Searching for life beyond Earth
The nature of life
As long as humans have been around, we have contemplated the nature of life. What is life? How does it start? How does it change? Where can it be found? Science has provided many answers to these questions but there remains so much more to discover.
Life as we know it
What we know about life we have learned from life on Earth, and we continue to learn from it in its many and varied forms. Observations, discoveries and interpretations of earth-bound life have informed our ideas and expectations of how and where life can exist. We continue to be surprised by instances of life in what we had thought to be impossible conditions.
The discovery of extremophiles, organisms that thrive in extremely hostile environments, have provided new impetus for the idea that we might find life elsewhere in the Solar System and beyond.
Astrobiology: the search for life beyond Earth
Astrobiology is the study of the origin of life on Earth, the search for life elsewhere and the future for life on Earth..
Astrobiology makes use of physics, chemistry, astronomy, biology, ecology, planetary science, and geology to investigate the possibility of life on other worlds.
Life in places other than on Earth?
As far as we know, earth is the only place in the universe which harbours life. There are many features of our world that make it suitable for life. Its distance from the Sun (not too hot, not too cold), its rocky nature, its oxygen-rich atmosphere and its hot molten core all contribute to life sustaining conditions such as warm temperatures, presence of liquid water and protection from solar radiation.
But is there anywhere else life could emerge?
There are 100 billion stars in our galaxy, and 100 billion other galaxies. Recently we have established that there are many planets orbiting many stars and some of those may turn out to have conditions similar to those on Earth.
Where do we search?
For a number of reasons Mars is the place where we have turned most of our energy.
What is it that makes Mars such a good contender?
Mars has many features that are similar to those of Earth. Mars is relatively close to Earth. It has a thin atmosphere, extinct volcanoes, valleys, deserts, polar ice caps, and has similar rotational periods though its ‘year’ and seasonal cycles are spread over two years because of its greater distance from the Sun. Conditions on Mars some 4 billion years ago were very similar to the conditions of Earth at the same time. Life certainly existed on Earth 3.5 billion years ago. We know this from studying the patterns in the rocks left behind by microbial mats — stromatolites.
Stromatolites: Evidence of life
Stromatolites are rock-like structures built by microbes. 3.5 billion year old stromatolites have been found on Earth. Given that Mars had similar conditions as Earth at the beginning, stromatolites are a focus of the search for evidence of life on Mars.
Exploring Mars
Our understanding of Mars has improved over time as we developed new technologies; telescopes, probes, and especially robotic rovers with the ability to analyse their surroundings. There are currently three rovers on Mars, two of which are still working and continually finding more tantalising evidence of conditions that provide a possibility of life existing there now or in the past.
Journey to Mars
Sending a rover to Mars demonstrates extraordinary technological and engineering achievements in rocketry, robotics, mission planning, programming and design. The surface of Mars is a very hostile environment for humans, and the journey to Mars takes approximately 6 to 10 months. Therefore, for the time being we have had to rely on robots to explore this red planet. Despite the increasing sophistication of rover technology and their capacity to traverse and analyse the Martian landscape, the idea of sending a manned voyage is always present.