Posted on 07/15/2022 11:01:16 AM PDT by Red Badger
TRAPPIST-1e TRAPPIST-1e is a rocky exoplanet in the habitable zone of a star 39 light-years from Earth and may have water and clouds, as depicted in this artist’s impression. Credit: NASA/JPL-Caltech
https://en.wikipedia.org/wiki/TRAPPIST-1e
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To search for alien life, astronomers will search for clues in the atmospheres of distant planets – and NASA’s James Webb Space Telescope just proved it’s possible to do so.
The ingredients necessary for life are spread throughout the universe. While Earth is the only known place with life in the universe, detecting life beyond our planet is a major goal of modern astronomy and planetary science.
We are two researchers who study exoplanets and astrobiology. Thanks in large part to powerful next-generation telescopes like James Webb, scientists like us will soon be able to measure the chemical makeup of atmospheres of planets orbiting around other stars. It is hoped that we will detect a chemical signature of life on one or more of these exoplanets.
Kepler-186 and the Solar System
There are many known exoplanets in habitable zones – orbits not too close to a star that the water boils off but not so far that the planet is frozen solid – as marked in green for both the solar system and Kepler-186 star system with its planets labeled b, c, d, e and f. Credit: NASA Ames/SETI Institute/JPL-Caltech
Habitable exoplanets
Life might exist in our solar system where there is liquid water – such as in the oceans of Jupiter’s moon Europa or in the subsurface aquifers on Mars. Searching for life in these places is incredibly difficult, however, as they are hard to reach and detecting life would require sending a probe to collect and return physical samples.
Many astronomers believe there’s a good chance that life exists on planets orbiting other stars, and it’s possible that’s where extraterrestrial life will first be found.
There are around 300 million potentially habitable planets in the Milky Way galaxy alone, according to theoretical calculations, and several habitable Earth-sized planets within only 30 light-years of Earth – essentially humanity’s galactic neighbors. Astronomers have discovered over 5,000 exoplanets so far, including hundreds of potentially habitable ones, using indirect methods that measure how a planet affects its nearby star. While these measurements can give astronomers basic information on the mass and size of an exoplanet, they don’t provide much else.
Chlorophyll Absorbs Wavelengths
Every material absorbs certain wavelengths of light, as shown in this diagram depicting the wavelengths of light absorbed most easily by different types of chlorophyll. Credit: Daniele Pugliesi/Wikimedia Commons, CC BY-SA
Looking for biosignatures
To detect life on a distant planet, astrobiologists will inspect starlight that has interacted with a planet’s surface or atmosphere. If the atmosphere or surface was transformed by life, the light may carry a clue, called a “biosignature.”
For the first half of its existence, Earth sported an atmosphere without oxygen, even though it hosted simple, single-celled life. Earth’s biosignature was very faint during this early era. That changed abruptly 2.4 billion years ago when a new family of algae evolved. The algae used a process of photosynthesis that produces free oxygen – oxygen that isn’t chemically bonded to any other element. From that time on, Earth’s oxygen-filled atmosphere has left a strong and easily detectable biosignature on light that passes through it.
When light bounces off the surface of a material or passes through a gas, certain wavelengths of the light are more likely to remain trapped in the gas or material’s surface than others. This selective trapping of wavelengths of light is why objects are different colors. Leaves are green because chlorophyll is particularly good at absorbing light in the red and blue wavelengths. As light hits a leaf, the red and blue wavelengths are absorbed, leaving mostly green light to bounce back into your eyes.
The pattern of missing light is determined by the specific composition of the material the light interacts with. Because of this, astronomers can learn something about the composition of an exoplanet’s atmosphere or surface by, in essence, measuring the specific color of light that comes from a planet.
This method can be used to recognize the presence of certain atmospheric gases that are associated with life – such as oxygen or methane – because these gasses leave very specific signatures in light. It could also be used to detect peculiar colors on the surface of a planet. On Earth, for example, the chlorophyll and other pigments plants and algae use for photosynthesis capture specific wavelengths of light. These pigments produce characteristic colors that can be detected by using a sensitive infrared camera. If you were to see this color reflecting off the surface of a distant planet, it would potentially signify the presence of chlorophyll.
Webb Biggest Orbital Telescope
The James Webb Space Telescope is the first telescope able to detect chemical signatures from exoplanets, but it is limited in its capabilities. Credit: NASA/Desiree Stover
Telescopes in space and on Earth
To detect these subtle changes to the light coming from a potentially habitable exoplanet, it takes an incredibly powerful telescope. For now, the only telescope capable of such a feat is the new James Webb Space Telescope. As it just began science operations in July 2022, Webb took a reading of the spectrum of the gas giant exoplanet WASP-96b. Although the spectrum showed the presence of water and clouds, a planet as large and hot as WASP-96b is unlikely to host life.
However, this early data shows that James Webb is capable of detecting faint chemical signatures in the light coming from exoplanets. In the new few months, Webb is set to turn its mirrors toward TRAPPIST-1e, a potentially habitable Earth-sized planet located a mere 39 light-years from Earth.
