‘Dark oxygen’ mission takes aim at other worlds

Scientists who recently discovered that iron ore beneath the dark ocean form gas, have announced plans to explore the depths of Earth’s oceans to understand the mysterious phenomenon.

Their work “may change the way we look at the possibility of life on other planets as well,” the researchers say.

The first discovery puzzled marine scientists. At first it was accepted that oxygen can be produced only by sunlight and plants – in a process called photosynthesis.

If air – the most important part of life – is produced in the dark with metal particles, the researchers believe that this process can happen on other planets, creating an environment with good air where life can thrive.

Lead researcher Prof Andrew Sweetman explained: “We are already talking to NASA scientists who believe that dark matter could also change our understanding of how life could exist on other planets without sunlight.

“We want to go there to see what’s going on.”

The first discovery started a scientific row around the world – there was to challenge their findings from other scientists and deep-sea mining companies that have planned to harvest precious metals from the ocean’s layers.

If gas is produced in this deep, dark place, it raises questions about what life can do under the sea, and how mining activities can affect marine life.

This means that the mining industry under the sea and environmental organizations – some of which have said that the findings provide evidence that plans for mining under the sea should be stopped – will take a closer look at this new research.

The system is to operate in areas under the sea with a depth of 10km (6.2 miles) using remote sensing equipment.

“We have instruments that can go to the deepest parts of the ocean,” said Prof Sweetman. “We’re sure we’ll find it’s happening somewhere else, so we’ll start investigating what’s causing it.”

Some of these experiments, in collaboration with NASA scientists, are aimed at understanding whether the same process would allow invisible life to live under the seas of other planets and moons.

“If there is air,” said Prof Sweetman, “there may be microbes that take advantage of it.”

The first, shocking biological results were published last year in the journal Nature Geoscience. They came from several trips to the deep sea area between Hawaii and Mexico, where Prof Sweetman and his colleagues sent sensors to the bottom of the ocean – about 5km (3.1 miles) deep.

This area is a large part of the ocean floor that is covered with naturally occurring metals, which are formed when metals dissolved in seawater collect on pieces of shells – or other debris. It is a process that takes millions of years.

The sensors that the team sent back repeatedly show the oxygen levels rising.

“I just ignored it, Prof Sweetman told BBC News at the time,” because I was taught that you only get oxygen through photosynthesis.

Eventually, he and his friends stopped neglecting their reading and began instead to understand what was going on. Experiments in their lab – with tissues the team collected after they were submerged in seawater – led the scientists to conclude that the metal particles were producing oxygen from the seawater. He discovered that the surrounding oceans produced electric currents that could split (or electrolyse) seawater molecules into hydrogen and oxygen.

Then came backlash, such as objections – posted online – from scientists and offshore mining companies.

One of the critics, Michael Clarke from the Metals Company, a Canadian mining company, told BBC News that the criticism focused on “a lack of scientific rigor in the testing and data collection”. Instead, he and other critics said there was no exhaust gas — just bubbles that the devices created while collecting samples.

“We found this impossible,” said Prof Sweetman. “But this [new] trials will give evidence.”

This may seem like a technical argument, but several multi-billion dollar mining companies are already exploring the possibility of harvesting tons of these metals from the ocean floor.

The natural deposits they look for contain the metals needed to make batteries, and demand for those metals is increasing as the economy shifts from fossil fuels to, for example, electric cars.

The race to remove the material has raised concerns among environmental groups and researchers. More than 900 scientists from 44 countries have signed the petition to highlight the dangers of the environment and call for a temporary ban on mining.

Speaking about his team’s recent research at a press conference on Friday, Prof Sweetman said: “Before we do anything, we need – as much as possible – to understand [deep sea] the environment.

“I think the right decision is to stop before we decide if this is the right thing to do as an international community.”