Initial results of Cassini’s March 12 flyby of Enceladus have been published. You can watch a replay of today’s press briefing, read the blog, and read illustrated bulletins about the organic material, chemical signatures, hot spot locations, the stellar occultation (see also the Quicktime animation). Another article shows the plume locations. An astrobiologist (Chris McKay) added his speculations about life. The encounter preview page contains links to more information, including the flyby details (PDF), and the video page contains an eye-grabbing animation of the flyby sequence as it was programmed with each instrument’s activities. Here is the rundown on the major findings:The hot spots align predominantly right along the “tiger stripe” fractures at the south pole.The highest temperatures lie at certain points along the tiger stripes where plumes have been seen.Temperatures are hotter than earlier measurements: -135° F. (compared to a background temperature of less than -300° F.). This indicates a great deal of energy is being transferred from the interior.Some transverse warm areas were detected, oriented perpendicular to the stripes.The material jets out at over 1000 mph and was strong enough to produce a measurable torque on Cassini, 120 miles away.Though most of the jets consist of ice grains 1/10,000 of an inch in diameter, simple organics were detected (methane, carbon monoxide, carbon dioxide, formaldehyde) and some complex organics (propane, propyne, acetylene).No ammonia was found. Scientists had hoped that ammonia might depress the melting point of water and make the plumes easier to explain.The plumes appear to emerge from localized regions about half a tennis court in area, but extended along narrow strips within the tiger stripes.Though this brief press flurry did not mention it, Cassini also took a gorgeous mosaic of the north pole of Enceladus – including areas not previously imaged at high resolution. The mosaic can be seen at the Imaging Team catalog page for March 13. Leader of the INMS (Ion and Neutral Mass Spectrometer) instrument Hunter Waite (Southwest Research Institute, San Antonio) was most surprised that the chemical brew emerging from the plumes resembles that of a comet. Enceladus is obviously not a comet. He described the cocktail as being “like carbonated water with an essence of natural gas.” At this time, no one speculated about the origin of the plumes or how they could be maintained for billions of years. John Spencer of the CIRS team (Composite Infrared Spectrometer) did say that the temperatures could be hotter further down enough to allow for liquid water. Water – that was the magic word. The astrobiologists kicked into gear. “Enceladus has got warmth, water and organic chemicals, some of the essential building blocks needed for life,” said Dennis Matson, project scientist (cf. 03/19/2008). “We have quite a recipe for life on our hands, but we have yet to find the final ingredient, liquid water, but Enceladus is only whetting our appetites for more.” These thoughts were also echoed on the NASA TV press briefing as if scripted. Matson and astrobiologist Chris McKay in a related feature talked about the feasibility of exotic life and contrasted the “primordial soup theory” with the “deep sea vent theory.” Either theory would work on Enceladus, they claimed. The confidence that life is nearly inevitable contrasted starkly against an admitted background of ignorance and controversy: “We don’t know how long it takes for life to start when the ingredients are there and the environment is suitable, but it appears to have happened quickly on Earth,” the article said. Then, with a bow to a Darwin metaphor, it continued, “So maybe it was possible that on Enceladus, life started in a ‘warm little pond’ below the icy surface occurring over the last few tens of millions of years.” More observations will be needed, of course. And indeed, more observations are on the way. A series of close encounters with Enceladus has been planned during Cassini’s extended mission, which begins (pending final approval) on July 1. The next is in August. The cameras, which were not the prime instruments for the recent flyby, will have a chance to take extreme high-resolution photos of the tiger stripes, and the Cosmic Dust Analyzer (CDA), which failed to operate, will get one more optimal chance to collect geyser particles. Seven more close flybys are planned through 2009. The March 12 encounter dipped 30 miles from the surface at closest approach; some of the daring flybys to come will be even closer – fast, low, and maybe even more thrilling. The little 300-mile-wide moon Enceladus seems to be a strong contender for Best Actor of the Saturn awards.Good grief, Enceladus has nothing to do with life. This is the distracting emotional appeal like the scantily-clad woman beside the truck at the used car lot. NASA throws in the distraction at every mention of the word water in a vain belief that it will garner public support for the space program. As could be expected, right on cue, National Geographic News picked up on this theme as the major aspect of the story. Dave Mosher at Space.com even said “seeds of life found near Saturn.” Incredible. All they found was poison gas like methane and acetylene, folks! Go experiment with your barbecue. Write us if anything crawls out except the spider that took