Astronomy
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The Ever-Working Mars Orbiter Passes 50,000 Orbits
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MRO was launched in 2005 and reached Mars orbit in March, 2006. After 10 years at work, it has accomplished a lot. In a recent press release, NASA calls the MRO “the most data-productive spacecraft yet.” Though most of us might know the orbiter because of it’s camera, the High-Resolution Imaging Science Experiment (HiRise), the MRO actually has a handful of other instruments that help the orbiter achieve its objectives. In broad terms, those objectives are:
- to study the history of water on Mars
- to look at small scale features on the surface, and identify landing sites for future Mars missions
- to act as a communications relay between Mars and Earth
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MRO’s HiRise camera gets all the glory, but it’s another onboard camera, the Context Camera (CTX), that is the real workhorse. The CTX is a much lower resolution than the HiRise, but its file sizes are much more manageable, an important consideration when every file has to travel from Mars to Earth—an average distance of about 225 million km.
CTX has captured 90,000 images so far in MRO’s mission, and each one captures details smaller than a tennis court. In the course of the mission so far, CTX has images that cover 99.1% of the Martian surface. Over 60% of the planet has been covered twice.
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Because the CTX captures image of the same surface areas twice, it documents changes on the surface. There have been over 200 instances of impact craters appearing in a second image of the same area. Scientists have used this to calculate the rate that meteorites impact Mars.
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Rethinking The Habitable Zone
With proof of liquid water in the farthest reaches of the solar system, it’s clear that the habitable zone isn’t the only place life might exist, but it may be years before that knowledge changes how — and where — astrobiologists look for habitable exoplanets.
If you want to look for life in space, most astronomy textbooks will tell you to stick to the Goldilocks Zone: the region around a star that’s the right temperature range for liquid water to exist on the surface of a planet, also called the habitable zone. The trouble is that water seems to be everywhere on icy moons in the outer solar system, well beyond the textbook habitable zone, and some planetary scientists have even suggested that there could be liquid seas out in the Kuiper Belt. Thanks to those discoveries, some experts are suggesting that it could be time to rethink how we define the habitable zone. But does that mean changing how we search for potentially habitable worlds in other solar systems?
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Observable Habitable Zones
It’s fascinating to think that an interesting new gas giant in a solar system like 51 Eridani may play host to another Enceladus or Europa, but with our current technology, those potentially habitable icy exo-moons are still invisible to astronomers here on Earth.
“The problem, of course, is that if you really have something the size of Enceladus or even Europa orbiting around a giant planet, around another star, you have a really tough time observing it, and if it's habitable five or ten kilometers below the surface, you're sort of out of luck,” said Lunine. “It would be a very, very difficult challenge to make the kinds of observations of a Europa or an Enceladus that are required to determine its habitability.”
Of course, that kind of observation is feasible for icy moons in our own solar system, because we can send probes to fly through the plumes of Enceladus or perhaps one day land on the surface of Europa, but to study objects in other solar systems, astronomers have to stick with looking for spectra through a telescope. So even if there might be miniature habitable zones in the other reaches of most solar systems, Earthbound astrobiologists can only speculate.
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Biology
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Boom Times For Fish Populations In Wisconsin Lakes
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Taking advantage of several decades' worth of data, Ryan Batt, the paper's lead author, and a team of researchers compared data on various physical, chemical and biological variables -- 595 variables in total. They found that as the lakes' temperatures rose and their nutrient concentrations increased, so did the number of organisms living there.
The findings challenge preconceptions about what a "normal" distribution of averages and extremes looks like for the plants and animals in an ecosystem.
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For example, in the three decades researchers have been tracking fish populations in Wisconsin's Lake Mendota, an average catch rate for bluegill, a popular and tasty fish, has been about five per hour of fishing. But in 1983 and 2004, that catch rate was more than 30 per hour.
