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Top 4 candidates in our solar system for terraforming
When it comes time for humanity to pick a new home, where will we go?
- Regardless of whether you think the Earth will suffer some catastrophe or not, most individuals believe that humanity will eventually have to live on another planet.
- There is no nearby planet that can support human life, however; we'll have to pick a good candidate and terraform it.
- Each celestial body presents its own unique challenges and requirements. Some need more carbon dioxide, others need less; some would become water worlds, others more Earth-like; and so on.
Whether you're feeling optimistic or pessimistic about humanity's long-term chances on Earth, most of us agree that we should colonize other planets. Whether that's out of humanity's sheer pioneering spirit or the pragmatic survival instinct to spread out so that a catastrophe on Earth doesn't wipe out the species, establishing a colony on a nearby planet seems like a must.
Trouble is, our neighboring celestial bodies are constantly bombarded by deadly radiation, lack water or oxygen, rain sulfuric acid, swing from extreme heat to cold, and possess many other inhospitable characteristics. No matter where we go in our solar system, we'll have to engage in one of the largest projects imaginable: terraforming. Depending on the environment we want to transform into a more Earth-like one, the nature of this project will vary tremendously. Here's some examples from some of the most likely candidates for terraforming in our solar system.
An artist's depiction of Mars' gradual transformation via terraforming.
Mars has always been an appealing target for terraforming, as it is arguably the most Earth-like planet in the solar system. It goes through similar seasons to Earth, has a relatively similar atmospheric composition, its day-night cycle is extremely close to our own, it possesses abundant water in the form of ice, and it lies in the Sun's habitable zone.
But the biggest problem with Mars is that it has no magnetosphere. Without an envelope of shielding magnetism, solar wind will blow away any atmosphere before it can accumulate. Proposals to create the right kind of atmosphere on Mars — like Elon Musk's flashy idea of nuking the polar ice caps to release stored CO2 and water vapor, thereby heating the planet up — won't work long term without a magnetosphere to protect the planet against solar wind. With Mars' current, flimsy atmosphere, between 1 and 2 kilograms of gas are lost to space every second. Not to mention that the lack of this protective magnetosphere also exposes the planet and all life on it to deadly radiation from the sun.
One proposal is to place a gigantic magnetic shield in orbit between Mars and the Sun to recreate the effects produced by, for instance, Earth's rotating iron outer core. This would be an incredible engineering task, likely requiring regular maintenance and fuel to keep the magnet powered. But it would be the first step to ensuring that Mars could be made habitable. Even prior to that point, Mars gradual growth of an atmosphere would make future exploration on the red planet easier and easier.
An artist's depiction of Venus if it were terraformed.
Compared to Mars, Venus has very little going for it. The surface temperature is 462°C, or 864°F; it has the opposite problem as Mars, with an atmosphere more than 90 times as dense as that of the Earth; and it's got no breathable oxygen. Not to mention that it's covered in volcanos and rains sulfuric acid. On the other hand, it's our closest planetary neighbor, and its gravity is about 90 percent that of Earth's compared to Mars' 38 percent, meaning our muscles and bones wouldn't atrophy while living there.
While Venus also suffers from a lack of a sufficiently strong magnetosphere, it's abundance of atmosphere means that concern can be put aside for a while in our hypothetical terraforming project. Venus's major problem is its excess of CO2, which makes the surface of the planet too hot for life and too heavy for humans.
One approach would be to use autonomous robots to expose Venus's underground deposits of calcium and magnesium, resulting in a chemical reaction that would store CO2 in a magnesium carbonate. This would need to be supplement by a bombardment of those elements mined from asteroids as well in order to remove enough carbon from the atmosphere for human life.
There are a variety of other methods, but they all rely on removing CO2 from the atmosphere rapidly. Seeing as how our inability to do that on Earth may be one of the biggest reasons to find another planet, Venus may not be the ideal target for terraforming in the future. An alternative to terraforming, however, would be to build a floating city in the Venusian clouds, a feat that isn't too far-fetched technologically.
A full-color image of Callisto as captured by NASA's Galileo spacecraft/
NASA/JPL/ DLR(German Aerospace Center)
Many of the Jupiter's Galilean moons are attractive targets for terraforming due to their high abundance of water, but only Callisto lies far enough away from the radiation belts generated by Jupiter's magnetosphere. On Earth, we're exposed to about 0.066 rems of radiation per day. In contrast, Ganymede receives 8 rems of radiation per day, Europa receives 540 rems per day, and Io receives a whopping 3,600 rems. Callisto, in contrast, is exposed to about 0.01 rems per day, which humans can tolerate.
