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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 ›
We explore the history of blood types and how they are classified to find out what makes the Rh-null type important to science and dangerous for those who live with it.
- Fewer than 50 people worldwide have 'golden blood' — or Rh-null.
- Blood is considered Rh-null if it lacks all of the 61 possible antigens in the Rh system.
- It's also very dangerous to live with this blood type, as so few people have it.
Golden blood sounds like the latest in medical quackery. As in, get a golden blood transfusion to balance your tantric midichlorians and receive a free charcoal ice cream cleanse. Don't let the New-Agey moniker throw you. Golden blood is actually the nickname for Rh-null, the world's rarest blood type.
As Mosaic reports, the type is so rare that only about 43 people have been reported to have it worldwide, and until 1961, when it was first identified in an Aboriginal Australian woman, doctors assumed embryos with Rh-null blood would simply die in utero.
But what makes Rh-null so rare, and why is it so dangerous to live with? To answer that, we'll first have to explore why hematologists classify blood types the way they do.
A (brief) bloody history
Our ancestors understood little about blood. Even the most basic of blood knowledge — blood inside the body is good, blood outside is not ideal, too much blood outside is cause for concern — escaped humanity's grasp for an embarrassing number of centuries.
Absence this knowledge, our ancestors devised less-than-scientific theories as to what blood was, theories that varied wildly across time and culture. To pick just one, the physicians of Shakespeare's day believed blood to be one of four bodily fluids or "humors" (the others being black bile, yellow bile, and phlegm).
Handed down from ancient Greek physicians, humorism stated that these bodily fluids determined someone's personality. Blood was considered hot and moist, resulting in a sanguine temperament. The more blood people had in their systems, the more passionate, charismatic, and impulsive they would be. Teenagers were considered to have a natural abundance of blood, and men had more than women.
Humorism lead to all sorts of poor medical advice. Most famously, Galen of Pergamum used it as the basis for his prescription of bloodletting. Sporting a "when in doubt, let it out" mentality, Galen declared blood the dominant humor, and bloodletting an excellent way to balance the body. Blood's relation to heat also made it a go-to for fever reduction.
While bloodletting remained common until well into the 19th century, William Harvey's discovery of the circulation of blood in 1628 would put medicine on its path to modern hematology.
Soon after Harvey's discovery, the earliest blood transfusions were attempted, but it wasn't until 1665 that first successful transfusion was performed by British physician Richard Lower. Lower's operation was between dogs, and his success prompted physicians like Jean-Baptiste Denis to try to transfuse blood from animals to humans, a process called xenotransfusion. The death of human patients ultimately led to the practice being outlawed.4
The first successful human-to-human transfusion wouldn't be performed until 1818, when British obstetrician James Blundell managed it to treat postpartum hemorrhage. But even with a proven technique in place, in the following decades many blood-transfusion patients continued to die mysteriously.
Enter Austrian physician Karl Landsteiner. In 1901 he began his work to classify blood groups. Exploring the work of Leonard Landois — the physiologist who showed that when the red blood cells of one animal are introduced to a different animal's, they clump together — Landsteiner thought a similar reaction may occur in intra-human transfusions, which would explain why transfusion success was so spotty. In 1909, he classified the A, B, AB, and O blood groups, and for his work he received the 1930 Nobel Prize for Physiology or Medicine.
What causes blood types?
It took us a while to grasp the intricacies of blood, but today, we know that this life-sustaining substance consists of:
- Red blood cells — cells that carry oxygen and remove carbon dioxide throughout the body;
- White blood cells — immune cells that protect the body against infection and foreign agents;
- Platelets — cells that help blood clot; and
- Plasma — a liquid that carries salts and enzymes.6,7
Each component has a part to play in blood's function, but the red blood cells are responsible for our differing blood types. These cells have proteins* covering their surface called antigens, and the presence or absence of particular antigens determines blood type — type A blood has only A antigens, type B only B, type AB both, and type O neither. Red blood cells sport another antigen called the RhD protein. When it is present, a blood type is said to be positive; when it is absent, it is said to be negative. The typical combinations of A, B, and RhD antigens give us the eight common blood types (A+, A-, B+, B-, AB+, AB-, O+, and O-).