up residence there over the winter. The scientists totally avoided the age issue today. John Spencer has frankly admitted being completely baffled and embarrassed that the science community has no answer for where this little moon got its energy, or for how it could maintain it over billions of years. Their plight has only gotten worse since the discovery of the plumes in 2005. Recall that yesterday (03/25/2008, footnote to main entry) we highlighted a new paper in next month’s Icarus that struck down both tidal heating and radioactivity – the leading theoretical possibilities – as plausible sources of the heat. That makes the scientists’ focus on exotic life even more distracting, as if the emperor, once exposed, quickly points to the sky and waxes eloquent about how the cloud shapes appear so very lifelike. Let’s watch instead how his minions are going to robe their little embarrassment now that King Billions-of-Years has mooned the crowd.(Visited 10 times, 1 visits today)FacebookTwitterPinterestSave分享0
(Visited 442 times, 1 visits today)FacebookTwitterPinterestSave分享0 Robot designers know that making things big is easy, but making them small is hard. How do you pack a multitude of capabilities in a tiny space? Consider these little guys.Tarantulas have eight eyes that are simple (like human eyes) instead of compound. Researchers found that they use their lateral eyes to calculate distance.Lycosa tarantula, a wolf spider found in Spain, hunts by ambushing its prey and dragging its meal back to its 20cm-deep burrow. Finding the way back, however, can be a math problem after darting this way and that in the chase. Science Daily says it “uses path integration to return to its burrow.” Did this little creature ace trigonometry class? “With this mechanism, it does not follow the same path back to its burrow; instead, it moves as though it had followed the sides of a right-angle triangle, returning along the hypotenuse.” Scientists in Madrid ran experiments in the lab. It must have been fun trying to paint the lateral eyes shut on these speedy runners. The researchers put the spiders through their paces on specially-designed arrays of black and white bands. What they found reveals an astonishing array of instruments packed into a tiny space:“To calculate the distance it has travelled, the animal needs an odometer that registers the route, its location with respect to the finish point, which would be the burrow, and a ‘compass‘ to track the direction of travel,” according to Joaquin Ortega Escobar, lead author of a paper published in the Journal of Experimental Biology on the function of each eye in these processes.The ‘compass’ would correspond to polarised light, which the median eyes use to measure the angle; direction is detected by the anterior lateral eyes. Through this research, the scientists have learned that it is principally the anterior lateral eyes (which until now had not been analysed), and to a lesser extent the posterior lateral eyes, that help tarantula wolf spiders measures the distance to their nest.Mosquitoes have some of the fastest wings in nature. Much as we despise them, we have to have a grudging admiration for a tiny creature that can flap wings 800 beats a second—four times faster than insects of a similar size. In Nature, Laura A. Miller describes efforts to understand the flight mechanics of mosquitoes (many species of which do not bite humans). Despite the fast wingbeats, which make that annoying whine, the thin wings only employ strokes of about 40° in amplitude—much shorter than in other flying insects. Science Daily says that the researchers at Oxford University, curious about the narrow wings and short beats, “predicted that they must make use of clever tricks as the wings reverse their direction at the end of each half-stroke.”How can a tiny brain of less than a million neurons achieve complex processes?In particular, the researchers wondered how they get enough lift. Even a mosquito needs lift to fly. The answer, they found with cameras running at 10,000 frames a second, was by a rotation mechanism in the wing attachment muscle that induces vortices on both forward and backward strokes, gaining lift in both directions. This sounds similar to what Illustra Media demonstrated in far larger animals, hummingbirds (see Flight: The Genius of Birds). Miller compares it to the force one feels holding a hand out the window of a moving car, rotating it into and out of the wind. The researchers (who must have had amazing technology to measure lift on such minuscule wings) found that mosquitoes actually employ three mechanisms to get all the lift they can: (1) leading-edge vortex, (2) wake capture, and (3) rotational drag—a trick unique to mosquitoes.Could drone designers learn from these tricks of the mosquito? “Mosquito-flight investigations are certainly on their way to generating plenty of future research buzz,” Miller quips.Honeybees have better eyesight than thought, Science Daily reports. They can clearly discern objects at angles of a mere 1.9°, as small as your thumb at arm’s length, but that’s not all; they can make out objects at just 0.6° almost as well, a third as wide. This is 30% better than earlier thought, according to an Australian team that gave eye tests to bees. “Among other things, honey bees help to answer questions such as: how can a tiny brain of less than a million neurons achieve complex processes, and what are its utmost limits? In the last few decades it has been shown that bees can see and categorize objects and learn concepts through vision, such as the concept of ‘symmetric’ and ‘above and below’….