Life could be evolving right now on nearest exoplanets

Life could be evolving right now on nearest exoplanets
Artist impression of a young Earth around a red Sun. Credit J. O'Malley-James, Carl Sagan Institute, Cornell University Credit: Jeff Tyson

Excitement about exoplanets skyrocketed when rocky Earth-like planets were discovered orbiting in the habitable zone of some of our closest stars – until hopes for life were dashed by the high levels of radiation bombarding those worlds.

Proxima-b, only 4.24 light years away, receives 250 times more X-ray radiation than Earth and could experience deadly levels of ultraviolet radiation on its surface. How could survive such a bombardment? Cornell University astronomers say that life already has survived this kind of fierce radiation, and they have proof: you.

Lisa Kaltenegger and Jack O'Malley-James make their case in a new paper, published in Monthly Notices of the Royal Astronomical Society. Kaltenegger is associate professor of astronomy and director of Cornell's Carl Sagan Institute, at which O'Malley-James is a research associate.

All of life on Earth today evolved from creatures that thrived during an even greater UV radiation assault than Proxima-b, and other nearby exoplanets, currently endure. The Earth of 4 billion years ago was a chaotic, irradiated, hot mess. Yet in spite of this, life somehow gained a toehold and then expanded.

The same thing could be happening at this very moment on some of the nearest exoplanets, according to Kaltenegger and O'Malley-James. The researchers modeled the surface UV environments of the four exoplanets closest to Earth that are potentially habitable: Proxima-b, TRAPPIST-1e, Ross-128b and LHS-1140b.

Lisa Kaltenegger, director of the Carl Sagan Institute at Cornell University, describes new research findings that demonstrate our nearest exoplanet neighbors could host life. Credit: Cornell University

These planets orbit small red dwarf stars which, unlike our sun, flare frequently, bathing their planets in high-energy UV radiation. While it is unknown exactly what conditions prevail upon the surface of the planets orbiting these flaring stars, it is known that such flares are biologically damaging and can cause erosion in planetary atmospheres. High levels of radiation cause biological molecules like nucleic acids to mutate or even shut down.

O'Malley-James and Kaltenegger modeled various atmospheric compositions, from ones similar to present-day Earth to "eroded" and "anoxic" atmospheres—those with very thin atmospheres that don't block UV radiation well and those without the protection of ozone, respectively. The models show that as atmospheres thin and ozone levels decrease, more high-energy UV radiation reaches the ground. The researchers compared the models to Earth's history, from nearly 4 billion years ago to today.

Although the modeled planets receive higher UV radiation than that emitted by our own sun today, this is significantly lower than what Earth received 3.9 billion years ago.

"Given that the early Earth was inhabited," the researchers wrote, "we show that UV radiation should not be a limiting factor for the habitability of planets orbiting M stars. Our closest neighboring worlds remain intriguing targets for the search for life beyond our solar system."

An opposite question arises for planets orbiting inactive M stars on which the radiation flux is particularly low: Does the evolution of life require the high levels of radiation of early Earth?

To judge the potential habitability of worlds with varying rates of radiation influx, the researchers assessed the mortality rates at different UV wavelengths of the extremophile Deinococcus radiodurans, one of the most radiation-resistant organisms known.

Not all wavelengths of UV radiation are equally damaging to : For example, write the researchers, "a dosage of UV radiation at 360 [nanometers] would need to be three orders of magnitude higher than a dosage of radiation at 260 [nanometers] to produce similar mortality rates in a population of this organism."

Many organisms on Earth employ survival strategies – including protective pigments, biofluorescence, and living under soil, water or rock – to cope with high levels of that could be imitated by life on other worlds, the researchers note. Subsurface life would be more difficult to find on distant without the kind of atmospheric biosignatures telescopes can detect.

"The history of life on Earth provides us with a wealth of information about how biology can overcome the challenges of environments we would think of as hostile," O'Malley-James said.

Said Kaltenegger: "Our research demonstrates that in the quest for life on other worlds, our closest worlds are fascinating targets to explore."