Blood antigen proteins play a variety of cellular roles, but recognizing foreign cells in the blood is the most important for this discussion.
Think of antigens as backstage passes to the bloodstream, while our immune system is the doorman. If the immune system recognizes an antigen, it lets the cell pass. If it does not recognize an antigen, it initiates the body's defense systems and destroys the invader. So, a very aggressive doorman.
While our immune systems are thorough, they are not too bright. If a person with type A blood receives a transfusion of type B blood, the immune system won't recognize the new substance as a life-saving necessity. Instead, it will consider the red blood cells invaders and attack. This is why so many people either grew ill or died during transfusions before Landsteiner's brilliant discovery.
This is also why people with O negative blood are considered "universal donors." Since their red blood cells lack A, B, and RhD antigens, immune systems don't have a way to recognize these cells as foreign and so leaves them well enough alone.
How is Rh-null the rarest blood type?
Let's return to golden blood. In truth, the eight common blood types are an oversimplification of how blood types actually work. As Smithsonian.com points out, "[e]ach of these eight types can be subdivided into many distinct varieties," resulting in millions of different blood types, each classified on a multitude of antigens combinations.
Here is where things get tricky. The RhD protein previously mentioned only refers to one of 61 potential proteins in the Rh system. Blood is considered Rh-null if it lacks all of the 61 possible antigens in the Rh system. This not only makes it rare, but this also means it can be accepted by anyone with a rare blood type within the Rh system.
This is why it is considered "golden blood." It is worth its weight in gold.
As Mosaic reports, golden blood is incredibly important to medicine, but also very dangerous to live with. If a Rh-null carrier needs a blood transfusion, they can find it difficult to locate a donor, and blood is notoriously difficult to transport internationally. Rh-null carriers are encouraged to donate blood as insurance for themselves, but with so few donors spread out over the world and limits on how often they can donate, this can also put an altruistic burden on those select few who agree to donate for others.
Some bloody good questions about blood types
A nurse takes blood samples from a pregnant woman at the North Hospital (Hopital Nord) in Marseille, southern France.
Photo by BERTRAND LANGLOIS / AFP
There remain many mysteries regarding blood types. For example, we still don't know why humans evolved the A and B antigens. Some theories point to these antigens as a byproduct of the diseases various populations contacted throughout history. But we can't say for sure.
In this absence of knowledge, various myths and questions have grown around the concept of blood types in the popular consciousness. Here are some of the most common and their answers.
Do blood types affect personality?
Japan's blood type personality theory is a contemporary resurrection of humorism. The idea states that your blood type directly affects your personality, so type A blood carriers are kind and fastidious, while type B carriers are optimistic and do their own thing. However, a 2003 study sampling 180 men and 180 women found no relationship between blood type and personality.
The theory makes for a fun question on a Cosmopolitan quiz, but that's as accurate as it gets.
Should you alter your diet based on your blood type?
Remember Galen of Pergamon? In addition to bloodletting, he also prescribed his patients to eat certain foods depending on which humors needed to be balanced. Wine, for example, was considered a hot and dry drink, so it would be prescribed to treat a cold. In other words, belief that your diet should complement your blood type is yet another holdover of humorism theory.
Created by Peter J. D'Adamo, the Blood Type Diet argues that one's diet should match one's blood type. Type A carriers should eat a meat-free diet of whole grains, legumes, fruits, and vegetables; type B carriers should eat green vegetables, certain meats, and low-fat dairy; and so on.
However, a study from the University of Toronto analyzed the data from 1,455 participants and found no evidence to support the theory. While people can lose weight and become healthier on the diet, it probably has more to do with eating all those leafy greens than blood type.
Are there links between blood types and certain diseases?
There is evidence to suggest that different blood types may increase the risk of certain diseases. One analysis suggested that type O blood decreases the risk of having a stroke or heart attack, while AB blood appears to increase it. With that said, type O carriers have a greater chance of developing peptic ulcers and skin cancer.
None of this is to say that your blood type will foredoom your medical future. Many factors, such as diet and exercise, hold influence over your health and likely to a greater extent than blood type.
