An anonymous reader quotes a report from MIT Technology Review: While avoiding the worst dangers of climate change will likely require sucking carbon dioxide out of the sky, prominent scientists have long dismissed such technologies as far too expensive. But a detailed new analysis published today in the journal Joule finds that direct air capture may be practical after all. The study concludes it would cost between $94 and $232 per ton of captured carbon dioxide, if existing technologies were implemented on a commercial scale. One earlier estimate, published in Proceedings of the National Academies, put that figure at more than $1,000 (though the calculations were made on what's known as an avoided-cost basis, which would add about 10 percent to the new study's figures). Crucially, the lowest-cost design, optimized to produce and sell alternative fuels made from the captured carbon dioxide, could already be profitable with existing public policies in certain markets. The higher cost estimates are for plants that would deliver compressed carbon dioxide for permanent underground storage. David Keith, a Harvard physics professor and lead author of the paper, is also the founder of Carbon Engineering, "a Calgary-based startup that has spent the last nine years designing, refining, and testing a direct air capture pilot plant in Squamish, B.C.," reports MIT. "Carbon Engineering plans to combine the carbon captured at its plants with hydrogen to produce carbon-neutral synthetic fuels, a process the pilot facility has already been performing." The company has secured $30 million, but is seeking additional funds to build a larger facility that will begin selling fuels. CNBC notes that Carbon Engineering is owned by several private investors, including Bill Gates.

NASA's veteran Curiosity rover has found complex organic matter buried and preserved in ancient sediments that formed a vast lake bed on Mars more than 3bn years ago. From a report: The discovery is the most compelling evidence yet that long before the planet became the parched world it is today, Martian lakes were a rich soup of carbon-based compounds that are necessary for life, at least as we know it. Researchers cannot tell how the organic material formed and so leave open the crucial question: are the compounds remnants of past organisms; the product of chemical reactions with rocks; or were they brought to Mars in comets or other falling debris that slammed into the surface? All look the same in the tests performed. But whatever the ultimate source of the material, if microbial life did find a foothold on Mars, the presence of organics meant it would not have gone hungry. "We know that on Earth microorganisms eat all sorts of organics. It's a valuable food source for them," said Jennifer Eigenbrode, a biogeochemist at NASA's Goddard Space Flight Center in Maryland. The Curiosity rover also discovered that methane on the red planet changes with the seasons. The Verge: Where the methane is coming from is still a mystery, but scientists have some ideas, including that microbes may be the source of the gas. Researchers at NASA and other US universities analyzed five years' worth of methane measurements Curiosity took at Gale Crater, where the rover landed in 2012. Curiosity detected background levels of methane of about 0.4 parts per billion, which is a tiny amount. (In comparison, Earth's atmosphere has about 1,800 parts per billion of methane.) Those levels of methane, however, were found to range from 0.2 to about 0.7 parts per billion, with concentrations peaking near the end of the summer in the northern hemisphere, according to a study published today in Science. This seasonal cycle repeated through time and could come from an underground reservoir of methane, the study says. Whether that reservoir is a sign that there is or was life on Mars, however, is impossible to say for now.

An anonymous reader writes: If you drop your phone today and it falls to the ground, you can be fairly certain that if it slips from your grip again tomorrow (butterfingers!), it won't suddenly soar into the sky. That's thanks to one of the basic ideas in Einstein's theory of general relativity, which posits that the laws of physics don't change over space and time. But to actually know that for a fact, you'd have to perform the same task over and over again, in as many locations as possible, and watch closely for any change in outcome. That's why, as Sophia Chen reports, a group of physicists has spent the past 14 years -- or 450 million seconds -- watching clocks tick.

Their results would have made Einstein heave a sigh of relief. The physicists were observing the 12 atomic clocks to see whether their subatomic particles' behavior changed over those 14 years -- but it was completely consistent, even as the clocks moved with the Earth around the sun. Now, these findings don't necessarily mean that the laws of physics are absolutely not changing across time and space. They only definitively show that the laws of physics stayed constant over the 14 years of the experiment. "Still, they can now say this with five times more certainty than they could a decade ago," Chen writes. "And if it holds true for Earth's location in the universe, it's not too much of a leap to imagine it's true elsewhere."