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PAH coronene (C₂₄H₁₂) Molecule - One of the molecules produced. © NASA, 1999
They bombarded this with ultraviolet light and to their amazement, within a short time new and complex chemicals had formed around the silicate grains. These included ketones, formaldehyde, polycyclic aromatic hydrocarbons (PAH), ammonia, methane, methanol, alchohols of various kinds, poly-oxymethylenes and dozens of other highly complex organic chemicals - some of which were unknown and had no name!

What was most surprising, though, was the fact that the chemical residues formed into vesicles similar to those found in the Murchison meteorite by David Deamer. The vesicles created in the vacuum chamber have some interesting and significant characteristics. One end is hydrophilic and the other end is hydrophobic - they both love and hate water! This enables molecules to be self-organizing in the presence of water and this ability, or characteristic, is a simple sorting process that may go some way towards understanding how life could self-organize, without some intelligent presence overseeing its assembly. In fact the vesicle behaves like a lipid, which is a fatty or oily bio- (rather than just an organic) molecule that is a major component in living cells and serves a variety of important functions.

The most important of these functions is the creation of a boundary, enclosure or membrane, that isolates whatever is inside from the harsh and potentially destructive Universe outside. Surrounding and isolating a cocktail of potentially life-making chemicals in this way, where they can carry out their processes without external perturbations, must be vitally important if life is to "get started". If it is possible for lipids to form from "raw", inorganic chemicals, by simple processes that would be common in space, then a major factor in understanding the origins of life has been discovered.

It is a step closer, towards self-assembling our "dune-buggy" of life. We now tip the parts out on to a tray, they now remain together, half of them no longer roll away across the floor to get lost or trodden on! But it is still a long way from a complete buggy. If we take a logical approach, though, we might finally assemble the buggy by putting sub-assemblies together - wheels, engines, chassis. The final buggy is then made from a few sub-assemblies. Did life happen by the same process? If so how did the subassemblies self-assemble?
Could it have been by natural physical processes that create structure? We can see this happening throughout the non-living world. Spheres form from liquid in free-fall. Tornadoes (Twisters) are helical in structure, like DNA. Crystals form amazing geometric shapes. All these are a form of structure and assembly. They are just three examples and there are many more. Can you think of any?

Meanwhile back in the space simulation chamber, further development of the chemicals continued as the experiment progressed. Compounds known as quinones and alkaloids developed from the PAH's. Alkaloids are common in plants, where they play a crucial role in many aspects of a plant's life. Quinones assist in the electrons' mobility inside living cells. They are used in photosynthesis in plants and bacteria, and in animal cells where they become muscle and brain "food".

It is becoming clear that life precursors could be created in space, from the simplest of chemicals and in the most unpromising of conditions. The question that now occurs is this: did life start in space, or was it that the chemical precursors of life could form in space and rain down on the planet as comets and other space debris?

The second option is quite likely, but the true origin of the first living cell is still as elusive as ever. But major breakthroughs happened in the last decade of the last millennium and perhaps the answers to our fundamental questions about life will be answered soon.