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"There are new records being set all the time," [Steve Carpenter, director of the UW-Madison Center for Limnology and a co-author of the study] says. "For physical and chemical variables, you may have to wait a long time to see a new record, then the new record isn't all that shocking. But often you don't have to wait all that long for a biological variable to set a record, and that new record can be, 'Wow, that's more yellow perch than we ever saw before. By a lot.'"
Data collected over long periods of time help researchers identify extremes that are less obvious, says NSF LTER program director John Schade. [...] "Extreme increases in populations of organisms are hard to predict, and can have significant consequences for human well-being and for the ecosystem services we all depend on," Schade says. "This work demonstrates just how fast, big, and common these increases can be. Without long-term research, we could not understand the causes and consequences of these extreme events."
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Not A Pipe Dream Anymore. Space-Farming: A Long Legacy Leading Us To Mars
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The idea of using plants to keep people alive and productive in space is not new, both in concept and in scientific inquiry. The article covers a large portion of the historical international research effort that will be the foundation for many of the trade studies and mission design plans for use of artificial ecosystems in space.
Research in the area started in 1950s and 60s through the works of Jack Myers and others, who studied algae for oxygen production and carbon dioxide removal for the US Air Force and the National Aeronautics and Space Administration (NASA). Studies on algal production and controlled environment agriculture were also carried out by Russian researchers in Krasnoyarsk, Siberia beginning in the 1960s including tests with human crews whose air, water, and much of their food were provided by wheat and other crops. NASA initiated its Controlled Ecological Life Support System (CELSS) Program in the early 1980s with testing focused on controlled environment production of wheat, soybean, potato, lettuce, and sweet potato. Findings from these studies paved the way to conduct tests in a 20 m2, atmospherically closed chamber located at Kennedy Space Center.
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Most recently, a group at Beihang University in Beijing designed, built and tested a closed life support facility (Lunar Palace 1), which included a 69 m2 agricultural module for air, water, and food production for three humans.
As a result of these international studies in space agriculture, novel technologies and findings have been produced; this includes the first use of light emitting diodes for growing crops, one of the first demonstrations of vertical agriculture, use of hydroponic approaches for subterranean crops like potato and sweet potato, crop yields that surpassed reported record field yields, the ability to quantify volatile organic compound production (e.g., ethylene) from whole crop stands, innovative approaches for controlling water delivery, approaches for processing and recycling wastes back to crop production systems, and more. The theme of agriculture for space has contributed to, and benefited from terrestrial, controlled environment agriculture and will continue to do so into the future. There are still numerous technical challenges, but plants and associated biological systems can and will be a major component of the systems that keep humans alive when we establish ourselves on the Moon, Mars and beyond.
Chemistry
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Mercuric Chloride
Do you have spots, freckles or pimples on your face? If so, would you consider using a lotion containing a highly toxic substance to get rid of them? Almost certainly not, I guess. Yet that is exactly what men and women in Britain in the late 18th and early 19th centuries did to enhance their looks.
The toxic substance was mercuric chloride, an inorganic compound more commonly known nowadays as mercury(II) chloride. The compound was one of the components of a skin cream known as Gowland’s lotion. The cream was marketed to men as: ‘an effectual remedy for all scorbutic and herpetic eruptions of the face and skin, from the most trivial to the most disfiguring and inveterate; from the smallest pimple or tetter to the most universally spreading eruptions or ulcerations. For redness of the nose, arms, or other part, and in short for every train and species of evil to which the skin is liable, whether vivid and inflamed, or languid and obdurate.’
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Mercuric chloride and its uses have a long history. Arabian alchemist Jabir ibn Hayyan, who is sometimes regarded as the father of early chemistry, discovered the compound around the year 800. He prepared it by the sublimation of mercury with a mixture of sodium chloride and other compounds. It has been claimed that this was the first synthesis of a definite chemical compound that does not occur in nature. In 1716, the German chemist Johann Kunkel showed that the compound could be made more simply by subliming a mixture of mercuric sulfate and sodium chloride. By that time, corrosive sublimate was already being used as a preservative to prevent wood rot.
