Life on Titan may be smelly and explosive (2)
"Terrestrial life uses about 700 molecules, but to find the right 700 there is reason to suppose that you need to be able to make 10 million or more. The issue is not how many molecules you can make, but whether you can make the collection you need to assemble a metabolism, Dr Bains says, "It is like trying to find bits of wood in a lumber-yard to make a table. In theory you only need 5. But you may have a lumber-yard full of offcuts and still not find exactly the right five that fit together. So you need the potential to make many more molecules than you actually need. Thus the 6-atom chemicals on Titan would have to include much more diverse bond types and probably more diverse elements, including sulphur and phosphorus in much more diverse and (to us) unstable forms, and other elements such as silicon."
Even if life were to be found on the distant world, it would be quite basic. "Rapid movement or growth needs a lot of energy, so slow-growing, lichen-like organisms are possible in theory, but velociraptors are pretty much ruled out," said Bains.
Dr Bains, whose research is carried out through Rufus Scientific in Cambridge, UK, and MIT in the USA, is seeking to work out just how extreme the chemistry of life can be. Any creatures found on Titan would be strange indeed. "Hollywood would have problems with these aliens," says Dr Bains.
"Beam one onto the Starship Enterprise and it would boil and then burst into flames, and the fumes would kill everyone in range. Even a tiny whiff of its breath would smell unbelievably horrible. But I think it is all the more interesting for that reason. Wouldn't it be sad if the most alien things we found in the galaxy were just like us, but blue and with tails?"
Several scientists are working on a potential Titan lander that would splash down in one of the moon's seas and take readings on its chemistry for 16 Earth days. The so-called Titan Mare Explorer has yet to be approved or rejected by NASA.