Bugs and humans will team up to explore space
When humans do decide to push out beyond Earth, to establish a permanent presence on other Solar System bodies, their survival could depend on the humblest of organisms - bacteria and other microbes.
It will be impossible for astronauts to take everything with them they need, or to keep their bases, on Mars say, continuously supplied by logistics ships.
And it's for that reason that quite a bit of scientific research is now looking at what can be done to make space explorers more self-sufficient.
Bacteria have a crucial role to play here - from being the key components in life-support systems to catalysing the production of rocket fuels.
It's in that light that I've written a story today about the microbes that survived 553 days living on the outside of the International Space Station (ISS).
Click on the video below and you can hear an explanation of the experiment from the Open University's Professor Charles Cockell who is fascinated by this type of study.
His group's ISS bugs are the longest-lived fully functioning, photosynthesising space microbes yet.
Sitting on, and in, small chunks of rock taken from a sea cliff in southern England, the organisms endured a vacuum, swings in temperature, damaging levels of UV and desiccation.
They couldn't do anything useful in such conditions; they went into a dormant state and hung on. But they proved their durability, and having the "right stuff" will be a quality required of any microbes taken on deep space missions.
So what could these tiny explorers do?
A fundamental role is likely to be in so-called closed-loop life-support systems, in which they work in tandem with mechanical filtration technologies to recycle waste water and air. Closed loop implies 100% recycling, or as close as is possible.
You can see the beginnings of what these future systems might be like in the Micro Ecological Life Support System (Melissa) project now being run in Barcelona, Spain.
Forty rats - which have the same oxygen requirement of one human astronaut - live inside a closed box that is sustained by a number of bioreactors.
Other roles could include the extraction/leaching of useful minerals from rock. This idea is merely an extension of a role microbes already play on Earth. For example, quite a bit of the copper and zinc we use today is extracted from ores using this type of process.
Microbes can also be used to break down rock to make the soil in which to grow plants. They can also improve the quality of that soil.
On the Moon, for example, it's been shown that about half of the essential elements needed to grow crops already exist in the regolith - the dusty layer that covers the surface.
Adding microorganisms, such as fungi, bacteria and algae, can get this soil into a state where it would support plant growth. You've no doubt heard about the famous experiment in which scientists grew French marigolds in Moon-like soils and even got them to flower.
I wrote recently in this blog about the nightmare that is lunar dust. This extremely fine material is the result of the Moon's surface being pulverised for billions of years by asteroids. The Apollo crews got covered in the stuff.
It is extremely damaging if it gets inside equipment, breaking seals and shorting electrical equipment. More than that, it's also potentially very hazardous if it gets into the lungs.
Some scientists have proposed using bacteria to tackle this dust problem, too. Some microbial communities have the ability to form crusts that catch small particles. They could be used as a living filtration system.
And I would think providing ready access to energy is going to be a fundamental role for future space microbes.
This could take the form of methane fuel production from the catalytic reaction of carbon dioxide and hydrogen. Work is under way also on the development of microbial fuel cells which can generate electricity and process waste sludge and water.
The point about all this - and to bring the discussion back to the space station microbes - is that none of the places we might want to go to set up a base can sustain unprotected microorganisms on its surface. That's true we believe also of Mars. The UV conditions are just too severe.
This means the "micro-nauts" would have to live inside boxes just like the astronauts; but they need to be hardy enough that if systems break down they can survive, for a short period at least, the sort of unshielded extremes that our ISS bugs managed to endure.
I suppose the ultimate use of bacteria in space would be terraforming - the use of microorganisms to turn an otherwise hostile environment into something more amenable to humans.
Perhaps one day, we'll despatch microbes to distant planets to transform them into habitable worlds, replacing their atmospheres with breathable gases.
It might take many millions of years to achieve, of course.
I'm not sure I'd have the patience. And over such timescales, it might be pointless anyway because by then we could have evolved into thinking machines that no longer need a cosy Earth.