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During the 19th and 20th centuries corrosive sublimate was widely employed not only as a wood preservative and for the treatment for syphilis, but also in photography and as a disinfectant, insecticide, fungicide, and rat poison. Nowadays, it is used as a catalyst for the synthesis of the vinyl chloride needed for the manufacture of PVC and as a reagent in analytical chemistry.
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Ecology
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El Salvador Passes World’s First Total Ban On Metals Mining
El Salvador has become the first nation in the world to ban the mining of gold and other metals, ending a decades-long fight by activists to protect the country’s limited water resources.
Lawmakers, many with signs reading “No to Mining, Yes to Life” on their desks, voted unanimously on Thursday in favor of the ban, which will end large-scale mining activities in El Salvador immediately. According to Mongabay, no old permits or license applications will be grandfathered in. The federal government will grant small-scale artisanal gold miners a two-year grace period to close their operations, and will provide technical and financial support to help them do so.
Several Latin American countries have begun limiting destructive mining practices in recent years. El Salvador, where toxic chemicals and heavy metals pollute an estimated 90 percent of surface waters, has had a moratorium on mining since 2008, The Guardian reported. Costa Rica, Argentina, and Colombia have implemented partial bans on mining.
But activists said the new total ban is a game-changing victory. It “makes tiny El Salvador the unlikely hero in a global movement to put the brakes on a modern day ‘gold rush’,” MiningWatch Canada wrote in a statement Thursday.
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Some Of Greenland’s Coastal Ice Will Be Permanently Lost By 2100
The current study suggests that the melting of Greenland’s coastal ice will raise global sea level by about 1.5 inches by 2100.
The find is important because it reveals exactly why the most vulnerable parts of Greenland ice are melting so quickly: the deep snow layer that normally captures coastal meltwater was filled to capacity in 1997. That layer of snow and meltwater has since frozen solid, so that all new meltwater flows over it and out to sea.
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“These peripheral glaciers and ice caps can be thought of as colonies of ice that are in rapid decline, many of which will likely disappear in the near future,” said Howat, associate professor of earth sciences at Ohio State. “In that sense, you could say that they’re ‘doomed.’ However, the ice sheet itself is still not ‘doomed’ in the same way. The vast interior ice sheet is more climatologically isolated than the surrounding glaciers and ice caps. “Also, since this ‘tipping point’ was reached in the late 90's before warming really took off, it indicates that these peripheral glaciers are very sensitive and, potentially, ephemeral relative to the timescales of response of the ice sheet.”
The problem lies between fresh surface snow and the ice, in a layer of older snow called the firn. Normally, meltwater drains through gaps in the firn down to the ice surface, where the bottom layer re-freezes. That’s how glaciers and ice caps grow.
When the firn around Greenland’s edges became fully saturated 20 years ago, it froze through from bottom to top. Since then, there haven’t been any gaps to capture meltwater, and the ice hasn’t been able to grow.
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Physics
Iron Particles And Magnetism Get Soft-Bodied Robots Moving
Scientists from North Carolina State University have developed a method of getting soft robotic objects to move using directed magnetic fields. They say that it could be used for applications ranging from remotely-triggered drug-delivery pumps within the body, to the development of remotely deployable structures.
The researchers started by adding iron microparticles to a liquid polymer, then applying a magnetic field to the mixture. This induced the iron particles to arrange themselves into parallel chains. The liquid was then left to dry, forming into an elastic polymer thin film, with the chains of iron particles embedded within it.
When that film was subsequently subjected to magnetic fields, the iron particle chains would try to align themselves with it, moving the film with them. By varying the strength and direction of the magnetic field, it was possible to get the material to move in different ways.
Using this technique, the scientists created three types of soft "robots." One is a cantilever that can lift up to 50 times its own weight, another is an accordion-like device that expands and contracts like a muscle, and the third is a tube that functions as a peristaltic pump.
"We're now working to improve both the control and the power of these devices, to advance the potential of soft robotics," says associate professor Joe Tracy.
Editors Note:
I will be away from the desk this evening and hope to return tomorrow to view and reply to comments &c.
You kids play nice.
:)