Even as we look for life beyond the Earth, there are plenty of places on our own planet we haven’t fully explored. And every time we do, we find organisms unexpectedly thriving under even the most extreme conditions. Colonies have been discovered in subways, among nuclear waste, and most recently, according to a new study, on the scorching surfaces of solar panels.
The study, published in Scientific Reports this week, found more than 500 different microbes living on solar panels at the University of Valencia in Spain. Genetic analysis revealed that most of the microbes are “extremophiles,” seeing as they live on surfaces with an average temperature of 51°C (124°F). Microbes have been found on solar panels before, but in much smaller numbers and in much different climates.
How did they get to Spain? Microbes can travel large distance by riding the wind. The species found on the panels probably came from places like the Sahara Desert or the Tibetan plateau. For these microbes, solar panels represent a sort of “urban microdesert,” with little water but lots of heat and radiation from the sun. These spots allow extremophile microbes to survive in the otherwise mild Mediterranean climate.
The solar-panel microbes are mainly pink, orange, or red. This is thanks to the carotenoids they produce, the same sorts of pigments found in carrots. These colors help some bacteria tolerate the heavy radiation they are bombarded with. For others, carotenoids strengthen cell walls against extreme heat. Microbes on the panels also produce special lipids (fatty chemicals), which researchers think help grip the smooth surface of the panels.
Extremophiles describe any microbe living in a harsh environment, from the high-pressure depths of the ocean to toxic hot springs. Their ability to survive where nothing else can is, in a word, otherworldly.