Johnald's Fantastical Daily Link Splurge |
- Life on Earth Arose Just Once
- The Enemy Within: Male Fish Dislike Their Reflections More Than Competitors
- Hubble Deciphers Misfit Star Mystery
- The Crystals at the Center of the Earth
- Gravity Lows Mark Burial Sites of Ancient Tectonic Plates
- Mice Show Pain on Their Faces Just Like Humans
- Photo: Icelandic Volcano Begins Erupting Again
- Finding the Right Asteroid for Astronauts to Land on
- Better Oil Dispersant Tests Delayed in Gulf
- New Global Map of Every Country’s Tallest Building
| Posted: 12 May 2010 12:56 PM PDT One isn't such a lonely number. All life on Earth shares a single common ancestor, a new statistical analysis confirms. The idea that life-forms share a common ancestor is "a central pillar of evolutionary theory," says Douglas Theobald, a biochemist at Brandeis University in Waltham, Mass. "But recently there has been some mumbling, especially from microbiologists, that it may not be so cut-and-dried." Because microorganisms of different species often swap genes, some scientists have proposed that multiple primordial life forms could have tossed their genetic material into life's mix, creating a web, rather than a tree of life. To determine which hypothesis is more likely correct, Theobald put various evolutionary ancestry models through rigorous statistical tests. The results, published in the May 13 Nature, come down overwhelmingly on the side of a single ancestor. A universal common ancestor is at least 102,860 times more probable than having multiple ancestors, Theobald calculates.
No one has previously put this aspect of evolution through such a stringent test, says David Penny, a theoretical biologist and Allan Wilson Centre researcher at Massey University in Palmerston North, New Zealand. "In one sense, we are not surprised at the answer, but we are very pleased that the unity of life passed a formal test," he says. He and Mike Steel of the University of Canterbury in Christchurch, New Zealand, wrote a commentary on the study that appears in the same issue of Nature. For his analysis, Theobald selected 23 proteins that are found across the taxonomic spectrum but have structures that differ from one species to another. He looked at those proteins in 12 species — four each from the bacterial, archaeal and eukaryotic domains of life. Then he performed computer simulations to evaluate how likely various evolutionary scenarios were to produce the observed array of proteins. Theobald found that scenarios featuring a universal common ancestor won hands down against even the best-performing multi-ancestor models. "The universal common ancestor (models) didn't just explain the data better, they were also the simplest, so they won on both counts," Theobald says. A model that had a single common ancestor and allowed for some gene swapping among species was even better than a simple tree of life. Such a scenario is 103,489 times more probable than the best multi-ancestor model, Theobald found. That's a 1 with 3,489 zeros after it. Theobald's study does not address how many times life may have arisen on Earth. Life could have originated many times, but the study suggests that only one of those primordial events yielded the array of organisms living today. "It doesn't tell you where the deep ancestor was," Penny says. "But what it does say is that there was one common ancestor among all those little beasties." Citations: Theobald, D. L. 2010. A formal test of the theory of universal common ancestry. Nature 465(May 13): 219-223. doi:10.1038/nature09014 Image: M. Steel and D. Penny/Nature 2010 |
| The Enemy Within: Male Fish Dislike Their Reflections More Than Competitors Posted: 11 May 2010 05:53 PM PDT Even though a male cichlid is one tough fish, he may be scared of his own reflection. A new study shows that squaring off to fight a mirror opponent can be worse than fighting a real foe.
Tangling with a real male doesn't stir up that response, the researchers report in a Biology Letters study released online the week of May 11. Desjardins hesitates to equate whatever is going on in the fish brain with the human concept of "fear," but she says the reaction to mirror images is indeed "negative."
