Cosmic dust necessary to spark life in space
Tiny particles of space dust could be vital for more quickly creating the complex molecules needed for life, scientists say.
An international team including researchers from Heriot-Watt, Friedrich Schiller University Jena in Germany and the University of Virginia has shown that mineral dust acts as a catalyst, helping simple compounds combine into more complex, potentially life-forming molecules even in the extreme cold of space.
“This could be how nature overcomes the harshness of space to kickstart chemistry that ultimately leads to life.”
The study, published in The Astrophysical Journal, found that surface reactions between carbon dioxide and ammonia – both common in space – only occur efficiently when dust is present.
These reactions form ammonium carbamate, a compound thought to be a chemical precursor to urea and other molecules essential to life.
Professor Martin McCoustra, an astrochemist from Heriot-Watt's School of Engineering and Physical Sciences, said: “Dust isn’t just a passive background ingredient in space.
“It provides surfaces where molecules can meet, react and form more complex species.
“In some regions of space, this dust chemistry is a prerequisite for making life’s molecular building blocks.
“We now know that surface reactions occur efficiently - more quickly - with the dust than without.”
Recreating deep space in a lab
In Dr Alexey Potapov’s laboratory in Jena, dusty sandwiches of thin layers of carbon dioxide and ammonia separated by a layer of porous silicate grains produced by laser evaporation made a realistic stand-in for cosmic dust.
When the samples frozen at –260°C (similar to interstellar clouds) were warmed to about –190°C (conditions found as these clouds evolve into protoplanetary disks), the molecules spread through the dust layer and reacted to form ammonium carbamate.
Without the dust layer, the icy molecules didn’t react as well.
The team identified this as an example of acid–base catalysis involving the transfer of protons – the first time such chemistry has been observed under simulated space conditions.
Dr Alexey Potapov said: “The findings suggest that dust grains play a far more active role in astrochemistry than previously thought.
“Floating through interstellar clouds and protoplanetary disks, these particles may provide the micro-environments where molecules meet and evolve into more complex forms.
Professor McCoustra added: “We’ve shown that dust can promote the chemistry needed to build more complex organics, even at extremely low temperatures.
“This could be how nature overcomes the harshness of space to kickstart chemistry that ultimately leads to life.”
The researchers plan to explore whether other molecules can form in the same way, and whether this dust-driven chemistry is taking place today in protoplanetary disks, where new planets are being born.