Will Astronauts Ever Visit Gas Giants Like Jupiter?

science - Posted On:2020-07-09 14:59:59 Source: slashdot

Trying to get an up close and personal look at the solar system's gas giants is a tricky and dangerous journey. From a report: Jupiter, like the other gas giants, doesn't have a rocky surface, but that doesn't mean it's just a massive cloud floating through the vacuum of space. It's made up of mostly helium and hydrogen, and as you move from the outer layers of the atmosphere toward the deeper parts, that gas grows denser and the pressures become more extreme. Temperatures quickly rise. In 1995, NASA's Galileo mission sent a probe into Jupiter's atmosphere; it broke up at about 75 miles in depth. Pressures here are over 100 times more intense than anything on Earth. At the innermost layers of Jupiter that are 13,000 miles deep, the pressure is 2 million times stronger than what's experienced at sea level on Earth, and temperatures are hotter than the sun's surface. So clearly, no human is going to be able to venture too far down into Jupiter's depths. But would it be safe to simply orbit the planet? Perhaps we could establish an orbital space station, right? Well, there's another big problem when it comes to Jupiter: radiation. The biggest planet in the solar system also boasts its most powerful magnetosphere. These magnetic fields charge up particles in the vicinity, accelerating them to extreme speeds that can fry a spacecraft's electronics in moments. Spaceflight engineers have to figure out an orbit and spacecraft design that will reduce the exposure to this radiation. NASA figured this out with the triple-arrayed, perpetually spinning Juno spacecraft, but it doesn't look as if this would be a feasible design for a human spacecraft. Instead, for a crewed spacecraft to safely orbit or fly past Jupiter, it would have to keep a pretty significant distance away from the planet. Read more of this story at Slashdot.

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120,000-year-old necklace tells of the origin of string

Science - Posted On:2020-07-09 14:45:00 Source: arstechnica

People living on the Israeli coast 120,000 years ago strung ocher-painted seashells on flax string, according to a recent study in which archaeologists examined microscopic traces of wear inside naturally occurring holes in the shells. That may shed some light on when people first invented string—which hints at the invention of things like clothes, fishing nets, and maybe even seafaring.

Picking up seashells has been a human habit for almost as long as there have been humans. Archaeologists found clam shells mingled with other artifacts in Israel’s Misliya Cave, buried in sediment layers dating from 240,000 to 160,000 years ago. The shells clearly weren’t the remains of Paleolithic seafood dinners; their battered condition meant they’d washed ashore after their former occupants had died.

For some reason, ancient people picked them up and took them home.

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Ancient seashell beads may help unravel the origins of string

Science - Posted On:2020-07-09 14:30:01 Source: arstechnica

People living on the Israeli coast 120,000 years ago strung ocher-painted seashells on flax string, according to a recent study in which archaeologists examined microscopic traces of wear inside naturally occurring holes in the shells. That may shed some light on when people first invented string—which hints at the invention of things like clothes, fishing nets, and maybe even seafaring.

Picking up seashells has been a human habit for almost as long as there have been humans. Archaeologists found clam shells mingled with other artifacts in Israel’s Misliya Cave, buried in sediment layers dating from 240,000 to 160,000 years ago. The shells clearly weren’t the remains of Paleolithic seafood dinners; their battered condition meant they’d washed ashore after their former occupants had died.

For some reason, ancient people picked them up and took them home.

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Manage your expectations about the benefits of emissions cuts, study says

Science - Posted On:2020-07-09 12:15:01 Source: arstechnica

The climate is sometimes compared to a huge ship, in that it takes some time to turn it in a new direction, meaning that actions to limit global warming produce very gradual results. While the lack of instant gratification is certainly frustrating, having some indications of progress could at least sustain patience with the energy transformation needed. The problem is that Earth’s climate system differs from that metaphorical huge ship in a key way—there is a significant amount of natural variability that can also mask a change in trend.

So before we see any change in climate trends from our present actions, we have to both wait for them to start and wait for them to become large enough to be detectable against a background of natural variability.

A new study led by Bjørn Hallvard Samset takes on the question of how long it will take to clearly see the effects of reducing emissions. “This paper is about managing our expectations,” the authors say in their new work. Failure of that management could mean that undertaking the work of climate mitigation would lose support if people are expecting instantaneous progress that doesn’t materialize.

