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Colossal Biosciences’s "de-extinction" news is just the latest in a slew of eyebrow-raising claims by privately funded researchers. Is the bar for belief lower when those making the claims have a lot of money, wonders Jonathan R. Goodman

As the US government freezes scientific funding and attacks my host institution (under the pretense of fighting anti-semitism — a claim no one here believes, given that the government is now doing far more actual harm to Harvard’s not-so-small population of Jewish faculty, researchers and students than was ever done by anti-Gaza-war protestors), it has become impossible to continue with my normal activities. I hope to resume them in the future.

Exoplanets are pretty exciting – in the last few decades we have gone from knowing absolutely nothing about planets beyond our solar system to having a catalogue of over 5,000 confirmed exoplanets. That’s still a small sample considering there are likely between 100 billion and 1 trillion planets in the Milky Way. It is also not a random sample, but is biased by our detection methods, which favor larger planets closer to their parent stars. Still, some patterns are starting to emerge. One frustrating pattern is the lack of any worlds that are close duplicates of Earth – an Earth mass exoplanet in the habitable zone of a yellow star (I’d even take an orange star).

Life, however, does not require an Earth-like planet. Anything in the habitable zone, defined as potentially having a temperature allowing for liquid water on its surface, will do. The habitable zone also depends on variables such as the atmosphere of the planet. Mars could be warm if it had a thicker atmosphere, and Venus could be habitable if it had less of one. Cataloguing exoplanets gives us the ability to address a burning scientific question – how common is life in the universe? We have yet to add any data points of clear examples of life beyond Earth. So far we have one example of life in the universe, which means we can’t calculate how common it is (except maybe setting some statistical upper limits).

Finding that a planet is habitable and therefore could potentially support life is not enough. We need evidence that there is actually life there. For this the hunt for exoplanets includes looking for potential biosignatures – signs of life. We may have just found the first biosignatures on an exoplanet. This is not 100%. We need more data. But it is pretty intriguing.

The planet is K2-18b, a sub-Neptune orbiting a red dwarf 120 light years from Earth. In terms of exoplanet size, we have terrestrial planets like Earth and the rocky inner planets of our solar system. Then there are super-Earths, larger than Earth up to about 2 earth masses, still likely rocky worlds. Sub Neptunes are larger still, but still smaller than Neptune. They likely have rocky surfaces and thick atmospheres. K2-18b has a radius 2.6 times that of Earth, with a mass 8.6 times that of Earth. The surface gravity is estimated at 12.43 m/s^2 (compared to 9.8 on Earth). We could theoretically land a rocket and take off again from its surface.

K2-18 is a red dwarf, which means it has a habitable zone close in. K2-18b orbits every 33 days, and had an eccentric orbit but staying within the habitable zone. This means it is likely tidally locked, but may be in a resonance orbit (like Mercury), meaning that it rotates three times for every two orbits, or something like that. Fortunately for astronomers, K2-18b orbits in front of its star from our perspective on Earth. This is how it was detected, but also this means we can potentially examine the chemical makeup of its atmosphere with spectroscopy. When the planet passes in front of its star we can look at the absorption lines of the light passing through it to detect the signatures of different chemicals. Using this technique with the Hubble astronomers have found methane and carbon dioxide in the atmosphere. They have also found dimethyl sulfide and a similar molecule called dimethyl disulfide. On Earth the only known source of dimethyl sulfide is living organisms, specifically algae. This molecule is also highly reactive and therefore short-lived, which means if it is present in the atmosphere it is being constantly renewed. Follow up observations with the Webb confirmed the presence of dimethyl sulfide, in concentrations 20 times higher than on Earth.

What does this mean? Well, it could mean that K2-18b has a surface ocean that is brimming with life. This fits with one model of sub-Neptunes, called the Hycean model, which means they can have large surface oceans and an atmosphere with lots of hydrogen. These are conditions suitable for life. But this is not the only possibility.

