Humans are more likely to have "first contact" with an advanced alien civilization, according to a recent NASA-funded paper.
- A new paper outlines some of the most promising ways scientists and space agencies can search for evidence of extraterrestrial civilizations.
- Because of a concept called "contact inequality," the researchers suggested it's relatively unlikely humans will discover evidence of alien civilizations that have similar levels of technology to us.
- However, near-future technology could soon allow scientists to search for both highly advanced and less advanced alien civilizations.
The 'ichnoscale'<p>To put the concept of technosignatures into perspective, researchers have developed a framework called ichnoscale. Ichnoscale ranks the size of a technosignature relative to what human technology is currently capable of producing.</p><p>The scale also ranks the number of potential targets throughout the Universe. For example, searching for a crashed alien probe on the Moon would represent one target, while scanning the stars for Dyson spheres would have millions of targets.</p><p>Together, these measurements help scientists estimate the most likely ways to discover evidence of alien civilizations. Of course, there's no guarantee that any one strategy will work, or that aliens even exist.</p><p>That's one reason why efforts to search for technosignatures have received little funding. But the researchers propose that many of these strategies could be tacked onto other astronomical missions at little cost.</p>
Socas-Navarro et al.<p>And even if the searches turn up nothing, the researchers said the results would still provide "enormous ancillary benefits on solar system research and advance our knowledge about the objects being scrutinized," and would "establish quantitative upper bounds on certain types of technologies or developmental stages of civilizations in the solar neighborhood."</p><p style="margin-left: 20px;">"The search for TS deals with questions that have profound implications on the future of humanity," the researchers concluded. "Perhaps one the most important is whether technological civilizations are ephemeral or, on the contrary, can be long lasting. A closely related question is whether space faring civilizations are common, and if humankind will eventually become one of them."</p><p style="margin-left: 20px;">"We do not yet have any answers for these and other important questions but if we can start to explore the search parameter space, even in the absence of any detection we may be able to gain some valuable insights."</p>
How do you get usable phosphorus into a system? A new study suggests lightning can do the trick.
- A chance discovery in suburban Illinois may change how we understand the dawn of life.
- Among other things, life needs water-soluble phosphorus, which was hard to come by 3.5 billion years back.
- This finding may imply that life has more opportunities to begin on other worlds than previously supposed.
In the beginning, there were a lot of meteorite impacts and lightning strikes<iframe width="730" height="430" src="https://www.youtube.com/embed/Z5DWKTNqByM" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe><p> Phosphorous is an important chemical for life on Earth, cells use it to help build DNA and RNA and it is required for several other important functions. There is plenty of phosphorous on Earth, but not all of it is water-soluble. It is thought that much of the phosphorus on Earth three and a half billion years ago, about the time when life first appeared, was trapped in minerals that can not dissolve in water. Given how important water is for life on Earth, this was an obstacle to the rise of life. </p><p>Until very recently, the leading theory about where most of the soluble phosphorous came from credited meteorites, many of which have small amounts of the stuff. However, this theory always had problems. The number of meteorites hitting the early Earth, while high, is thought to have fallen drastically after the event which is theorized to have created the moon. The problem gets worse over time, with fewer and fewer expected impacts as the solar system stabilized. </p><p>Additionally, meteorite impacts are often catastrophic events more often known for ending life than helping to start it. The amount of phosphorous that could arrive this way is also limited, with the