A fresh examination of
radar data for Venus obtained by NASA’s Magellan spacecraft in
the 1990s indicates the presence of a large underground cavity
created by a lava flow, the first subsurface feature ever
detected on Earth’s planetary neighbor.
Researchers said the radar data was consistent with a
geological feature called a lava tube that is found in certain
volcanic locations on Earth. Lava tubes also exist on the moon
and are thought to be present on Mars.
Venus has carefully guarded its secrets, with its surface
shrouded by thick noxious clouds. But radar can peer through
these clouds.
Scientists had theorized the presence of lava tubes on
Venus, considering its history of volcanism.
“Moving from theory to direct observation marks a major step
forward, opening the door to new lines of research and providing
crucial information for future missions aimed at exploring the
planet,” said Lorenzo Bruzzone, a radar and planetary scientist
at the University of Trento in Italy, senior author of the study
published on Monday in the journal Nature Communications.
The researchers analyzed data acquired by Magellan’s
Synthetic Aperture Radar remote-sensing instrument from 1990 and
1992 at locations bearing signs of localized surface collapses
suggestive of lava tubes beneath. They used a recently developed
data-analysis method aimed at identifying underground cavities
like lava tubes.
The structure they detected, interpreted as part of an empty
lava tube, is on the western flank of the Nyx Mons, which is a
shield volcano – a broad and gently sloped volcano whose overall
shape resembles a warrior’s shield – measuring about 225 miles
(362 km) wide and located in the planet’s northern hemisphere.
The area has a large number of pits caused by surface collapses.
“Our knowledge of Venus is still limited, and until now we
have never had the opportunity to directly observe processes
occurring beneath its surface,” University of Trento radar
scientist and study lead author Leonardo Carrer said.
Venus has a diameter of about 7,500 miles (12,000 km),
slightly smaller than Earth. Magellan mapped 98% of the Venusian
surface. Its data helped give scientists a basic understanding
of the surface of Venus, which possesses more volcanoes than any
other planet in our solar system and exhibits extensive evidence
of past lava flows on its surface.
“Lava tubes are natural underground tunnels created by
volcanic activity. They usually form within basaltic lava flows,
where low-viscosity lava continues to move beneath a solidifying
surface,” Bruzzone said.
The Magellan instrument’s side-looking observation geometry
was able to spot radar reflections coming from underground
cavities.
The apparent lava tube identified in the data has an
estimated average diameter of about six-tenths of a mile (1 km),
a roof thickness of at least 490 feet (150 meters) and an empty
cavity reaching a height of at least a quarter of a mile (375
meters). Due to the Magellan data’s limitations, only the
initial portion of the structure could be directly observed. The
researchers suspect it is much longer, stretching perhaps
several miles.
Its dimensions make it both wider and taller than lava tubes
found on Earth or predicted for Mars. It lies at the upper end
of the size range expected – and in one case already observed –
on the moon. The researchers said the structure’s size is not
entirely surprising considering that lava channels observed on
the Venusian surface are larger and longer than those present on
other planets and moons in our solar system.
“Intense volcanic activity is known to have played a major
role in shaping the surface and geology of Venus, as well as in
driving exchanges between the planet’s interior and its
atmosphere. Recent studies suggest that some volcanoes on Venus
may still be active today, a possibility that future missions to
the planet are expected to clarify and better constrain,”
Bruzzone said.
By its very nature, a lava tube would not be related to
ongoing volcanism, Bruzzone said.
Venus is the second planet from the sun, Earth third and
Mars fourth. Venus has received much less scientific attention
than Mars, but two important missions are looming – the European
Space Agency’s Envision and NASA’s Veritas.
Both spacecraft will carry advanced radar systems capable of
capturing higher-resolution images. Envision will carry an
orbital ground-penetrating radar capable of probing the Venusian
subsurface to depths of several hundred yards (meters).
“The coming decade promises to be a pivotal one for Venus
research,” Carrer said.
Published on February 9, 2026
