Nasa stunned by unexpected discovery on Mars that "shouldn't be there"

NASA scientists have found an "unexpected" but key ingredient for life on Mars, hidden in a cluster of yellow crystals.

It's the first time these yellow crystals have been found on the Red Planet in 30 years of exploration.

"It forms in only a narrow range of conditions that scientists haven't associated with the history of this location," according to Nasa.

The crystals were discovered by the Curiosity rover while driving over a rock in the Gediz Vallis channel, which is thought to be an extinct river.

Using its Alpha Particle X-Ray Spectrometer (APXS), a high-tech tool that can see what samples of rock and soil are made of, Curiosity confirmed the crystals were elemental sulfur.

While minerals containing sulfur have been observed on the Red Planet, elemental sulfur has not been found on its own until now.

And there are apparently tons of these rocks in the channel.

"Finding a field of stones made of pure sulfur is like finding an oasis in the desert," said Ashwin Vasavada, Curiosity's project scientist.

"It shouldn't be there, so now we have to explain it.

"Discovering strange and unexpected things is what makes planetary exploration so exciting."

What is sulfur?

Sulfur is one of six building blocks for life, alongside carbon, hydrogen, nitrogen, oxygen and phosphorus.

These elements combined make up 98 per cent of living matter on Earth.

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On Earth, sulfur is commonly used for making car batteries, fertiliser, oil refining, water processions and metal mining.

It can only form in a very narrow set of conditions.

Scientists had not previously associated Mars with these conditions, which is why experts were shocked at the findings.

However, it may prove helpful in forging permanent habitation bases in the future.