'Dark oxygen' mission takes aim at other worlds

Scientists who recently discovered that metal lumps on the dark seabed make oxygen, have announced plans to study the deepest parts of Earth's oceans in order to understand the strange phenomenon.

Their mission could "change the way we look at the possibility of life on other planets too," the researchers say.

The initial discovery confounded marine scientists. It was previously accepted that oxygen could only be produced in sunlight by plants - in a process called photosynthesis.

If oxygen - a vital component of life - is made in the dark by metal lumps, the researchers believe that process could be happening on other planets, creating oxygen-rich environments where life could thrive.

Lead researcher Prof Andrew Sweetman explained: "We are already in conversation with experts at Nasa who believe dark oxygen could reshape our understanding of how life might be sustained on other planets without direct sunlight.

"We want to go out there and figure out what exactly is going on."

The initial discovery triggered a global scientific row - there was criticism of the findings from some scientists and from deep sea mining companies that plan to harvest the precious metals in the seabed nodules.

If oxygen is produced at these extreme depths, in total darkness, that calls into question what life could survive and thrive on the seafloor, and what impact mining activities could have on that marine life.

That means that seabed mining companies and environmental organisations - some of which claimed that the findings provided evidence that seafloor mining plans should be halted - will be watching this new investigation closely.

The plan is to work at sites where the seabed is more than 10km (6.2 miles) deep, using remotely-operated submersible equipment.

"We have instruments that can go to the deepest parts of the ocean," explained Prof Sweetman. "We're pretty confident we'll find it happening elsewhere, so we'll start probing what's causing it."

Some of those experiments, in collaboration with scientists at Nasa, will aim to understand whether the same process could allow microscopic life to thrive beneath oceans that are on other planets and moons.

"If there's oxygen," said Prof Sweetman, "there could be microbial life taking advantage of that."