Earlier studies of fish and mirrors have suggested that fish just mistake their reflections for some impertinent, other fish that needs a good trouncing. The new paper gives the first indication of differential brain activity when fish meet mirrors, Desjardins says. Scientists have a long tradition of studying animal reactions to mirrors as a way of trying to explore animal consciousness. Great apes, elephants, dolphins and magpies show evidence of recognizing themselves when gazing into mirrors, says Diana Reiss of Hunter College in New York City, who studies animal cognition. In experiments done so far, other animals — including monkeys and fish — don't seem to get it. The new study does not demonstrate mirror self-recognition in fish. "I want to be clear about that," Reiss says. Yet the fish do perceive something different about their reflected opponent. Desjardins and Fernald tested reactions to mirrors in males of an African cichlid species, Astatotilapia burtoni. Hormones as well as behavior looked similar regardless of whether the fish menaced a mirror image or a real male behind a clear partition. To see into the brain, researchers used two marker genes to compare activity in various brain regions. "It's a kind of fishy MRI," Desjardins says. What fired up more in the mirror fighters was the amygdala, a structure that's involved in emotions in people. Using this technique in a mirror study is certainly uncommon and possibly unprecedented, Desjardins says. Reiss adds, "It's an interesting tool." Even with older approaches, though, a few studies have found that some animals without mirror recognition still perceive differences between reflections and reality, notes Joshua Plotnik of Emory University in Atlanta, who worked with Reiss in documenting mirror self-recognition in elephants. Work by other researchers shows differences in heart rates or in behaviors when monkeys encounter a reflection versus a real monkey, even though scientists have not shown self-recognition in monkeys. As far as mirror self-recognition (or not), the new work "does not really change much," says comparative psychologist Thomas Suddendorf of the University of Queensland in Brisbane, Australia. What could change though, says Desjardins, is the current, widespread use of mirrors in experiments that probe behaviors unrelated to self-recognition. Researchers may want to show a fish or other creature another of the same size and species, for example. If animals are sensing that something is off about the mirror, "I think mirrors need to be used with caution," Desjardin says. Image: flickr/Ben Lawson |
| Hubble Deciphers Misfit Star Mystery Posted: 11 May 2010 01:44 PM PDT The massive, hot star seemed out of place when astronomers first spotted it in 2006, and now thanks to Hubble, we know why. The misfit, 30 Dor #016, appears to have been ejected from a cluster of even heftier stars, pinging off of them and off into space at tremendous speed. The star is traveling away from the R136 star cluster at about 250,000 miles per hour. Just 1 or 2 million years old, the star already appears to have traveled 375 light-years from its place of birth. "These results are of great interest because such dynamical processes in very dense, massive clusters have been predicted theoretically for some time, but this is the first direct observation of the process in such a region," astronomer Nolan Walborn of the Space Telescope Science Institute in Baltimore said in a press release. Walborn is a member of the team that tracked down the star, 30 Dor #16 is 90 times more massive than the sun and resides in the Tarantula Nebula, approximately 170,000 light-years from Earth. It's part of the Large Magellanic Cloud, the Milky Way's third-closest neighbor. You can see the R136 cluster in the middle left part of the imageabove. The runaway star is in the upper right, a bright blue spot trailing red dust. Check the annotated image below to make sure you've got your stars properly aligned.
Images: European Southern Observatory. High resolution versions available. See Also:
WiSci 2.0: Alexis Madrigal's Twitter, Tumblr, and forthcoming book on the history of green technology; Wired Science on Twitter and Facebook. |
| The Crystals at the Center of the Earth Posted: 11 May 2010 09:55 AM PDT Seismic waves traveling between Earth's poles move faster than those moving east-west, and now scientists think they may know why. The iron alloys in the solid inner core of the Earth appear to have crystallized in such a way that it's easier for energy to pass on the north-south axis than on the east-west, as described in a new study led by Maurizio Mattesini, a geologist at the Universidad Complutense de Madrid, which appeared in the journal Proceedings of the National Academy of Sciences. "The structure of the atoms looks different in one direction than the other," explained Norm Sleep, a Stanford geologist who was not part of the new study, In the textbooks of yore, the Earth's inner regions like the mantle and core were presented as simple, fairly homogeneous regions. But the geology of the core is turning out to be much more complex as scientists make use of more and better seismographs to generate better data about how seismic waves travel through the planet. The outer core is composed mostly of liquid iron. The inner core is solid ball about 750 miles in diameter, or a little less than the maximum width of the state of Texas, which formed as the Earth cooled over geologic time, said David Stephenson, a geologist at CalTech. "The center of the earth is literally a crystal," said Stephenson. Over time, it grew and now is no longer a single crystal but an aggregate of them.
