Giving some credence to the view that life could well have originated in space, a new study has shown that a number of small organic molecules can form in a cold, space-like environment full of radiation.
Investigators at the University of Sherbrooke in Canada created simulated space environments in which thin films of ice containing methane and oxygen were irradiated by electron beams.
When electrons or other forms of radiation impinge on so-called molecular ices, chemical reactions occur and new molecules are formed, said the study published in the Journal of Chemical Physics.
The researchers used several advanced techniques including electron stimulated desorption (ESD), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD).
The experiments were carried out under vacuum conditions, which is required for the analysis techniques employed and mimics the high vacuum condition of outer space.
Frozen films containing methane and oxygen used in these experiments further mimic a space-like environment, since various types of ice (not just frozen water) form around dust grains in the dense and cold molecular clouds that exist in the interstellar medium.
These types of icy environments also exist on objects in the solar system, such as comets, asteroids and moons.
All of these icy surfaces in space are subjected to multiple forms of radiation, often in the presence of magnetic fields, which accelerate charged particles from the stellar (solar) wind toward these frozen objects.
Previous studies investigated chemical reactions that might occur in space environments through the use of ultraviolet or other types of radiation, but this study looked at the role of secondary electrons.
Copious amounts of secondary electrons are produced when high-energy radiation, such as X-rays or heavy particles, interact with matter.
These electrons, also known as low-energy electrons, or LEES, are still energetic enough to induce further chemistry.
The researchers investigated how the low-energy electrons interacted with icy films.
They found that a variety of small organic molecules were produced in icy films subjected to low-energy electrons.
Propylene, ethane and acetylene were all formed in films of frozen methane, the study said.
When a frozen mixture of methane and oxygen was irradiated with low-energy electrons, they found direct evidence that ethanol was formed.
Indirect evidence for many other small organic molecules, including methanol, acetic acid and formaldehyde was found.
The findings suggest a possibility that life’s building blocks might have been made through chemical reactions induced by secondary electrons on icy surfaces in space exposed to any form of ionising radiation.