Did We Just Put Tardigrades on the Moon? Probably.

James Maynard
Aug 6, 2019 · 5 min read

As far as tiny, cute, yet utterly bizarre animals go, tardigrades are almost certainly the best known. Also known as water bears, these creatures are only about a millimeter (1/25th of an inch) long, and they are known to survive in extreme conditions, even outer space. Now, it appears thousands of these tiny creatures may now be living on the Moon.

When the Beresheet spacecraft, designed and managed by Israeli space company SpaceIL, crashed into the Moon on April 11, the collision may have spread live tardigrades on the lunar surface.

A tardigrade seen in a microscopic photograph. Image credit: University of Oxford

“For the first 24 hours we were just in shock. We sort of expected that it would be successful. We knew there were risks but we didn’t think the risks were that significant,” Nova Spivack, founder of the Arch Mission Foundation, stated. It was his organization which designed the tardigrade payload.

The robotic lander included thousands of tardigrades (as well as human DNA) encased in resin between layers of nickel, much like an insect trapped in amber between layers of metal. Tape used in holding the biological time capsule in place was also coated with thousands of tardigrades. It is unknown whether the tiny creatures survived the crash, although they are among the most resilient creatures on Earth.


Making the Tardigrade

Normally, these creatures make their home nearly anywhere, although they prefer wet environments like beds of moss. Sediment at the bottom of lakes is a favorite habitat. They are also the only creatures known to be able to survive the harsh environment of space.

Also known as water bears or moss piglets, these hardy creatures live at temperatures as low as -200 Celsius (-328 Fahrenheit), or as high as 150 C (300 F). They survive pressures six times greater than the greatest depths of the ocean, and are highly resistant to radiation and boiling liquids. One study subjected these creatures to the conditions of low Earth orbit for 10 days, and these tiny animals survived the ordeal.

Tardigrades are able to enter a state called tun, in which they expel water from their bodies, retract their legs, and wrap themselves in a tiny, protective ball for 10 years or more.

“I wish I were a waterbear — Then I’d be comfy anywhere
In a vacuum, boiled or frozen — Centuries of happy dozing
Pressure never leaves you in despair, when you’re a waterbear”

— Mal Webb

Their tiny bodies, stretching from 0.5 to 1.2 mm (0.02 to 0.05 inches) in length, are marked by eight legs and tiny hands radiating from an adorably pudgy body.

The term tardigrade is a member of a phylum, a very broad category of animal. Biologists know of roughly 1,000 species within the tardigrade phylum. By comparison, human beings are members of the phylum Chordata, which contains more than 60,000 different species.

A tiny tardigrade with its belly filled with algae.
A tiny tardigrade with its belly filled with algae.
Just 13 days after waking from three decades of sleeping, this tiny tardigrade filled itself up on a well-deserved breakfast of algae. Image credit: Tsujimoto et al. 2016 Cryobiology (photo by Megumu Tsujimoto (NIPR))

Tardigrades have lived on Earth for 500 million years. They are born as fully-formed adults, if a little smaller. They molt their shells as they grow older, as their otherwise-developed bodies grow in size.

A pair of tardigrades frozen in a freezer for more than 30 years in were thawed out and rehydrated. Within a single day, one of creatures was stretching it’s legs following a three-decade nap. Three weeks later, eggs were seen inside the creature’s body. The tardigrade soon laid 19 eggs, of which 14 hatched.

A study published in 2017 examined how different species would react to extinction-level events, including impacts with giant asteroids, gamma-ray bursts, and supernova blasts. The study looked at events so powerful, even the ultra-hardy extremophiles, which live in poisonous, boiling water, would be wiped out of existence. Even the death of the Sun may not be able to kill off this hardy species.

“Surprisingly we find that although human life is somewhat fragile to nearby events, the resilience of Ecdysozoa such as Milnesium tardigradum renders global sterilisation an unlikely event,” the study concluded.

A tardigrade, looking like it is standing.
A tardigrade, looking like it is standing.
Tardigrades are harder to kill than the second Terminator. Image credit: ESA/Dr. Ralph O. Schill

One study profiled in the journal Cell Biology in 2016 suggested tardigrades are, essentially, just a head with four pairs of legs.

Tardigrades may be the first creatures from Earth to travel near the speed of light, as the Starlight program from NASA aims to propel wafer-sized payloads, including tardigrades, into space, propelling the craft with lasers.


This Isn’t How I Pictured Colonizing the Moon

The Beresheet mission launched February 21, and crashed during an attempted landing on April 11. Beginning in 1959, space agencies have purposely (and accidentally) crashed probes on the lunar surface, but the Beresheet accident was the first accidental crash on the Moon since 1971.

A streak and impact spot appear on the Moon where the Beresheet spacecraft impacted the surface. Image credit: NASA
A streak and impact spot appear on the Moon where the Beresheet spacecraft impacted the surface. Image credit: NASA
The impact site of the Beresheet spacecraft on the Moon is seen in this pair of images from the Lunar Reconnaissance Orbiter (LRO). Image credit: NASA

Also included on the failed lander were 30 million digitized pages about the human race.

The DVD-sized time capsule sent to the Moon was the product of the Arch Mission Foundation, an organization dedicated to creating a “backup of planet Earth.” The goal of the organization is to design archives of human knowledge which could last millions or billions of years, and disperse them across the Solar System.

In order to send 30 million pages of data in a form that would be easily readable in millions of years, high-resolution nano-scale images were engraved into a glass matrix. Nickel deposits are then placed on the glass, a single atom at a time.

The Arch Mission Foundation plans to encode the entire English-language contents of Wikipedia on synthetic DNA. This sample will be sent to the Moon by space technology developer Astrobotic.

“Our job, as the hard backup of this planet, is to make sure that we protect our heritage — both our knowledge and our biology. We have to sort of plan for the worst,” Spivak stated.

These may be the first permanent residents of the Moon. Image credit: Newscom

Investigation of the path the spacecraft when it impacted the lunar surface, it is likely the tardigrades survived the impact, the organization determined. The design of the disk would have greatly aided chances for the tardigrades to have survived the impact, investigations reveal. Even if the disk was broken during the crash, analysis shows the disk would have likely broken into large pieces, saving much of its payload. Still, the tiny creatures would not awaken until they were placed in an atmosphere, and allowed to re-hydrate.

It is still uncertain if any of the tardigrades survived the crash, but if any species could survive such an impact and the harsh conditions on the lunar surface, tardigrades could do it. If the first lunar colonists from Earth are tardigrades, so be it.


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James Maynard

Written by

Writing about space since I was 10, still not Carl Sagan. Mailing List/Podcast: https://thecosmiccompanion.substack.com

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