Astronomy
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If We Successfully Land On Mars, Could We Live There?
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The atmosphere of Mars is mostly carbon dioxide, the surface of the planet is too cold to sustain human life, and the planet’s gravity is a mere 38% of Earth’s. Plus, the atmosphere on Mars is equivalent to about 1% of the Earth’s atmosphere at sea level. That makes getting to the surface tricky. How will NASA get there? How can we hope to survive against such odds?
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Habitation Built to Last
NASA is already considering what kind of habitation we’ll need to survive on the surface of Mars. Six companies began designing possible habitat prototypes in 2016, with completed prototypes expected in 24 months.
All these habitats will likely have a few things in common — they have to be self-sustaining, sealed against the thin atmosphere, and capable of supporting life for extended periods without support from Earth. To get an idea for what to expect, think about the ISS. “The International Space Station has really taught us a tremendous amount of what is needed in a deep space habitat,” said Davis. “We’ll need things like environmental control and life support systems (ECLSS), power systems, docking ports, [and] air locks so that crew can perform space walks to repair things that break or to add new capabilities.” Expect big robust equipment to travel across the stars to Mars during the first manned mission. Whatever the astronauts use must be up for the long journey.
Davis also posed an interesting question: how much space is needed for each crewmember? Could you imagine spending months in one location, surrounded by the same walls day in and day out? How far apart would they have to be to keep claustrophobia at bay? “In the days of the Space Shuttle, missions ran for 7-15 days, and there was not a lot of space for each crewmember. In a space station, where crewmembers are onboard for a much longer time (typically 6 months), we have found that crewmembers simply need more space.” Based on this logic, it’s possible that habitable bases on Mars will require more square footage for inhabitants.
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Terraforming: It Won’t Be Quite Like the Movies at First
When you think of astronauts on Mars, what comes to mind? Did you picture a red planet turning green with time and continued human colonization? Unfortunately, those days are far in the future, if they even happen at all. During the interview, Davis explained, “Terraforming has a connotation of humans making another planetary body, like Mars, Earth-like. But really, it’s about humans changing their environment to make it more supportive of our need.” What does this mean?
The first few trips to Mars will only include the essentials. One of NASA’s first goals for its astronauts is to learn how to live on the planet. Since it differs greatly from Earth, survival is an important skill for astronauts to master. “The initial base will probably include a habitat and a science lab. [The inside of] these modules will be much like the space station, but there will be differences.” One example Davis gave included preventing toxic dust from getting into the habitat and lab. Microbial life is another threat to astronauts. Without more research on the planet, NASA can’t say for certain what dangers could threaten human life. With this in mind, all scientists involved with the Mars mission will take these and other potential risks under consideration.
Asteroid Belt: Facts & Formation
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Origin
Early in the life of the solar system, dust and rock circling the sun were pulled together by gravity into planets. But not all of the ingredients created new worlds. A region between Mars and Jupiter became the asteroid belt.
Occasionally people wonder whether the belt was made up of the remains of a destroyed planet, or a world that didn't quite get started. However, according to NASA, the total mass of the belt is less than the moon, far too small to weigh in as a planet. Instead, the debris is shepherded by Jupiter, which kept it from coalescing onto other growing planets.
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Building a belt
The Main Belt lies between Mars and Jupiter, roughly two to four times the Earth-sun distance, and spans a region about 140 million miles across. Objects in the belt are divided into eight subgroups named after the main asteroids in each group. These groups are the Hungarias, Floras, Phocaea, Koronis, Eos, Themis, Cybeles and Hildas.
Although Hollywood often displays ships making close calls through asteroid belts, the trip is generally uneventful. A number of spacecraft have safely traveled through the asteroid belt without incident, including NASA's New Horizons mission to Pluto.
"Fortunately, the asteroid belt is so huge that, despite its large population of small bodies, the chance of running into one is almost vanishingly small — far less than one in a billion," wrote New Horizons principle investigator Alan Stern. "If you want to come close enough to an asteroid to make detailed studies of it, you have to aim for one."
Within in the asteroid belt are relatively empty regions known as Kirkwood gaps. These gaps correspond to orbital resonances with Jupiter. The gas giant's gravitational pull keeps these regions far emptier than the rest of the belt. In other resonances, the asteroids can be more concentrated.
Biology
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The Mysterious Powers Of Spider Silks
As they report today in an advance online paper in Nature Genetics, Penn scientists and their collaborators sequenced the full genome of the golden orb-weaver spider (Nephila clavipes), a prolific silk-spinner that turns out to produce 28 varieties of silk proteins. In addition to cataloguing new spider silk genes, the researchers discovered novel patterns within the genes that may help to explain the unique properties of different types of silk.