One of the problems with chemical biosignatures is that they frustratingly all have abiotic sources. Oxygen can occur through the splitting of water or CO2 by ultraviolet light, and by reactions with quartz. Methane also has geological sources. What about dimethyl sulfide? Well, it has been found in cometary matter with a likely abiotic source. So there may be some geological process on K2-18b pumping out dimethyl sulfide. Or there may be an ocean brimming with marine life creating the stuff. We need to do more investigation of K2-18b to understand more about its likely surface conditions, atmosphere, and prospects for life.

This, unfortunately, is how these things are likely to go – we find a potential biosignature that also has abiotic explanations and then we need years of follow up investigation. Most of the time the biosignatures don’t pan out (like on Venus and Mars so far). It’s a setup for disappointment. But eventually we may go all the way through this process and make a solid case for life on an exoplanet. Then finally we will have our second data point, and have a much better idea of how common life is likely to be in our universe.

The post Possible Biosignature on K2-18b first appeared on NeuroLogica Blog.

The 2000-year-old Antikythera mechanism may have been a kind of astronomical calculator, but researchers are unsure whether it would have worked without jamming

When science was under attack, Dr. John Ioannidis played the role of enabler. Along with his copious COVID misinformation, that will be his permanent legacy.

The post Tell us Dr. John Ioannidis, Exactly Who is Waging This “War on Science”? first appeared on Science-Based Medicine.

The idea of varying your lifestyle throughout your menstrual cycle to help relieve PMS or period pain seems intuitive, but the evidence reveals a nuanced picture, finds columnist Alexandra Thompson

Astronomers have detected the most promising signs yet of a possible biosignature outside the solar system, although they remain cautious.

On a faraway planet, James Webb Space Telescope has picked up signs of molecules that, on Earth, are produced only by living organisms – but researchers say we must interpret the results cautiously

Gamma-ray bursts are the most powerful events in the Universe, briefly outshining the combined light of their entire galaxies. A team of astronomers has figured out a clever technique to use the light from gamma-ray bursts to map out the large-scale structure of the Universe at different ages after the Big Bang. They found that the Universe might be less uniform at large scales than previously thought.

A team of researchers has identified a promising new approach that may one day help to restore vision in people affected by macular degeneration and other retinal disorders.

Why do comets and their meteoroid streams weave in and out of Earth's orbit and their orbits disperse over time? Researchers show that this is not due to the random pull of the planets, but rather the kick they receive from a moving Sun.

A new study suggests the universe may rotate -- just extremely slowly. The finding could help solve one of astronomy's biggest puzzles.

Researchers developed a machine-learning-guided technique to solve complex, long-horizon planning problems more efficiently than some traditional approaches, while arriving at an optimal solution that better meets a user's goals.

A recently created RoboBee is now outfitted with its most reliable landing gear to date, inspired by one of nature's most graceful landers: the crane fly. The team has given their flying robot a set of long, jointed legs that help ease its transition from air to ground. The robot has also received an updated controller that helps it decelerate on approach, resulting in a gentle plop-down.

A recently created RoboBee is now outfitted with its most reliable landing gear to date, inspired by one of nature's most graceful landers: the crane fly. The team has given their flying robot a set of long, jointed legs that help ease its transition from air to ground. The robot has also received an updated controller that helps it decelerate on approach, resulting in a gentle plop-down.

Astronomers have found a planet that orbits at an angle of 90 degrees around a rare pair of peculiar stars. This is the first time we have strong evidence for one of these 'polar planets' orbiting a stellar pair.

A new study analyzing data from NASA's Perseverance rover has uncovered compelling evidence of multiple mineral-forming events just beneath the Martian surface -- findings that bring scientists one step closer to answering the profound question: Did life ever exist on Mars?

It is harder for our bodies to absorb key nutrients from plant-based foods, so some vegans may be short on essential amino acids for healthy muscles and bones despite eating plenty of protein

Beginning around 3000 years ago, Tel Shiqmona in modern-day Israel was a major centre for the production of Tyrian purple, a valuable commodity produced from marine snails

A weakening of Earth’s magnetic field known as the Laschamps event would have increased the threat of solar radiation, perhaps requiring ancient humans to invent protective measures