heat and trauma of impact potentially vaporizing much of the stuff and leaving a pittance readily accessible in the environment. </p><p>This is where the chance finding in Illinois comes in. In 2016, a hunk of <a href="https://geology.utah.gov/map-pub/survey-notes/glad-you-asked/what-are-fulgurites-and-where-can-they-be-found/" target="_blank">fulgurite</a>, a clump of fused sediment created by a lightning strike, was found in Glen Ellyn, a small Chicago suburb. The sample was given to the nearby Wheaton College. </p><p>A team of researchers from the University of Leeds examined the specimen as part of an investigation into the formation of fulgurite, but were surprised to discover that it contained a large amount of <a href="https://www.mindat.org/min-3582.html" target="_blank">schreibersite</a>, a water-soluble phosphate mineral. </p><p> Lead author and Ph.D. candidate Benjamin Hess explained how this find might alter theories on how water-soluble phosphates came into being billions of years ago:</p><p>"Most models for how life may have formed on Earth's surface invoke meteorites which carry small amounts of schreibersite. Our work finds a relatively large amount of schreibersite in the studied fulgurite. Lightning strikes Earth frequently, implying that the phosphorus needed for the origin of life on Earth's surface does not rely solely on meteorite hits."</p><p>Their findings were published in Nature Communications and can be read in their entirety <a href="https://www.nature.com/articles/s41467-021-21849-2" target="_blank" rel="noopener noreferrer">here</a>. </p>
Okay, this is cool and all, but how can we possibly use this information?<iframe width="730" height="430" src="https://www.youtube.com/embed/upRqAaCEEhw" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe><p> In addition to shedding light on the Earth's past environment and how it changed over time, this finding might also aid the search for life on other planets. </p><p>Lead author Mr. Hess speculated that the finding "also means that the formation of life on other Earth-like planets remains possible long after meteorite impacts have become rare."</p><p>This is important because, as co-author Dr. Jason Harvey explains:</p><p style="margin-left: 20px;"><em>"The early bombardment is a once in a solar system event. As planets reach their mass, the delivery of more phosphorus from meteors becomes negligible. Lightning, on the other hand, is not such a one-off event. If atmospheric conditions are favourable for the generation of lightning, elements essential to the formation of life can be delivered to the surface of a planet. This could mean that life could emerge on Earth-like planets at any point in time."</em></p><p>While these speculations presume that alien life forms will require the same substances we do to exist, the discovery of a new source of usable phosphorus is an exciting find for those interested in alien worlds and in the early geology or biology of Earth. While we might never know precisely where the phosphorous used in the first life form came from, this discovery will help to make sense of where we came from and where we might find others like us out amongst the stars. <br></p>
Sound waves behave quite differently on Mars than on Earth.
- NASA's Perseverance rover landed on Mars on February 18, and is currently preparing to begin its main mission of searching for signs of ancient life.
- The rover contains two microphone systems, one of which was recently used to capture sounds of the rover traveling at speeds below .01 mph.
- NASA hopes to return Perseverance's rock collection to Earth by 2031.
Three lines of evidence point to the idea of complex, multicellular alien life being a wild goose chase. But are we clever enough to know?
- Everyone wants to know if there is alien life in the universe, but Earth may give us clues that if it exists it may not be the civilization-building kind.
- Most of Earth's history shows life that is single-celled. That doesn't mean it was simple, though. Stunning molecular machines were being evolved by those tiny critters.
- What's in a planet's atmosphere may also determine what evolution can produce. Is there a habitable zone for complex life that's much smaller than what's allowed for microbes?
Protozoa—a term for a group of single-celled eukaryotes—and green algae in wastewater, viewed under the microscope.
