Podcaster: Tony Darnell
Title: Deep Astronomy – Exoplanet Radio – Ep. 39: Biosignatures: The Search for Life Beyond Earth
Organization: Deep Astronomy
Link : https://deepastronomy.space
Twitter @DeepAstronomy, https://facebook.com/DeepAstronomy
YouTube: https://www.youtube.com/deepastronomy
Description: From September 20, 2023.
In recent years, scientists have made great strides in the search for extraterrestrial life. They have discovered thousands of exoplanets. And some of them are located in the habitable zone of their star, which means that liquid water could exist on their surface and is essential for life as we know it.
The search for life however, is a little more involved than finding planets, measuring their location and distance around the star and figuring out their location within a habitable zone. Astronomers need more information to learn if life may be there.
Bio: Tony Darnell is the owner of Deep Astronomy website and a host for the same hangout channel in Youtube. He has worked in the field of astronomy all my life, his first job was at a school district planetarium in Boulder, Colorado. With the exception of a stint in the Army in the 1980’s he has worked in many aspects of astronomical research.
Most of his time has been spent writing software to retrieve, process and analyze data taken from telescopes. He has worked with data from some of the world’s largest ground-based and space-based telescopes: from the four meter Blanco telescope in Chile to the Hubble Space Telescope.
Astronomy education has always been his passion and he has written articles for DeepAstronomy.space website and produce astronomy videos for YouTube on the DeepAstronomy channel.
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Transcript:
In recent years, scientists have made great strides in the search for extraterrestrial life. They have discovered thousands of exoplanets, and some of them are located in the habitable zone of their star, which means that liquid water could exist on their surface and is essential for life as we know it. The search for life, however, is a little more involved than finding planets, measuring their location and distance around the star, and figuring out their location within a habitable zone.
Astronomers need more information to learn if life may be there. The first thing we need to know is whether or not the planet has an atmosphere, and thanks to the Webb Space Telescope, we are starting to get a handle on that data point with every observation it makes, using its onboard near-infrared spectrometer. Once astronomers detect an atmosphere, the real fun begins.
Finding biosignatures. Biosignatures are indicators of the presence of life, traces left behind by living organisms. These indicators can be chemical, biological, or physical.
An example of a physical biosignature would be things like fossils, and since that requires that we have a physical presence on the planet, I mean we can’t see those from here, not even with JWST, then we are left with chemical and biological indicators. The best examples of biosignatures that we can detect from so far away are atmospheric gases and organic molecules. Certain gases, such as oxygen and methane, can be produced by biological processes.
However, they can also be produced by non-biological means. For example, oxygen can be produced by photosynthesis, but it can also be produced by geological activity. The presence of atmospheric gases in a planet’s atmosphere could be a sign of life, but it is important to consider other evidence as well, like organic compounds.
Organic molecules are the building blocks of life. They include amino acids, lipids, carbohydrates, and nucleic acids. Organic molecules can be detected in the atmospheres of exoplanets using a technique called transit spectroscopy.
Spectroscopy involves splitting light into its component wavelengths. Organic molecules absorb light at specific wavelengths, so by looking for dips in the spectrum of an exoplanet, scientists can identify the presence of organic molecules. JWST is currently the best instrument we have that can detect biosignatures in this way.
It looks at absorbed starlight that has passed through the exoplanet’s atmosphere to see what elements were absorbed. Just recently, it reported the possibility of the organic molecule dimethyl sulfide in the planet K2-18b, a compound that on Earth is produced primarily by phytoplankton, which are microscopic organisms that live in the ocean. Dimethyl sulfide can also be produced by some other biological processes, but it is not known to be produced by anything other than life.
Dimethyl sulfide is a gas, so it can be detected in the atmospheres of exoplanets using spectroscopy. It is also relatively stable in the atmosphere, so it can accumulate to detectable levels. All this makes dimethyl sulfide an ideal biosignature gas.
It’s important to note that the detection of a single biosignature is not definitive evidence of life. However, the presence of multiple biosignatures in the same place would be very strong evidence. Additionally, if a biosignature is detected in a place where it is unlikely to be produced by non-biological processes, such as, say, in a Martian meteorite, then it is more likely to be a sign of life.
The James Webb Space Telescope and the future Habitable Worlds Observatory are two powerful tools that we have to search for life on other planets. Imagine the day when we discover signs of life beyond Earth. It would be a watershed moment in human history, one that would change our understanding of our place in the universe forever.
Exoplanet Radio is produced by Deep Astronomy. The music is by G.O.D.Z. and available at lochnessproductions.com. Get all episodes from exoplanetradio.com or anywhere you get podcasts. You are listening to the 365 Days of Astronomy Podcast. Cool.
[Speaker 2]
The 365 Days of Astronomy Podcast is produced by the Planetary Science Institute. Audio post-production is by me, Richard Drumm. Project management is by Aviva Yamani and hosting is donated by Libsyn.com.
This content is released under a Creative Commons Attribution, non-commercial 4.0 international license. Please share what you love, but don’t sell what’s free. This show is made possible thanks to the generous donations of people like you.
Please consider supporting our show on patreon.com forward slash CosmoQuestX and get access to bonus content. Without your passion and contribution, we won’t be able to share the stories and inspire the world. We invite you to join our community of storytellers and share your voice with listeners worldwide.
As we wrap up today’s episode, we’re looking forward to unraveling more stories from the universe. With every new discovery from ground-based and space-based observatories and each milestone in space exploration, we come closer to understanding the cosmos and our place within it. Until next time, let the stars guide your curiosity.
End of podcast:
365 Days of Astronomy
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The 365 Days of Astronomy Podcast is produced by Planetary Science Institute. Audio post production by me, Richard Drumm, project management by Avivah Yamani, and hosting donated by libsyn.com. This content is released under a creative commons Attribution-NonCommercial 4.0 International license. Please share what you love but don’t sell what’s free.
This show is made possible thanks to the generous donations of people like you! Please consider supporting our show on Patreon.com/CosmoQuestX and get access to bonus content. Without your passion and contribution, we won’t be able to share the stories and inspire the worlds. We invite you to join our community of storytellers and share your voice with listeners worldwide.
As we wrap up today’s episode, we are looking forward to unravel more stories from the Universe. With every new discovery from ground-based and space-based observatories, and each milestone in space exploration, we come closer to understanding the cosmos and our place within it.
Until next time let the stars guide your curiosity