Scientists have found key evidence which suggests life may once have existed on Mars.
Nasa's Curiosity rover has detected boron, a key ingredient for life, on the dusty surface of the Red Planet.
The discovery is a huge boost in the hunt for extraterrestrials and could back up a theory suggesting life on Mars may have been forced underground when disaster turned the planet into a "frigid desert".
Patrick Gasda, a postdoctoral researcher at Los Alamos National Laboratory said: "Because borates 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.
"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."
RNA is ribonucleic acid, a nucleic acid present in all modern life which is involved in the decoding and expression of genes from DNA.
It is known to be unstable, so unless boron is present it decomposes quickly.
Gasda's work is detailed in a study published this week in the journal Geophysical Research Letters.
It describes how Nasa's buggy found the element in calcium sulphate mineral "veins" in the rocky surface.
That means boron was present in Mars groundwater and indicates that the Gale crater, where Nasa's robo buggy is right now, may have been home to life.
It bolsters the bizarre theory that life originated on Mars and was carried to Earth on an asteroid.
Astronomer Caleb Sharf has previously claimed: "We can find pieces of Mars here on Earth and we suspect that there are pieces of Earth on Mars.
"If that material can carry living organisms on it, it's possible that we are Martian."
These hypotheses have forced bonkers scenarios in which officials have asked Nasa experts whether life existed there in recent times.
Dana Rohrabacher, an American senator, publically asked a project scientist overseeing Nasa's Mars 2020 rover mission if aliens ever lived on the Martian surface.
He quizzed: "You have indicated that Mars was totally different thousands of years ago.
"Is it possible that there was a civilisation on Mars thousands of years ago?"
Nasa's Ken Farley responded: "So, the evidence is that Mars was different billions of years ago, not thousands of years ago, and there is no evidence I'm aware of..."
However, there soon may be life on Mars if tech entrepreneur Elon Musk has his way.
The Space X founder has announced plans to put humans on the surface of the Red Planet by 2030.
This story originally appeared in The Sun.