Credit: sinhyu via Adobe Stock<p>Another way the story of life on Earth might not get repeated elsewhere in the cosmos relates to the composition of planetary atmospheres. Our world did not begin with its oxygen-rich air. Instead, oxygen didn't show up until almost two billion years after the planet formed and one billion years after life appeared. Earth's original atmosphere was, most likely, a mix of nitrogen and CO2. Remarkably it was life that pumped the oxygen into the air as a byproduct of a novel form of photosynthesis invented by a novel kind of single-celled organism, the nucleus-bearing eukaryotes. The appearance of oxygen in Earth's air was not just a curiosity for evolution. Life soon figured out how to use the newly abundant element and, it turns out, oxygen-based biochemistry was supercharged compared to what came before. With more energy available, evolution could build ever larger and more complex critters.</p><p>Oxygen may also be unique in allowing the kinds of metabolisms in multicellular life (especially ours) needed for making fast and fast-thinking animals. Astrobiologist <a href="http://faculty.washington.edu/dcatling/Catling2008CatalystMag.pdf" target="_blank" rel="noopener noreferrer">David Catling</a> has argued that only oxygen has the right kind of chemistry that would allow for animals to form on any world.</p><p>Atmospheres may play another role in what can and can't happen in the evolution of life. In 1959, <a href="https://astro.uchicago.edu/alumni/su-shu-huang-1949.php" target="_blank" rel="noopener noreferrer">Su-Shu Huang</a> proposed that each star would be surrounded by a "<a href="https://www.nasa.gov/ames/kepler/habitable-zones-of-different-stars" target="_blank" rel="noopener noreferrer">habitable zone</a>" of orbits where a planet would have temperatures neither too hot nor too cold to keep life from forming (i.e. liquid water could exist on the planet's surface). Since then, the habitable zone has become a staple of astrobiological studies. Astronomers now know that the outer part of the habitable zone will be dominated by worlds with lots of greenhouse gases like CO<em>2</em>. A planet in a location like Mars, for example, would require a thick CO2 blanket to keep its surface above freezing. But all that CO2 could present its own problems for life. Almost all forms of animal life on Earth, including sea creatures, die when placed in CO2-rich environments. This has led astronomer <a href="https://eschwiet.github.io/" target="_blank" rel="noopener noreferrer">Eddie Schwieterman</a> and colleagues to propose a <a href="https://iopscience.iop.org/article/10.3847/1538-4357/ab1d52" target="_blank" rel="noopener noreferrer">habitable zone for complex life</a>: A band of orbits where planets can stay warm without requiring heavy CO2 atmospheres. According to Schwieterman, animal life of the kind we know would only be able to form in this much thinner band of orbits. </p>
The results could help NASA's Perseverance rover find evidence of ancient life on Mars.
- In a recent study, researchers simulated the environment of ancient Mars and tested whether a type of extremophile found on Earth could grow on fragments of a meteorite from Mars.
- Extremophiles are organisms that have adapted to survive in conditions in which most life forms cannot, such as ice, volcanoes, and space.
- The results showed that the extremophiles were able to convert the rock into energy. What's more, the microbes left behind biosignatures that could help scientists identify evidence of past life on Mars.
Northwest Africa (NWA) 7034
Credit: NASA<p>Extremophiles are organisms that thrive in conditions where most life forms would die. Scientists have observed them in volcanoes, soda lakes, Antarctic ice, and hydrothermal vents. Some have even <a href="https://bigthink.com/surprising-science/tardigrades-extremophiles" target="_self">survived the vacuum of space</a>. The team behind the recent study focused on a particular class of extremophiles called chemolithotrophs, which are microbes that use inorganic compounds as a source of energy.<br></p><p>To test whether chemolithotrophs might have been able to evolve on Mars, the team placed a chemolithtrophic microbe called <a href="https://en.wikipedia.org/wiki/Metallosphaera_sedula" target="_blank"><em>Metallosphaera sedula</em></a> onto bits of Black Beauty. The researchers simulated the ancient Martian environment by keeping the microbe-covered rock bits in a bioreactor that controlled temperature and levels of carbon dioxide and air.</p>
The high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) image of the focused ion beam (FIB) section extracted for STEM analysis from the NWA 7034 fragment used in this study
Credit: Milojevic et al.<p>Using microscopy, the researchers saw that the microbe successfully converted rock pieces into biomass.</p><p style="margin-left: 20px;">"Grown on Martian crustal material, the microbe formed a robust mineral capsule comprised [sic] of complexed iron, manganese and aluminum phosphates," Milojevic told Science Alert.</p><p style="margin-left: 20px;">"Apart from the massive encrustation of the cell surface, we have observed intracellular formation of crystalline deposits of a very complex nature (Fe, Mn oxides, mixed Mn silicates). These are distinguishable unique features of growth on the Noachian Martian breccia, which we did not observe previously when cultivating this microbe on terrestrial mineral sources and a stony chondritic meteorite."</p>