The process of terraforming these moons would all follow essentially the same recipe. First, heat up their icy surfaces either through giant mirrors, nuclear devices, or some other method. Then, let the radiation from Jupiter split the resulting water vapor into hydrogen and oxygen — the hydrogen will be blown into space by solar wind, while the oxygen will settle close to the surface. Use bacteria to convert the moons' ammonia into nitrogen, and there's a breathable atmosphere.
Of course, these planets would be completely covered in oceans hundreds of kilometers deep, and Callisto wouldn't have its own magnetosphere to keep that atmosphere in place long term, but their abundance of water makes it an attractive target nonetheless. More concerning is the possibility that life already exists beneath the Galilean moons' icy surfaces, in the warm waters by thermal vents. If we were to discover such life, would it be ethical to disrupt the only alien life we have ever known?
A composite image of Titan in infrared as seen by NASA's Cassini spacecraft. Because Titan's atmosphere is so hazy, viewing it in the wavelengths of visible light is not possible. Using the infrared spectrum enables us to see through the clouds to the moon's surface.
The appeal of terraforming Titan lies in its vast reservoir of resources. Its hydrocarbon reserves (such as petroleum) are several hundred times greater than all known reserves on Earth. It's covered in a wide variety of organic compounds, particularly methane and ammonia, as well as a great deal of water. And its atmosphere is primarily nitrogen as well — a composition that scientists believe resembles that of early Earth's.
Together, these ingredients would be of significant benefit to any terraforming project. If Titan's atmosphere does resemble early Earth's, then transitioning to an atmosphere that resembles modern Earth would be (relatively) straightforward. One proposal would be to position mirrors in orbit to direct focused sunlight onto the moon's surface. Since the surface ice contains many greenhouse gases, this could warm Titan up considerably, releasing water vapor and consequently oxygenating the atmosphere. It also spends most of its time within Saturn's magnetosphere, protecting its atmosphere from the solar wind.
But perhaps more so than any other body in our solar system, Titan could already have extraterrestrial life owing to its abundance of organic chemicals. And, if all of Titan's ice were melted, it would become an ocean planet 1700 km deep, or over 1,000 miles deep, making the establishment of fixed, permanent structures a challenge.
There are challenges common to all of these potential candidates for terraforming. The big one, of course, is getting there. Many of these targets are incredibly distant. For a comparison, it took Voyager 1 a little over three years to get to Saturn, where Titan, the most distant candidate, is located, and a ship with all of the necessary equipment, people, and resources would be significantly slower than a lightweight probe. Then, there's the issue of establishing a semipermanent colony while the long work of terraforming goes on. It's difficult to speculate about the capabilities we'll have at our disposal when terraforming a planet becomes a feasible project, but it could be hundreds, possibly thousands of years before any of these planets are completely terraformed. And these are just some of the known issues: a project of this scale is bound to have unexpected problems and consequences. Despite these major challenges, the vast majority of humanity believes that establishing a second home in our solar system is a necessity — the question is, which will it be?
- Terraform Mars? How about Earth? ›
- How bacteria can make Mars livable - Big Think ›
- Venus' clouds shows signs of alien life, MIT scientists say - Big Think ›
All this from a wad of gum?
- Researchers recently uncovered a piece of chewed-on birch pitch in an archaeological dig in Denmark.
- Conducting a genetic analysis of the material left in the birch pitch offered a plethora of insights into the individual who last chewed it.
- The gum-chewer has been dubbed Lola. She lived 5,700 years ago; and she had dark skin, dark hair, and blue eyes.
Five thousand and seven hundred years ago, "Lola" — a blue-eyed woman with dark skin and hair — was chewing on a piece of pitch derived from heating birch bark. Then, this women spit her chewing gum out into the mud on an island in Denmark that we call Syltholm today, where it was unearthed by archaeologists thousands of years later. A genetic analysis of the chewing gum has provided us with a wealth of information on this nearly six-thousand-year-old Violet Beauregarde.
This represents the first time that the human genome has been extracted from material such as this. "It is amazing to have gotten a complete ancient human genome from anything other than bone," said lead researcher Hannes Schroeder in a statement.
"What is more," he added, "we also retrieved DNA from oral microbes and several important human pathogens, which makes this a very valuable source of ancient DNA, especially for time periods where we have no human remains."
