Beyond Earth: Purple Bacteria’s Link to Finding Life Elsewhere

Key Takeaway

Astrobiologists propose that purple bacteria might be better biosignatures than green plants for detecting life on exoplanets, offering a new perspective in the search for extraterrestrial life.

Purple bacteria that use simpler forms of photosynthesis and don’t produce oxygen might be more prevalent on a wider range of exoplanets than green plants, and could serve as a stronger biosignature for detecting potential life on other worlds.

Summary

• Astrobiologists are searching for signs of life on exoplanets. They are looking beyond green plants and chlorophyll for these signs. They focus on alternative biosignatures to detect possible life.
• A recent study shows that purple bacteria are unique. They have simpler systems for photosynthesis. They also use different pigments, known as bacteriochlorophyll. These bacteria can grow in a wider variety of conditions compared to green plants.
• Purple bacteria live in many places on Earth. They are found in shallow waters, marshes, and deep-sea hydrothermal vents. They might have been common on early Earth. This was before plants started doing photosynthesis.
• Purple bacteria thrive on planets that circle cooler red dwarf stars. Red dwarf stars are the most abundant type in our galaxy.
• On exoplanets dominated by purple bacteria, their clear pigments would produce a unique “light fingerprint” detectable by future telescopes.
• The researchers modeled Earth-like planets where purple bacteria dominate the surface and showed the impact on the reflectance spectra of these exoplanets.
• Studying the signatures of purple bacteria could improve the chances of detecting life on exoplanets with upcoming telescopes, complementing the traditional search for green plant-like biosignatures.
• The research provides a new resource to guide the detection of purple bacteria, expanding the database of potential signs of life for future exoplanet observations.

The Cosmic Hunt for Purple Life: Bacteria Could Outshine Plants as Biosignatures

Astrobiologists always search for signs of life in space. They often look for green plants’ signs on distant planets. But, a new study shows we might have missed something important. It suggests purple bacteria could be a more common sign of life in the universe.

Before plant photosynthesis evolved, Earth looked very different. It was full of purple bacteria instead of green plants. These purple bacteria are tough. They live in many places, from shallow marshes to deep hydrothermal vents. They use a basic form of photosynthesis that doesn’t make oxygen.

Purple bacteria are different from green ones. They use special pigments, like bacteriochlorophyll. These pigments absorb infrared and low-energy red light. This lets them thrive in harsh conditions that plants can’t handle. This ability makes them likely to survive on many exoplanets.

According to Lígia Fonseca Coelho, a postdoctoral associate at the Carl Sagan Institute and lead author of the study,

“Purple bacteria can thrive under a wide range of conditions, making it one of the primary contenders for life that could dominate a variety of worlds.”

The research team characterized the reflectance spectra of various purple sulfur and non-sulfur bacteria found on Earth, involving a vibrant palette of colors, including yellow, orange, brown, and red. These distinct hues result from the unique pigments that enable the bacteria to harness energy from different wavelengths of light.

On a hypothetical exoplanet dominated by purple bacteria, the surface would emit a distinctive “light fingerprint” detectable by next-generation telescopes. By modeling Earth-like planets where these bacteria reign supreme, the researchers demonstrated the impact of their signatures on the reflectance spectra of terrestrial exoplanets.

Lisa Kaltenegger, director of the Carl Sagan Institute and co-author of the study, emphasized the importance of expanding our understanding of potential biosignatures:

“We need to create a database for signs of life to make sure our telescopes don’t miss life if it happens not to look exactly like what we encounter around us every day.”

The study shows important results for finding life on exoplanets. These planets orbit red dwarf stars, the most common stars in our galaxy. By looking beyond signs of green plant life, we boost our chances of finding different kinds of life.

As we eagerly await the launch of next-generation telescopes, such as the James Webb Space Telescope and the Extremely Large Telescopes, the study provides a valuable resource to guide the detection of purple bacteria, potentially Revealing a new chapter in the cosmic tale of life’s diversity.

HASHTAGS:

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Sources

• Cornell University News
• Monthly Notices of the Royal Astronomical Society
• NASA Exoplanet Exploration
• Universe Today
• YouTube Video