Lava Tubes on Moon & Mars are Really, Really Big - Enough to Fit Entire Planetary Base

List members , it's official now - even mainstream science has declared underground Lava tubes on our Moon and on Mars as the best potential sites to build a base . Interestingly , Earth too has many such Lava tubes...hmm :))

Lava Tubes on the Moon and Mars are Really, Really Big. Big Enough to Fit an Entire Planetary Base

Could lava tubes on the Moon and Mars play a role in establishing a human presence on those worlds? Possibly, according to a team of researchers. Their new study shows that lunar and Martian lava tubes might be enormous, and easily large enough to accommodate a base.

Both the Moon and Mars were volcanically active at one time, and all that activity has left its mark on both worlds. Mars hosts the largest volcano in the Solar System, Olympus Mons, as well as numerous lava tubes. The Moon has no volcanoes, but orbiters have spotted lava tubes on the surface. And those tubes are attracting more and more attention, as future plans for a habitat of some sort on both worlds are taking shape.

A team of researchers from Italian universities have completed a new study into these tubes. Its title is “Lava tubes on Earth, Moon and Mars: A review on their size and morphology revealed by comparative planetology.” The lead author is Riccardo Pozzobon, a planetary geologist at the Department of Geosciences of the University of Padua. The study is published in the journal Earth-Science Reviews.

The evidence for lava tubes—or pyroducts—on Mars and the Moon is in the form of long sinuous raised channels, and in so-called “sky-lights,” where the roof of a lava tube has caved in. There are lots of orbiter images of these features, though unfortunately they haven’t been explored yet.

This is a cropped version of a HiRISE image of a lava tube skylight on the martian volcano Pavonis Mons. Image Credit: By NASA / Jet Propulsion Laboratory / University of Arizona –, Public Domain, File:Pavonis Mons lava tube skylight crop.jpg - Wikimedia Commons

In their paper, the authors write that “On the Moon subsurface cavities have been inferred from several skylights in Maria smooth plains and corroborated using gravimetry and radar sounder, while on Mars several deep skylights have been identified on lava flows with striking similarities with terrestrial cases.”

“We can find lava tubes on planet Earth, but also on the subsurface of the Moon and Mars according to the high-resolution pictures of lava tubes’ skylights taken by interplanetary probes. Evidence of lava tubes was often inferred by observing linear cavities and sinuous collapse chains where the galleries cracked”, explained co-author Francesco Sauro in a press release.

Spectacular high Sun view of the Mare Tranquillitatis pit crater revealing boulders on an otherwise smooth floor. The 100 meter pit may provide access to a lunar lava tube. Image Credit: By NASA/GSFC/Arizona State University –, Public Domain, File:Mare Tranquillitatis pit crater.jpg - Wikimedia Commons

To try to better understand them, the authors of the new paper created an overview of lava tubes on Earth, then compared them to data from Mars and the Moon.

“These collapse chains represent ideal gateways or windows for subsurface exploration. The morphological surface expression of lava tubes on Mars and the Moon is similar to their terrestrial counterpart. Speleologists thoroughly studied lava tubes on Earth in Hawaii, Canary Islands, Australia and Iceland,” Sauro said.

An image of a lava tube on Mars’ Alba Mons, from NASA’s Viking Orbiter. Image Credit: NASA

Lava tubes are formed by flowing lava. As the outside of the flowing lava cools and hardens, it forms a tube through which liquid lava flows. That lava can drain out of the tube, leaving a hollow structure that can travel for a long way, and be very voluminous. On Earth, the longest lava tube is the Kazamura Cave in Hawaii. It’s 65.5 km (40.7 mi) long. Sometimes they’re apparent from linear pit chains on the surface which are connected linearly underground.

There’s a key difference between lava tubes on Earth and other places, though. On Earth, lava tubes and their skylights form from volcanic activity. But on the Moon and Mars, some tubes and skylights can form from impact melt and other processes. “Likewise,” the authors write, “on the Moon not all skylights formed in volcanic terrains, but also in impact melts, therefore in these cases other processes are probably responsible for their formation. For these reasons, any study aiming to identify lava tube collapses and skylight candidates on the surface of these planetary bodies has to follow a rigorous approach based on a geomorphological comparison with terrestrial analogues.”

This figure from the study shows the main morphological and morphometric characters of tectonic pit chains on Mars (l) and on the Moon (r). For more info, see the study. Image Credit: Pozzobon et al, 2020.