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New Study Detects Ringing of the Global Atmosphere

science - Posted On:2020-07-09 09:14:56 Source: slashdot

An anonymous reader quotes a report from Phys.Org: A ringing bell vibrates simultaneously at a low-pitched fundamental tone and at many higher-pitched overtones, producing a pleasant musical sound. A recent study, just published in the Journal of the Atmospheric Sciences by scientists at Kyoto University and the University of Hawai'i at Mnoa, shows that the Earth's entire atmosphere vibrates in an analogous manner, in a striking confirmation of theories developed by physicists over the last two centuries. In the case of the atmosphere, the "music" comes not as a sound we could hear, but in the form of large-scale waves of atmospheric pressure spanning the globe and traveling around the equator, some moving east-to-west and others west-to-east. Each of these waves is a resonant vibration of the global atmosphere, analogous to one of the resonant pitches of a bell. Now in a new study by Takatoshi Sakazaki, an assistant professor at the Kyoto University Graduate School of Science, and Kevin Hamilton, an Emeritus Professor in the Department of Atmospheric Sciences and the International Pacific Research Center at the University of Hawaii at Mnoa, the authors present a detailed analysis of observed atmospheric pressure over the globe every hour for 38 years. The results clearly revealed the presence of dozens of the predicted wave modes. The study focused particularly on waves with periods between 2 hours and 33 hours which travel horizontally through the atmosphere, moving around the globe at great speeds (exceeding 700 miles per hour). This sets up a characteristic "chequerboard" pattern of high and low pressure associated with these waves as they propagate. "For these rapidly moving wave modes, our observed frequencies and global patterns match those theoretically predicted very well," stated lead author Sakazaki. "It is exciting to see the vision of Laplace and other pioneering physicists so completely validated after two centuries." Read more of this story at Slashdot.

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Shock-Dissipating Fractal Cubes Could Forge High-Tech Armor

science - Posted On:2020-07-08 23:44:58 Source: slashdot

An anonymous reader quotes a report from Phys.Org: Tiny, 3-D printed cubes of plastic, with intricate fractal voids built into them, have proven to be effective at dissipating shockwaves, potentially leading to new types of lightweight armor and structural materials effective against explosions and impacts. "The goal of the work is to manipulate the wave interactions resulting from a shockwave," said Dana Dattelbaum, a scientist at Los Alamos National Laboratory and lead author on a paper to appear in the journal AIP Advances. "The guiding principles for how to do so have not been well defined, certainly less so compared to mechanical deformation of additively manufactured materials. We're defining those principles, due to advanced, mesoscale manufacturing and design." The researchers tested their fractal structures by firing an impactor into them at approximately 670 miles per hour. The structured cubes dissipated the shocks five times better than solid cubes of the same material. Although effective, it's not clear that the fractal structure is the best shock-dissipating design. The researchers are investigating other void- or interface-based patterns in search of ideal structures to dissipate shocks. New optimization algorithms will guide their work to structures outside of those that consist of regular, repeating structures. Potential applications might include structural supports and protective layers for vehicles, helmets, or other human-wearable protection. The research will be published in the July 2020 issue of AIP Advances. Read more of this story at Slashdot.

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CDC to issue new guidelines on reopening schools after Trump blowup

Science - Posted On:2020-07-08 18:59:59 Source: arstechnica

On the heels of criticism from President Trump, the US Centers for Disease Control and Prevention is planning to release updated guidance documents outlining how schools can safely reopen amid the COVID-19 pandemic.

Vice President Mike Pence announced the upcoming documents Wednesday, just hours after Trump took to Twitter to blast the agency’s current guidelines.

“Well, the president said today, we just don’t want the guidance to be too tough,” Pence said in a press briefing for the White House Coronavirus Task Force. “That’s the reason why next week, the CDC is going to be issuing a new set of tools, five different documents that will be giving even more clarity on the guidance going forward.”