Webb can look for biosignatures by studying planets as they pass in front of their host stars and capturing starlight that filters through the planet’s atmosphere. But Webb was not designed to search for life, so the telescope is only able to scrutinize a few of the nearest potentially habitable worlds. It also can only detect changes to atmospheric levels of carbon dioxide, methane and water vapor. While certain combinations of these gasses may suggest life, Webb is not able to detect the presence of unbonded oxygen, which is the strongest signal for life.
Leading concepts for future, even more powerful, space telescopes include plans to block the bright light of a planet’s host star to reveal starlight reflected back from the planet. This idea is similar to using your hand to block sunlight to better see something in the distance. Future space telescopes could use small, internal masks or large, external, umbrella-like spacecraft to do this. Once the starlight is blocked, it becomes much easier to study light bouncing off a planet.
There are also three enormous, ground-based telescopes currently under construction that will be able to search for biosignatures: the Giant Magellan Telescope, the Thirty Meter Telescope, and the European Extremely Large Telescope. Each is far more powerful than existing telescopes on Earth, and these telescopes might be able to probe the atmospheres of the closest worlds for oxygen, despite the handicap of Earth’s atmosphere distorting starlight.
Animals, including cows, produce methane, but so do many geologic processes.
Is it biology or geology? Even using the most powerful telescopes of the coming decades, astrobiologists will only be able to detect strong biosignatures produced by worlds that have been completely transformed by life.
Unfortunately, most gases released by terrestrial life can also be produced by nonbiological processes – cows and volcanoes both release methane. Photosynthesis produces oxygen, but sunlight does, too, when it splits water molecules into oxygen and hydrogen. There is a good chance astronomers will detect some false positives when looking for distant life. To help rule out false positives, astronomers will need to understand a planet of interest well enough to understand whether its geologic or atmospheric processes could mimic a biosignature.
The next generation of exoplanet studies has the potential to pass the bar of the extraordinary evidence needed to prove the existence of life. The first data release from the James Webb Space Telescope gives us a sense of the exciting progress that’s coming soon.
Written by:
Chris Impey, University Distinguished Professor of Astronomy, University of Arizona
Daniel Apai, Professor of Astronomy and Planetary Sciences, University of Arizona
This article was first published in The Conversation.
I'm really tired of that crap. Those "artist's impressions" are worse than useless. Show me real imagery, real data.
The artists impression increases the chance of their being clouds and water there by how much?
Jwst nasa trying really hard to justify their huge delays and cost overruns.
“... Just Proved It’s Value in the Search for Alien Life”
I’ll accept that as true, but how valuable, in terms of money spent, is the search for alien life?
Years later, Patricia Neal, in an interview said that she and Michael Rennie had a had time getting thru the shoots because they couldn’t stop laughing at the ridiculous script!................
They are real easing photographsic images
Is this the same guy who does artists interpretations of the earth instead of, you know, an actual picture?
A figure most likely based on extrapolating data from known exoplanets and applying it to the total number of stars estimated to be in the milky way.
One problem here is that the star type which our sun belongs comprises about 7 percent of total stars.
So, the number likely drops to about 21 million. Still a large number but it drops significantly further when only the percentage of stars in the milky way that occupy our galaxy's habitable zone are counted.
That number drops further when stars not having relatively stable output are taken from the mix. On and on the reduction goes.
I just hope they don’t find life on Uranus.
Ha! They got me too. I’m thinking, wow - if it can capture THAT image it’s amazing ... and then they tell us it’s an ‘artist representation.’
I want my dollar back.
The mount for the Large Magellan Telescope is being built here, locally:
https://en.wikipedia.org/wiki/Giant_Magellan_Telescope
Well, it WILL be, just as soon as they complete the building that it’s going to be built in..
Can’t wait to get a tour of that, in a few years.
A great big Army camoflage ball, lost in space!
Now if we could just get a good picture of a UFO we’d really have something 🤪
Speaking of light, that one reminded me of
Mat 5:14 Ye are the light of the world. A city that is set on an hill cannot be hid.
😃
Thanks Red Badger.
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The closest star system to us is only four and one half light Year’s away, now at a speed we can understand let’s get up to say 700 miles per hour we may speed up or slow down depending on what we pass on the way,don’t forget to set the alarm because we will reach our destination in only 850 million years...
Blow’s my mind just to think about it....
To do interstellar travel by any conventional means that we know of today IS impossible.
But I hope you are not assuming that we know everything there is to know.
The math proves that there are ways to travel faster than light. Commonly called ‘wormholes’ it is the bending of space/time to effectively jump from one place to another.
Bob Lazar explained that this is exactly how the alien spacecraft currently being studied at Area 51/ S4 work.
Bob Lazar. Boy there’s a name I haven’t heard in a while. Of course it was on Art Bell’s old show on Coast to Coast Am and what a show it was. I would get an hours sleep staying up all night to listen and then go to work. Heheh, I was younger then ;)
Well, let us hope we make it someday but it would be nice to send the better minds out there first, imho.
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