A new approach to estimating the likelihood of life on Venus has been proposed by researchers at NASA’s Ames Research Center, reviving the debate over whether Earth’s closest planetary neighbor may once have hosted life.
The Venus Life Equation (VLE), introduced at the 2025 Lunar and Planetary Science Conference, offers a structured way to assess life’s potential not just in the past, but also in the present and future.
Reframing The Search For Life In The Solar System
According to Science Alert, most efforts to find life beyond Earth focus on Mars and the icy ocean moons of the outer Solar System. Venus, by contrast, receives far less attention—even though it has some surprising similarities to Earth.
Despite its harsh surface conditions, Venus is a rocky planet with a similar size, mass, and composition to Earth. It also sits on the inner edge of the habitable zone, the region where liquid water could theoretically exist.
The key difference lies in how their atmospheres evolved. While Earth developed a stable, life-supporting climate, Venus experienced a runaway greenhouse effect, turning it into one of the most extreme and hostile environments in the Solar System.
Introducing The Venus Life Equation
The new equation, titled Probability of Planetary Life: The Venus Life Equation and Unknowns for Other Worlds, was presented by Diana Gentry, Director of the Aerobiology Laboratory at NASA Ames. It follows the conceptual model of the Drake Equation, serving not as a predictive tool, but as a “scaffold for estimating the chance of life based on factors that can be constrained or quantified through observation, experiment, and modelling.”
The Venus Life Equation is defined as: L = O × R × C, where “O (origination), the chance of life arising and becoming established prior to the time in question; R (robustness), the potential size and diversity of the biosphere over time; and C (continuity), the chance that conditions amenable to life persisted spatially and temporally until the time in question,” the researchers explained.
Unlike the Drake Equation, the VLE narrows the scope to a single planet, considering specific events in planetary history rather than interstellar probabilities.
Schematic of the VLE. The final estimate for L in this figure represents an illustrative example using potential low and high ranges of estimates for each factor. (Izenberg et al. 2021)
Challenges In Defining The Equation’s Variables
Each variable of the equation poses distinct challenges. Origination includes life starting via abiogenesis, panspermia, or multiple independent events. One of the hardest to assess is the chance of “breakout”.
For Robustness, the model depends on nutrient availability (especially CHNOPS), energy sources, and the planet’s biological diversity.” A low R value indicates a small or fragile biosphere more vulnerable to extinction from the threats captured in the final continuity term,” the authors state.
Continuity, the third term, considers the long-term survival of habitable conditions. This includes geological and orbital stability, nutrient recycling, and threats such as volcanic activity or large impacts. Even biogenic instability can tip the balance, as Earth’s Great Oxygenation Event once did.
“A value of 0 for C indicates that there has been at least one total extinction event between the point in time of the origin event (including breakout) and the time being assessed,”the researchers write. Whether Earth itself ever experienced a full extinction followed by a resurgence of life remains unknown.
