Data from Cassini’s last orbits, even up to its last gasps as it plunged into Saturn on September 15, are not supporting long ages.Astrobiology Magazine reported “fresh findings from Cassini” yesterday, based on a JPL press release. Several findings touch on the issue of age: can phenomena at Saturn survive for billions of years?Young RingsLife for ring experts just got more complicated. The sharp edge of Saturn’s B ring is pretty well explained by resonances with the moon Mimas. The sharp edge of the outer A ring, however, cannot be explained by one moon (Janus). A new theory argues that seven moons—Pan, Atlas, Prometheus, Pandora, Epimetheus, Mimas and Janus—must work in concert to keep the edge confined. The reason, Science Daily explains, is that rings have a tendency to spread out. Astrobiology Magazine sets up the issue:Key among the questions scientists hope to answer using data from Cassini are the age and origins of the rings. Theoretical modeling has shown that, without forces to confine them, the rings would spread out over hundreds of millions of years — much younger than Saturn itself. This spreading happens because faster-moving particles that orbit closer to Saturn occasionally collide with slower particles on slightly farther-out orbits. When this happens, some momentum from the faster particles is transferred to the slower particles, speeding the latter up in their orbit and causing them to move farther outward. The inverse happens to the faster, inner particles.Moon resonance theories allow for moons to absorb some of the angular momentum. The question is whether this delicate arrangement could survive for billions of years. The answer is not helped by personification fallacies, like that of Radwan Tajeddine, who quipped, “All of these moons work as a group to contain the ring. Together they are strong. United they stand.” Moons couldn’t care less what happens. Moons and rings simply follow the forces that impinge on them. The point is that today we see their forces converging to constrain the A ring to a sharp edge, but could that persist for billions of years? Project scientist Linda Spilker goes with the flow of Tajeddine’s proposal of cooperating moons, saying, “If these moons weren’t working together, the A ring would have spread out over hundreds of millions of years” (New Scientist). That sounds like a long time until you realize that a hundred million years represents only 3% of the assumed age of the solar system, including Saturn.Young AtmosphereThis is not Cassini’s only finding that indicates the rings are young. The brightness of the rings also remains unexplained. They should be much darker by now, as contaminants collect to make them ‘dirty’ over time. Other forces such as sputtering (erosion on the atomic scale), sunlight pressure, micrometeoroid bombardment and gas drag take their toll. And as Cassini sampled Saturn’s atmosphere on its final plunge, the ion and neutral mass spectrometer and cosmic dust analyzer confirmed that ring material is falling into the planet. Nature says that mission scientists had expected to find mostly water ice—But instead of water, Cassini found a witch’s brew of chemicals, including methane, a molecule that could be carbon monoxide and more-complex molecules. The concentrations of these chemicals are highest around Saturn’s equator and at high altitudes, which suggests that the material is shedding off the planet’s rings.The article goes on to say that the particles were not predicted. If they are indeed coming from the rings, how long can the rings supply the molecules?By analyzing the types of materials that could be coming off the rings, Perry’s team concluded that they must be fragments of tiny dust particles, which measure just 1 to 10 nanometres across but are relatively heavy. When these particles spiralled off the rings and slammed into Cassini’s mass spectrometer, they shattered into smaller pieces.Exactly how those particles make that journey from the rings to the atmosphere remains to be seen. “We have a lot of work to do to understand how they are getting in there,” Perry said. “None of the models predict this.”So there is “far more than just water around” in the upper atmosphere. The density of infall from the rings must be extremely sparse, as evidenced by the fact that Cassini survived 22 high-dive orbits between Saturn and the rings. Nevertheless, 4.5 billion years is a long time for material to spiral out of the rings into a giant planet with a big, gravitational vacuum cleaner.Young EnceladusScientists are still struggling to keep Enceladus old. The geyser plumes found emanating from the little moon’s south pole were probably among the top 3 surprises Cassini found. At New Scientist, Leah Crane uses a string of double entendres to ask if the plumes resemble ‘astronaut pee’ vented from the international space station into space through nozzles. There’s probably more difference than similarity, one planetary scientist responds. The question of how Enceladus could eject 200 kg per second for billions of years looms over all such sideshows.Analysis of Cassini’s 635 GB of science data, collected over 13 years in orbit, will continue for years – perhaps decades. For instance, scientists are still analyzing molecules in Titan’s atmosphere from measurements taken in 2005 and thereafter (Phys.org). Already nearly 4,000 science papers have been published. Young scientists may get their PhD’s from Cassini’s data. Will any of them be able to keep Saturn, Titan, Enceladus and the rings billions of years old? If the ‘scenarios’ sound more and more contrived, that’s a sign they are desperate. (Visited 420 times, 1 visits today)FacebookTwitterPinterestSave分享0