In the mid-1990s, geologists began to notice an interesting thing. Seismic waves traveling north-south were reaching their destinations about 3 percent faster than waves moving along east-west paths. "It's one of these things that's been detected for some time but kind of why it occurs has been somewhat of a puzzle," Sleep said. They didn't know why, but then again, the middle of the globe is perhaps the most difficult place to gather data on Earth. The new paper suggests that as the crystals formed, they received a particular alignment. That alignment, known as anisotropy, makes it easier for waves to travel in one direction than the other. The most significant thing about the new paper, Stephenson said, is that the researchers were able to match up the results that seismologists have been getting on the speed of seismic waves through the core with new laboratory tests with particular kinds of iron crystals. Image: NASA "Hemispherical anisotropic patterns of the Earth's inner core" by Maurizio Mattesinia, Anatoly B. Belonoshkob, Elisa Buforna, María Ramíreza, Sergei I. Simakc, Agustín Udíasa, Ho-Kwang Maod, and Rajeev Ahujae in the Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1004856107 See Also: WiSci 2.0: Alexis Madrigal's Twitter, Tumblr, and forthcoming book on the history of green technology; Wired Science on Twitter and Facebook. |
| Gravity Lows Mark Burial Sites of Ancient Tectonic Plates Posted: 10 May 2010 11:36 AM PDT
When these slabs of rock were buried long ago, they released water that reduced the density of overlying rock, Caltech geophysicist Michael Gurnis and his colleagues reported online May 9 in Nature Geoscience. Low-density rock has less mass, and so less gravitational pull.
Beneath those four areas, seismic waves travel slower than normal at shallow depths –1,000 kilometers or less — but faster than normal deeper down, says Gurnis. Because sound waves travel faster through dense material (for example, water compared with air) the difference in speed with depth told the team that lighter, less dense material is lying over a layer of very dense material. Most likely, the top layer's relative buoyancy stems from its water-rich composition, the researchers contend.
The water could have been injected in the mantle as a result of slow-motion tectonic collisions between lighter and heavier plates. As dense slabs slipped downward through the mantle, water in those rocks — as well as water in the seafloor sediments that had accumulated above those slabs — was released. "When that water was added to the surrounding rocks, it lowered their melting point and reduced their density," buoying them upward, Gurnis explains. The dehydrated remains of the dense tectonic plates now lie deep in the mantle, where they boost the speed of seismic waves, says Gurnis. The notion that upwelling deep in the mantle could be linked to water carried downward in long-buried tectonic slabs is new, says Carolina Lithgow-Bertelloni, a geophysicist at University College London. A similar upwelling of water-rich material near subduction zones has long been associated with volcanism at Earth's surface, she notes. Previously, studies suggested that hot spots along the core-mantle boundary create buoyant plumes of rock that rise within Earth's mantle (SN: 7/9/05, p. 24). In the new study, however, lowered density arises from presumed changes in the composition of rock, not its temperature. See Also: |
| Mice Show Pain on Their Faces Just Like Humans Posted: 10 May 2010 09:57 AM PDT
People have been using similar facial-expression coding systems in babies and other humans who are unable to verbally express their pain. "No one has every looked for facial expression of pain in anything other than humans," said Jeffery Mogil of McGill University, co-author of the study published on May 9 in Nature Methods. Most pain drugs fail in human trials, because pain-drug effectiveness in rodent trials is based on sensitivity to touch, which is not a good indicator of spontaneous pain, Mogil says. The mouse grimace scale adds another way to catalog pain and pain mitigation in laboratory animals. "This is a true measure of spontaneous pain, a measure that was derived from the analogous human scale," said Mogil. "If pain researchers would adopt this, we could get more accurate translations [of drug effectiveness] to humans."
