1001 GMT October 15, 2019
If this happens in space, this liquid-like behavior could help organic molecules form at the edges of infant planetary systems, according to sciencenews.org.
The experiment provides a peek into the possible origins of life.
Shogo Tachibana of Hokkaido University in Sapporo, Japan and colleagues combined water, methanol and ammonia, all found in comets and interstellar clouds where stars form, at a temperature between ‒263°C and ‒258°C.
The team then exposed this newly formed ice to ultraviolet radiation to mimic the light of a young star.
As the ice warmed to ‒213°C, it cracked like a brittle solid. But at just five degrees warmer, bubbles started appearing in the ice, and continued to bubble and pop until the ice reached ‒123°C.
At that point, the ice returned to a solid state and formed crystals.
Tachibana said, “We were so surprised when we first saw bubbling of ice at really low temperatures.”
The team reported its finding in Science Advances.
Follow-up experiments showed fewer bubbles formed in ice with less methanol and ammonia. Ice that wasn’t irradiated showed no bubbles at all.
Tachibana said, “Analyses traced spikes of hydrogen gas during irradiation suggested the bubbles are made of hydrogen that the ultraviolet light split off methane and ammonia molecules.
“The irradiated ice took on another liquid like feature: Between about ‒185°C and ‒161°C, it flowed like refrigerated honey, despite being well below its melting temperature.”
That liquidity could help kick-start life-building chemistry.
In 2016, Cornelia Meinert of the University Nice Sophia Antipolis in France and colleagues showed that irradiated ice forms a cornucopia of molecules essential to life, including ribose, the backbone of RNA, which may have been a precursor to DNA.
But it was not clear how smaller molecules could have found each other and built ribose in rigid ice.
Meinert added, “At the time, critics said complex molecules could have been contamination.
“Now this is helping us argue that at this very low temperature, the small precursor molecules can actually react with each other.
“This is supporting the idea that all these organic molecules can form in the ice and might also be present in comets.”