“Photoreceptors in the visual system detect variations in light intensity. There are eight photoreceptors beyond each hexagonal facet of a bee’s compound eye, and their eyes are made out of thousands of facets!“Butterflies have an amazing mouthpart called the proboscis that lets them slurp nectar like drinking through a straw. Only they don’t need to suck; the proboscis is designed to bring fluid in automatically, by capillary action. These mouthparts are clearly shown in Illustra Media’s documentary Metamorphosis, which shows how after hatching from the chrysalis, the proboscis emerges in half-channels. The butterfly uses other mouthparts called palpi to knit the two halves together into a single channel. The proboscis can be rolled up into a neat little circle like a hose reel, and extended for use.Recently, Phys.org tried to unravel other mysteries of the mouthparts of butterflies. And like the “bee team” reported above, researchers at Kent State (UK) wanted to learn about this to imitate it. “An insect’s proboscis, a body part that allows them to drink liquids, acts like a highly-sophisticated sponge and straw that uses capillary action to send nectar or other liquids to the insect’s digestive system,” the team says. The channel size is crucially important for the type of liquid the insect needs to drink.The team’s findings show that capillary action is an essential and ideal method for removing small amounts of fluids from surfaces, Lehnert said. By copying this natural method, scientists say the mouthparts of flies and butterflies can serve as models for developing new devices for improved drug delivery systems.Even though engineers can only approach the efficiency of the butterfly proboscis, Lehnert attributed the insect’s design to evolution. “In order to feed on nectar and other liquid films, natural selection has favored the evolution of specialized mouthparts in fluid-feeding insects,” the press release writer says. Then Lehnert mixes convergent evolution with personification to portray natural selection as a refining agent:“It was previously known that flies and butterflies independently evolved mouthparts adapted for feeding on fluids, but what was unknown before our study was that they both use the same principles for ingesting fluids – capillary action,” Lehnert said. “Our findings have applications to the production of novel microfluidic devices that can be developed to mimic the functionality of insect mouthparts, which have the advantage of being impacted by natural selection over millions of years.“Ants rescue their dead. Did you know that? Neither did scientists; Phys.org reports that researchers in Europe, studying African ants, didn’t expect to see this. “We have observed helping behaviour vis-à-vis injured animals for the first time in invertebrates,” one said. For social insects where nest members are clones with no individuality, this is quite amazing; “obviously, it pays off for the colony as a whole to invest in the rescue service,” they say. The ants’ triage service will sound remarkably familiar to those in the human military:When an ant is injured in a fight, it will “call” its mates for help by excreting chemical substances. The injured insect is then carried back to the nest where it can recover after receiving treatment. What is the “therapy” like? Usually, treatment involves removing the termites still clinging to the ant.Dung Beetles seem disgusting, rolling balls of poop around to feed on, but they actually play a part in the balance of nature. And they have an amazing trick that has come to the light of science: they navigate by the Milky Way. Really! At The Conversation, James Foster of Lund University describes experiments to figure out how they do it. His team created an artificial Milky Way sky to watch them under controlled conditions. They found that it isn’t constellations that guide them, but the brightness patterns between the Milky Way and the other parts of the sky that help them orient themselves, so that they can roll their ball in a straight line.This brightness-comparison strategy may be less sophisticated than the way birds and human sailors identify specific constellations, but it’s an efficient solution to interpreting the complex information present in the starry sky—given how small the beetles’ eyes and brains are. In this way, they overcome the limited bandwidth of their information processing systems and do more with less, just as humans have learnt to do with technology.So there you have it: insects and arachnids with remarkable superpowers, using well-designed equipment. The genius in these animals is so good, scientists study it in order to copy it. Knowing what we have learned, it makes it hard to swat, step on, or spray these sophisticated little living robots.Don’t feel too sorry for that mosquito after your blood. This is not the “very good” world of the original creation before the Fall. Still, God has left enough evidence of his creative power to stand in awe of his wisdom. It should draw us to seek him, humble ourselves, repent, and trust in his way of escape from the consequences of sin.