Mogil first noticed that mice can sense the pain of other mice in 2006. He saw that mice were communicating their pain visually, which had to be either by interpreting each other's facial expressions or body movements. Mogil wondered if we could see whatever the mice were seeing. To test for facial expressions of the mice, Mogil put them through mild to moderate pain tests (similar to a headache or swollen finger, easily treated with Tylenol or aspirin) and used high-definition cameras to monitor their expressions. Pictures from before and after the pain stimulus were shown to technicians at the lab of colleague Kenneth Craig. The technicians used five facial expressions to determine if the mice were in pain: eye squinting, nose bulge, cheek bulge, ear position and whisker changes. While two of the expressions, whisker and ear movement, are impossible for humans to create, the other three were taken directly from the human facial expression of pain scale. "It suggests that this is all a matter of evolution," Mogil said. The problem with pain is that it is both an emotional and a physical response. In humans, one area of the brain is associated with the emotional aspect of pain. When that area is destroyed by a stroke, patients report feeling sensations, but they don't describe it as pain. If this area is damaged in the mice, you can block most of the pained facial expressions without reducing other pain responses. "What we are seeing in the pain face is the emotional reaction, it could actually be the 'I'm not happy face,'" Mogil said. Mogil also tested his mouse grimace scale on mice who have migraines. His team could see changes in their facial expressions when they were probably having a migraine, and could see the expressions diminish when they were treated with migraine drugs. To pet owners and Cute Overload readers, the discovery of facial expressions in other mammals won't come as a surprise. It also wouldn't have surprised Charles Darwin, who predicted that all mammals express emotion through their faces in his 1872 book The Expression of the Emotions in Man and Animals. His book also theorizes that these facial expressions are evolutionarily conserved. Psychologist Amanda C de C Williams of the University College London thinks this study highlights the evolutionary hardwiring of facial expressions. "These expressions predate when mice and humans split on the evolutionary scale," she says. "If there are characteristic expressions, then all mammals should share them." For a long time, scientists thought facial expressions were culturally and behaviorally determined. Studies of tribes in Papua New Guinea done by Paul Eckman (who is loosely the basis for the character Cal Lightman in the show Lie to Me) in 1972 found universally recognized facial expressions in completely isolated cultures and overthrew this theory. While Eckman didn't do research on pain expressions, the mouse grimace scale beefs up his argument that facial expressions are not only ubiquitous across human cultures, but also all mammals. "It suits us to think that animals don't have a real depth of feeling or emotion, so it's OK to treat them badly," Williams said. "Farming practices aren't very sensitive to animals' feelings. It's convenient to just hope they aren't feeling these things." Images: Jeffery Mogil See Also:
Citation: "Coding of Facial Expression of Pain in the Laboratory Mouse" byDale J Langford, Andrea L Bailey, Mona Lisa Chanda, Sarah E Clarke, Tanya E Drummond, Stephanie Echols, Sarah Glick, Joelle Ingrao, Tammy Klassen-Ross, Michael L LaCroix-Fralish, et al. Nature Methods, early online publication, May 9, 2010.doi:10.1038/nmeth.1455 |
| Photo: Icelandic Volcano Begins Erupting Again Posted: 07 May 2010 02:20 PM PDT Iceland's Eyjafjallajökull volcano began erupting again earlier this week. This image, captured May 6 by the European Space Agency's Envisat satellite, clearly shows the grayish brown ash of the plume blowing east. The eruption is the latest in a string that began March 20 and that grounded flights in many parts of Europe for a week. How big a problem the ash clouds become depends not just on the size of the eruption, but on the direction of the wind. Planes can't fly through ash-heavy airspace because there is a danger that the silicates in the plume will turn into glass inside the jet engines. Image: European Space Agency
WiSci 2.0: Alexis Madrigal's Twitter, Tumblr, and forthcoming book on the history of green technology; Wired Science on Twitter and Facebook. |
| Finding the Right Asteroid for Astronauts to Land on Posted: 07 May 2010 01:46 PM PDT The Little Prince, who stood tall on his fictional house-sized asteroid B612, may soon have company. Since President Obama announced last month that NASA plans to send people to an asteroid by 2025 (SN: 5/8/10, p. 10), scientists have been scrambling to fill in the details. Before astronauts can embark on such a journey, they need to choose a destination.
Asteroids come in a menagerie of sizes, shapes and trajectories. Some are little more than giant loose rubble piles, while others are densely packed. Though Obama's proposal didn't point to any specific destinations, Elvis says that a worthy asteroid ought to have a few key features, including a slow spin rate, no problematic satellites and a solar orbit that allows for a long and recurring launch window. "Are they spinning rapidly? Are they elongated? Is there strange, irregular gravity?" Elvis asks. If the asteroid is "lumpy and nasty, that's not good."
