You are here
Nearly 15 years have passed since NASA sent its Galileo spacecraft flying into Jupiter's outer atmosphere to die—eliminating the possibility of contaminating nearby Jovian moons with any traces of Earth bacteria. However, a new study seeking evidence of water plumes on the surface of Jupiter's moon Europa demonstrates that, even now, Galileo is providing valuable information.
Since Galileo's end, the Hubble Space Telescope has periodically observed the Jovian system. Sometimes, when the telescope has looked, it has observed water vapor emissions coming from the surface of Europa. This indicates the existence of periodic jets of water emanating from the moon's interior.
The prospect of the water gushing from the moon's interior has tantalized scientists, as that warm, vast interior ocean is thought to be one of the best places in the Solar System beyond Earth—if not the best—to look for extant life. Since the ice sheet covering Europa is thought to be at least several kilometers thick, being able to sample the ocean from space or the moon's surface would greatly aid this search.
Fundamental physics, as we've seen, finds itself in a difficult situation. Nothing unexpected has turned up at the Large Hadron Collider. We have phenomena like dark matter and dark energy that are defying explanation. And some of the most exciting ideas that theoreticians are coming up with have steadfastly refused to submit to any form of experimental testing.
On possible route out of this mess is to focus on some of the oddities in the data that we already have. For example, there are a few measurements that seem to show particle behavior that's inconsistent with physics' Standard Model. And there are other cases where two different routes to the same measurement give different results, a possible sign that some new physics is influencing one experimental approach but not another. But before we pursue these oddities, the first step is to confirm that something unexpected is really happening.
This is exactly the situation we have with the decay of neutrons. We have two different ways of measuring the neutron's half-life, and the values they produce disagree by an appreciable amount. To find out whether this disagreement is real, however, we have to up the precision of the measurements. And that's precisely what a large US-Russian collaboration has done.
The Department of Energy (DOE) sent a document to Congress last week formally executing a waiver to kill a project that would have used weapons-grade plutonium and uranium oxides as fuel for electricity generation in Georgia.
The Mixed Oxides (MOX) project, which required the construction of a special facility near the Savannah River nuclear site in South Carolina, has already cost the DOE north of $7.6 billion and would likely cost the federal government tens of billions more to complete, according to the document which was seen by Reuters. Instead of reusing the weapons-grade waste, the DOE proposes to mix the waste with an inert substance and dispose of the mixture at the Waste Isolation Pilot Plant (WIPP).
Simply disposing of the waste was also proposed by the Obama Administration. A disposal plan would cost $19.9 billion, Reuters reported.
In yet another jaw-dropping interview that seemed to be broadcast from an alternate universe, venture capitalist Tim Draper tenaciously defended the failed blood testing company Theranos and its disgraced founder and CEO, Elizabeth Holmes.
In the interview, which aired on CNBC, Draper called the limping start-up “one of those extraordinary companies” and said he was glad to have backed Holmes, who he knows personally. Draper provided $500,000 in seed money when Holmes was just starting the company as a 19-year-old Stanford drop-out. “It was a great mission and she did a great job,” he said. “I’m thrilled with what she’s done.”
He went so far as to call Holmes a “great icon,” to which CNBC “Closing Bell” co-host Kelly Evans responded bluntly: “Icon of what?” Draper didn’t respond to the question, though.
For most watching the Falcon 9 rocket launch on Friday afternoon from Florida, the spectacle did not appear all that different from any SpaceX rocket launch and subsequent droneship landing. But sometimes, looks can be deceiving.
This rocket ascending into space had been almost entirely remade. After eight years of flying the Falcon 9 rocket, SpaceX has taken all of the lessons it has learned from 51 flights and engineered them into this new, and probably final, variant of the booster.
For most of this decade, the company’s chief executive officer and lead designer, Elon Musk, has talked a good game about rapid and reusable launch. Now, the Block 5 version of the rocket may finally deliver on these promises. Musk held a teleconference with space reporters on Thursday afternoon, a day before the launch. Although he expressed the usual pre-flight jitters and did not want to take anything for granted, Musk said that after slogging through the Block 5 development process he is now convinced that rockets can be flown, landed, and flown again within 24 hours. “We still need to demonstrate it,” he said. “It’s not like we’ve done it. But it can be done.”
Recent events in Hawaii have been producing some remarkable images. But if you’re not a geologist—or resident of Hawaii—you might be wondering what the heck is going on. We’re here to help: while lava spewing from back yards in a subdivision seems wild, it’s not really surprising.Why is Kīlauea an active volcano in the first place?
