November 26, 2013
Seahorses belong to the genus Hippocampus, which gets its name from the Greek words for “horse” and “sea monster.” With their extreme snouts, weirdly coiled bodies and sluggish movements produced by to two puny little fins, these oddly shaped fish seem like an example of evolution gone terribly awry. And yet, new research published today in Nature Communications shows that it is precisely the seahorse’s uncanny looks and slow motions that allow it to act as one of the most stealthy predators under the sea.
Seahorses, like their close relatives the pipefish and sea dragons, sustain themselves by feasting on elusive, spastic little crustaceans called copepods. To do this, they use a method called pivot feeding: they sneak up on a copepod and then rapidly strike before the animal can escape, much like a person wielding a bug swatter tries to do to take out an irritating but otherwise impossible-to-catch fly. But like that lumbering human, the seahorse will only be successful if it is able to get near enough to its prey to strike at very close range. In the water, however, this is an even greater feat than on land because creatures like copepods are extremely sensitive to any slight hydrodynamic change in the currents around them.
So how do those ungainly little guys manage to feed themselves? As it turns out, the seahorse is a more sophisticated predator than appearance might suggest. In fact, it is precisely its looks that make it an ace in the stealth department. To arrive at this surprising conclusion, researchers from the University of Texas at Austin and the University of Minnesota used holographic and particle image velocimetry–fancy ways of visualizing 3D movements and water flow, respectively–to monitor the hunting patterns of dwarf seahorses in the lab.
In dozens of trials, they found that 84 percent of the seahorses’ approaches successfully managed not to sound the copepod’s retreat alarms. The closer the seahorse could get to its unsuspecting prey and the faster it struck, the greater its odds of success, they observed. Once in range of the copepod, seahorses managed to capture those crustaceans 94 percent of the time. Here, you can see that method of attack, in which the seahorse’s giant head looks like a floating bit of marine sludge drifting toward the blissfully ignorant copepod:
The way the seahorse’s movements and morphology–especially its head–interact with the water particles, the researchers found, likely take the credit for its exceptional hunting skill. The animal’s arched neck acts like a spring for generating an explosive strike, they describe, while the shape of its snout–a thin tube with the mouth positioned at the very end–allows it to drift through the water while creating minimal disturbance.
To emphasize this pinnacle of engineering, the team compared water disruptions caused by seahorses with those of sticklebacks, a relative of the seahorse but with a more traditional fishy look. Thanks to the shape and contours of the seahorse’s head, that predator produced significantly less fluid deformation in the surrounding water than the stickleback. The poor stickleback possesses neither the morphology nor posture to generate “a hydrodynamically quiet zone where strikes occur,” the authors describe. In other words, while the seahorse may appear a bit odd so far as fishes go, evolution was obviously looking out for that funny but deadly animal’s best interests.
June 28, 2013
Every day, it seems, a new exoplanet is found (or, in the case of Tuesday, scientists discovered three potentially habitable exoplanets orbiting one star). But there are loads of hurdles that we’ll have to clear before we ever have the chance to visit them: the massive doses of radiation that would be absorbed by would-be astronauts, the potential damage caused by interstellar dust and gas to a craft moving at extremely high speeds, and the fact that traveling to even the nearest habitable exoplanet would take almost 12 years in a spacecraft traveling at the speed of light.
The biggest problem, though, might be the enormous amount of energy such a craft would require. How do you fuel a spacecraft for a journey more than 750,000 times farther than the distance between the Earth and the Sun?
Based on our current technology for exploring space and potential future approaches, here’s a rundown of the possible ways of propelling spacecraft.
Conventional Rockets: These create thrust by burning a chemical propellant stored inside, either a solid or liquid fuel. The energy released as a result of this combustion lifts a craft out of Earth’s gravitational field and into space.
Pros: Rocket technology is well-established and well-understood, as it dates to ancient China and has been used since the very beginning of the space age. In terms of distance, its greatest achievement thus far is carrying the Voyager 1 space probe to the outer edge of the solar system, roughly 18.5 billion miles away from Earth.
