There is a window to Mars in a paradisiacal volcano in Costa Rica

Laguna Caliente do Poás, one of the most extreme stratovolcanoes on the planet, recreates the conditions of a primitive Red Planet.

In the middle of the arid and desolate landscape of Poás volcanoa recent satellite image captures a stunning contrast of lush green.

What Landsat 8 caught in the volcano, 2,697 meters high and estimated to be between 1.5 million and 700 thousand years old, was the Hot Lagoonwhose pH is around zero, similar to that of battery acid.

The lagoon of one of the most extreme stratovolcanoes on the planet is toxic to animals and plants, but it houses a resilient microbial community, made up mainly of bacteria of the genus Acidophiluscapable of surviving by feeding on metallic compounds dissolved in corrosive waters.

Situated in the heart of Poás Volcano National Park in the province of Alajuela, Costa Rica, Caliente is one of the best terrestrial analogues for studying the conditions that may have allowed it to emerge billions of years ago. NASA’s Astrobiology team guarantees that Poás challenges the traditional perception of a habitable environment.

The similarity between Poás and certain areas of Mars arouses great scientific interest. Studies show that more than 3 billion years ago the red planet had volcanic and hydrothermal systems comparable to those on Earth. One such location is the region known as Home Plate, explored by NASA’s Spirit rover in 2009, explains . There, scientists believe that an acidic and geothermal environment almost identical to that of Laguna Caliente may have existed.

The volcano’s activity is intense: in the last two hundred years, Poás has recorded dozens of significant eruptions and several dozen smaller events. Since 2005, 13 mild eruptive phases have occurred, according to the . The most recent one began on January 5, 2025 and remained active for much of the year, temporarily affecting air quality in San José — about 16 kilometers away — and causing ashfall on nearby plantations.

In 2022, it will be clear that the low biodiversity and high resilience of the microbial community in Laguna Caliente are very similar to what researchers expect to have developed in potential Martian ecosystems.