"There were so many surprises that emerged from our study: new silk genes, new DNA sequences that presumably confer strength, toughness, stretchiness and other properties to silk proteins; and even a silk protein made in venom glands rather than silk glands," said senior author Benjamin F. Voight, PhD, an associate professor in the departments of Genetics and Systems Pharmacology and Translational Therapeutics. "All this new information should greatly advance our efforts to capture the extraordinary properties of these silks in human-made materials."
Even though spider silks have been studied for more than 50 years, earlier foundational work had identified only a comparative handful of spider silk genes. Even recent work from species with smaller silk repertoires than the golden orb-weaver's were incomplete. To find all of the silk genes hidden across the golden orb-weaver's genome -- the veritable "lab rat" of spider silk science -- required the construction of the entire genome, a daunting task in itself.
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[Spider silk proteins, known as spidroins] have been classified into seven categories according to their protein sequences and functions; these categories include aciniform silk for wrapping prey (and tying down partners for mating); and the super-strong major ampullate silk from which spiders (and Spider-Man) swing while at work. However, some of the newly discovered spidroins have sequences that do not fit neatly into any of these categories, suggesting that the encoded silk proteins may have novel functions, or that the existing categories need to be redefined.
An extensive computational analysis of the orb-weaver's spidroin genes revealed nearly 400 short sequences -- many never before described -- that appear repeatedly in these genes with small variations and in different combinations. These repetitive spidroin "motifs" are of great interest to biologists and engineers because they are likely to confer the key properties of a given spider silk, such as high-tensile strength, flexibility, or stickiness. The analysis also revealed novel, higher-order organizations of these motifs into groups of motifs ("cassettes") and groups of groups ("ensembles").
Trackers May Tip A Warbler’s Odds Of Returning To Its Nest
Strapping tiny trackers called geolocators to the backs of birds can reveal a lot about where the birds go when they migrate, how they get there and what happens along the way. But ornithologists are finding that these cool backpacks could have not-so-cool consequences.
Douglas Raybuck of Arkansas State University and his colleagues outfitted some Cerulean warblers (Setophaga cerulea) with geolocators and some with simple color tags to test the effects the locators might have on breeding and reproduction. This particular species globe-trots from its nesting grounds in the eastern United States to wintering grounds in South America and back each year. While the backpacks didn’t affect reproduction, birds wearing the devices were less likely than those wearing tags to return to the same breeding grounds the next year. The birds may have gotten off track, cut their trips short or died, possibly due to extra weight or drag from the backpack, the team reports May 3 in The Condor.
The study adds to conflicting evidence that geolocators affect some birds in negative ways, such as altering their breeding biology. At best, potential downsides vary from bird to bird and backpack to backpack. But that shouldn’t stop researchers from using geolocators to study migrating birds, the researchers argue, because the devices pinpoint areas crucial to migrating birds and can aid in conservation efforts.
Chemistry
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Crystal Clear
In graduate school organic chemistry, it can feel strange to run a reaction in a 500ml flask, and filling a 2 litre flask seems like a trip to a land of giants. Crystallisation is often nothing more than an interesting oddity – brushed off when you really need to confirm a structure, for example. But when I began working in an industrial preparatory laboratory, I quickly got used to the idea of a 12 or even 20 litre flask in my hood. Crystallisation then became a routine tool of purification, and a necessary craft that I needed to master.
In theory it’s terribly simple: you take your crude mixture, dissolve it in a solvent in which the compound is soluble when hot and insoluble when cool. As the hot, concentrated solution cools, the compound comes out of solution, forming a regular lattice that will select the desired molecule and reject impurities.
In reality it’s not so straightforward. First you need to find a solvent in which the compound has a suitable ‘solubility curve’ (relating solubility to concentration and temperature). And then there’s the process itself: as solutions are cooled or made more concentrated, the first tiny crystals begin to nucleate. Cool too fast or raise the concentration too much and you risk ‘oiling out’ (where the compound comes out of solution as a sticky oil, rather than nice crystals). But if you pick the right solvent and lower the temperature of your saturated solution in a careful, controlled manner, you can encourage pure crystals to grow, and keep impurities in the mother liquor.
And of course, sometimes cooling or concentration doesn’t work. Luckily, there are alternatives. Adding small amounts of an antisolvent (in which the compound is insoluble) can force crystallisation. If you do it too quickly, though, you may precipitate crystals too quickly, with impurity-laden mother liquor embedded within.
One amazing aspect of crystallisation is our ability to control the overall size of the crystals. The slower the crystallisation takes place, the larger and more uniform the crystals will be. ‘Ostwald ripening’ can also help avoid crystals ending up too small and blocking filters. The partially crystallised slurry is repeatedly heated and cooled slightly, such that smaller crystals will re-dissolve and larger crystals will grow.