Cons: The Voyager 1 is projected to run out of fuel around the year 2040, an indication of how limited in range conventional rockets and thrusters can carry a spacecraft. Moreover, even if we could fit a sufficient amount of rocket fuel onto a spacecraft to carry it all the way to another star, the staggering fact is that we likely don’t even have enough fuel on our entire planet to do so. Brice Cassenti, a professor at Rensselaer Polytechnic Institute, told Wired that it would take an amount of energy that surpasses the current output of the entire world to send a craft to the nearest star using a conventional rocket.
Ion engines: These work somewhat like conventional rockets, except instead of expelling the products of chemical combustion to generate thrust, they shoot out streams of electrically-charged atoms (ions). The technology was first successfully demonstrated on NASA’s 1998 Deep Space 1 mission, in which a rocket closely flew past both an asteroid and a comet to collect data, and has since been used to propel several other spacecraft, including an ongoing mission to visit the dwarf planet Ceres.
Pros: These engines produces much less thrust and initial speed than a conventional rocket—so they can’t be used to escape the Earth’s atmosphere—but once carried into space by conventional rockets, they can run continuously for much longer periods (because they use a denser fuel more efficiently), allowing a craft to gradually build up speed and surpass the velocity of one propelled by a conventional rocket.
Cons: Though faster and more efficient than conventional rockets, using an ion drive to travel to even the nearest star would still take an overwhelmingly long time—at least 19,000 years, by some estimates, which means that somewhere on the order of 600 to 2700 generations of humans would be needed to see it through. Some have suggested that ion engines could fuel a trip to Mars, but interstellar space is probably outside the realm of possibility.
Nuclear Rockets: Many space exploration enthusiasts have advocated for the use of nuclear reaction-powered rockets to cover vast distances of interstellar space, dating to Project Daedalus, a theoretical British project that sought to design an unmanned probe to reach Barnard’s Star, 5.9 light-years away. Nuclear rockets would theoretically be powered by a series of controlled nuclear explosions, perhaps using pure deuterium or tritium as fuel.
Pros: Calculations have shown that a craft propelled in this way could reach speeds faster than 9000 miles per second, translating to a travel time of roughly 130 years to Alpha Centurai, the star nearest the Sun—longer than a human lifetime, but perhaps within the realm of a multi-generational mission. It’s not the Millenium Falcon making the Kessel Run in less than 12 parsecs, but it’s something.
Cons: For one, nuclear-powered rockets are, at present, entirely hypothetical. In the short-term, they’ll probably stay that way, because the detonation of any nuclear device (whether intended as a weapon or not) in outer space would violate the Partial Nuclear Test Ban Treaty, which permits such explosions in exactly one location: underground. Even if legally permitted, there are enormous safety concerns regarding the launch of a nuclear device into space atop a conventional rocket: An unexpected error could cause radioactive material to rain across the planet.
Solar Sails: In comparison to all the other technologies on this list, these operate on a rather different principle: Instead of propelling a craft by burning fuel or creating other sorts of combustion, solar sails pull a vehicle by harnessing the energy of the charged particles ejected from the Sun as part of the solar wind. The first successful demonstration of such a technology was Japan’s IKAROS spacecraft, launched in 2010, which traveled towards Venus and is now journeying towards the Sun, and NASA’s Sunjammer, seven times larger, is going to launch in 2014.
Pros: Because they don’t have to carry a set amount of fuel—instead using the power of the Sun, much like a sailboat harnesses the energy of the wind—a solar sail-aided spacecraft can cruise more-or-less indefinitely.
Cons: These travel much slower than rocket-powered crafts. But more important for interstellar missions—they require the energy ejected from the Sun or another star to travel at all, making it impossible for them to traverse the vast spaces between the reach of our Sun’s solar wind and that of another star system’s. Solar sails could potentially be incorporated into a craft with other means of propelling itself, but can’t be relied upon alone for an interstellar journey.
Antimatter Rockets: This proposed technology would use the products of a matter-antimatter annihilation reaction (either gamma rays or highly-charged subatomic particles called pions) to propel a craft through space.