Explore further

The hunt is on for closest Earth-like planets

More information: Jack T O'Malley-James et al, Lessons from early Earth: UV surface radiation should not limit the habitability of active M star systems, Monthly Notices of the Royal Astronomical Society (2019). DOI: 10.1093/mnras/stz724
Provided by Cornell University
Citation: Life could be evolving right now on nearest exoplanets (2019, April 9) retrieved 20 May 2019 from https://phys.org/news/2019-04-life-evolving-nearest-exoplanets.html
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Apr 09, 2019
"How could life survive such a bombardment? Cornell University astronomers say that life already has survived this kind of fierce radiation, and they have proof: you."

Not only has human, animal and plant life been able to survive radiation from solar and cosmic winds, but also extremophiles that live on or near the surfaces of hot underwater volcanos.
There is no law in the Universe that says that organic or inorganic life forms must appear even similarly like those of Earth. There could be rock-like life on those planets, or even diaphanous-bodied life that live in an atmospheric environment where they live on clouds. Anything is possible. Most humans haven't the imagination or are willing to accept such enormous differences. Some are even averse to such possibilities.

Apr 09, 2019
There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.


Hamlet Act 1, Scene 5, Lines 167–168.

Apr 09, 2019
There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.


Hamlet Act 1, Scene 5, Lines 167–168.

1+6+7=14, followed by:
168=2^3*3*7, where 2+3+3+7=15, as in Act 1, Scene 5

Just saying :)

Does anyone know what is the repeated sum of the digits of pi? I.e. 1+6+7=14, then 1+4=5

Apr 09, 2019
It looks as if the Earth is not the only place infected with Life.

I just want to have it found while I am still alive, . . or brought back.

Apr 09, 2019
Don't sweat it Gigel.
When one of the the trumpsterfire's sycophants tries to explain to the senile buffoon.
That an Irrational Number such as Pi means that donnie can't be reassured he's getting the biggest slice of the graft pie?

The Bogus POTUS & vp pfenning will join with the biblebabblers to make mathematics as illegal as art & literacy.

Apr 09, 2019
The Earth was a chaotic, irradiated, hot mess. Yet in spite of this, life somehow gained a toehold and then expanded.


another one:

life could be....


These scientists have idea what they are talking about. As if there was some fairy tale happening. We really don't quite know what it was or is. But somehow this beautiful earth just kind of happened. "BELIEVE US!" Even thought the chances of this happening are basically zero. But even more incredibly, some even more wonderful might be happening on a planet far away!!

Evolutionists will be laughed at someday. Forever.


Apr 09, 2019

Evolutionists will be laughed at someday. Forever.



You mean in the way the idiots who think some impossible supernatural being started it all are laughed at now? Sorry, not going to happen.

Apr 09, 2019
Evolution by human selection is self-evident. Do you suppose that a Great Dane could mate with a Chihuahua?

So if human selection works, why would you argue with selection by random chance-- that is, by divine providence? I don't believe this, I think it's fitness landscapes, but hey, that evolution is life pathways chosen by some supermagic sky daddy isn't nearly as disgusting as the jebus trolls.

Apr 09, 2019

There is no law in the Universe that says that organic or inorganic life forms must appear even similarly like those of Earth. There could be rock-like life on those planets, or even diaphanous-bodied life that live in an atmospheric environment where they live on clouds. Anything is possible.
@SEU Sure, anything is possible in the realm of fiction and imagination, but science does not really work that way. Scientists who propose alternative biochemistries, e.g. with methane or ammonia as a solvent and silicon instead of carbon as the basis of such life, need also to explain and model how such lifeforms could function, up to and including their basic metabolism.
To my knowledge this has not yet happened, so carbon and water have prevailed as the primary life ingredients. Carbon is a *far* more versatile element than silicon, able to form hundreds to thousands of times more molecules, while water is rightfully called the "universal solvent".

Apr 09, 2019
Evolution by human selection is self-evident. Do you suppose that a Great Dane could mate with a Chihuahua?

So if human selection works, why would you argue with selection by random chance-- that is, by divine providence? I don't believe this, I think it's fitness landscapes, but hey, that evolution is life pathways chosen by some supermagic sky daddy isn't nearly as disgusting as the jebus trolls.

says Da Schneibo

Once again, for about the millionth time, you're not making any sense. Are you by any chance related to rrwillsj? She doesn't make sense either. Both of you should stay away from alcoholic adult beverages.

