In April 2019 the Israeli spacecraft Beresheet crashed into the lunar surface carrying thousands of dehydrated tardigrades inside a “lunar library” – and later impact tests put the survival cutoff for tardigrades at around 900 metres per second, almost exactly Beresheet’s crash speed, meaning we still don’t know whether Earth life is now lying dormant on the Moon with no water to revive it. – Image for illustrative purposes only (Image credits: Pixabay)
In 2019 a privately built spacecraft from Israel set out to achieve the first commercial landing on the Moon. Instead it slammed into the surface at high speed, scattering its contents across Mare Serenitatis. Among those contents were thousands of dehydrated tardigrades tucked inside a compact archive. Years later scientists still cannot say with certainty whether any of those microscopic animals survived the crash.
The Mission That Ended in Impact
The spacecraft, named Beresheet, reached lunar orbit without incident. Its final descent began normally until the main engine shut down unexpectedly about ten kilometres above the surface. Telemetry recorded at 149 metres altitude showed the vehicle still moving at nearly one kilometre per second. The lander struck the basalt-rich plain at a shallow angle and broke apart on contact.
SpaceIL and Israel Aerospace Industries had designed the mission as a low-cost demonstration. The loss of the vehicle was therefore a technical setback rather than a total surprise. What made the event notable was the payload that rode along with the main spacecraft.
A Nickel Archive Carrying Hidden Passengers
Engineers had packed a small stack of nickel sheets into the lander. The sheets held microscopic etchings that preserved roughly thirty million pages of text, language keys, human DNA samples, and a full copy of the English Wikipedia. The archive was meant to serve as a durable backup of human knowledge that could last for geological ages on an airless world.
Shortly before launch, several thousand tardigrades in their dried tun state were added between the sheets. They were sealed with tape and epoxy resin. The addition remained undisclosed until after the crash. The animals were intended to show that living material could travel alongside the recorded information.
Laboratory Tests Set a Clear Limit
Researchers at the University of Kent later fired desiccated tardigrades from a light-gas gun into sand targets. The animals withstood impacts up to roughly 0.9 kilometres per second and shock pressures of 1.14 gigapascals. Above those values only fragments were recovered. Survivors from the highest successful shots revived more slowly than usual, indicating some internal stress even when they remained whole.
These laboratory numbers sit very close to the final speed recorded for Beresheet. The spacecraft’s metal structure would have generated even higher pressures on contact with lunar regolith. Whether the archive was thrown clear before the worst of the shock remains unclear from available imagery.
Life Without Water on the Lunar Surface
Even if some tardigrades endured the impact, revival would require liquid water. The Moon offers none at the crash site. Daytime temperatures reach 120 degrees Celsius while nights drop to minus 170. The animals can remain in suspended animation for long periods, yet they cannot resume normal activity without rehydration.
The crash therefore did not establish a self-sustaining population. At most it left a small number of dormant organisms scattered across a few square metres of dust. They will stay paused until water arrives or they are moved to a location where water exists.
What the Episode Means for Future Missions
Planetary-protection rules already limit biological material on most spacecraft. The Beresheet payload had not been declared in advance, prompting quiet discussions among space agencies about private missions. The same impact data now helps scientists judge how life might travel between other worlds on natural ejecta.
- Survival thresholds constrain models of panspermia from Mars to its moons.
- Similar numbers apply to material collected from icy plumes on Enceladus.
- Future landers will need clearer disclosure of any biological components.
The tardigrades remain on the Moon in a state that is neither confirmed dead nor proven alive. Their presence marks the first time humans have accidentally delivered Earth life to another celestial body. Whether that delivery succeeded in any meaningful sense is still unknown.