Pros: Using antimatter to power a rocket would theoretically be the most efficient fuel possible, as nearly all of the mass of the matter and antimatter are converted to energy when they annihilate each other. In theory, if we were able to work out the details and produce enough antimatter, we could build a spacecraft that travels at speeds nearly as fast as that of light—the highest velocity possible for any object.
Cons: We don’t yet have a way to generate enough antimatter for a space journey—estimates are that a month-long trip to Mars would require about 10 grams of antimatter. To date, we’ve only been able to create small numbers of atoms of antimatter, and doing so has consumed a large amount of fuel, making the idea of an antimatter rocket prohibitively expensive as well. Storing this antimatter is another issue: Proposed schemes involve the use of frozen pellets of antihydrogen, but these too are a far way off.
More speculative technologies: Scientists have proposed all sorts of radical, non-rocket-based technologies for interstellar travel. These include a craft that would harvest hydrogen from space as it travels to use in a nuclear fusion reaction, beams of light or magnetic fields shot from our own Solar System at a distant spacecraft that would be harnessed by a sail, and the use of black holes or theoretical wormholes to travel faster than the speed of light and make an interstellar journey possible in a single human’s lifetime.
All of these are extremely far away from implementation. But, if we do ever make it to another star system at all (a big if, to be sure), given the problems with most existing and near-future technologies, it might indeed be one of these pie-in-the-sky ideas that carry us there—and perhaps allow us to visit a habitable exoplanet.
May 30, 2013
If the watch on your wrist ran slow by five minutes over the course of a year, you probably wouldn’t think anything of it. But scientists and engineers rely on ultra-accurate atomic clocks for a range of applications, and the quest for ever-more-accurate clocks has gone on for millennia.
Now, a group of researchers led by Andrew Ludlow of the National Institute of Standards and Technology has set the bar higher than ever. Their newest atomic clock, unveiled yesterday, is predicted to become inaccurate by an amount of 1.6 seconds of time after running for a total of 1018 seconds—or, in other words, it loses one full second over the course of about 50.8 billion years.
In the paper describing their clock, the researchers provided a pair of analogies for this level of accuracy: “[It] is equivalent to specifying the age of the known universe to a precision of less than one second,” they wrote, “or Earth’s diameter to less than the width of an atom.”
Like all clocks, atomic clocks keep consistent time by basing the duration of a second off a physical event that happens with regularity. While mechanical clocks use the swinging of a pendulum to maintain time, atomic clocks use a mechanism that occurs with even more regularity: the specific frequency of light needed to cause an atom to fluctuate between two energy states (specifically, to go from a ground state into an excited state), which is always a uniform value. For example, the current international standard that defines the duration of a second is 9,192,631,770 cycles of the amount of microwave radiation that causes cesium atoms to fluctuate between the two energy states and in the process emit the most light possible.
A few factors, though, can distort even the most careful measurements of this frequency. What the researchers behind this new clock have done is create an innovative design (using a different element) that minimizes these distortions more than any clock before.
Their design, called an “optical lattice clock,” traps ytterbium atoms inside a lattice box of laser beams. Held in place, the atoms are bombarded by a second type of laser, which forces their electrons to jump up in energy level. A sensor checks to make sure that all the atoms reach the higher energy level, and the precise light frequency needed to force them to do so is then converted into the exact length of a second.
Normally, any slight physical movement of the atoms as they’re bombarded can lead to subtle changes in the frequency of light needed to raise their energy level (a result of Doppler shift), throwing off the accuracy of the clock. But, as described in the MIT Technology Review, where news of the clock was first published, the box of laser beams “holds the atoms in a vice-like grip that minimises any Doppler effects.” Additionally, the lattice traps a relatively large number of atoms (between 1,000 and 1,000,000) compared to most atomic clocks, so averaging the amount of radiation needed to raise each of these to the higher energy level provides a more accurate value of the radiation’s precise frequency, which is then used to set time.
Comparing two such clocks together, the authors found something remarkable–each “tick” measures intervals of time so perfectly that one clock will only lag behind the true time by a tenth of a second when our Sun envelopes the Earth as it evolves into a red giant about 5 billion years from now.
