We need to talk about radiation in space

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Get away from it all: go beyond in your quest for relaxation. Space hotels promise to capitalize on the ultimate dream. But there’s an elephant in orbit, and nobody talks about it.

“We’ve seen a lot of great orbital hotel concepts lately,” says Dr. Iwan Cornelius. “But none of them seem to be worried about radiation.”

Cornelius is the Managing Director of Amentum Scientific, an Australian predictive scientific modeling company that quantifies radiation exposure risks for the aviation, transport, mining and space industries.

“I guess being sick in space is not good,” jokes the former radiation worker. “It’s a long way to your local GP – and the emergency department.”

Radiation exposure has bothered NASA since the early days of its space programs. This is why the International Space Station (ISS) has a tiny bunker surrounded by water and equipment where astronauts can take shelter.

“One thing you’ll notice with all these concept diagrams for space hotels is that there’s not a whole lot of information about a radiation haven,”

“One thing you’ll notice with all these concept diagrams for space hotels is that there’s not a whole lot of information about a radiation haven,” Cornelius notes.

Space weather forecasting is in its infancy: think solar storms, the cosmic ray background, and relativistic electron precipitation.

A sentinel probe sits halfway between Earth and the Sun. When it detects the passage of charged particles, it triggers an alarm. The advice he gives varies from a few days to a few hours or even a few minutes.

“If we’re talking about a crowded hotel in space, where will they go? Cornelius asks. “How long will it take to get there? Does everyone have access to a shelter – including staff? I don’t know if this is being considered”.

And solar events are not the only source of space radiation.

“We really don’t know much about it,” Cornelius says. “So we need to analyze the numbers to understand the risks.”

Overexposed

Amentum Scientific provides radiation exposure risk models for military and commercial pilots. It’s a surprisingly unregulated space.

“So in Europe, it’s a regulatory requirement that they monitor pilot and crew radiation exposures,” says Cornelius. “Once outside the EU, it’s magically no longer a problem. Nobody wants to know. »

Pilots and cabin crew receive a greater dose of background radiation than nuclear fuel workers and hospital equipment operators. But, as Cornelius points out, the likelihood is very low that aircrew will accidentally be exposed to high-level radiation.

Very little space time reaches our atmosphere. But that’s enough to make a difference.

“There are a few clinical studies showing a slightly elevated incidence of cancer in pilots,” Cornelius says, “but these are weird studies, like melanomas in areas of the body that you wouldn’t expect due to exposure. under the sun. This indicates that it is an X-ray or something else capable of penetrating skin and clothing on the aircraft.

Even protected by Earth’s magnetosphere, astronauts in low Earth orbit are at even greater risk. Some have even reported “seeing” flashes of light. The researchers speculate that it could be cosmic rays hitting the optic nerves or triggering the visual cortex.

“There are a few clinical studies showing a slightly elevated incidence of cancer in pilots,”

Anyone traveling to the Moon or Mars will be completely unprotected – except for the protection they carry with them. And that means damaged DNA and cognitive impairment are almost a certainty.

“Research is ongoing on active shielding – typically creating a synthetic magnetosphere,” Cornelius explains. “But I think we’ll use wormholes before they come. It’s very, very early.”

Rain or shine…

Radiation is a falsely banal word. It encompasses a whole spectrum – from mildly warming infrared to cell-dividing gamma rays.

“Yes, the magnetosphere will deflect a lot of the lower energy stuff, but the higher energy stuff will just pass through and still be where the space station is,” Cornelius explains.

Guests of space hotels are unlikely to face exceptionally high risk. Especially if they only visit for a few days every few years.


Also read: What will happen when humans colonize space?


“As far as short-term space missions go, I wouldn’t be worried about going there for that – as long as there’s a good solar forecast,” Cornelius says.

That’s another matter for the janitor. Hotel staff with similar levels of protection as space shuttle astronauts could absorb about 10 millisievert (mSv) over a period of six months. And that doesn’t include events like solar flares.

The current annual safety limit for the general public is only one mSv. For medical professionals, it’s about three mSv. Shielding is expensive: only mass can absorb radiation.

The alternative is evacuation. This, however, is not always possible, especially in the short term. The ebb and flow of the general background of galactic cosmic radiation can be predicted up to three months in advance, Cornelius explains. But nothing can yet predict a solar event.

“As far as short-term space missions go, I wouldn’t be worried about going there for that – as long as there’s a good solar forecast,”

“A lot of researchers are working on it,” he says. “I’m sure they’ll get there eventually.”

But science is only beginning to grasp the complexities of space weather. The same Van Allen Belts that deflect solar radiation now seem to generate their own storms.

Two radiation belts filled with electrons and charged particles surround the Earth. The interior is fairly stable, but the exterior swells and shrinks over time. Credit: NASA

“There is a precipitation of electrons,” Cornelius says. “Based on what the magnetic fields do, those electrons can go towards the Earth. And that radiation causes a reaction that produces different kinds of radiation. Ultimately, you get gamma rays and X-rays in a beam – a kind of space lightning.

And just like “normal” lightning of the kind we see in a thunderstorm, it’s not something you want to be struck with.

“We have the technology,” Cornelius says. “We build the modeling tools to predict it. We have the hardware to detect it.

deep impact

Space tourism is already taking off. The first tourist was Californian millionaire Dennis Tito, who flew to the ISS in 2001 for $20 million.

Since then, a multitude of space hotel ideas have been floated. Among the latest is orbital assembly‘s Voyager Station. This is supposed to accommodate 400 guests by 2027 in an artificial gravity spinning wheel. A smaller pioneer station, for 28 people, is planned for 2025.

So there is orbital reef. This commercial space station has attracted big names such as Amazon, Boeing, and Arizona State University. Its first stage – slated for launch in the late 2020s – will encapsulate some 830 cubic meters and will accommodate up to 10 people.

On all these boats, sealed safes will not be the solution. “It’s counterintuitive, but the density of lead means it can produce more radiation than comes in,” says Cornelius.

A high-speed charged particle is very likely to strike tightly packed lead atoms. Cornelius says that these collisions produce a lot of neutrons: “And the heavier something is, the more impacts it has.”

That’s why water is – for now – the best protection. “Water is very good at slowing down neutrons,” Cornelius explains. “So in addition to being less dense – and therefore not generating as many secondary particles – it also slows them down. It occupies a good middle ground.

But being less dense means a lot more is needed. And water also tends to be consumed.

“Effluent also contains a lot of water, so I guess you can use it as protection as well,” says Cornelius. In low Earth orbit, foil sheets are an option. “Most of the activity here is low-energy electrons,” Cornelius explains. “You can knock them down with a piece of aluminum a few millimeters thick.”



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