Mould found at the site of the Chernobyl nuclear disaster appears to be feeding off the radiation. Could we use it to shield space travellers from cosmic rays?

In May 1997, Nelli Zhdanova entered one of the most radioactive places on Earth – the abandoned ruins of Chernobyl's exploded nuclear power plant – and saw that she wasn't alone.

Across the ceiling, walls and inside metal conduits that protect electrical cables, black mould had taken up residence in a place that was once thought to be detrimental to life.

In the fields and forest outside, wolves and wild boar had rebounded in the absence of humans. But even today there are hotspots where staggering levels of radiation can be found due to material thrown out from the reactor when it exploded.

The mould – formed from a number of different fungi – seemed to be doing something remarkable. It hadn't just moved in because workers at the plant had left. Instead, Zhdanova had found in previous surveys of soil around Chernobyl that the fungi were actually growing towards the radioactive particles that littered the area. Now, she found that they had reached into the original source of the radiation, the rooms within the exploded reactor building.

With each survey taking her close to harmful radiation, Zhdanova's work has also overturned our ideas about how radiation impacts life on Earth. Now her discovery offers hope of cleaning up radioactive sites and even provide ways of protecting astronauts from harmful radiation as they travel into space.

Eleven years before Zhdanova's visit, a routine safety test of reactor four at the Chernobyl Nuclear Power Plant had quickly turned into the world's worst nuclear accident. A series of errors both in the design of the reactor and its operation led to a huge explosion in the early hours of 26 April 1986. The result was a single, massive release of radionuclides. Radioactive iodine was a leading cause of death in the first days and weeks, and, later, of cancer.

In an attempt to reduce the risk of radiation poisoning and long-term health complications, a 30km (19 mile) exclusion zone – also known as the "zone of alienation" – was established to keep people at a distance from the worst of the radioactive remains of reactor four.

But while humans were kept away, Zhdanova's black mould had slowly colonised the area.

Like plants reaching for sunlight, Zhdanova's research indicated that the fungal hyphae of the black mould seemed attracted to ionising radiation. But "radiotropism", as Zhdanova called it, was a paradox: ionising radiation is generally far more powerful than sunlight, a barrage of radioactive particles that shreds through DNA and proteins like bullets puncture flesh. The damage it causes can trigger harmful mutations, destroy cells and kill organisms.

Along with the apparently radiotropic fungi, Zhdanova's surveys found 36 other species of ordinary, but distantly related, fungi growing around Chernobyl. Over the next two decades, her pioneering work on the radiotropic fungi she identified would reach far outside of Ukraine. It would add to knowledge of a potentially new foundation of life on Earth – one that thrives on radiation rather than sunlight. And it would lead scientists at Nasa to consider surrounding their astronauts in walls of fungi for a durable form of life support.

At the centre of this story is a pigment found widely in life on Earth: melanin. This molecule, which can range from black to reddish brown, is what leads to different skin and hair colours in people. But it is also the reason why the various species of mould growing in Chernobyl were black. Their cell walls were packed with melanin.

Just as darker skin protects our cells from ultraviolet (UV) radiation, Zhdanova suspected that the melanin of these fungi was

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