This new clock—and the gradual refinement of atomic clocks as a whole—might seem like a purely academic pursuit, but in reality there are a ton of very useful applications of the technology. Take, for instance, the “maps” app on your phone. Without the ability to closely synchronize clocks over great distances, the GPS system wouldn’t be able to work, because it relies upon the exact comparison of the time it takes signals to travel from several different satellites to your GPS-enabled device.
Future pursuits that could use this newest advance in atomic clock technology could fall within the science of geodesy, which seeks to precisely measure tiny changes in Earth’s shape and its gravitational field over time. All clocks tick at infinitesimally slower rates at sea level than at a mile high, because the force of gravity is stronger when closer to the Earth. Currently, with the most sophisticated atomic clocks, this difference in speed can only be measured when elevation changes by thousands of feet, but with the new clock, they will be detectable when the clock is raised or lowered by a mere centimeter, making the system potentially useful for measuring slight changes in glacier ice thickness or elevation gained by mountain ranges over time as tectonic plates collide.
February 12, 2013
This Friday afternoon at approximately 2:26 Eastern time, an asteroid roughly half the size of a football field (147 feet) in diameter will pass extremely close to the Earth—just 17,200 miles from our planet’s surface. That said, there’s no need to worry, as NASA scientists confirmed with certainty nearly a year ago that the asteroid will not make an impact and poses absolutely no threat.
Nevertheless, the proximity of the asteroid’s path is noteworthy: it will come within a distance 2 times the Earth’s diameter, passing us by even closer than some geosynchronous satellites that broadcast TV, weather and radio signals. As Phil Plait writes in his comprehensive post on the asteroid over at Slate, “This near miss of an asteroid is simply cool. It’s a big Universe out there, and the Earth is a teeny tiny target.”
The asteroid—likely made of rock and referred to as 2012 DA14 by scientists—was first spotted last February by astronomers at Spain’s Observatorio Astronómico de La Sagra. Asteroids, like planets, orbit the Sun, and this one passed us by on its last orbit as well, but at a much greater distance—it came within roughly 1.6 million miles last February 16. After this year’s near miss, the rock’s orbit will be altered significantly by the influence of Earth’s gravity, and scientists calculate that it won’t come near us again until the year 2046 at the soonest.
On Friday, though, it will pass by Earth between 18:00 and 21:00 UTC (1-4 p.m. Eastern time, or 10 a.m.-1 p.m. Pacific) and come closest at roughly 19:26 UTC (2:26 p.m. Eastern, 11:26 a.m. Pacific). That means that observers in Eastern Europe, Asia and Australia get to see its closest pass at nighttime, whereas those in North America, Western Europe and Africa will have to wait until after sunset, when the asteroid has already begun to move away.
For all observers, the asteroid will be too small to see with the naked eye, though it should be viewable with binoculars or a telescope. Universe Today has the technical details on where exactly to spot the asteroid in the sky. A number of observatories and organizations will also broadcast video streams of the asteroid live, including NASA.
A fly-by like the one on Friday isn’t particularly rare in terms of mere proximity. There are seven closer asteroid passes on record—in 2011, a tiny asteroid set the record for near misses by coming within 3300 miles of Earth, and in 2008, an even smaller one actually made contact with the atmosphere, burning up over Africa.
Both of those rocks, though, were less a meter across.What distinguishes this asteroid is that it’s passing close by and theoretically large enough to cause major damage if an impact were to occur. While an asteroid of this size passes this closely roughly every 40 years on average, a collision with an object this size only happens once every thousand years or so.
What kind of damage would that impact wreak? For a comparison, many are noting the Tunguska event, an explosion over a remote area Russia in 1908 that was likely caused by an asteroid of similar size burning up in the atmosphere. The explosion knocked down more than 80 million trees covering an area of some 830 square miles; scientists estimate it released more than 1,000 times as much energy as the nuclear bomb dropped on Hiroshima and triggered shock waves that would have registered a 5.0 on the Richter scale.
