Lunar Ark
© University of Arizona.Artist impression of the proposed underground lunar ark.
Researchers at the University of Arizona have proposed an audacious plan to backup Earth's biodiversity in the event of a planetary obliteration, i.e. nuclear war. The idea is to store the genetic material from millions of species below the moon's surface in lava tubes, which could act as a 'lunar ark' that preserves Earth's most cherished resource: the evolution of billions of years of life.

This project is similar to Norway's "Doomsday" Seed Vault, which hosts more than 850,000 different seed samples in the frigid Arctic. Seeds are kept at -18 °C (-3 °F) and should be protected against a number of potential disasters, ranging from global warming to nuclear war.

Likewise, the lunar ark would deposit cryogenically frozen seeds, spores, sperm, and egg samples from millions of species of animals. In order to protect these precious samples, the ark would be stored inside one of the more than 200 lava tubes identified so far beneath the moon's surface.

A lava tube, or pyroduct, is a natural conduit formed by flowing lava from a volcanic vent that moves beneath the hardened surface of a lava flow.

These yawning, subterranean caverns can have heights that dwarf Dubai's Burj Khalifa. Untouched for the last billions of years, these lava tubes provide the perfect shelter from punishing solar radiation, which is why they've been identified as sites for future human bases.

Mare Tranquilitatis
© NASACave entrances like this one in Mare Tranquilitatis may open into lava tubes.
But if we ever colonize the moon in a lava tube, why not take the extra step and build a genetic ark. Besides the ample space and radiation shielding, the temperature inside the lava tubes hovers around a constant -25° Celsius (-15° F), which is ideal for storing sensitive biological samples.

Earth also has lava tubes formed during its early years, but these are much smaller, about the size of subway tunnels, and have been eroded over time by earthquakes, plate tectonics, and other natural processes. The lunar caverns are much better suited to acting as a genetic vault.
"Earth is naturally a volatile environment," said Jekan Thanga, a professor of aerospace and mechanical engineering at the University of Arizona College of Engineering. "As humans, we had a close call about 75,000 years ago with the Toba supervolcanic eruption, which caused a 1,000-year cooling period and, according to some, aligns with an estimated drop in human diversity. Because human civilization has such a large footprint, if it were to collapse, that could have a negative cascading effect on the rest of the planet."
Of course, building an ark on the moon is a huge undertaking. By Thanga's calculations, it would take at least 250 rocket launches to carry about 50 samples from each of the 6.7 million species on Earth. For comparison, it took about 40 rocket launches to build the International Space Station.

These samples would be housed in an underground facility powered by solar panels positioned on the moon's surface. Two or more elevator shafts would lead down to the facility where biological samples would be housed in various cryogenic preservation modules.

Inside the modules, the samples would float above metal surfaces thanks to a phenomenon known as quantum levitation. Maintenance would be ensured by robots navigating above magnetic tracks.

This lava tube is in Hawaii, but the features could be even bigger on the Moon.
© ZME ScienceThis lava tube is in Hawaii, but the features could be even bigger on the Moon.
All of this may sound wack, but it definitely is in the realm of possibility — we already have the technology at our disposal after all. It's just a matter of directing resources and gaining public support.

Just the other day, China and Russia announced that they have plans to build a lunar outpost together. Elsewhere, the US has plans for its own lunar base called Artemis after it lands astronauts back on the moon in 2024.
"What amazes me about projects like this is that they make me feel like we are getting closer to becoming a space civilization, and to a not-very-distant future where humankind will have bases on the moon and Mars," said Álvaro Díaz-Flores Caminero, a University of Arizona doctoral student leading the thermal analysis for the project. "Multidisciplinary projects are hard due to their complexity, but I think the same complexity is what makes them beautiful."
The project was described in a paper presented over the weekend during the IEEE Aerospace Conference.