The authors wanted a way to quantify lunar and Martian lava tubes, and to understand their morphology. Though we’ve never explored these tubes on either world, there’s lots of orbital data available. That was key to this study.

“We measured the size and gathered the morphology of lunar and Martian collapse chains (collapsed lava tubes), using digital terrain models (DTMs), which we obtained through satellite stereoscopic images and laser altimetry taken by interplanetary probes”, said Riccardo Pozzobon. “We then compared these data to topographic studies about similar collapse chains on the Earth’s surface and to laser scans of the inside of lava tubes in Lanzarote and the Galapagos. These data allowed us to establish a restriction to the relationship between collapse chains and subsurface cavities that are still intact.”

What they found was that Earthly lava tubes pale in comparison to their lunar and Martian counterparts. Earthly tubes have diameters in the 10 to 100 meter (33 to 330 ft) range. But Martian tubes are about 100 times wider than that, and lunar tubes are positively gargantuan in comparison: 1000 times wider. The difference is due to the lower gravity on both worlds, and its effect on volcanism.

This figure from the study shows some tubes, vents, and skylights on the Arsia Mons volcano on Mars. Image Credit: Pozzobon et al, 2020.

This figure from the study shows some tubes, vents, and skylights on the Arsia Mons volcano on Mars. Lava tubes on Mars can be 100 times wider than on Earth, according to the study. Image Credit: Pozzobon et al, 2020.

“Tubes as wide as these can be longer than 40 kilometres, making the Moon an extraordinary target for subsurface exploration and potential settlement in the wide protected and stable environments of lava tubes,” Pozzobon said. “The latter are so big they can contain Padua’s entire city centre.”

But are they stable environments? Many orbital pictures show collapsed lava tubes, with skylights dotting the tubes. According to Matteo Massironi, they are stable, thanks to the lower gravity, and impacts are to blame for the collapses and skylights.

“What is most important is that, despite the impressive dimension of the lunar tubes, they remain well within the roof stability threshold because of a lower gravitational attraction,” explains Matteo Massironi, who is professor of Structural and Planetary Geology at the Department of Geosciences of the University of Padua. “This means that the majority of lava tubes underneath the maria smooth plains are intact. The collapse chains we observed might have been caused by asteroids piercing the tube walls. This is what the collapse chains in Marius Hills seem to suggest. From the latter, we can get access to these huge underground cavities.”

These huge underground areas would solve some of the problems associated with habitats on Mars and the Moon. At the top of the list is radiation. While Earth’s atmosphere and magnetosphere keep life on Earth mostly safe from radiation, the same isn’t true for the Moon or for Mars. Long-term exposure to all that radiation is a significant cancer risk.

But a habitat under all that rock would be well-protected from both cosmic radiation and solar radiation. It would also be safe from micrometeorites, another hazard that has to be contended with. The temperature would also be more stable. And on Mars, the tubes and caves could possibly provide a viable habitat for any life that might exist on that planet. After all, here on Earth caves and lava tubes are a specialized habitat that provides shelter for adapted organisms.

Lava tubes on Earth and Mars. On the left is Australia’s Undara Lava Tube, and on the right is a Martian lava tube at Arsia Mons. Image Credit: Pozzobon et al, 2020.

“Lava tubes could provide stable shields from cosmic and solar radiation and micrometeorite impacts which are often happening on the surfaces of planetary bodies,” said co-author Francesco Sauro. “Moreover, they have great potential for providing an environment in which temperatures do not vary from day- to night-time. Space agencies are now interested in planetary caves and lava tubes, as they represent a first step towards future explorations of the lunar surface (see also NASA’s project Artemis) and towards finding life (past or present) in Mars subsurface.”

But before talk of bases and habitats in lava tubes heats up too much, it’s worth keeping mind that we haven’t seen inside one yet. And while Earthly lava tubes have been explored, we just don’t know how close the comparison will really be. So it’s time for one of the space agencies to prioritize that in their mission planning and selection.

Astronauts with the ESA have already done some lava tube exploring here on Earth as part of their training. In 2016, ESA astronauts Luca Parmitano and Pedro Duque explored lava tubes and caves in Spain’s Canary Islands. These landscapes are used because they’re thought to be very similar to Mars.

ESA astronauts exploring lava caves and tubes in Spain as part of their training. Image Credit: ESA–M. Barnabei

The ESA also put out the word that they’d like to hear proposals for lunar lava tube exploration.