The Hawaiian chain of islands (there are also seamounts that no longer reach above sea level) is the result of a “hotspot” in the Earth’s mantle. Hotspots in the Earth's interior are areas of rising hot rock that can turn to liquid hot magma near the Earth’s surface. These hotspots are basically stationary, while tectonic plates slowly slide around on the surface. That means a hotspot will punch a line of eruptions through the plate a bit like a sewing machine.
The Big Island of Hawaii is the youngest in the chain, still straddling the hotspot that fuels its volcanoes—there are five individual volcanoes that make up the island. Of those five, Kīlauea is the youngest, comprising the southeastern edge of the island. Kīlauea’s summit is home to a collapsed crater called Halemaʻumaʻu Crater. In 2008, a new vent appeared in the floor of the crater, which has hosted a lake of roiling lava ever since.
From Neanderthals to human hunter-gatherers to the mounted horde of Genghis Khan, the Eurasian Steppe has long been a crossroads of humanity. And for the last 5,000 years or so, domesticated horses have shaped how people moved through, lived in, and dominated that vast grassland stretching from Hungary and Romania to Northeastern China. A paleogenomic study adds new evidence to the debate about where people first domesticated horses, and a related study reveals the impact of horsemanship on the peopling of the steppe.
The first evidence we have of domesticated horses comes from a site called Botai in Northern Kazakhstan, where archaeologists have found evidence of milking, corrals, and the use of harnesses. But there’s still debate about whether hunter-gatherers at Botai started domesticating horses—which they’d previously hunted for meat—in order to milk and ride them. It's possible they learned from herders farther west, such as the people whose graves have been found at Khvalynsk dating from around 7,150 to 5,930 years ago.
To get a better picture, Copenhagen University evolutionary geneticist Eske Willerslev and his colleagues examined the ancestry of 74 people who lived on the Eurasian Steppe from 11,000 years ago up through the Medieval period. Among other things, they wanted to see whether the Botai had interbred with the Yamnaya, the pastoral descendants of the Khvalynsk people. If they had, that would be a clue that the Botai had interacted with the Yamnaya enough to perhaps exchange cultural ideas as well as genes.
Two stem cell clinics will “vigorously defend” their dubious treatments against civil suits levied this week by the Department of Justice at the request of the Food and Drug Administration.
The two clinics are no stranger to federal officials’ bad sides; they have both received warnings and wrist-slaps in the past. In August of last year, the FDA sent a warning letter to US Stem Cell Clinic of Sunrise, Florida and its chief scientific officer Kristin Comella for “significant deviations” from good practices. That was shortly after researchers determined that three women had permanently lost their vision after the clinic posed as a legitimate research facility conducting a clinical trial and injected an unproven concoction of cells directly into their eyeballs. The women reported paying $5,000 for the procedure, and the clinic’s supposed clinical trial never took place.
The other clinic, California Stem Cell Treatment Center Inc. of Rancho Mirage and Beverly Hills, California, and affiliates—including StemImmune Inc. and Cell Surgical Network—were likewise chided by the FDA for inappropriately obtaining vials of smallpox vaccine from the Centers for Disease Control and Prevention. (The CDC maintains a stash of vaccines against the eradicated virus for research and emergency military purposes.) The clinic was mixing the vaccine into unproven, unapproved cell treatments for cancer and injecting it directly into patients’ tumors.
On Thursday, a few hours before SpaceX was due to launch a new version of its Falcon 9 rocket, company CEO Elon Musk admitted he was nervous. SpaceX had significantly revamped the nine-engine booster that had powered its astonishing rise to the top of the aerospace industry. Now came the final test.
"The reason that it's so hard to make an orbital rocket work is that your passing grade is 100 percent, and you can't fully and properly test an orbital rocket until it launches," Musk said. He paused a moment and then added, "Man, anyway, I'm stressed."
As it turned out, the Block 5 version of the Falcon 9 rocket did not undergo its orbital test on Thursday, as the ground control systems at Kennedy Space Center stopped the rocket's countdown with just 58 seconds to go. Because there were only about 30 minutes left in the two-hour launch window to send the Bangabandhu Satellite-1 to geostationary transfer orbit, the company ultimately had to scrub and turn around to try for a second launch attempt Friday.
Next time you picture a Mongol horde sweeping across the Asian steppes on horseback, imagine that about two-thirds of them have liver disease. Hepatitis B is a virus that attacks the liver, causing scarring, organ failure, and sometimes cancer. Its origins and evolutionary history are still a bit of an enigma, but viral DNA left behind in the bones and teeth of ancient people from the Asian steppe may help reconstruct part of our long history with the disease.
