist. Below are pictures of clouds and frost on Mars:
- Mars is known as a "self-sterilising" planet. Its surface is saturated by ultra-violet radiation by the
Sun. If a person is exposed to Ultra-violet rays for too often and for too long, they can become very
unwell, which is why it is important to wear sun cream on sunny days. Even on cloudy days in summer, exposure to sunlight for too
long can be dangerous. Fortunately, Earth's atmosphere filters out most of these dangerous rays as it is quite thick. It offers
protection from the Sun for the people on Earth. On Mars, the atmosphere
is much thinner and doesn't provide the same protection.
The soil is extremely dry on Mars because of the lack of water, and this soil also undergoes an oxidising process, which is
what causes the soil to rust (it forms a metal oxide) and appear rusty-coloured. This self-sterilisation of Mars
prevents micro-organisms (small and basic but living objects) from forming on or under the surface.
For
- Mars does have water in its atmosphere. It may only be a small amount, but could provide life to certain living organisms that need very little water. Also, water in the atmosphere and strong evidence that water once flowed around the planet, suggest that there may be a possibility of liquid water deep under the surface. The picture below shows two 'islands' that may have formed as water flowed around them. We can see examples of this in rivers on sand on
Earth.
- Missions to Mars show the planet to be made up of many rocks and pebbles (more evidence of water!) similar to ones on
Earth.
- A face and two hearts have been discovered on Mars. People believed that these could have been created by advanced beings!
- It is known that tiny micro-organisms can exist on
Earth in some very extreme conditions. They can live deep below the surface and never be exposed to light or in extremely cold or hot places, in places impossible for the survival of humans or most other creatures. Mars may appear inhospitable for humans, but could have conditions suitable for organisms similar to the ones living in the extreme places on
Earth. In fact, Martian conditions are not as extreme as conditions can be on Earth where some forms of life exist.
- If Mars did have water, it will also have had a thicker atmosphere. This thicker atmosphere would have prevented the dangerous rays of the sun from hitting the planet, with its atmosphere filtering them out as happens on
Earth. People believe that Mars' temperature was also higher which greatly increases the chances of life on the planet. Below is an artist's impression of what Mars may have looked like when water flowed on its surface billions of years ago.
- A piece of rock from Mars, which landed on Earth when a meteorite hit Mars and scattered its rocks, contains signs of life. Small fossils and evidence of a basic once-living micro-organism provided the strongest proof yet that life did once exist on Mars billions of years ago. The picture below shows these tiny bacteria-like micro-organisms, about one thousandth of the size of a human hair!
The search for life continues on Mars with the missions to explore the surface and whatever is below it. One day, humans will walk on the planet. When humans do visit Mars, they will be expected to survive on the planet for about three years. They will have to wait for Earth to be in the correct position to return home. In these three years, they will have to learn to adapt to the hostile conditions on Mars and will have a longer period of time in space to discover the secrets of another planet. What may be more of a challenge is whether a bunch of human beings can live with each other for such a length of time with no means of escape.