_This podcast series is excerpted from a two-day class called “Building Science Fundamentals” taught by Dr. Joe Lstiburek and Dr. John Straube of Building Science Corporation._ For information on attending a live class, go to BuildingScienceSeminars.com In our last episode, Dr. Joe Lstiburek compared air barriers and vapor barriers, and explained how airtightness helps keep homes free of mold and rot. This week Dr. Joe explains how water and salt move through masonry by osmosis, often causing serious damage to foundations. He also offers some solutions to this common problem. __________________________________________________ Osmosis isn’t a problem everywhere In new construction, it’s real easy: you coat the top of the footing, you’ve got your stone (capillary) break, you’ve got your dampproofing. You don’t have to worry about salt, and you don’t have to worry about capillarity — life is good. It’s kind of hard to retrofit this. It’s a wonderful way to do it in new construction, but it’s tough if you’ve got a 100-, 200-, or 300-year-old structure to deal with. What’s so bad about salt and water? The physics of the osmosis forces works like this: water takes the salt in solution to a surface, the water evaporates, and the salt is left behind. And as more water evaporates, more salt accumulates, so the concentration of salt goes up. As the concentration of salt goes up, water rushes to the concentration of salt in order to dilute it — because one of the rules of physics is that nature doesn’t like these kinds of concentrations. The action of the water rushing to the surface actually creates hydrostatic forces. This pressure from the water rushing through the pore system causes the material to flake apart, and the explosive flaking is referred to as spalling. Let me summarize this: salt is very bad; water is very bad; salt and water together — whoa! Osmosis is powerful stuff The pressures are extraordinary. With diffusion, pressures are 3 to 5 psi — it’s nothing. Water vapor never pushed nothing off of nothing. Capillary pressures are fairly impressive — 300 to 500 psi. It moves water to the top of a 400-foot tree. That’s a pretty impressive force. But it isn’t anywhere close to the league of osmosis pressures, which are 3000 to 5000 psi. The compressive strength of even good concrete is 2000 to 3000 psi — salt and water will beat concrete every time. Osmosis beats capillarity which beats diffusion. Wow. Bridges fall down, life comes to an end, when you have salt and water. Sacrificial mortars are one solution Well, old-timers figured stuff out. What these folks noticed was that the mortar was eaten away much faster than the masonry, and certain mortars were eaten away much faster than others. The pore structure of the mortar was very critical to this. And someone said, “Aha! Maybe if I get the pore structure just right, all of the salt will end up in the mortar instead of the brick. And the mortar can sacrifice itself to protect the integrity of the brick.” That’s when we figured out that softer, weaker mortars are actually the ideal complement to clay brick that’s been fired at a specific temperature. And the solution would be to re-point the mortar as it was eaten away. You never want to have a mortar that’s stronger than the brick, because then the brick sacrifices itself to protect the mortar. That’s why historic preservationists — the old ones that know stuff because they’ve been around a long time — go to an enormous amount of trouble in old buildings to match the mortar chemistry precisely. The general rule is: if you don’t know what’s going on, don’t mess with the building. Or if something’s been around for two or three hundred years, don’t mess with the strategy. If you come up with the right mix, all of the deterioration happens in the joints, and you simply re-point them on a 15 or 20 year basis. Parging protects the entire surface Well, why not just coat the whole thing with a sacrificial layer? And instead of doing this on a 10-year basis, why not extend this to a 30- or 40-year basis? The way you think of this sacrificial layer is as a sort of lime-based poultice that sucks the salt poison out of the assembly. So how do you know when you have to replace it? Well, when it falls off. It’s the building telling you it’s time to put on another sacrificial layer.Related topicsRead about a real-world example of water damage in a brick foundation. And find strategies for keeping bulk water away from a basement.
West Bengal Chief Minister Mamata Banerjee on Tuesday said she would have shared Teesta water with Bangladesh had there been enough water available. “Bangladesh has stopped giving us Hilsa. This is because we could not give them Teesta water. We would have given if we had surplus water,” Ms. Banerjee said on the floor of the State Legislative Assembly.The sharing of Teesta water is a major bilateral issue between India and Bangladesh. Ms. Banerjee has said that entire north Bengal will run dry if the water was shared with Bangladesh. Instead, she has proposed sharing the waters of other north Bengal rivers such as Torsa, Manshai, Sankosh and Dhansai.
The government on Thursday hit out at the civil society members, led by anti-corruption crusader Anna Hazare, over the Lokpal bill saying they go to public after every meeting “which is not right”. Law Minister Veerappa Moily said, “I am the convenor of the Lokpal drafting committee. We are keen to bring the bill. It is our genuine intention to bring the bill in Parliament in the monsoon session. But we observe that after every meeting is over, the civil society members go to public attacking us. This is not right.” On Wednesday, the seventh Lokpal drafting committee meeting ended in a deadlock, with Human Resource Development Minister Kapil Sibal saying another meeting would take place on June 20, where the members ‘will try to arrive at a consensus’. RTI activist and panel member Arvind Kejriwal had said on Wednesday the meeting was not good and nothing would come out of it. “Out of forty issues, we had agreement on 34 issues and disagreement on six issues,” Moily said on Thursday. “They wanted a big Lokpal, we agreed. We agreed to every demand, but are we drafting a legislation or redrafting the Constitution for the Lokpal? They want changes in Constitution. Do they want to rewrite their Constitution? We want to bring a legislative bill, not a constitutional amendment,” Moily added. Attacking the government a day after the breakdown of talks over Lokpal draft bill, Hazare threatened to go on a hunger strike again accusing it of being uninterested in a strong bill. Referring to the government announcements on two drafts in case of disagreements, Hazare stated that he was not optimistic about expecting anything from the government anymore. advertisementFor more news on India, click here.For more news on Business, click here.For more news on Movies, click here.For more news on Sports, click here.