Massive Lava Tubes Detected Under Venus Surface

Scientists have spotted signs of massive underground structures on Venus, including lava tubes that stretch up to a kilometer wide. These findings, drawn from radar images and computer models, suggest the planet's volcanic past runs deep below its harsh surface. The work points to areas around large volcanoes where hollow tunnels formed as lava flowed and cooled.

Background

Venus sits as Earth's closest neighbor, but its thick clouds and searing heat make direct study tough. For decades, spacecraft like NASA's Magellan have pierced through the haze with radar to map the surface. That mission, from the early 1990s, showed vast plains marked by winding channels and dome-like hills, signs of widespread lava flows in the past.

Researchers have long puzzled over these features. Channels snake for hundreds of kilometers, much like rivers of lava on Earth. But Venus lacks Earth's shifting plates, so its geology works differently. Hot material seems to rise from deep inside, pushing up the crust without breaking it into pieces. Recent studies build on old data to look below the surface, where empty spaces from drained lava might hide.

Lava tubes form when a flow's outer layer hardens fast, trapping molten rock inside. As the inner lava empties, a tunnel remains. On Earth, these tubes dot places like Hawaii. On Venus, with gravity close to Earth's at 91 percent, similar caves could exist and stay intact.

Key Details

A team of researchers modeled these tubes using a method called finite element limit analysis. This technique tests how much weight a structure can hold before collapsing. They found tubes up to one kilometer across could stand firm, especially in strong rock areas. Narrower ones, a few hundred meters wide, match the size of surface channels seen in images.

Evidence from Radar Scans

An international group led by experts from the University of Padova examined old radar and height data from past missions. They zeroed in on shield volcanoes over 100 kilometers wide, spots ripe for lava tubes. Four chains of pits stood out, curved lines of holes on volcano slopes covered in lava. These pits line up downhill, just where lava would flow and leave collapsed roofs behind.

The pits mark where tube sections caved in, exposing the voids below. All four sites sit amid thick lava fields, fitting the pattern perfectly. Such features give a glimpse into Venus's fire history without needing to land there.

Other data adds weight. Magellan gravity maps show odd pulls over certain spots, hinting at empty spaces underground. Surface changes near volcanoes like Idunn Mons and Maat Mons suggest fresh lava or ash. A review of evidence says Venus likely has active volcanoes today.

"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." – Marcin Chwała and colleagues

Models of explosive eruptions show ash and gas rising high, even reaching cloud layers. Winds bend these plumes, affecting the air's makeup over time.

What This Means

These tubes could shield future probes from Venus's killer heat, over 460 degrees Celsius, and crushing pressure. Humans might one day explore inside, safe from surface storms. The finds tie into signs of live geology, like coronae—huge rings from rising hot blobs. Of 75 studied, 52 show buoyant material below, driving surface shifts.

Coronae span hundreds of miles, with cracks around them from inner forces. Without plate tectonics, these plumes reshape Venus steadily. Hot material rises, hits a barrier hundreds of miles down, and spreads out, forming the odd shapes.

NASA plans missions to check this. VERITAS will map the surface in high detail with radar, spotting pits or gravity quirks that scream lava tubes. DAVINCI will drop a probe through the air, snapping pictures on the way down and measuring gases that hint at fresh volcanism. VERITAS eyes a 2031 launch, DAVINCI a bit earlier.

If tubes prove real and stable, they open doors to study Venus up close. Pit chains or skylights—natural openings—could let robots in. This builds the case that Venus stirs today, its crust morphing slowly. Past flows left these marks, and new ones might still pour out. The planet's story, once locked in clouds, now shows through these hidden paths.