The virus showed up in what have been considered extraneous sequences of DNA that are associated with DNA samples but not part of the human genome. Typically, software gets rid of these sequences and uses what's left to assemble the human genome.Viruses and genomes
While DNA sequencing has focused on the human portion of human genome data, that's starting to change. “Originally, this was nothing we paid much attention to. It was just expensive and kind of a waste product, but now we've started investigating this waste product for possible positives,” said Copenhagen University evolutionary geneticist Eske Willerslev. It's how his team found evidence that Mongol warriors from the steppe carried an early form of the pathogen that would later become the 541-542 CE Justinian Plague.
Seven years on from the Great East Japan Earthquake of March 2011, Fukushima Daiichi nuclear power plant has come a long way from the state it was reduced to. Once front and center in the global media as a catastrophe on par with Chernobyl, the plant stands today as the site of one of the world’s most complex and expensive engineering projects.
Beyond the earthquake itself, a well understood series of events and external factors contributed to the meltdown of three of Fukushima’s six reactors, an incident that has been characterized by nuclear authorities as the world’s second worst nuclear power accident only after Chernobyl. It’s a label that warrants context, given the scale, complexity, and expense of the decontamination and decommissioning of the plant.
DeepMind is an artificial intelligence research company that specializes in deep learning. That's an approach, inspired by neural networks, that passes an input through multiple, sequential layers of analysis (the "deep") to come up with an output. The method seems to be working pretty well for the company; it's the one that made AlphaGo, which it claims is “arguably the strongest Go player in history.”On the grid
Now that DeepMind has solved Go, the company is applying DeepMind to navigation. Navigation relies on knowing where you are in space relative to your surroundings and continually updating that knowledge as you move. DeepMind scientists trained neural networks to navigate like this in a square arena, mimicking the paths that foraging rats took as they explored the space. The networks got information about the rat’s speed, head direction, distance from the walls, and other details. To researchers' surprise, the networks that learned to successfully navigate this space had developed a layer akin to grid cells. This was surprising because it is the exact same system that mammalian brains use to navigate.
A few different cell populations in our brains help us make our way through space. Place cells are so named because they fire when we pass through a particular place in our environment relative to familiar external objects. They are located in the hippocampus—a brain region responsible for memory formation and storage—and are thus thought to provide a cellular place for our memories. Grid cells got their name because they superimpose a hypothetical hexagonal grid upon our surroundings, as if the whole world were overlaid with vintage tiles from the floor of a New York City bathroom. They fire whenever we pass through a node on that grid.
We’ve covered several studies seeking to clarify the role of human-caused climate change in the unbelievable amounts of water Hurricane Harvey dumped on Houston last year. The general approach of these studies was to simulate today’s climate and a pre-global-warming climate, and to then compare the behavior of hurricanes around Houston.
Since most people understand that hurricanes are fueled by warm ocean water, however, perhaps it would be conceptually simpler to focus on the seawater beneath Harvey.
That has now been done by a new study led by Kevin Trenberth of the National Center for Atmospheric Research. By analyzing the heat energy present in the Gulf of Mexico—and how much was lost as Harvey spun through—researchers get a fairly direct measure of Harvey’s fuel.
Humans, and the invasive species we bring with us, are frequently viewed as destroying ecosystems. But we alter them just as often, inadvertently picking winners and losers from among the species as we transform their environment. A paper out in today's Nature describes a case where our actions made a butterfly species a winner, but then changed the game so fast that the local population went extinct.
All of this because one man died and his cattle ranch shut down.The cast
This is a story with a lot of moving parts, so we'll take some time to introduce them. The protagonist is Edith’s checkerspot butterfly, or Euphydryas editha. A native to the west coast of the United States, one of its populations lived on a site called Schneider’s Meadow, named after the rancher whose cattle grazed there. These and other populations of the butterfly lay eggs on a plant called Collinsia parviflora. That plant provides a good growth environment for the butterflies' offspring, but the plant is a bit fickle, prone to sudden die-backs that lead to a reasonably high rate of caterpillar mortality.
A Falcon 9 rocket has gone vertical on Thursday morning at Launch Complex 39A in Florida, and SpaceX is on track for the liftoff of a brand-new version of its workforce booster. The launch of the Bangabandhu Satellite-1 to geostationary transfer orbit is set for 4:12pm ET (20:12 UTC) Thursday, with a launch window that stretches for a little more than two hours.
The highlight of this flight is the debut of the Block 5 version of the Falcon 9 rocket (which Ars previewed thoroughly last week). SpaceX founder Elon Musk has said this will be the final "substantial" upgrade to the Falcon 9 rocket, optimizing the booster for reuse. The company hopes to be able to fly each Block 5 first stage 10 times before significant refurbishment is required.