Ecology
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Following Recent Surge, Wind Now Generates 5.5 Percent Of U.S. Electricity
The U.S. wind energy industry experienced its fastest first-quarter growth since 2009, installing 2,000 new megawatts of capacity — enough to power about 500,000 homes — on its way to producing 5.5 percent of the country’s electricity.
The American Wind Energy Association (AWEA) also reported that another 21,000 megawatts of wind energy capacity is now under construction or in advanced development — enough to power an additional 5 million average U.S. homes. The AWEA said that 908 utility-scale wind turbines were erected in the first quarter of 2017, driving a nearly four-fold increase in wind energy growth over the first quarter of 2016. Forty-one U.S. states — most recently Rhode Island and North Carolina — now have utility-scale wind power projects. Texas is by far the wind energy leader in the U.S., with a wind power capacity of 21,000 megawatts.
Federal credits for wind energy production, state renewable energy mandates, and falling costs to build and install wind turbines are all driving growth in wind energy capacity. The AWEA released statistics showing that the wind energy industry is increasingly becoming an important economic force in the U.S., giving it political clout in conservative states like Texas. The AWEA said that more than 100,000 people are employed in the wind industry and that wind energy companies now pay roughly $250 million a year in land lease payments to farmers, ranchers, and other landowners.
Hannah Hunt, a senior analyst at AWEA, said that a key technological development that will enable wind energy installations to be built in more parts of the country is an increase in the height of the turbines from 80 to 100 meters, where wind speeds are higher.
Scientists Track Porpoises To Assess Impact Of Offshore Wind Farms
A new study by scientists at the University of Maryland Center for Environmental Science’s Chesapeake Biological Laboratory, Cornell University and Duke University is the first in a series to understand how marine mammals like porpoises, whales, and dolphins may be affected by the construction of wind farms off the coast of Maryland. The new research offers insight into previously unknown habits of harbor porpoises in the Maryland Wind Energy Area, a 125-square-mile area off the coast of Ocean City that may be the nation’s first commercial-scale offshore wind farm.
Offshore wind farms provide renewable energy, but activities during the construction can affect marine mammals that use sound for communication, finding food, and navigation.
“It is critical to understand where marine mammals spend their time in areas of planning developments, like offshore wind farms, in order to inform regulators and developers on how to most effectively avoid and minimize negative impacts during the construction phase when loud sounds may be emitted,” said Helen Bailey, the project leader at the UMCES’ Chesapeake Biological Laboratory.
Scientists from the University of Maryland Center for Environmental Science used underwater microphones called hydrophones to detect and map the habits of harbor porpoises, one of the smallest marine mammals. Bailey describes harbor porpoises as “very shy” ranging 4 to 5 feet long with a small triangular fin that can be hard to spot. They swim primarily in the ocean, spending summers north in the Bay of Fundy and migrating to the Mid-Atlantic, as far south as North Carolina, in the winter. There are about 80,000 of them in the northwestern Atlantic.
“There was so little known about them in this area,” said Bailey. “It was suspected they used the waters off Maryland, but we had no idea how frequently they occurred here in the winter until we analyzed these data.”
Physics
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Soft Artificial Retina Might Make For Smoother Eye Implants
Repairing people's sense of sight by way of retinal implants is a field of research that is seeing some rather promising advances, with a number of devices under development that promise to restore vision by stimulating optical neurons at the back of the eye. But researchers at the University of Oxford say they have broken new ground in the area by crafting the first such implant entirely from soft, natural materials, which brings with it the prospect of more successful integration in the human body.
The hope is that retinal implants can be used to restore vision in people suffering from conditions like age-related macular degeneration (AMD) and retinitis pigmentosa. The retina is a light-sensitive tissue that sits against the rear of our eye, capturing light and turning it into electrical signals that stimulate neurons and trigger a response in the brain, which turns the signals into an image.
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"The human eye is incredibly sensitive, which is why foreign bodies like metal retinal implants can be so damaging, leading to inflammation and or scaring," says the leader of the research team, Vanessa Restrepo-Schild. "But a biological synthetic implant is soft and water based, so much more friendly to the eye environment."
To that end, Restrepo-Schild and her team developed a two-layered artificial retina they say works much like the real thing. Made up of hydrogels and cell-membrane proteins arranged in a 4x4 array, the two-layered synthetic retina is designed like a camera. The cells respond to light like pixels do, producing distinct electrical signals as grey-scale images and patterns of light are moved across the device. The team believes that these electrical signals, with further work, could be hooked up to living tissue and stimulate the neurons at the back of the eye.
Such a feat is a way off – the device has only been tested in the lab so far – but the team's next step will explore this very possibility, first by enabling the artificial retina to respond to different colors, and then possibly shapes and symbols. Restrepo-Schild has filed a patent for the technology and, further down the track, hopes to test it on animals and then eventually conduct clinical trials in humans.