In the pitch, researchers identified the DNA of the Epstein-Barr virus, which infects about 90 percent of adults. They also found DNA belonging to hazelnuts and mallards, which were likely the most recent meal that Lola had eaten before spitting out her chewing gum.
Insights into ancient peoples
The birch pitch was found on the island of Lolland (the inspiration for Lola's name) at a site called Syltholm. "Syltholm is completely unique," said Theis Jensen, who worked on the study for his PhD. "Almost everything is sealed in mud, which means that the preservation of organic remains is absolutely phenomenal.
"It is the biggest Stone Age site in Denmark and the archaeological finds suggest that the people who occupied the site were heavily exploiting wild resources well into the Neolithic, which is the period when farming and domesticated animals were first introduced into southern Scandinavia."
Since Lola's genome doesn't show any of the markers associated with the agricultural populations that had begun to appear in this region around her time, she provides evidence for a growing idea that hunter-gatherers persisted alongside agricultural communities in northern Europe longer than previously thought.
Her genome supports additional theories on northern European peoples. For example, her dark skin bolsters the idea that northern populations only recently acquired their light-skinned adaptation to the low sunlight in the winter months. She was also lactose intolerant, which researchers believe was the norm for most humans prior to the agricultural revolution. Most mammals lose their tolerance for lactose once they've weaned off of their mother's milk, but once humans began keeping cows, goats, and other dairy animals, their tolerance for lactose persisted into adulthood. As a descendent of hunter-gatherers, Lola wouldn't have needed this adaptation.
A hardworking piece of gum
A photo of the birch pitch used as chewing gum.
These findings are encouraging for researchers focusing on ancient peoples from this part of the world. Before this study, ancient genomes were really only ever recovered from human remains, but now, scientists have another tool in their kit. Birch pitch is commonly found in archaeological sites, often with tooth imprints.
Ancient peoples used and chewed on birch pitch for a variety of reasons. It was commonly heated up to make it pliable, enabling it to be molded as an adhesive or hafting agent before it settled. Chewing the pitch may have kept it pliable as it cooled down. It also contains a natural antiseptic, and so chewing birch pitch may have been a folk medicine for dental issues. And, considering that we chew gum today for no other reason than to pass the time, it may be that ancient peoples chewed pitch for fun.
Whatever their reasons, chewed and discarded pieces of birch pitch offer us the mind-boggling option of learning what someone several thousands of years ago ate for lunch, or what the color of their hair was, their health, where their ancestors came from, and more. It's an unlikely treasure trove of information to be found in a mere piece of gum.
The non-contact technique could someday be used to lift much heavier objects — maybe even humans.
- Since the 1980s, researchers have been using sound waves to move matter through a technique called acoustic trapping.
- Acoustic trapping devices move bits of matter by emitting strategically designed sound waves, which interact in such a way that the matter becomes "trapped" in areas of particular velocity and pressure.
- Acoustic and optical trapping devices are already used in various fields, including medicine, nanotechnology, and biological research.
Sound can have powerful effects on matter. After all, sound strikes our world in waves — vibrations of air molecules that bounce off of, get absorbed by, or pass through matter around us. Sound waves from a trained opera singer can shatter a wine glass. From a jet, they can collapse a stone wall. But sound can also be harnessed for delicate interactions with matter.
Since the 1980s, researchers have been using sound to move matter through a phenomenon called acoustic trapping. The method is based on the fact that sound waves produce an acoustic radiation force.
"When an acoustic wave interacts with a particle, it exerts both an oscillatory force and a much smaller steady-state 'radiation' force," wrote the American Physical Society. "This latter force is the one used for trapping and manipulation. Radiation forces are generated by the scattering of a traveling sound wave, or by energy gradients within the sound field."
When tiny particles encounter this radiation, they tend to be drawn toward regions of certain pressure and velocity within the sound field. Researchers can exploit this tendency by engineering sound waves that "trap" — or suspend — tiny particles in the air. Devices that do this are often called "acoustic tweezers."
Building a better tweezer
A study recently published in the Japanese Journal of Applied Physics describes how researchers created a new type of acoustic tweezer that was able to lift a small polystyrene ball into the air.
Tweezers of Sound: Acoustic Manipulation off a Reflective Surface youtu.be
It is not the first example of a successful "acoustic tweezer" device, but the new method is likely the first to overcome a common problem in acoustic trapping: sound waves bouncing off reflective surfaces, which disrupts acoustic traps.