Ten flights of an individual booster would be hugely significant, as SpaceX has thus far only ever reused each of its Falcon 9 rockets a single time. Additionally, the company hopes to reduce the turnaround time between launches of a Falcon 9 booster, now several months, to a matter of weeks.
Dogs supposedly trained to detect and respond to potentially life-threatening blood sugar levels in people with diabetes were, in reality, often untrained, un-housebroken puppies with hefty price tags—currently set at $25,000. At least, that’s according to a lawsuit filed this week by Attorney General Mark Herring on behalf of the Commonwealth of Virginia.
According to the lawsuit, the non-profit company Service Dogs by Warren Retrievers and its owner Charles Warren Jr. made extraordinary claims about their “diabetic alert dogs.” The company and Warren said that the dogs were highly trained, and that their performance was “backed by science.” The SDWR website advertised the animals as being able to: detect low/high blood sugar levels through scents in skin and breath; retrieve needed food and medications, such as insulin; seek help when required; and even dial 911 in an emergency.
“Diabetic Alert Dogs are 100% accurate and often alert as much as 20-45 minutes before a meter shows there’s even a problem,” the company boasted. And customers were promised regular access to trainers as needed to help personalize the dogs' training.
Back in 1998, the European Center for Medium-Range Weather Forecasts housed the 27th most-powerful supercomputer in the world, with 116 cores providing a maximum performance of 213 teraflops. Today, the ECMWF forecasting center has the world's 27th and 28th most powerful supercomputers, each with 126,000 cores and 20 times the computing power of its machine two decades ago.
This dramatic increase in computing power at the European center—as well as similar increases at US-based and other international numerical modeling centers—helps to explain the dramatic increase in hurricane-forecast accuracy over the same time period.
Based upon new data from the National Hurricane Center for hurricanes based in the Atlantic basin, the average track error for a five-day forecast fell to 155 nautical miles in 2017. That is, the location predicted by the hurricane center for a given storm was just 155 nautical miles away from the actual position of the storm five days later. What is incredible about this is that, back in 1998, this was the average error for a two-day track forecast.
The problem with scientific papers is that they hide about half of the interesting stuff. Recently, a group of scientists set out to directly measure a property of a laser, something that goes by the exciting-sounding name of "spatial hole burning." In the process, though, they discovered how to turn a laser into a very high-speed microwave device, a discovery that may make the next generations of Wi-Fi and mobile data much easier to implement.
Was this discovery an accident, or did the scientists know that the application potential was there before they started? The paper is silent on the issue. But are we seriously going to put a laser in every cell phone?Your laser is full of holes
When you form a picture of light from a laser, you might imagine something like light from a laser pointer: red or green, a nice directed beam, possibly a bit sparkly when you shine it on the wall. Lasers emit light with a single pure color, right? Unfortunately, life is not that simple.
Prostate cancer screening is now something to consider for men aged 55 to 69, according to the federal panel tasked with making recommendations for such preventative care options. In a finalized recommendation released Tuesday, the US Preventive Services Task Force (USPSTF) revealed that it has officially warmed to the screening—ever so slightly.
Back in 2012, the task force famously recommended against the then-common blood screening for elevated levels of PSA protein, which can indicate prostate cancer as well as other conditions. But, given new data from large, randomized clinical trials showing that routine screening can save a small number of lives, the USPSTF now says the scales have tipped in screening’s favor.
The USPSTF doesn’t offer an emphatic endorsement, but rather, a cautious consideration:
Genetically modified foods have been used for decades with no major safety issues; more than 90 percent of the soybeans and all of the sugar beets grown in the US are now GMO. Yet the technology remains controversial, with worries about the crops cutting across the entire political spectrum.
One controversial solution to societal unease has been the call to place labels on foods that contain GMOs. While these have been considered on local and state levels, a relatively obscure 2016 federal law mandated that labels be applied nationwide. The task of devising the labeling system was given to the Department of Agriculture. Last week, the USDA finally got around to proposing some possible solutions and is now asking for public comment on them.Labels and the law
There's nothing inherently unsafe about genetically engineering crops or agricultural animals. None of the genetic material survives digestion to enter human cells (otherwise our cells would be awash in the DNA of gut bacteria). And, so far at least, careful design and testing has ensured that the proteins made by the altered DNA don't cause health problems such as allergic reactions. But the public has been consistently uneasy about the technology, with polls showing that only slightly more than a third of the general public thinks eating GMO foods is safe.