Venus has long been known as Earth’s evil twin. While they both are roughly the same size and formed in the same inner region of the solar system, Venus is far less hospitable to life as we know it. Its surface temperatures can reach over 900 degrees Fahrenheit. Its clouds are made of sulfuric acid, and its surface atmospheric pressure is almost 100 times that of Earth, the equivalent of being 3,000 underwater.
And beneath all those extreme conditions, the planet could harbor cavernous structures called lava tubes, as an international team of researchers suggests in a new paper accepted for publication in the journal Icarus.
On Earth, lava tubes are the byproduct of volcanic activity that is left behind as liquid lava retreats, and are believed to exist on the Moon and Mars as well.
While they may not serve as a great place to build a shelter for space travelers on Venus — the conditions are far too extreme for any human presence — the case that the planet may harbor them is building.
That’s in part due to the planet’s surface gravity being only around 91 percent of Earth’s, allowing tubes up to 0.62 miles across to be structurally stable, the researchers found.
“Our results suggest that lava tubes with widths of a few hundred meters may remain stable, and these dimensions are consistent with observed Venusian channel sizes,” the paper reads.
The researchers are now calling on “future missions with higher-resolution imaging and geophysical investigation capacities” to look for pit chains, rows of circular depressions that have been found on several planetary bodies, skylights, or vertical openings leading to underground channels, and subsurface voids.
The scientists used a common technique, called Finite Element Limit Analysis (FELA), to estimate the upper bounds of lava tube sizes that can exist on Venus’s surface.
The findings build on previous studies that attempted to model the planet’s “explosive volcanism.” It’s also not the first time astronomers have found evidence for the tubes’ existence. A study last year similarly concluded that lava tubes could indeed exist on the planet.
“Earth lava tubes have smaller volumes, Mars tubes have slightly bigger volumes, and then the Moon’s tubes have even bigger volumes,” said University of Padova researcher Barbara De Toffoli during a meeting last year, as quoted by New Scientist. “And then there’s Venus, completely disrupting this trend, displaying very, very big tube volumes.”
However, to confirm the existence of these huge channels firsthand could prove immensely difficult. Apart from an extreme local environment, the planet is covered in a thick layer of dense clouds, making analyzing its surface from orbit a great challenge.
Fortunately, NASA’s Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI) mission, which is tentatively scheduled to launch in 2030, will see an orbiter and atmospheric probe explore the planet’s surface.
An additional mission, dubbed Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy (VERITAS), was designed to scan the planet’s surface with high-resolution near-infrared and radar instruments.
While DAVINCI has survived major budgets and was allocated the funds for an additional year, the fate of the VERITAS mission remains uncertain. The Trump administration’s proposed NASA budget would’ve killed both missions, but a counteroffer by Congress, recently approved by the Senate, has kept the hopes of searching for Venus’ suspected lava tubes alive.
More on the lava tubes: Scientists Confirm Massive Underground Tunnels on Venus