Wednesday , May 18 2022

Humans contaminate the moon with durable microscopic beings called tardigrades


An Israeli spacecraft named Beresheet almost went out on the moon in April. He took selfies with the lunar surface in the background, but then lost contact with the Earth and presumably crashed into the lunar surface. It has now been revealed that the mission was carrying a load of dehydrated microscopic life forms known as tardigrades.

Beresheet was the first phase of a privately funded initiative to transfer living DNA to the moon. The project is intended to act as the Noah's Ark Mark II, providing a repository from which plants and animals could be regenerated to repopulate Earth if the catastrophe were like a flood of biblical proportions, overtook the planet.

Whether the project is farsighted or stupid, what has aroused interest is the fact that, as a result of the collapse, tardigrades can now be scattered on the moon's surface. They are durable creatures and could probably survive on the moon for a long time. This is a problem? I believe this, but probably not for the reasons you might think.

Tardigrades are weird little creatures. Measuring up to about half a millimeter, they have four pairs of stubborn legs and a front end that even the sweetest parent would not consider beautiful. Impressive or distinctive are my adjectives of choice. The moon will be appropriate given the context of the story – with a rounded structure that resembles a pain in the center that can protrude outwards, revealing a set of dangerous-looking sharp teeth.

Credit: Goldstein Lab / Wikimedia Commons [CC BY-SA 2.0]

They are often called water bears, but the images of tardigrades I've seen remind me of a slightly over-inflated swell, one of those big balloons that floats above the head of carnivals. The legs protrude at a slight angle, as if they were too swollen to stand upright. And this is probably the clue why beings are extremely unlikely to survive endlessly on the moon.

Tardigrades can survive extreme temperatures and pressures, including the frigid vacuum of space. They don't seem to mind that they are exposed to radiation and are universally difficult little beings. When they are dehydrated, they twist into a spore-like state that slows their metabolism by a hundredfold, allowing them to survive potentially over 100 years.

But to live their lives to the fullest requires water. This is where they get their oxygen and food, usually colonize lumps of algae or sludge to absorb nutrients from other living creatures, even other tardigrades. So, while the tardigrades will technically stay alive on the moon for some time in their twisted state, unless they are rescued, rehydrated and recharged, they will eventually perish.

Interplanetary pollution

I'm not worried about polluting the moon with organisms that can come to life. My concern is the pollution of the moon, complete shutdown. There is already quite a large amount of debris from the excess space ships and debris left by the astronauts. As more missions to the moon are planned, ultimately with human travelers and perhaps even settlements, we must learn to clean as we go along. Otherwise, we will have the crisis we see on Earth, with the blight on environmental damage from plastics.

However, there is another issue that we need to address. What if the spacecraft crashed when it approached Mars and not the moon? The planet has a poor record for successful landings, though it has improved significantly over the last decade. Would tardigrades survive the invasion of the atmosphere? Although the atmosphere of Mars is thin, it still provides sufficient durability to cause serious damage to the outer shell of the inbound vehicle.

If they had survived, would they have ended up being more successful on Mars than on the moon? We know that there is a lot of ice below the immediate surface of much of the planet. Would an impacted spacecraft deliver enough energy to melt local ice? Is it possible for this molten water to survive without sublimation or freezing long enough for the tardigrades to rehydrate and wake up?

The surface of Mars must be kept pristine. Credit: NASA

I have no idea, but let's speculate that the answer to both questions is yes and that after a crash, a flock? the shallow? pack? – the tardigrades is reactivated. What happens next? As described above, tardigrades need water to survive, not just to rehydrate them. They live on liquids derived from other living things. And as far as we know, there are no living beings on Mars.

But we still send spacecraft to search for life. Shipment of cargo from the tardigrades to Mars would be irresponsible, even if we did not believe they would survive. Irresponsible because Mars has the potential to live. Limited life for sure, but we have no right to endanger this life. And we have a responsibility to keep Mars as close to our virgin as possible, studying it carefully.

This is why space agencies take such strict precautions with respect to spacecraft construction. The premises where the craft is built are cleaner and more sterile than the operating room. They take every precaution to ensure that no earthly life is transferred to Mars.

NASA and ESA are currently planning a mission to return Mars samples to Earth. And safeguards about the possibility of returning Martian life to Earth with rocks are central to the design and construction of the spacecraft.

Last week we had an asteroid passing near Earth. She might be a killer bee next week. Or a plague of thieving spells. But for now, these are the water bears of the moon. We must let them slowly shrink into oblivion.

Monica Grady, Professor of Planetary and Space Sciences, Open University.

This article first appeared in Conversation.

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