“In autumn 2019, ESA called up universities and industries with a campaign seeking ideas for developing technologies for lunar caves exploration. They are specifically looking for systems that would land on the lunar surface to operate missions exploring lunar tubes,” said Unibo professor Jo De Waele, who is one of the authors of this study and a speleologist.

“Since 2012, in collaboration with some European universities including Bologna and Padua, ESA has been carrying out two training programmes for astronauts focusing on the exploration of underground systems (CAVES) and planetary geology (PANGAEA). These programmes include lava tubes on the island of Lanzarote. So far, 36 astronauts from five space agencies have received training in cave hiking; moreover, six astronauts and four mission and operation specialists have received geological field training.”

The Corona Volcano on Lanzarote in the Canary Islands. It features lava tubes and skylights that mimic conditions on Mars. Image Credit: Pozzobon et al, 2020.

The Corona Volcano on Lanzarote in the Canary Islands. It features lava tubes and skylights that mimic conditions on Mars. Image Credit: Pozzobon et al, 2020.

It might be considered overly-ambitious to send astronauts into lunar lava caves. They’re specialized environments even here on Earth. If there were any accidents, an injured astronaut in a cave on the Moon would be a very delicate situation.

Over on the NASA side of things, scientists are considering robotic exploration. NASA scientists have proposed the “Moon Diver” mission. It would use a rover tethered to a lander to explore lava tubes on the Moon. The lander would land in proximity to a skylight, then the tethered rover would be deployed to climb its way down to the floor of the tube.

Four panels from a video presentation on the Moon Diver concept. Image Credit: KISSCaltech

A mission to explore lava tubes on Mars is likely a long, long way off. But if one is ever developed, it won’t have a shortage of targets. The United States Geological Service says that there are over 1,000 candidate cave entrances on Mars.

This is a map of lave cave candidates in the post-volcanic Tharsis Region on Mars. Image Credit: USGS/Mars Global Cave Candidate Catalog.

It’s clear that space agencies have set their sights on lava tubes. A lunar habitat might be years or decades away, but it seems likely that we’ll build one. And when we do, it’ll take a special kind of human to live in an underground lava tube on another world.


Folks , I think this is almost a "disclosure level" article , because it's openly revealing a long held secret - that underground lava tubes on any world , are the most suitable locations to build a colony or a obviously implies that this is true NOT just for humans looking to colonise , but also any Extraterrestrial species :))

Entire cities could fit inside the moon's monstrous lava tubes

Just don't slice your spacesuit open on the cave wall.

A prototype rover creeps through a lava tube in Spain’s Canary Island of Lanzarote, part of a training campaign to explore settings on Earth that could be similar to those on the moon and Mars.

A prototype rover creeps through a lava tube in Spain’s Canary Island of Lanzarote, part of a training campaign to explore settings on Earth that could be similar to those on the moon and Mars. (Image credit: ESA/Robbie Shone)

Mars is pockmarked with absolutely massive lava tubes, with ceilings as high as the Empire State Building, new research shows. And the moon hosts even more gargantuan tubes, with heights that dwarf Dubai's Burj Khalifa, the world's tallest building, and "skylights" as big as football fields.

These yawning, subterranean caverns, which are shielded from punishing solar radiation, could be used as sites for future human bases, scientists argue.

A lava tube is a tunnel under a world's surface, formed by an intense flow of molten rock during a volcanic explosion. On Earth, they're most easily spotted when they collapse, forming long furrows in the dirt. Partial collapses sometimes form chains of "skylights" that reveal hidden lava tubes that are mostly intact. Researchers have speculated that lava tubes might exist on Mars and the moon since the 1960s, but in recent years Martian and lunar orbiters have beamed home images showing how common these formations likely are, both on the Red Planet and on our moon. Now, researchers argue in a new paper published July 20 in the journal Earth-Science Reviews, it's time to explore them in earnest.

Here's why: These lava tubes are truly enormous, and might offer safer habitats than the lunar or Martian surfaces.

"The largest lava tubes on Earth are maximum [about] 40 meters [130 feet] of width and height," said study co-author Riccardo Pozzobon, a geoscientist at the University of Padova, Italy. "So like a very large motorway tunnel."

