The Hunt for Giant Lava Tubes on Venus: A Subsurface Frontier

Scientists are actively investigating the potential for large, stable lava tubes on Venus, a planet characterized by extreme surface conditions. Theoretical modeling suggests Venus's gravitational environment could support structures significantly larger than those found on other planetary bodies. Analysis of decades-old data from NASA's Magellan mission has identified a feature consistent with a collapsed lava tube, adding observational evidence. Future missions equipped with advanced radar are planned to further explore and confirm these subsurface formations.

Introduction to Venusian Lava Tubes

Venus, a planet similar in size to Earth, features surface temperatures exceeding 900 degrees Fahrenheit (482 degrees Celsius), sulfuric acid clouds, and atmospheric pressure nearly 100 times that of Earth. Researchers have proposed the existence of large lava tubes on Venus, which are subterranean channels formed when molten lava flows cease and the surface solidifies. Such structures are also theorized to exist on the Moon and Mars.

Theoretical Predictions and Structural Stability

An international research team utilized Finite Element Limit Analysis (FELA) to model the potential dimensions of lava tubes on Venus. Venus's surface gravity, approximately 91 percent of Earth's, is a key factor in their structural stability.

Calculations suggest that lava tubes on Venus could remain stable at widths up to 0.62 miles (1 kilometer), with estimated stable widths of several hundred meters. These estimates align with the sizes of some channels observed on the Venusian surface. The findings support existing models of Venus's volcanic activity and indicate that potential Venusian lava tubes could possess volumes significantly larger than those found on other planetary bodies.

Evidence from Magellan Mission Data

Scientists have identified what may be a second reported lava tube on Venus through the analysis of data from NASA's Magellan mission, which mapped Venus using radar between 1990 and 1992. This analysis contributes to the ongoing assessment of Venus's geological activity. The dense cloud cover on Venus necessitates radar imagery for geological studies.

Magellan data previously revealed long chains of pits, or collapsed surface areas, some extending for thousands of miles, which indicated the presence of underground lava tubes. Recent research focused on localized surface collapses, which can expose subterranean voids. A specific feature on the western flank of Nyx Mons, a major Venusian volcano, exhibited a radar pattern consistent with the collapse of lava tube roofs. Preliminary analysis suggests this conduit could extend for several dozen kilometers underground, though only a portion is currently ascertainable. Further observations are required to confirm its full extent and stability.

Challenges and Future Exploration Missions

The harsh Venusian environment and dense atmospheric conditions pose challenges for confirming these subsurface structures through orbital surface analysis. However, several upcoming missions aim to investigate:

• NASA's Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI) mission, tentatively scheduled for 2030, will deploy an orbiter and an atmospheric probe to explore the planet's surface.
• NASA's Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy (VERITAS) mission, designed for high-resolution surface scanning, is awaiting final budget approval.
• The European Space Agency's EnVision mission is expected to carry advanced radar instruments, including the Subsurface Radar Sounder (SRS). The SRS is designed to penetrate Venus's surface to depths of several hundred meters and could potentially detect conduits even in the absence of surface openings.

These missions are expected to provide data relevant to the confirmation and study of Venus's suspected lava tubes.