Is there a construction process which can deliver a value of sustainable prosperity? This is the term being used by Worldwatch in preparation for the upcoming Rio+20 conference. It moves beyond the “do no further harm” approach of the original definition of sustainability (Brundtland report), and recognizes the need to actively restore the Earth’s systems to full health.The key difference in terminology is that this concept must, in toto, include all of the world’s population, rich and poor.Sustainable prosperity is a challengeWOW – that is a really tall order, considering that green building represented 25% of new construction activity in 2010, and a third of all new nonresidential construction (McGraw-Hill Construction report, Green Outlook 2011). Those numbers are rising faster than expected – so that is all good. But … it includes any shade of green, including the very light green LEED-certified level. Few of these green projects have reached a net-zero level, and probably only a handful are actively involved in restoring the natural resources.So while I commend us all for getting on board, what will it take to get to sustainable prosperity? What does that future look like, and what might be the construction process which could accommodate this level “beyond green”? That folks, is the topic of my dissertation. I won’t give away any of my trade secrets (because I don’t have any yet…), but I can tell you that it is hopeful. There are little gems of “value enhancing” construction which are popping up in our industry.First, do no harm — then, imagine ways to restore our damaged environmentFor example, Boldt Construction is fine-tuning the use of target value design with lean construction, as an interactive, solutions-oriented, vision of way of designing to ideal state. (Here’s a link to a very clear description of IPD, GMP and TVD.)There are wonderful stories of owners, like Gary Christensen, who were willing to explore the possibilities of sustainability and ended up with “a beautiful, high performance building that’s good for the environment and didn’t cost us any more to do.” His project, the Banner Bank Building, collects stormwater from its surrounding seven acres and reuses it in its sewage system, and uses a water capture on the roof to flush toilets.Could we also capture the steam from the HVAC, harvest the energy and the water? Or scrub carbon dioxide out of the air?Imagining a “dream building”Mr. Watanabe, one of the past presidents of Toyota, offered his vision for a “dream car” — a vehicle that cleans the air, prevents accidents, promotes health, evokes excitement, and can drive around the world on a single tank of gas. The technology parts are already being refined, and the Toyota Production System has developed the process and the people to handle the innovations.What is the vision of a “dream building” – and how will we get there?Vera Novak writes the Eco Build Trends blog and is currently earning her PhD in Construction from Virginia Tech.
Embattled Commonwealth Games OC chief Suresh Kalmadi is likely to appear before CBI on Wednesday for questioning in connection with the agency’s probe into alleged financial irregularities in the conduct of the mega sporting event.Official sources said that Kalmadi has been asked to come to the CBI office for questioning and he has informed the investigating agency he would make his appearance on Wednesday.The chief of the Games’ Organising Committee is likely to be quizzed on a number of issues regarding the Games including alleged bungling in Queen’s Baton Relay.CBI officials had yesterday visited the Games OC office here and questioned some officials. Besides they had seized certain documents related to QBR and other contracts with various firms.The sources said Kalmadi will also be asked questioned about certain contracts given to foreign firms for carrying out overlays work for the games in October last.The CBI had late last month contacted Kalmadi over phone asking him to appear before it for questioning but the OC chief had said he will be available only after January three.Kalmadi had earlier in the day said he has not yet heard from the CBI about possible date of his questioning.”I am yet to hear from the CBI. As and when I am informed, I will be available. I am extending full cooperation to all investigating agencies,” Kalmadi told PTI.The sleuths have grilled Kalmadi’s three key aides in connection with the scam. Sources said Manoj Bhori, political advisor to OC head, P K Srivastava and A K Sinha, both assistants to Kalmadi, were also called in for interrogation.advertisementThe CBI had earlier conducted raids at the residences of Kalmadi, OC Secretary General Lalit Bhanot, R K Sacheti, who is Joint Director General of the OC, and Sangeeta Welingkar, member of the Games Image and Look Group.The agency has so far filed three FIRs in connection with the alleged financial irregularities.While one case is related to a Rs 107-crore deal struck with a Swiss score keeping firm, the CBI had registered two other FIRs in connection with the contract given to AM Films for the Baton Relay ceremonies by the OC in London.The CBI has decided to approach the Sports Ministry to seek removal of Kalmadi and Bhanot from their posts citing failure of certain junior OC officials to cooperate with it which, it claimed, was hampering the probe.With PTI inputs