Apr 09, 2019

There is no law in the Universe that says that organic or inorganic life forms must appear even similarly like those of Earth. ..Anything is possible.
@SEU Sure, anything is possible in the realm of fiction and imagination, but science does not really work that way. Scientists who propose alternative biochemistries, e.g. with methane or ammonia as a solvent and silicon instead of carbon as the basis of such life, need also to explain and model how such lifeforms could function, up to and including their basic metabolism.
To my knowledge this has not yet happened, so carbon and water have prevailed as the primary life ingredients. Carbon is a *far* more versatile element than silicon, able to form hundreds to thousands of times more molecules, while water is rightfully called the "universal solvent".

says Sahster

I agree that water is necessary. But the rest are still unknowns. We have only been at this a very short time in the scheme of things.

Apr 09, 2019
-contd-
@Sahstar
Water is compatible with Carbon. It may also be compatible with Silicon as a lubricant and many other elements. Not being a chemist or geologist, I can't go much further into it. But the Earth has all of the elements that are included in the Periodic Table, so that much of those very elements make up the human body as well as animals.
But an exoplanet orbiting around 2 Stars, eg - there may be elements in that planet that are missing from Earth, so that any life arising there would have to be compatible with what is most available to it. At this point in our existence, we can only conjecture and imagine what might be where no man has gone before.

Apr 09, 2019
Well, time to choose which channel I will be watching the Black Hole extravaganza tomorrow.
Vox.com will also be showing it. Not sure about physorg.

Apr 10, 2019
Proxima Centauri b orbits its star with an orbital period of 11days
but
what is Proxima Centauri b axial rotation
what is Proxima Centauri b length of day
because
Proxima Centauri b orbital period of 11 days is the length of one year on Proxima Centauri b
what is of interest
What is Proxima Centauri b length of day?

Apr 10, 2019
Scientists who propose alternative biochemistries, e.g. with methane or ammonia as a solvent and silicon instead of carbon as the basis of such life, need also to explain and model how such lifeforms could function


Sahster, I agree, unless of course we find something unusual. Perhaps one reason people come up with these ideas is they are trying to imagine just how strange those aliens might be. However, it is clear to me we cannot yet understand how far carbon-water based lifeforms can differ from one another evolving in different environments throughout the galaxy. When you look at the shocking diversity of life on Earth over time, you can bet there are living worlds out there that would completely blow our minds with familiar carbon-water bio-chemistries. Count on it.

Apr 10, 2019
Unfortunately, scientists also found no intelligent life on Earth, since we're poisoning the environment for all mammalian life. Since when does a top predator outweigh all it's wild prey, by orders of magnitude? Enjoy what time you have here, and, don't have kids.

Apr 10, 2019
Unfortunately, scientists also found no intelligent life on Earth, since we're poisoning the environment for all mammalian life. Since when does a top predator outweigh all it's wild prey, by orders of magnitude? Enjoy what time you have here, and, don't have kids.
says michael

Have you forgotten that it is scientists who have created those same poisons that are destroying animals and their habitat? Before there were scientists there were farmers and animal husbandry to feed humans and animals. Everything was natural. And as the population got larger, humans decided to find a better way to grow and protect crops and animals from the ravages of insects, weather, drought, floods, etc. And eventually, humans began using plants and chemicals to prevent their potential food from destruction. So now we have Monsanto and Roundup, etc.
Science and scientists did all of that. Perhaps in a few hundred years, the Earth will clean itself of the toxic wastes science gave us.

Apr 10, 2019
Unfortunately, scientists also found no intelligent life on Earth


Michael, your comment is an insult to dolphins. :-) Unfortunately, many of our (corrupt) leaders are more than happy to get rich destroying the planet, so our intelligence is subverted by corruption.

On a much more subtle note, perhaps we should be a little uneasy that we have no clear evidence of intelligent alien life. There are a trillion or so planets in the Milky Way, with many habitable planets even older than Earth. You have to wonder how many civilizations destroyed themselves and what our true odds of surviving are. If we were wise, we would take the silence from the galaxy as a warning to be careful of missteps that we cannot undo.