The most important consideration, though, is that the asteroid is easy to get to. While the majority of asteroids reside in a belt between the orbits of Mars and Jupiter, some come close to Earth. A relatively nearby asteroid that circles the sun at a speed similar to the Earth's would be ideal, Elvis reported. So far, six of 6,699 known near-Earth asteroids seem to have amenable orbits. For many researchers, the visit will be a mini–Mars-mission — a chance to test strategies and equipment before traveling to the red planet. A round-trip journey to a nearby asteroid might take about half a year. A mission to Mars would take more than twice as long. "If you want to climb Mount Everest, you don't climb K2 first," says astronaut and astronomer John Grunsfeld of the Space Telescope Science Institute in Baltimore. Practicing deep space maneuvers on a nearby asteroid would be like climbing Washington's Mount Rainier before tackling the Himalayas. To find their Mount Rainier, astronomers first need to map all the asteroids. Scientists have pinpointed many of those big enough to destroy the Earth, but a lot of the rocks smaller than a kilometer in diameter haven't been identified, says planetary scientist Bill Bottke of the Southwest Research Institute in Boulder, Colorado. Bottke recently coauthored a National Research Council report outlining possible approaches to cataloging all asteroids near Earth. Once the asteroids are tallied, selection criteria such as those proposed by Elvis can be considered. (Regardless of choice, it is unlikely that the asteroid will have enough gravity to allow a landing. Rather, astronauts would probably tether their spacecraft to the asteroid and move as it moves, possibly zipping to the rock in a smaller vehicle.) Planetary scientist Paul Abell of NASA's Johnson Space Center in Houston says an asteroid's composition might also affect its desirability. Visiting an asteroid that holds water-ice, for example, might help astronauts figure out how to extract water for drinking and for fuel, a technique that could come in handy during pit stops on a long trip to Mars. Of course, a crewed mission to an asteroid would garner rich scientific rewards in its own right. Visiting an asteroid "tells you about what existed back when planets were forming," Bottke says. Asteroids may host carbon-containing molecules, which could hold clues to the beginning of life on Earth. So far, scientists have gleaned much of their information about the early solar system from meteorites that have landed on Earth, but these samples lose a lot of material as they flame through the atmosphere, he says.
But having "non-artificial intelligence," as planetary astronomer Andrew Rivkin of Johns Hopkins University's Applied Physics Laboratory in Laurel, Maryland, puts it, doesn't mean a thing unless the astronauts survive the trip. Keeping them safe on a long flight to an asteroid, as well as to Mars, will pose new challenges. "Going to an asteroid is a new idea, but I don't think all of the complications have been thought through," Bottke says. "I think everyone's being a little cavalier about jumping on the bandwagon." For instance, researchers will need to quantify the doses of radiation that astronauts will experience on the journey. An inopportune solar flare could be deadly, and the requisite protective shielding could be too heavy to carry. If researchers can identify a flight plan that will keep astronauts healthy and safe, Earth's homebodies may be protected as well. Another hope — and another reason to probe a nearby asteroid — is that such a mission could uncover new ways to deflect or destroy a life-threatening rock careening toward Earth. "A lot of the objects that we'll be able to get to as human beings are the ones that represent the greatest threat," Abell says. The difficulties of the proposed visit are great, but the morale boost from accomplishing the mission is "powerful, if not tangible," Rivkin says. Adds Grunsfeld, who has been on five space flights: "This is about the bigger picture. It's the start of humans going out and exploring the solar system." Asteroids to watch:More than 6,500 asteroids are known to enter Earth's neighborhood. Of these, 1,100-plus are classified as "potentially hazardous" — meaning they can approach Earth relatively closely and have diameters larger than 150 meters. The orbits of a few of these asteroids are shown below. 25143 Itokawa grabbed public attention when it became the target of the Japanese Hayabusa mission, which launched in 2003, imaged the asteroid and attempted to collect soil samples. (The recovery capsule is expected to land in Australia in June.) The asteroid's next close approach will be in March 2030, when it will pass within 56.3 million kilometers of Earth. Recent observations suggest asteroid 2005 YU55 is 400 meters long, twice as large as previously thought. The measurements were taken in April as the Arecibo telescope in Puerto Rico tracked the asteroid passing within 2.3 million kilometers of Earth. On its next approach, in November 2011, the body is expected to get much closer — a mere 325,000 kilometers away. 6344 P-L was first discovered in 1960, but then researchers lost track of it. The asteroid was rediscovered in 2007 and given the name 2007 RR9 before it was recognized. The asteroid has a highly elongated orbit that takes 4.7 years to traverse, and its next close approach to Earth will be in November 2040, when it will pass within 11 million kilometers. Images: 1) Eros./NASA. 2) Artist's rendering of the NEAR spacecraft that landed on Eros./NASA. See Also: |
| Better Oil Dispersant Tests Delayed in Gulf Posted: 07 May 2010 11:28 AM PDT A promising alternative to the highly toxic oil dispersant being used in the Gulf is finally being tested, but slowly. Dispersit was approved 10 years ago by the Environmental Protection Agency for emergency cleanup use. In lab comparisons, it's twice as good at breaking down South Louisiana crude oil as Corexit 9500, the primary dispersant used by British Petroleum and the U.S. Coast Guard. It's also half as toxic. Even as British Petroleum has started using Corexit in the Gulf and ordered 15 million gallons from the manufacturer, those early tests are being run yet again on Dispersit. The Coast Guard and British Petroleum have not ordered Dispersit in bulk, which could potentially save valuable days if Dispersit is judged effective for field use. "They're performing the same lab tests that were done originally in the EPA approval testing. They're not even testing it at sea," said Bruce Gebhardt, an executive at U.S. Polychemical corporation, Dispersit's manufacturer. "That's the frustrating part."
