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Tardigrades: The microscopic organisms that could be the first interstellar space travellers © Getty Images

Tardigrades could be the first interstellar space travellers

Published: 18th February, 2022 at 15:46
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A team of physicists, philosophers and biologists have come up with a list of organisms that could withstand the harsh conditions of interstellar space, and tardigrades take the top spot.

In 2019 a spacecraft containing strange, microscopic organisms crash-landed on the Moon. The Beresheet Lunar Lander was the first non-governmental craft to attempt landing on the lunar surface, and it carried a collection of items including a digital copy of Wikipedia, human DNA samples, an Israeli flag, and thousands of tiny animals called tardigrades. We can’t say for sure if any of the so-called ‘water-bears’ survived the crash, but if they did, they are the only Earthlings to have spent years away from their home planet. Until now.

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We spoke to Stephen Lantin, who is part of a team funded by NASA that have drawn up plans to send these ‘water-bears’ to distant stars.

How did the team choose which organisms to send into space?

First and foremost, we decided the organisms needed to be very small. The smaller they are, the more we can pack a bunch of them in. And if a couple of them die, at least we might have some that survive.

Also, the more mass you have, the more energy you need to impart on the spacecraft in order to get it moving.

So that narrowed it down to things like tardigrades, certain forms of bacteria, single cells, and also a worm called C. elegans. This worm is the model organism chosen for a lot of studies in science.

Out of the organisms you chose, it was the tardigrades that seemed to get the most attention. Can you tell me what they actually are?

They're pretty simple organisms. They're known as water bears, because if you look microscopically, they look like eight-legged bears. But what's really cool about them is their radiation tolerance. They have the ability to withstand very extreme environments. People tend to throw around the word ‘extremophiles’, but tardigrades are more ‘extremo-tolerant’ organisms.

You know, if you go outside and find some mossy rocks, take a sample and put it under a microscope: you'll probably find tardigrades.

Read more about 'water-bears':

Can tardigrades survive space?

As part of our selection process we asked, can these organisms survive the space environment? Experiments on the International Space Station have explored this idea, and there are quite a few organisms that can actually survive the radiation environment in space without a lot of shielding. Radiation from the Sun, which we refer to as solar cosmic radiation, and the farther you get out, there’s also galactic cosmic radiation, that comes from elsewhere.

So the organisms we picked, such as tardigrades, have mechanisms that can repair their DNA if it’s damaged by radiation. There's also this really interesting thing called cryptobiosis, a method where these organisms can undergo a sort of hibernation, but on a more intense scale. Their metabolic activity just completely drops. It's almost like they're dead, but they're not, because once conditions are right, sort of like a seed, they can revive themselves. It's really fascinating.

How would you have contact with them while they’re in space?

That's the point, so we’d have different sensors on board along with these organisms, so we can sort of study their behaviour over time. Ideally, we would send them out in there in their dehydrated, cryptobiotic form, and then we would remotely wake them up, with some water or something. We would monitor how many of these tardigrades actually revive in space. Then we can look at how their cells change, is there a genetic response? By looking at the different cells of these tardigrades, we can almost understand what's going on even if we're really, really far away.

And would that tell us about what would happen to humans if we were in their situation?

Yeah, absolutely. This, more than anything, would be testing how life responds to radiation environments that we ourselves haven't experienced. Testing these sorts of things will mean we can better characterise the response not just for small organisms, but for bigger ones as well.

Would they return?

Right now, we definitely don't envision them returning. They get accelerated to very high speeds [on take off], and in order to get them back, we would need to somehow accelerate them in the other direction.

So doesn’t that risk them contaminating other ecosystems?

That is definitely where we get the most flack from people outside of [our research group]. What about all the potential ecosystems that have that might have life on them? Are we ruining them by shooting out life into them?

The short answer is if the spacecrafts are being launched with very high speeds, there's virtually no chance of them surviving an actual impact to the planet.

Anything that is launched that fast and hits any sort of target gets vaporised instantly. There's not really a way at this point to get them to colonise other planets.

We also consider how and what targets we choose when we're shooting these off into space. There's an ethical component to this research, which is why we brought on board our philosopher, Michael Latimer. He is very familiar with the ethics of doing these sorts of things. We had some very interesting conversations.

Tardigrades are microscopic organisms, and they're thought to be the toughest animal in the world © Getty Images
Tardigrades are microscopic organisms, and they're thought to be the toughest animal in the world © Getty Images

Why shouldn’t we just send robots? What is the benefit to sending organisms?

Robots, of course, are good to use – we can use robotics to study exoplanets closer to the source and learn lots of really good information. But, it's not really an either/or. You can probably do both.

In terms of sending biology, this is something that we really have no experience with. We've never really done this before, in terms of sending biologicals that that far into space. The only stuff we've tested is in low-Earth orbit and the Moon. There are some plans to do research outside of low-Earth orbit. There's a biosensing programme at NASA's Ames Air Base in California. But largely, this space is untapped.

We thought it would be a good opportunity to push this out into the world, and see what people thought.

When could tardigrades be sent into space?

We worked with a NASA-funded programme called Project Starlight, and its method for sending spacecraft into interstellar space could be ready in, as a rough estimate, 20 years.

Starlight’s whole big thing is laser sail propulsion: shooting lasers, either from the ground or from a separate spacecraft, and direct it to a laser sail.

You mean, like the wind sail on a boat?

Exactly. Doing that sort of imparts the momentum from the photons in the laser [into the sail] which launches something at really high speeds, wherever you want it to go.

Now, this stuff is new, but it's not completely new. The propulsion physics have been tested. So, we know that something like this would work.

The only problem is scaling it up. We would need very, very large laser arrays ­– like on the size of kilometres – to accelerate things to significant fractions of the speed of light and send a craft like this into space.

That's not to say that large scientific projects like this haven't been done before. Look at CERN: they built a 17-kilometre ring to study particle acceleration. If there's the imperative to do something like this, we could. We have the energy to do it, there’s a lot of good nuclear fusion research coming online. This is something that could be reasonably done.

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However, no one's really working on the biological payloads for interstellar space quite yet. We hope with our paper that we can convince people to start thinking about these things.

About our expert

Stephen Lantin is a Ph.D. Student and NASA Space Technology Graduate Researcher in the UF ABE Department. His current research focuses on automated nutrient analysis in controlled environment, field, and space agriculture using hyperspectral imaging. Previously, Stephen studied interstellar space biology in the UCSB Experimental Cosmology Group and worked on electric propulsion technology in both the public and private sectors.

Authors

Amy BarrettEditorial Assistant, BBC Science Focus

Amy is the Editorial Assistant at BBC Science Focus. Her BA degree specialised in science publishing and she has been working as a journalist since graduating in 2018. In 2020, Amy was named Editorial Assistant of the Year by the British Society of Magazine Editors. She looks after all things books, culture and media. Her interests range from natural history and wildlife, to women in STEM and accessibility tech.

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