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Warning of Serious Brain Disorders in People With Mild Coronavirus Symptoms

science - Posted On:2020-07-08 15:30:00 Source: slashdot

Doctors may be missing signs of serious and potentially fatal brain disorders triggered by coronavirus, as they emerge in mildly affected or recovering patients, scientists have warned. From a report: Neurologists are on Wednesday publishing details of more than 40 UK Covid-19 patients whose complications ranged from brain inflammation and delirium to nerve damage and stroke. In some cases, the neurological problem was the patient's first and main symptom. The cases, published in the journal Brain, revealed a rise in a life-threatening condition called acute disseminated encephalomyelitis (Adem), as the first wave of infections swept through Britain. At UCL's Institute of Neurology, Adem cases rose from one a month before the pandemic to two or three per week in April and May. One woman, who was 59, died of the complication. A dozen patients had inflammation of the central nervous system, 10 had brain disease with delirium or psychosis, eight had strokes and a further eight had peripheral nerve problems, mostly diagnosed as Guillain-Barre syndrome, an immune reaction that attacks the nerves and causes paralysis. It is fatal in 5% of cases. Read more of this story at Slashdot.

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Weather scrubs Wednesday’s Starlink launch attempt [Updated]

Science - Posted On:2020-07-08 12:00:01 Source: arstechnica

11:50pm ET Wednesday Update: Due to unfavorable weather at the launch site, SpaceX scrubbed Wednesday's launch attempt. The company has not yet confirmed a new launch attempt for the mission.

— Eric Berger (@SciGuySpace) July 8, 2020

Original post: Storms rolled through the Kennedy Space Center on Tuesday afternoon—as they often do during the summer—but SpaceX continued to press forward toward launching its 10th batch of Starlink satellites.

The company will seek to launch 57 Starlink satellites, along with two Earth-observation satellites for BlackSky Global, on a Falcon 9 rocket at 11:59am ET on Wednesday (15:59 UTC) from Launch Complex-39A at Kennedy Space Center. The weather looks decent, with a 60-percent chance of favorable conditions at liftoff.

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New data indicates that some Polynesians carry Native American DNA

Science - Posted On:2020-07-08 12:00:00 Source: arstechnica

The Polynesians were the greatest explorers of the world. Starting from Taiwan, they sailed across vast stretches of the Pacific, settling—and in some cases, continuing to trade between—astonishingly remote islands from New Zealand to Hawaii. But it's never been quite clear whether they made the final leap, sailing from Rapa Nui to reach the nearest major land mass: South America.

There are some hints that they have, primarily the presence of South American crops throughout the Pacific. But there has been no clear genetic signature in human populations, and the whole analysis is confused by the redistribution of people and crops after the arrival of European sailors.

Now, a new study finds clear genetic indications that Polynesians and South Americans met—we've just been looking at the wrong island—and wrong part of South America—for clear evidence. The researchers also raise a tantalizing prospect: that South Americans were already living on a Polynesian island when the Polynesians got there.

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Genetic data suggests Polynesians and Native Americans met

Science - Posted On:2020-07-08 11:45:01 Source: arstechnica

The Polynesians were the greatest explorers of the world. Starting from Taiwan, they sailed across vast stretches of the Pacific, settling—and in some cases, continuing to trade between—astonishingly remote islands from New Zealand to Hawaii. But it's never been quite clear whether they made the final leap, sailing from Rapa Nui to reach the nearest major land mass: South America.

There are some hints that they have, primarily the presence of South American crops throughout the Pacific. But there has been no clear genetic signature in human populations, and the whole analysis is confused by the redistribution of people and crops after the arrival of European sailors.

Now, a new study finds clear genetic indications that Polynesians and South Americans met—we've just been looking at the wrong island—and wrong part of South America—for clear evidence. The researchers also raise a tantalizing prospect: that South Americans were already living on a Polynesian island when the Polynesians got there.

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SpaceX will try to launch Starlink satellites with “visors” on Wednesday

Science - Posted On:2020-07-08 08:44:57 Source: arstechnica

Storms rolled through the Kennedy Space Center on Tuesday afternoon—as they often do during the summer—but SpaceX continued to press forward toward launching its 10th batch of Starlink satellites.

The company will seek to launch 57 Starlink satellites, along with two Earth-observation satellites for BlackSky Global, on a Falcon 9 rocket at 11:59am ET on Wednesday (15:59 UTC) from Launch Complex-39A at Kennedy Space Center. The weather looks decent, with a 60-percent chance of favorable conditions at liftoff.

SpaceX first attempted to launch this mission back on June 26 but stood down a couple of hours before the planned launch, citing the need for additional time to conduct pre-launch checkouts.

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SpaceX will try to launch Starlink satellites with “visors” on Tuesday

Science - Posted On:2020-07-08 08:29:57 Source: arstechnica

Storms rolled through the Kennedy Space Center on Monday afternoon—as they often do during the summer—but SpaceX continued to press forward toward launching its 10th batch of Starlink satellites.

