An important component of amino acids known as carbonic acid has been spotted in space for the first time.
Carboxylic acids, of which carbonic acid is an example, form the backbone of amino acids, which are the building blocks of proteins. Carbonic acid also plays a key part in our breathing system, transferring carbon dioxide from the blood to our lungs so we can exhale it, and has a crucial role in atmospheric and geological processes, which help to sustain life on our planet.
Finding where carboxylic acids come from in space could help us explain how life eventually came to be on Earth, but only the two simplest carboxylic acids, formic acid and acetic acid, had been identified in space before now. The more complex carbonic acid (H2CO3), which has three oxygen atoms in its structure, gives off a fainter signal that is more difficult to identify.
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Now, at the Spanish Astrobiology Centre in Madrid and his colleagues have identified carbonic acid in a cloud of gas and dust called G+0.693-0.027, which is close to the centre of the Milky Way and about 100,000 light years away from Earth.
鈥淐arbonic acid鈥檚 characterisation was really, really difficult even on Earth because this molecule rapidly decomposes into carbon dioxide and water,鈥� says Sanz-Novo. This process can be triggered by just a single water molecule, he says. However, in water-free parts of space, the acid can exist more stably as a gas.
To find the molecule, the researchers looked for millimetre-wavelength light coming from G+0.693-0.027 using two telescopes at the Yebes and IRAM observatories in Spain. They compared what they saw with previous laboratory measurements of carbonic acid.
Sanz-Novo and his colleagues think the acid is probably being formed in icy grains of dust in the cloud. When these grains are disturbed in some way, the acid is released as a gas. 鈥淥nce it鈥檚 in the gas phase, it rotates and emits photons at exact frequencies,鈥� says Sanz-Novo. 鈥淭hat allows us to collect the spectra and compare these data with laboratory measurements [of carbonic acid].鈥�
鈥淚t鈥檚 another important brick in the wall that we鈥檙e building to understand astrochemistry,鈥� says at the University of Kent, UK. 鈥淥nce we can get that, that brings up all the questions of how this can lead to amino acids and prebiotic chemistry, and how the origins of life work.鈥澛燗mino acids have been found in meteorites, he says, but we don鈥檛 necessarily know how they got there or how they were made.
arXiv
