We all know how hard life can be, but spare a thought for the microbes recently discovered 1.6 kilometres (1 mile) below the seabed off the coast of Canada. The living conditions are cramped, the environment is a searing 100°C (212F), and yet these hardy cells appear to be thriving. In the midst of the historic landing of Phoenix in the arctic wastes of Mars yesterday, the interest in finding life on the Red Planet has, yet again, reached fever pitch. Although Phoenix isn’t built to look for life, it is assessing the Martian surface water content for signs that it may (or may have been able to) support life. This new discovery of life so deep below the Earth’s surface may set some new limits on just how extreme life can be on other planets…
Off the Newfoundland coastline, scientists have burrowed far below the seabed. Smashing the previous record for subterranean life, this new discovery has found one of the most basic forms of terrestrial life living a mile deep (the previous record held at 842 meters, or 0.5 miles). As I’m no biologist, I’ll leave it to the Reuters news source to describe as to what was found:
Prokaryotes are microbes lacking nuclei, comprising archaea and some types of bacteria. The lack of cell nuclei distinguishes them from eukayrotes, or all animal and plant life. – Reuters
These prokaryote specimens were scooped from sediments dating 111 million years old. At these depths, the sediment is subjected to temperatures from 60-100°C (140-212F), and John Parks, professor at the University of Wales (UK), belives that this type of microbe can live even deeper. He believes more prokaryotes could be discovered up to 4 km (2.5 miles) below the seabed. This leads to the question as to whether life on other planets may not be found on the surface, but deep inside their crust.
“If there is a substantial subsurface biosphere on earth there could also be substantial biospheres on other planets. Just taking a scoop from the surface of Mars is not going to tell you whether there is life on Mars or not.” – Prof. John Parks
This obviously relates to the attempts made by previous Mars landers to analyse the surface for extraterrestrial microbes. However, a lot of information can be gained by analysing the surface composition for the materials required by life (as we know it) to survive. The Phoenix lander for instance was not designed for life hunting in mind, but it was designed to analyse the top layer of regolith for water content and evidence that liquid water may have once flowed in recent Mars history. Now we have extended our limit on where life may thrive, missions to Mars will need to burrow deeper into the surface, or we’ll simply have to wait till we can do it ourselves.
It is not clear where these subterranean microbes get their energy from. Sunlight probably isn’t a factor; methane and heat from volcanic vents seem more obvious candidates.
There is a problem associated with finding life this deep. It complicates possible plans to bury carbon dioxide emissions deep underground to slow the effects of climate change. It is a completely untouched ecosystem, dumping our waste could have serious consequences for these colonies of microbes. However, it might take some convincing as the U.N. Climate Panel has announced that carbon dioxide burial may be the key tool in the future to prevent this greenhouse gas from escaping into the atmosphere.