The company will seek to launch 57 Starlink satellites, along with two Earth-observation satellites for BlackSky Global, on a Falcon 9 rocket at 11:59am ET on Tuesday (15:59 UTC) from Launch Complex-39A at Kennedy Space Center. The weather looks decent, with a 60-percent chance of favorable conditions at liftoff.

SpaceX first attempted to launch this mission back on June 26 but stood down a couple of hours before the planned launch, citing the need for additional time to conduct pre-launch checkouts.

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Duke scientist questions his own research with new study faulting task fMRI

Science - Posted On:2020-07-08 08:14:57 Source: arstechnica

It all started with a rejected grant proposal. Ahmad Hariri, a neuroscientist at Duke University, was interested in using so-called "task fMRI"—in which subjects perform specially designed cognitive tasks while having their brains scanned—combined with genetic testing and psychological evaluations. The goal was to identify specific biomarkers for differences in how people process thoughts and emotions that might determine whether a given subject would be more or less likely to experience depression, anxiety, or age-related cognitive decline like dementia in the future.

"The idea was to collect this data once, then collect it again and again and again and be able to track changes in an individual's brain over time to help us understand what changes over the course of their lives," Hariri told Ars. So he submitted a funding proposal outlining his plans for a longitudinal study along those lines. The proposal hypothesized that an individual's history of trauma, for instance, would map onto how their amygdala reacted to threat-related stimuli. And that would, in turn, enable the researchers to say something about the future mental well-being of the individual.

Hariri and his team designed four core, task-related measures to that end: one targeting the amygdala's threat response, one targeting the hippocampus and memory, one targeting the striatum and reward, and the fourth targeting the prefrontal cortex and executive control. He thought he was on solid scientific ground. So he was shocked when the proposal wasn't even scored by reviewers, based on skepticism regarding the reliability of fMRI to collect that kind of data.

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WHO To Review Evidence of Airborne Transmission of Coronavirus

science - Posted On:2020-07-08 03:14:58 Source: slashdot

After hundreds of experts urged the World Health Organization to review mounting scientific research, the agency acknowledged on Tuesday that airborne transmission of the coronavirus may be a threat in indoor spaces. The New York Times reports: W.H.O. expert committees are going over evidence on transmission of the virus and plan to release updated recommendations in a few days, agency scientists said in a news briefing. The possibility of airborne transmission, especially in "crowded, closed, poorly ventilated settings, cannot be ruled out," said Dr. Benedetta Allegranzi, who leads the W.H.O.'s committee on infection prevention and control. She said the agency recommends "appropriate and optimal ventilation" of indoor environments, as well as physical distancing. Agency staff fielded several questions from reporters about transmission of the virus by air, prompted by an open letter from 239 experts calling on the agency to review its guidance. Many of the letter's signatories have collaborated with the W.H.O. and served on its committees. [...] W.H.O. scientists said that for the past few months, the infection prevention committee has been weighing the evidence on all the ways in which the coronavirus spreads, including by tiny droplets or aerosols. "We acknowledge that there is emerging evidence in this field, as in all other fields," Dr. Allegranzi said. "And therefore, we believe that we have to be open to this evidence and understand its implications regarding the modes of transmission and also regarding the precautions that need to be taken." It will also be important to understand the importance of transmission by aerosols compared with larger droplets, and the dose of the virus needed for infection from aerosols, she said. "These are fields that are really growing and for which there is evidence emerging, but it is not definitive," she said. "However, the evidence needs to be gathered and interpreted, and we continue to support this." Read more of this story at Slashdot.

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Mathematician Ronald Graham Dies At 84

