Can
bacteria live on other planets?Can
bacteria live on other planets?
Every so often someone claims to have found traces of bacterial life on Mars or on meteorites or some other such specimen. From what we have seen so far, can bacterial life exist on one of the other worlds in our solar system?
Some things that would need to be present:
1) Water – all bacteria on earth need water in which to live and replicate – even the bacteria in soil exist in a thin film of water. This means that there must be some form of atmosphere – water boils at tremendously low temperatures in a vacuum.
2) A temperature range between about -15°C and 160°C
The asteroids shall not be considered as they have no atmosphere and hence, no liquid water. Of the planets in our solar system, Pluto and Mercury (as well as the moon) can be similarly discounted.
Venus is not a good candidate as its surface temperature of 480°C would make bacteria as we know them, impossible.
Mars has a low atmospheric pressure but this is not necessarily a problem. Its atmosphere contains some (very little) oxygen, lots of carbon dioxide and is saturated with water vapour even though there appears to be no liquid surface water. Temperatures range from –100°C to about 0°C and, in theory, it gets enough sunlight to power photosynthesis.
The gaseous planets (Jupiter, Saturn, Uranus and Neptune) are less well-known quantities. Jupiter is known to generate its own heat and the other three possibly do so – this means that even though they are far from the sun, temperatures deep within the atmosphere may reach (or even exceed) those needed for bacterial life. This deep within the atmosphere, pressures would be enormous and light (probably) non-existent. Photosynthesis would likely be impossible but fermentation may be possible as huge lightening storms are known to range the atmosphere of Jupiter and it has been suggested that these could produce simple organic molecules that could be split for the production of energy.
All in all, what we know of bacteria gives some hope of finding similar organisms within the solar system – especially considering the fact that we may not have yet defined the limits for life of this type.