Of course, unlike in 1908, we now have the power to observe approaching asteroids well ahead of time—and might have the ability to prevent potential collisions. Bill Nye is among those who argue that this event should serve as a wake-up call for the importance of investing in asteroid-detecting infrastructure, such as observatories and orbiting telescopes. The B612 Foundation supports this mission, and advocates for the development of technologies that could slightly alter the path or speed of an approaching object to avoid an impact.
This time, at least, we’re lucky. But Ed Lu, a former astronaut and head of B612, says this event should not be taken lightly. ”It’s a warning shot across our bow,” he told NPR. “We are flying around the solar system in a shooting gallery.”
December 28, 2012
Over the past year, we’ve seen a ton of scientific milestones and discoveries of historic importance, from the discovery of the Higgs Boson to the landing of a mobile laboratory on Mars. Science, though, is defined by its relentless march forward: No matter how much we learn, there are always more questions to answer. So, after our roundup of 2012′s most surprising (and significant) scientific events, we bring you the most exciting studies, projects and science developments we’ll be watching for in 2013.
1. Comet Ison: Back in September, a pair of Russian astronomers discovered a new comet heading in our direction. At the time, it was just a faint blip detectable only with the most sophisticated telescopes, and it was unclear how visible it would become during its approach. Now, though, astronomers are predicting that when it passes by us and closely orbits the sun in November and December of 2013, it could be the astronomical sight of our lifetimes. “Comet Ison could draw millions out into the dark to witness what could be the brightest comet seen in many generations—brighter even than the full Moon,” astronomer David Whitehouse writes in The Independent. One thing’s for sure: we’ll be watching.
2. Lake Vostok: For more than a decade, a team of Russian scientists has worked to drill nearly 12,000 feet down into Antarctica’s icy depths with a single purpose: to obtain samples from the ultra-deep isolated subglacial lake known as Lake Vostok. After barely reaching the water’s surface last Antarctic summer, they now plan to return at the end of 2013 to drill fully into the lake and use a robot to collect water and sediment samples. The lake may have been isolated for as long as 15 to 25 million years—providing the tantalizing potential for long-term isolated evolution that could yield utterly strange lifeforms. The lake could even serve as a model for the theoretical ice-covered oceans on Jupiter’s moon Europa, helping us better understand how evolution might occur elsewhere in the solar system.
Rival American and British teams were also racing to probe the depths of other subglacial lakes in search of life—the American team’s efforts to reach subglacial Lake Whillans is expected to meet with success this January or February, while the British have been forced to cease their drilling efforts into subglacial Lake Ellsworth due to technical difficulties.
3. Algae Fuel: Experts predict that 2013 will be the year when vehicle fuels derived from algae finally take off. A handful of biofuel stations in the San Francisco area started selling algae-based biodiesel commercially for the first time last month, and after the product met state fuel standards, the pilot program is expected to be expanded shortly. Because algae use less space, grow more quickly and can be more efficiently converted into oil than conventional crops used for biofuels, advocates are excited about the possibility that algae-based fuels could wean us off petroleum without using up precious food crops.
4. Cosmic Microwave Background: Energy left over from the Big Bang still radiates through the universe—and the European Space Agency’s plans to use the Planck satellite to measure this energy more precisely than ever before could help us better understand the formation of the universe. The 1965 measurement of this microwave energy first supported the concept of the Big Bang, and subsequent examination of variations in the radiation has led to more sophisticated theories about our universe’s earliest days. The Planck satellite, launched in 2009, has already collected a wide range of valuable astronomical data and images, but plans to release all this info in early 2013 has the cosmology world all atwitter.
5. Supercomputers to the Rescue: A number of supercomputers around the world could have a remarkable impact at solving problems in health, the environment and other fields over the next year. Yellowstone, a 1.5 petaflops cluster computer in Wyoming, was installed this past summer and will spend 2013 crunching numbers (1.5 quadrillion calculations per second, to be exact) to refine climate models and help us better understand how storms and wildfires move across the planet. Meanwhile, Watson, IBM’s world-famous Jeopardy-winning supercomputer, is currently being trained by doctors to recognize medical symptoms and serve as a diagnostic tool, providing treatment options based on case histories and clinical knowledge. So far, the computer has been trained to recognize breast, lung and prostate cancers.