An image from the Mars Reconnaissance Orbiter shows a possible lava tube on Mars near the southern flank of the Martian volcano Arsia Mons.
An image from the Mars Reconnaissance Orbiter shows a possible lava tube on Mars near the southern flank of the Martian volcano Arsia Mons. (Image credit: Mars Reconnaissance Orbiter/NASA)

That's certainly big enough space for some people to fit inside. But on Mars collapsed lava tubes tend to be about 80 times larger than Earth's, with diameters of 130 to 1,300 feet (40 to 400 m). Lunar lava tubes seem to be still larger, the researchers found, with collapse sites 300 to 700 times the size of Earth's. Lunar lava tubes likely range from 1,600 to 3,000 feet (500 to 900 m).

A lava tube on the moon, Pozzobon told Live Science, could easily contain a small city within its walls.

The sheer scale of these extraterrestrial lava tubes is likely a result of low Martian and lunar gravity, as well as differences in how volcanoes operated on those bodies compared to Earth.

To assess the size of lunar and Martian lava tubes, the researchers collected 3D laser scans of their counterparts — both collapsed and intact — on Earth. Then they collected all the available satellite images of collapsed lava tubes on Mars and the moon and modeled the size of the intact tubes based on the relationships between collapsed and intact tunnels on Earth.

Lava tubes make appealing human habitats for a number of reasons, including protection from meteors that don't burn up as easily in the thin Martian and lunar atmospheres, the researchers wrote. They also likely contain useful chemicals, like water ice and volatile chemicals that can be used to make fuel. A thick layer of rock overhead can also, as Live Science previously reported, offer shielding against solar radiation. And skylights would still offer easy access to the surface.

Science-fiction authors like Kim Stanley Robinson have occasionally imagined pressurizing craters or lava tubes and filling them with air. But Pozzobon said that scenario is unlikely, not least because in the moon's lava tubes, openings can be as wide as a football field.

"Due to their huge size and the possibility of having leaks due to the fracturing of the rocks, I would see pressurizing them very unlikely," Pozzobon told Live Science. "What is more likely is to establish settlements within these voids, either to host humans or for storing equipment."

Even stashing a base inside a lava tube presents challenges, however.

"Although a lava tube could provide a shelter to thermal excursion, radiation and micro impacts, it is not easily accessible and the basaltic rocks of its interior can be razor-like sharp and the terrain very uneven," he said. "So the engineering challenges of placing inflatable habitats within such impressive caves is not trivial and requires very detailed studies."

Right now, the immediate challenge is gathering more information about the intact lava tubes on the moon and Earth. Right now, researchers can only identify them from satellite images of skylights or collapses. But differentiating a skylight from a simple hole in the ground is tricky. Researchers look for angled images of the holes that reveal the void underneath, he said, or other geological hints of a nearby cave. But nothing beats direct exploration, the researchers wrote.

Models suggest that Martian lava tubes were more likely to have grown to the point of collapse when the planet was volcanically active, and might be harder to find intact. A greater proportion of lunar tubes are probably structurally sound, the researchers wrote. That makes the moon's lava tubes better candidates for exploration.

It's important, the researchers wrote, that scientists develop a detailed plan for exploring the tubes. Right now, no rover is autonomous enough or built with the right equipment to go spelunking on the moon or Mars. And before designing and launching a rover to perform that task, satellites equipped with ground-penetrating radar or other remote-sensing technology should build detailed maps of tube formations underground. The process of discovering ideal sites for human sub-lunar or sub-Martian habitation will likely take a long time and involve many intermediate steps, the researchers wrote..

So while Earth may seem like a particularly inhospitable place right now, it's a little too soon to pack up and relocate to an extraterrestrial lava tube.

Originally published on Live Science.


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Thanks @Soretna , cosmic/solar radiation is such a big factor that underground habitats like Lava tubes are invariably the best potential locations for selecting a site to build bases/colonies on other worlds .

Besides radiation , there could be other cosmic hazards on the surface of planets that have very thin atmospheres , or none at all . So it's really not the worth the risk to try and build bases on the surface of other planets .

Some extraterrestrial species probably realised this fact long before humans did...!

Somewhat similar factors (though in a different context) made the D.U.M.B. concept so prevalent among major world powers , starting from the 1970s .

I wonder what Elon Musk thinks about all this :))


Folks , I think this "disclosure" proves why it is (almost) futile , to search for extraterrestrial civilisations on the surface of other planets - the real deal is UNDERGROUND !!