César Menor Salván

One theory regarding the origin of life on Earth suggests that comets brought the molecular building blocks necessary for life to develop. Now, a team led by the University of Cambridge (United Kingdom) is questioning this possibility. Using computer simulations focusing on hydrogen cyanide — an important prebiotic compound — they estimate that, whilst the possibility of such molecules arriving and surviving intact cannot be completely ruled out, the event would be extremely unlikely. “It’s quite a romantic idea, but our results suggest it is highly improbable,” the authors note in a press release. The study is published in Scientific Reports.

A team led by a Spanish researcher has identified, near the centre of the Milky Way, a type of sugar composed of four carbon atoms, known as erythrulose, which on Earth is found in raspberries and self-tanning products. This would suggest that complex and biologically relevant molecules can form in space. Ribose and glucose had previously been discovered in samples from meteorites and asteroids, but until now no sugar had been directly detected in the interstellar medium. The finding is published in Nature Astronomy.

NASA’s Curiosity rover has found more than 20 organic molecules in clay-rich rocks on Mars, according to a chemical analysis published in Nature Communications. Among them is a nitrogen-containing molecule with a structure similar to that of DNA precursors, according to a press release from the University of Florida. This organic matter may have been preserved for more than 3.5 billion years in Gale Crater, the article states.

A Japanese research team has identified the five nucleic bases (adenine, guanine, cytosine, thymine, and uracil)—which form the building blocks of DNA and RNA—in samples from the asteroid Ryugu, according to a study published in Nature Astronomy, which compares the composition of these samples with those from the asteroids Bennu and Orgueil. “The detection of various nucleic bases in asteroid and meteorite materials demonstrates their widespread presence throughout the solar system and reinforces the hypothesis that carbonaceous asteroids contributed to the prebiotic chemical inventory of the early Earth,” the authors write.

Amino acids are the building blocks of proteins. These are known as the building blocks of life, but they cannot replicate themselves. To do so, they need the instructions provided by RNA. How this relationship began is still a mystery. Now, a British team has shown how it could have started from relatively simple conditions. According to the researchers, who published their findings in the journal Nature, ‘understanding the origin of protein synthesis is fundamental to understanding where life comes from.’

The research article A bacterium that can grow by using arsenic instead of phosphorus was one of the big science stories because it discussed the possibility of arsenic-based life. However, it has been the subject of criticism until now. After nearly 15 years of debate and failed attempts by other groups to replicate the findings, Science has now decided to retract the article, despite finding no evidence of fraud or misconduct on the part of the authors, who disagree with the decision.

Until now, one hypothesis suggested that life on Earth could have arisen from lightning striking a body of water. However, a new study claims that the synthesis of molecules necessary for the emergence of life could have originated from ‘micro-lightning’ in water droplets. According to the study, published in Science Advances, the formation of organic compounds with carbon-nitrogen bonds from gas molecules could be a possible mechanism for creating the basic components of life on the early Earth.

The red colour of Mars corresponds to a type of ferrihydrite that is the dominant form of iron oxide in Martian dust, although previous studies have attributed it to anhydrous haematite. The persistence of ferrihydrite, whose formation requires water, suggests that it formed during a cold, wet period, followed by a transition to the planet's current arid environment. The result, based on ESA and NASA space data and new laboratory experiments, is published in Nature Communications.

US researchers have published a model showing that ice in the mid-latitudes of Mars could allow photosynthetic life to develop. Its thickness and composition would attenuate harmful ultraviolet radiation, but allow sufficient visible light to pass through. The work is published in the journal Communications Earth & Environment.

Fifteen years ago, the European Space Agency's (ESA) Mars Express probe revealed the presence of large deep deposits on Mars, in an area called the Medusae Fossae Formation (MFF), located at its equator. Now, new data from the probe's MARSIS radar indicate that the deposits are deeper than previously thought - up to 3.7 kilometers thick - and include both ice-rich and dusty layers. The results are published in Geophysical Research Letters.