So what are the implications should Sandford discover the kind of organic molecules in the cometary samples that have been created in the laboratory? For his part, Sandford is not really interested in the implications. 'In our lab we don't really have an attitude about [it], we're interested in discovering what kind of things were dropped on the early Earth and then we'd like to know what, if any, roles that material could have played', he says.
But if Sandford does discover convincing evidence that complex organic molecules, like HMT and the kind of lipid membranes he created in his laboratory, would have been dropped on the early Earth, then it is fair bet that they were somehow involved in the origin of life. The level of that involvement will still be open to interpretation, however. For instance, David Williams, professor of astronomy at University College, London, told Chemistry in Britain that even though the creation of complex organic molecules in space sounds reasonable, it seems even more likely to him that the prebiotic molecules responsible for life developed on Earth. The interstellar molecules may simply have acted as foodstuff for early organisms.
Other, more extreme, possibilities also exist. Sandford has speculated that the inside of a comet - with its potential cargo of prebiotic molecules and lipid membranes, together with the periodic warming it receives as it orbits the sun - might well be the ideal environment for the creation of life, or at least the beginnings of life.
The truth, unfortunately, may not be so clear cut. As Sandford says, 'life is a fairly complex thing, even in simple organisms, and it's quite possible that for life to get started it had to beg, borrow and steal compounds from anywhere it could get them'.
- Scott A. Sandford, Louis J. Allamandola and Max P. Bernstein, Organic chemistry: from the interstellar medium to the solar system in C. E. Woodward, J. M. Shull and H. A. Thronson (eds), ORIGINS, ASP Conference Series Vol. 148, 1998.
- David A. Williams, Introductory lecture: frontiers of astrochemistry in Faraday Discussions, 1998, 109, 1.
- Visit Nasa's Astochemistry Lab on the web at http://web99.arc.nasa.gov/~astrochm/
Source: Chembytes E-zine, January 1999