Spectral color

Astrobiologists are developing a ‘color catalog’ to identify extraterrestrial life

Cornell’s Carl Sagan Institute has revolutionized the way researchers think about space and its inhabitants by creating a method of identifying extraterrestrial life: color cataloging.

The process of color cataloging involves analyzing the pigments of microorganisms in extreme environments on Earth and recording the color they reflect when exposed to certain wavelengths of light. The colors – ranging from dark purples to vibrant greens – are cataloged to provide a reference when analyzing color reflections from other planetary surfaces.

“[Life] has different shapes, different colors, different organisms, different relationships between organisms, so it varies,” said Lígia Fonseca Coelho, an astrobiologist working with Professor Lisa Kaltenegger, astronomer and director of the Carl Sagan Institute.[Catalogs] are a way… to try to solve [this variation].”

Coelho and Kaltenegger are currently working on expanding a catalog they created that encompasses the colors reflected by a variety of microorganisms on Earth, focusing specifically on the frigid microorganisms of Hudson’s Bay. in Canada. They do this by cataloging specific samples of life on Earth from specific types of environments, in order to add their signatures to a database. Kaltenegger explained that this database will act as a forensic toolkit that will help researchers find life in the universe, both inside and outside this solar system.

According to Kaltegger, the microbiota analysis procedure was originally developed in 2015 at the Carl Sagan Institute. Coelho continued to help develop the method in 2015 helping to include microorganisms from frozen environments that were originally missing from the catalog.

Coelho collected over 80 different biota from frozen environments. They are microorganisms that thrive in ice, mirroring some of the conditions seen in space. The microorganisms were then taken to Portugal to be identified, with the most dynamic being taken to the Carl Sagan Institute at Cornell.

Coelho had discovered this dynamism by chance. After leaving collected microbiota on her bench, she noticed that they were exponentially more colorful than the hydrated and observed samples. The moment of oblivion led to the monumental discovery that microorganisms displayed more vibrant pigments when exposed to more extreme conditions. From a more universal perspective, this information can be applied to studying possible extraterrestrial life on anything from icy exoplanets to extreme desert planets.

The biopigments produced by these microbes have great advantages. The first is that they are produced under stressful situations, so the colors can be predicted based on the type of environment the microorganisms would inhabit. The second is that their dynamism allows them to be easily identified in these extraterrestrial environments.

“We use Earth as the key to finding life in the cosmos – it’s the only place we know life exists,” Kaltenegger said. “Using the diversity of life on Earth as a key, we can begin to search for it on other planets and moons.”

On March 15, Kaltenegger and Coelho recently published the article “Color Catalog of Life in Ice: Surface Biosignatures on Icy Worlds” in the journal Astrobiology with some of these findings. “[We] wondered if there is life that can thrive in icy environments on Earth. If it can thrive here, maybe it can thrive on frozen planets or icy moons elsewhere too,” Kaltenegger said. “[I]If it leaves a colorful imprint on frozen worlds, then we may be able to spot it with the next generation of telescopes that will search the cosmos for life.

Kaltenegger explained that these colorful frozen microorganisms on Earth are what lead to the conclusion of possibilities of other diverse life forms similarly evolving.

However, according to Coelho, although the Earth is the only reference for the colors living things reflect in different environments, it is not a perfect system. The researchers acknowledged that the planets explored may not exactly match the colors present in the catalog, but it may give them an idea of ​​what to look for.

The creation of this reference has deepened the understanding of the colors that make up the Earth, as well as how life on Earth may possibly be related to the planets of the universe. “We have created the first spectra catalog of life that can survive and thrive in frozen environments on Earth,” Kaltenegger said. “[We] have a key to finding life on other frozen worlds in the cosmos.