Life in a grain of cosmic dust
doi:10.1038/nindia.2008.243 Published online 18 July 2008
New research has deciphered how floating dust clouds in space churn out basic molecules essential for the formation of life on an earth-like planet. With computer-based simulation studies, the research team has found that grains in interstellar dust cloud play host to reactions that cook up hydrogen, water and methyl alcohol (methanol)1. The researchers predict that such cosmic grains might produce glycine, the simplest amino acid and building block of protein.
Hovering in empty space between stars, the dust clouds spawn comets and ultimately collapse to give birth to stars. The dust grains in clouds are mainly silicates or carbonaceous measuring between 20 angstroms and a few microns. The outer surface of a grain is dotted with microwells that look like hemispherical wells on egg baskets.
The researchers found that atoms of hydrogen, oxygen, and carbon scan the grains for suitable sites, to which atoms are bound through a weak force known as van der Waals force. At the slightest change in temperature, the atoms hop from one site to another on the same grain reacting and creating molecules of hydrogen, water and even methanol. The reactions happen 6 and 20 degrees above absolute zero.
The reactions produce heat releasing the molecules from the grains' surface. Then on exposure to ultraviolet rays they form more complex prebiotic molecules. "Given the abundance of hydrogen production, dust grains in interstellar cloud may take one million years to produce complex prebiotic molecules," says lead researcher Sandip K. Chakrabarti. "As the grains stick together to form comets and planetsimals, they can smuggle the molecules on far away planets, especially to those closer to a star. Depending on the planetary environment they may or may not survive to form more complex molecules," he adds.
The authors of this work are from: Indian Centre for Space Physics, Kolkata, India; S. N. Bose National Centre for Basic Sciences, Kolkata and Maharaja Manindra Chandra College, Kolkata.
- Das. A. et al. Formation of water and methanol in star forming molecular clouds. Astron. Astrophys. 486, 209-220 (2008) | Article |