What is the most common blood type?
In the United States, the most common blood type is O+. Roughly one in three people sports this type of blood. Of the eight well-known blood types, the least common is AB-. Only one in 167 people in the U.S. have it.
Do animals have blood types?
They most certainly do, but they are not the same as ours. This difference is why those 17th-century patients who thought, "Animal blood, now that's the ticket!" ultimately had their tickets punched. In fact, blood types are distinct between species. Unhelpfully, scientists sometimes use the same nomenclature to describe these different types. Cats, for example, have A and B antigens, but these are not the same A and B antigens found in humans.
Interestingly, xenotransfusion is making a comeback. Scientists are working to genetically engineer the blood of pigs to potentially produce human compatible blood.
Scientists are also looking into creating synthetic blood. If they succeed, they may be able to ease the current blood shortage, while also devising a way to create blood for rare blood type carriers. While this may make golden blood less golden, it would certainly make it easier to live with.* While antigens are typically proteins, they can be other molecules as well, such as polysaccharides.
China has reached a new record for nuclear fusion at 120 million degrees Celsius.
This article was originally published on our sister site, Freethink.
China wants to build a mini-star on Earth and house it in a reactor. Many teams across the globe have this same bold goal --- which would create unlimited clean energy via nuclear fusion.
But according to Chinese state media, New Atlas reports, the team at the Experimental Advanced Superconducting Tokamak (EAST) has set a new world record: temperatures of 120 million degrees Celsius for 101 seconds.
Yeah, that's hot. So what? Nuclear fusion reactions require an insane amount of heat and pressure --- a temperature environment similar to the sun, which is approximately 150 million degrees C.
If scientists can essentially build a sun on Earth, they can create endless energy by mimicking how the sun does it.
If scientists can essentially build a sun on Earth, they can create endless energy by mimicking how the sun does it. In nuclear fusion, the extreme heat and pressure create a plasma. Then, within that plasma, two or more hydrogen nuclei crash together, merge into a heavier atom, and release a ton of energy in the process.
Nuclear fusion milestones: The team at EAST built a giant metal torus (similar in shape to a giant donut) with a series of magnetic coils. The coils hold hot plasma where the reactions occur. They've reached many milestones along the way.
According to New Atlas, in 2016, the scientists at EAST could heat hydrogen plasma to roughly 50 million degrees C for 102 seconds. Two years later, they reached 100 million degrees for 10 seconds.
The temperatures are impressive, but the short reaction times, and lack of pressure are another obstacle. Fusion is simple for the sun, because stars are massive and gravity provides even pressure all over the surface. The pressure squeezes hydrogen gas in the sun's core so immensely that several nuclei combine to form one atom, releasing energy.
But on Earth, we have to supply all of the pressure to keep the reaction going, and it has to be perfectly even. It's hard to do this for any length of time, and it uses a ton of energy. So the reactions usually fizzle out in minutes or seconds.
Still, the latest record of 120 million degrees and 101 seconds is one more step toward sustaining longer and hotter reactions.
Why does this matter? No one denies that humankind needs a clean, unlimited source of energy.
We all recognize that oil and gas are limited resources. But even wind and solar power --- renewable energies --- are fundamentally limited. They are dependent upon a breezy day or a cloudless sky, which we can't always count on.
Nuclear fusion is clean, safe, and environmentally sustainable --- its fuel is a nearly limitless resource since it is simply hydrogen (which can be easily made from water).
With each new milestone, we are creeping closer and closer to a breakthrough for unlimited, clean energy.
The symbol for love is the heart, but the brain may be more accurate.
- How love makes us feel can only be defined on an individual basis, but what it does to the body, specifically the brain, is now less abstract thanks to science.
- One of the problems with early-stage attraction, according to anthropologist Helen Fisher, is that it activates parts of the brain that are linked to drive, craving, obsession, and motivation, while other regions that deal with decision-making shut down.
- Dr. Fisher, professor Ted Fischer, and psychiatrist Gail Saltz explain the different types of love, explore the neuroscience of love and attraction, and share tips for sustaining relationships that are healthy and mutually beneficial.