The archaea are perhaps the strangest form of life to be found on our planet. They are an ancient branch of microbial life discovered by scientists in 1977.

Unlike the better known bacteria and so-called eukaryotes (plants and animals), many of the archaea thrive in extreme environments like volcanic vents and acidic hot springs.

This makes them scientifically interesting and potentially useful.

Because they evolved when the Earth was an inhospitable place they can live without sunlight and do not need carbon as food. Instead they survive on sulphur, hydrogen, and other materials that are poisonous to ordinary organisms.

The Archaea - a different type of life

These thermophilic (heat-loving) microorganisms, can live and reproduce at temperatures near the boiling point of water and may have practical benefits.

A useful enzyme, alcohol dehydrogenase (ADH), is derived from a member of the archaea called Sulfolobus solfataricus.

It can survive to 88 C (190 F) in nearly boiling water - as well as very acidic conditions like the acid found in a car battery.

To understand how ADH does it scientists first needed to learn about its basic structure. For this, an Italian research team conducted an experiment onboard the Space Shuttle.

After collecting Sulfolobus solfataricus from the Solfatara volcanic area near Naples, the Italian team purified the ADH enzyme for crystallisation in space.

To determine the molecular structure of ADH scientists have to grow crystals of it. The better the crystal the more detailed analysis of it can be made.

Compared to crystals grown in Earth's gravity, the space crystals showed an improved quality.