science - Posted On:2020-07-07 21:14:59 Source: slashdot

The American Mathematical Society has announced the passing of Ronald Graham, "one of the principal architects of the rapid development worldwide of discrete mathematics in recent years." He died July 6th at the age of 84. From the report: Graham published more than 350 papers and books with many collaborators, including more than 90 with his wife, Fan Chung, and more than 30 with Paul Erdos. In addition to writing articles with Paul Erdos, Graham had a room in his house reserved for Erdos's frequent visits, he administered the cash prizes that Erdos created for various problems, and he created the Erdos number, which is the collaboration distance between a mathematician and Erdo's. He also created Graham's number in a 1971 paper on Ramsey theory written with Bruce Rothschild, which was for a time the largest number used in a proof. Graham received his PhD from the University of California, Berkeley in 1962 under the direction of D.H. Lehmer. He worked at Bell Laboratories until 1999, starting as director of information sciences and ending his tenure there as chief scientist. Graham then joined the faculty at the University of California, San Diego and later became chief scientist at the California Institute for Telecommunications and Information Technology, a joint operation between the university and the University of California, Irvine. [...] Graham was an AMS member since 1961. For more information, see his "special page," these video interviews by the Simons Foundation, an audio interview about the mathematics of juggling, and his page at the MacTutor website. Graham's most recent appearance on Slashdot was in 2016, when a trio of researchers used a supercomputer to generate the largest math proof ever at 200 terabytes in size. The math problem was named the boolean Pythagorean Triples problem and was first proposed back in the 1980's by mathematician Ronald Graham. Read more of this story at Slashdot.

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Independent reviewers offer 80 suggestions to make Starliner safer

Science - Posted On:2020-07-07 18:15:00 Source: arstechnica

Following the failed test flight of Boeing's Starliner spacecraft in December, NASA on Monday released the findings of an investigation into the root causes of the launch's failure and the culture that led to them.

Over the course of its review, an independent team identified 80 "recommendations" for NASA and Boeing to address before the Starliner spacecraft launches again. In addition to calling for better oversight and documentation, these recommendations stress the need for greater hardware and software integration testing. Notably, the review team called for an end-to-end test prior to each flight using the maximum amount of flight hardware available.

This is significant, because before the December test flight, Boeing did not run an integrated software test that encompassed the roughly 48-hour period from launch through docking to the station. Instead, Boeing broke the test into chunks. The first chunk ran from launch through the point at which Starliner separated from the second stage of the Atlas V booster.

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Why Time Feels So Weird in 2020

science - Posted On:2020-07-07 15:00:00 Source: slashdot

Some days seem to pass very slowly while some weeks, and even months, fly by. A set of simple perception tests illustrate some factors that can distort our sense of time. Read more of this story at Slashdot.

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Brazil President Jair Bolsonaro Tests Positive for Covid-19 After Months of Dismissing the Seriousness of the Virus

science - Posted On:2020-07-07 13:00:00 Source: slashdot

Brazilian President Jair Bolsonaro has tested positive for Covid-19, following months of downplaying the virus. From a report: Bolsonaro himself announced the result, speaking on Brazilian TV channels Tuesday. "Everyone knew that it would reach a considerable part of the population sooner or later. It was positive for me," he said, referring to the Covid-19 test he took Monday. "On Sunday, I wasn't feeling very well. On Monday, it got worse when I started feeling tired and some muscle pain. I also had a 38-degree [Celsius] fever. Given those symptoms, the presidential doctor said there was suspicion of Covid-19," Bolsonaro said, adding that he then went to hospital where scans of his lungs "came back clean." Earlier on Tuesday, Bolsonaro told CNN affiliate CNN Brasil that he had been treated with hydroxychloroquine and azithromycin as he awaited the result of his fourth Covid-19 test in four months. Hydroxychloroquine, though enthusiastically boosted by both Bolsonaro and US President Donald Trump, has not been proven as an effective treatment for Covid-19. Bolsonaro nevertheless credited the controversial antimalarial drug for his well-being on Tuesday. "I am feeling very well. I believe that the way they administered the hydroxychloroquine on, the effect was immediate," he said. Read more of this story at Slashdot.

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Congress may allow NASA to launch Europa Clipper on a Falcon Heavy

Science - Posted On:2020-07-07 11:30:01 Source: arstechnica

The US House of Representatives released its proposed fiscal year 2021 budget for NASA on Tuesday, funding the agency at $22.63 billion. This is the same amount of funding that was enacted for NASA's budget this year.

This is just the beginning of the budget process, of course. The White House released its budget request back in February, and now the House and Senate will establish their priorities. Months of negotiations will ensue, compounded by the COVID-19 crisis and the 2020 presidential election. After the fiscal year 2020 budget ends in October, a continuing resolution is likely. The 2021 budget seems unlikely to be resolved before December.

Still, the new document does tell us where Democrats and Republicans in the House think NASA funding should go. And there are a few important clues within worth discussing.

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