“Exploring the Cosmos: The Bold ‘Dark Oxygen’ Mission Targeting Distant Worlds”

The original, scientifically puzzling results were released last year in the journal Nature Geoscience. They originated from multiple expeditions to a region of the deep ocean situated between Hawaii and Mexico, where Prof Sweetman and his team placed sensors on the ocean floor – at a depth of approximately 5km (3.1 miles).

This locale is part of an extensive area of ocean floor that is laden with naturally occurring metallic nodules, which develop when dissolved metals in seawater gather on pieces of shell – or other remnants. This phenomenon takes millions of years.

The sensors the team deployed consistently indicated increasing oxygen levels.

“I simply disregarded it,” Prof Sweetman stated to BBC News at the time, “because I had learned that oxygen is obtained solely through photosynthesis.”

Eventually, he and his colleagues ceased ignoring their measurements and embarked on understanding the phenomenon. Laboratory experiments – with nodules that the group collected immersed in beakers of seawater – led scientists to infer that the metallic formations were producing oxygen from seawater. The nodules, they discovered, generated electric currents capable of splitting (or electrolyzing) molecules of seawater into hydrogen and oxygen.

This was followed by a backlash, manifesting as rebuttals – shared online – from scientists and seabed mining enterprises.

One critic, Michael Clarke from the Metals Company, a Canadian deep-sea mining enterprise, informed BBC News that the critique centered around a “lack of scientific rigor in the experimental design and data gathering.” Essentially, he and other detractors asserted that no oxygen production was occurring – merely bubbles formed by the equipment during sample collection.

“We’ve dismissed that possibility,” Prof Sweetman replied. “However, these [new] experiments will furnish the evidence.”

While this might seem a minor, technical dispute, several multi-billion-pound mining corporations are already investigating the opportunity to extract tons of these metals from the seabed.

The natural reserves they are aiming for contain metals essential for manufacturing batteries, and the demand for these metals is soaring rapidly as many economies transition from fossil fuels to, for instance, electric vehicles.

The competition to extract these resources has raised alarms among environmental organizations and researchers. More than 900 marine scientists from 44 nations have signed a petition, external underscoring the environmental hazards and advocating for a moratorium on mining activities.

Discussing his team’s most recent research expedition at a press conference on Friday, Prof Sweetman stated: “Before we proceed with anything, we must – as thoroughly as possible – comprehend the [deep sea] ecosystem.

“I believe the prudent choice is to postpone before we determine if this is the appropriate course of action for global society.”