As scientific ambitions go, it's a big one: no less than the creation of an artificial life form. Since the early 1980s, scientists have been attempting to create synthetic cells. And apparently the final breakthrough is expected very soon.

"This is a critical time for artificial life," says Dr Seth Bullock, who chaired the ALife XI conference - a gathering of more than 400 scientists, philosophers and engineers at the University of Winchester last month. "The field is on the verge of synthesising living cells."

Artificial life, often referred to as alife, is a very diverse field of study, encompassing simulations, computer models, robotics and biochemistry. Researchers concern themselves with the reconstruction or simulation of living processes in a variety of media - including robotics and chemical systems, as well as computational modelling. It's also a very esoteric community, but their work has proven, despite much controversy, to have many practical applications.

Pieces of the jigsaw

"There are many aspects to what makes up a living organism," says Alex Penn of the School of Electronics and Computer Science at the University of Southampton. "The key aspects are production of a self-sustaining metabolism, a membrane to separate this metabolic system from its environment and an informational system, such as DNA, to support replication and heredity."

Penn argues that although there has been no single breakthrough, different groups are approaching the problem of making a whole cell from different angles. "Although we are not yet at the stage of creating a totally self-producing, self-reproducing, autonomous living cell, considerable advances have been made on individual aspects."

At the forefront of the artificial life movement is a research group led by Craig Venter, the American biologist who founded the Institute for Genomic Research and who is a leading cartographer of the human genome. Venter has recently managed to insert artificially constructed chromosomes into existing living cells: not quite artificial life, but something approaching a synthesis of it. Rival research institutions are also close to fitting other pieces of the jigsaw in to place. Mark Bedau at the European Centre for Living Technology in Venice has manufactured artificial vesicles - in effect, artificial cell walls - thought to be a key step in the origin of proto-cellular life.

Although the creation of a synthetic life form is a mainly a practice of biologists, the results are of keen interest to any scientist interested in understanding living systems and their origins. "One route to understanding a system and its origins is to attempt to reconstruct it," says Penn.

Since the movement's rise, it has often been perceived as an endeavour perused by maverick scientists operating on the edge of mainstream science. "The alife community has always been a place where [scientific] outsiders could gather," says Mark Bedau, editor of the Artificial Life Journal. "It's been seen as something of an amateur science and yet the robot being used to explore Mars uses principles that have come out of the alife community."

Moreover, artificial life has produced many practical achievements much closer to home. Its ideas and principles have helped inspire a range of innovations, ranging from the development of household robotics such as Rod Brooks' iRobot vacuum cleaner through to computer games that use evolutionary artificial intelligence approaches, to the special effects in Hollywood blockbusters. The battle scenes in the film Troy, for example, were produced with software developed by Torsten Reil's Natural Motion company, which in turn was based on principles spun out of the alife movement.

Elsewhere, financial systems modelling biologically-inspired evolutionary algorithms are used to analyse complex financial portfolios by companies such as CodeFarm and Icosystem, while BT is investing in alife approaches as a means for understanding and manipulating the behaviour of large, complicated, open socio-technological systems such as wireless networks. The idea is that the BT could build telecommunications networks that could self-regulate and repair.

"Cells are constantly processing information. Everything that is alive is a fantastic information processor," says Klaus Peter Zauner of the University of Southampton. Just as 19th-century engineers studied the flight of birds and dreamed of being airborne, he says, so today's computer engineers marvel at the intelligence in all forms of life and contemplate the potential of more efficient computation.

Great leaps forward

There are, however, major conceptual challenges that need to be overcome before the synthetic cells are possible. First, the coupling of the three essential components of a living cell: metabolism; membrane and inheritance system is not yet fully understood. "Second, and more generally," says Penn, "we need to better understand the respective roles of evolution and self-organisation and how they combine to produce living systems."

A decade ago, artificial life was criticised by the evolutionary biologist John Maynard Smith as being a "fact-free science", but the recent leaps forward mean that it is belatedly being accepted into the scientific mainstream.