That Corexit would be the first line of dispersant defense in the Gulf makes sense. Originally synthesized by Exxon, various formulations of it have been used for decades to dilute spilled oil and accelerate its natural breakdown. "Corexit 9500 is the dispersant that was in all the stockpiles. When something like this happens, you need hundreds and hundreds of tons," said Alun Lewis, a dispersant expert and oil-spill consultant. "There's a big bank of knowledge about Corexit," he said. "I don't know of testing that's been done with Dispersit, besides approval testing by the EPA." That lack of testing is part of a general trend by the oil industry and Coast Guard, who have been slow to develop new cleanup tools or strategies. Over the last decade, as the oil industry successfully lobbied governments for lax offshore drilling regulation –the Deepwater Horizon's operators didn't even need to complete an environmental impact assessment –there has been little emphasis on testing products like Dispersit. "The reality is, we blow them out of the water. But Corexit is the Exxon product, the 800-pound gorilla," said Gebhardt. "We've never been able to move off the shelves. We were never successful in getting them to switch stockpiles. The Coast Guard expressed interest, but it's a big expense, and you don't do it unless you're in pain. Now they're in pain." Lab tests only provide general information, and field tests on Dispersit need to be run. But the delay in starting open-water tests, rather than the same flask-based experiments that originally suggested Dispersit's superiority, seems perplexing. So does the decision not to have Dispersit production start immediately in earnest, making a stockpile immediately available. Twenty thousand gallons of Corexit 9500 are now being used in the Gulf every day. An earlier formulation was linked to respiratory, nervous system and blood disorders among cleanup crews for the Exxon Valdez oil spill. Environmentalists worry that Corexit could affect workers, harm fish and shellfish in the Gulf, and ultimately enter the human food chain. Neither the Coast Guard nor authorities at the the Deepwater Horizon unified command center responded to queries. According to Gebhardt, the Coast Guard has not told him how long it will take to complete the basic lab tests. The testing schedule was apparently hindered by difficulties in recovering usable oil samples from choppy seas. "I've got all my suppliers sitting, waiting with their stocks. I could make product quickly. I can't do that until they give me the go. We could be up in three days, running at 20,000 gallons a day," said Gebhardt. "I just hope the call comes soon." Image: Dispersant spray maintenance team./United States Coast Guard. See Also:
Brandon Keim's Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecological tipping points. |
| New Global Map of Every Country’s Tallest Building Posted: 07 May 2010 11:11 AM PDT You can now see the tallest building in every country of the world on one big map, thanks to an obsessive documentarian of engineering accomplishments. The anonymous cartographer described the new map on the website, Google Earth Hacks using his handle, blackdogprod. "I have fanatically spent the last year thoroughly studying every country in the world to find the correct building," blackdogprod wrote. "I've used every resource available on the internet to find and verify the tallest building in every country, with the most accurate height available." Finally, you can settle that debate over the tallest building in Uganda. It is the Kampala Hilton at 295 feet! And in Trinidad and Tobago, the International Waterfront Towers take the blue ribbon at 394 feet. The tallest building in the world, the Burj Khalifa skyscraper in Dubai stands 2,717 feet tall. That's an order of magnitude higher than the tallest building in most countries. If that sounds preposterous, wait until you see it from space. The image below was captured by a GeoEye satellite and has a resolution of half a meter (1.65 feet). Images: 1) Google Earth. 2) GeoEye See Also:
WiSci 2.0: Alexis Madrigal's Twitter, Tumblr, and forthcoming book on the history of green technology; Wired Science on Twitter and Facebook. |
Though robots have successfully landed on two asteroids so far — Eros and Itokawa — people could accomplish experiments that robots couldn't. "Having humans in the mix gives you a lot of flexibility," Abell says. A human with a hammer could pick up a rock and then choose to discard it in favor of a more intriguing rock somewhere else.
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