The Colombian island of Gorgona, in the Pacific Ocean, is part of a very small group of territories in the world that serve as natural analogs of Mars. How can that be? Not precisely because of its very rich biodiversity, but because of a class of rocks called komatiites and basalts, which on the red planet formed billions of years ago and on Earth, 90 million years ago. They are younger than those of Mars, but they are still its “sisters”, and that can make Gorgona a laboratory that would help decipher Mars.
The komatiites and basalts found in Gorgona are also the youngest on Earth, which allows the study of volcanic processes comparable to those that would have occurred on Mars. And that study is carried out by researchers from the Planetary Sciences and Astrobiology Group (GCPA) of the National University of Colombia (UNAL), who integrated data from orbital sensors, analysis of Martian meteorites and previous geological studies, and subjected them to new statistical methodologies that allow precise comparison of the composition of different planetary bodies.
The rocks have the same “chemical signature”
“We asked ourselves whether in Colombia there were places comparable to scenarios such as Hawaii or Iceland. When reviewing the information, we found that the rocks of Gorgona, especially the komatiites, could be a good analog for Mars,” said David Tovar, doctoral candidate in Sciences-Geosciences at UNAL and in Space Research and Astrobiology at the University of Alcala de Henares (Spain), quoted by the UNAL News Agency.
The result not only confirmed that geochemical affinity, but also opened the door to using this territory as a direct reference to study Mars from Earth. “The applications are many, especially because we already have another place here on Earth, but particularly in our country, that will allow the development of research projects focused on planetary geology and astrobiology, and that we will be able to start leading from Colombia,” Tovar added in the same outlet.
This comparison is not based on superficial similarities, but on the “chemical signature” of the rocks, which makes it possible to trace processes from the interior of the planets. It is about the proportion of oxides such as iron, magnesium, aluminum or titanium that compose them, and reveals the conditions of temperature, pressure and origin of the magma that formed them.
“We applied meta-analysis of previously published data, that is, a systematic and comparative review of existing studies, together with ‘compositional figures of merit’, a methodology that allows measuring how similar one material is to another. With that we found that the rocks of Gorgona, particularly the komatiites and basalts, are indeed very similar to those of Syrtis Major on Mars,” Tovar explained.
Study with concrete applications in planetary exploration
To arrive at that comparison, the analysis integrated two fundamental sources of information about Mars: 1) data from remote sensors installed on satellites that orbit the planet —such as spectrometers that analyze the radiation reflected by the surface and allow inferring its mineralogical composition—; and 2) Martian meteorites recovered on Earth, fragments of the crust of Mars that have traveled millions of kilometers and that can be analyzed in the laboratory with high precision to determine their geochemical composition.
On that basis, the team analyzed the composition of the rocks in terms of their main oxides and applied statistical tools that allow establishing distances and proximities between materials, that is, quantifying how similar they are from the chemical point of view. The result: not all rocks match, but those most relevant to understanding volcanic processes do, such as basalts and komatiites, which show a clear affinity with the formations of Syrtis Major.
Beyond the finding, the study has concrete applications in planetary exploration. “Geochemical analogs allow calibrating instruments. If we take instruments to Mars, we must first test them with known materials here on Earth, and those materials are precisely the komatiites and basalts of Gorgona,” the expert explained, and stressed that this type of progress opens the door to greater participation of the country in international projects. “We will be able to contribute to space missions that take instruments to Mars and that have as reference the rocky material of Gorgona. That is something extraordinary,” he said.