Key molecule for life may have formed on interstellar ice

A key molecule for life may have formed in the cold, far-reaches of space, alongside budding stars and planets.

Amino acids are the building blocks of proteins, making them vital for life on Earth. Some scientists suspect that they may have been transported to our planet by meteorites or asteroids. In fact, a few organic molecules, such as carbonic acid, have been spotted floating around in space over the past few decades. But how exactly these molecules formed is unclear.

Now, Ralf Kaiser at the University of Hawaii at Manoa and his colleagues have found a key amino acid, called carbamic acid, could be created via reactions on clumps of ice in deep space.

Carbamic acid is a simple amino acid that is a precursor to more complex compounds found naturally in various enzymes.

To explore if carbamic acid could form in the extremely cold conditions of space, the team placed the reactants that form carbamic acid – carbon dioxide and ammonia – into a refrigerator that can go down to 5 kelvin (-268°C).

The researchers then slowly increased the temperature and found that at 62 K, carbon dioxide and ammonia reacted to form carbamic acid. They also found that ammonium carbamate – a salt that aids in processing the compound urea, the major component of urine – was created at 39 K, adding credence to the idea that life’s building blocks could have come to Earth from space.

These conditions are similar to the ones seen in molecular clouds around young stars and planets, says Kaiser, making it possible that carbamic acid and ammonium carbamate first emerged on ice in these regions.

“Eventually, they can be incorporated in meteorites or asteroids, which would take these compounds into our solar system or other solar systems,” he says.

The team hopes that the findings will help astronomers look for these amino acids in space, which can be done using instruments such as the James Webb Space Telescope.

“By finding out where these molecular precursors are and under which conditions they can be formed, we can predict where life could be or could have been formed,” says Kaiser.