To minimize the problems of reflectivity, the team behind the recent study configured ultrasonic transducers such that the sound waves that they produce overlap in a strategic way that is able to lift a small bit of polystyrene from a reflective surface. By changing how the transducers emit sound waves, the team can move the acoustic trap through space, which moves the bit of matter.
Move, but don't touch
So far, the device is only able to move millimeter-sized pieces of matter with varying degrees of success. "When we move a particle, it sometimes scatters away," the team noted. Still, improved acoustic trapping and other no-contact lifting technologies — like optical tweezers, commonly used in medicine — could prove useful in many future applications, including cell separation, nanotechnologies, and biological research.
Could future acoustic-trapping devices lift large and heavy objects, maybe even humans? It seems possible. In 2018, researchers from the University of Bristol managed to acoustically trap particles whose diameters were larger than the sound wavelength, which was a breakthrough because it surpassed "the classical Rayleigh scattering limit that has previously restricted stable acoustic particle trapping," the researchers wrote in their study.
In other words, the technique — which involved suspending matter in tornado-like acoustic traps — showed that it is possible to scale up acoustic trapping.
"Acoustic tractor beams have huge potential in many applications," Bruce Drinkwater, co-author of the 2018 study, said in a statement. "I'm particularly excited by the idea of contactless production lines where delicate objects are assembled without touching them."
Australian parrots have worked out how to open trash bins, and the trick is spreading across Sydney.
- If sharing learned knowledge is a form of culture, Australian cockatoos are one cultured bunch of birds.
- A cockatoo trick for opening trash bins to get at food has been spreading rapidly through Sydney's neighborhoods.
- But not all cockatoos open the bins; some just stay close to those that do.
Dumpster-diving trash parrots
In a study about these smart birds just published in Science, researchers define animal culture as "population-specific behaviors acquired via social learning from knowledgeable individuals."
Co-lead author of the study Barbara Klump of the Max Planck Institute of Animal Behavior in Konstanz, Germany says, "[C]ompared to humans, there are few known examples of animals learning from each other. Demonstrating that food scavenging behavior is not due to genetics is a challenge."
An opportunity presented itself in a video that co-author Richard Major of the Australian Museum shared with Klump and the other co-authors. In the video, a sulphur-crested cockatoo used its beak to pull up the handle of a closed garbage bin — using its foot as a wedge — and then walked back the lid sufficiently to flip it open, exposing the bin's edible contents.
Major has been studying Cacatua galerita for 20 years and says, "Like many Australian birds, sulphur-crested cockatoos are loud and aggressive." The study describes them as a "large-brained, long-lived, and highly social parrot." Says Major, "They are also incredibly smart, persistent, and have adapted brilliantly to living with humans."(Research regarding some of the ways in which wild animals adapt to the presence of humans has already produced some fascinating results and is ongoing.)
Clever cockie opens bin - 01 youtu.be
The researchers became curious about how widespread this behavior might be and saw a research opportunity. After all, says John Martin, a researcher at Taronga Conservation Society, "Australian garbage bins have a uniform design across the country, and sulphur-crested cockatoos are common across the entire east coast."
Martin continues, "In 2018, we launched an online survey in various areas across Sydney and Australia with questions such as, 'What area are you from, have you seen this behavior before, and if so, when?'"
Word gets around
Credit: magspace/Adobe Stock
Although the cockatoos' maneuver was reported in only three suburbs before 2018, by the end of 2019, people in 44 areas reported observing the behavior. Clearly, more and more cockatoos were learning how to successfully dumpster dive.
As further proof, says Klump, "We observed that the birds do not open the garbage bins in the same way, but rather used different opening techniques in different suburbs, suggesting that the behavior is learned by observing others." One individual bird in north Sydney invented its own method, and the scientists saw it grow in popularity throughout the local population.
To track individual birds, the researchers marked 500 cockatoos with small red dots. Subsequent observations revealed that not all cockatoos are bin-openers. Only about 10 percent of them are, and they are mostly males. The other cockatoos apparently restrict their education to a different lesson: hang around with a bin-opener, and you will get supper.
Thanks to the surveys, the researchers consider the entire project to be a valuable citizen-science experiment. "By studying this behavior with the help of local residents, we are uncovering the unique and complex cultures of their neighborhood birds."
The few seconds of nuclear explosion opening shots in Godzilla alone required more than 6.5 times the entire budget of the monster movie they ended up in.