Nasa's Curiosity rover has discovered the element boron on Mars, boosting scientists' hopes that life could have once existed on the Red Planet.
"Because borates [boron-containing compounds] may play an important role in making RNA – one of the building blocks of life – finding boron on Mars further opens the possibility that life could have once arisen on the planet," said Patrick Gasda, researcher at Los Alamos National Laboratory and lead author of the paper detailing the findings, published in the journal Geophysical Research.
"Borates are one possible bridge from simple organic molecules to RNA. Without RNA, you have no life. The presence of boron tells us that, if organics were present on Mars, these chemical reactions could have occurred."
A key component of RNA is a sugar called ribose, however, like other sugars, it is very unstable and decomposes quickly in water, a major stumbling block to the creation of life. The ribose needs another element to stabilize it and this is where boron has an important role to play because when the two compounds mix, the ribose is stabilized long enough for RNA to be produced.
"We detected borates in a crater on Mars that's 3.8 billion years old, younger than the likely formation of life on Earth," said Gasda. "Essentially, this tells us that the conditions from which life could have potentially grown may have existed on ancient Mars, independent from Earth."
The boron that Curiosity identified was discovered in calcium sulphate mineral veins – deposits formed when a water-based solution passes through cracks in a mineral rock - which tells scientists that it was present in Mars' groundwater.
There is no concrete evidence for the existence of life on Mars but several recent discoveries have lent more weight to the idea that it could have existed. Evidence that the Curiosity rover gathered from the Gale Crater – where the recent boron discovery was made – led Nasa to announce in 2013 that an ancient freshwater lake could have harboured the right conditions for microbial life to flourish.
A future Nasa mission to the Red Planet, known as Mars 2020, will hope to build on Curiosity's recent findings. The Mars 2020 rover will be equipped with instruments designed specifically to search for signs of past life on the planet.