If I am wrong, and we are the only space-faring species, then the galaxy is ours if we can survive long enough to take it. Either way, we should be far more careful with Earth.

Apr 10, 2019
Unfortunately, scientists also found no intelligent life on Earth

If we were wise, we would take the silence from the galaxy as a warning to be careful of missteps that we cannot undo.

My observation, humans, in groups, cannot act with wisdom.

And, yes, I agree, the fact that no other 'advanced' cultures have been discovered points out several potentialities, including the ridiculous cost of traveling between stars. If we could do that efficiently, we'd be able to create anything we'd want to, locally. There is no economics in star travel, so why would anything try to 'communicate' in the first place! Just brings up Musk's neuroses about giving away our location...like Ricky and Lucy and the telegraph haven't been doing that for quite a while.

And, it's either hard for abiogenesis to occur, or, evolution elsewhere didn't cause the 'arms race' it did here on Earth. We're a short stub on the evolutionary tree of life, riding the limb we're cutting off.

Apr 11, 2019
My observation, humans, in groups, cannot act with wisdom.


I disagree, it is corruption that masks our wisdom. Ask if leaders really want to solve a problem for the benefit of all, or are they looking for a way to benefit themselves at the expense of others? 99.9% of the time it is the later. Here in the U.S. we have done nothing in response to mass shootings for decades. This is the result of NRA-sponsored corruption and propaganda. New Zealand, on the other hand, had one mass shooting and put forth a solution banning assault weapons in less than one month. The difference is not intelligence, it is the level of corruption. I am not just picking on the U.S. either. The U.S. Founding Fathers came up with our present form of democracy as the most resistant to corruption over 200 years ago. Their wisdom was not masked by corruption. Unfortunately, that system is not perfect.

Apr 12, 2019
"You mean in the way the idiots who think some impossible supernatural being started it all are laughed at now? Sorry, not going to happen."

You can say that again! ad infinitum!

Apr 12, 2019
It looks as if the Earth is not the only place infected with Life.

I just want to have it found while I am still alive, . . or brought back.

Sadly, this forum is infected with you....gSKUM.

Apr 12, 2019
I don't see any evidence presented that life on earth was hammered by all this deadly radiation, since they do mention subsurface locations offering protection (duh!). Although it seems clear that red dwarf systems are not nice places to evolve, you might want a short visit!

It seems highly likely that such subsurface locations would have been ideal on a primitive earth anyway, if not for the radiation alone. (Photosynthesis was a bit into the future.) And there is nothing surprising about the effects of 360nm UV being less hazardous than 260nm since the latter is the peak absorption band for polynucleic acids - maximum mutation rate.

There was also plenty of radiation on the early planet from isotopes galore. It seems likely that some of this would have been useful in expanding evolution, but mostly destroying it. There is no certainty that any body that is under heavy radiation as noted is incapable of supporting life. Not a day at the beach, but not absolutely inhospitable.

Apr 13, 2019
the dimwitted antigoracle, devoid of honor and integrity, wrote:
It looks as if the Earth is not the only place infected with Life.

I just want to have it found while I am still alive, . . or brought back.

Sadly, this forum is infected with you....gSKUM.


This forum is infected with you, a troll who is so stupid that he will claim a figure of 6% and then post a link to 'prove' it that says 14%.

I don't know who's paying you, but they're not getting their money's worth.

Apr 13, 2019
the dimwitted antigoracle, devoid of honor and integrity


Well said.

Apr 21, 2019
I don't see any evidence presented that life on earth was hammered by all this deadly radiation, since they do mention subsurface locations offering protection
.

They do make climate models that confirm the surface was hammered, which they consider a proxy for habitability; most habitability discussions center on surface habitability since it is well known and sets the net primary productivity (almost all through land plants) for modern Earth.

My observation, humans, in groups, cannot act with wisdom.


I disagree, it is corruption that masks our wisdom.


Psychologists and betting agencies has shown that groups are wiser than any individuals. And the amount of corruption is globally relatively low and not the worst drain on economy.

The Fermi question "where are they" were immediately responded to by himself: as long as we don't know that interstellar travel is possible we cannot worry about observations (except true positives).

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