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Updated: 2 hours 4 min ago

NASA’s <em>Juno</em> spacecraft achieves orbit around Jupiter

5 July 2016
Nature: On 4 July NASA’s Juno spacecraft successfully entered Jupiter’s orbit. Launched in August 2011, the craft took almost five years to make the roughly 2.7 billion km trip. Juno is to complete two 53-day orbits of the planet before burning its main engine and settling into a shorter, 14-day orbiting pattern. The first spacecraft in more than two decades to visit Jupiter, Juno will investigate the giant planet’s composition, Great Red Spot, and massive radiation belts. The ultimate goal is to gain insight into how Jupiter, and the entire solar system, evolved.

Ice-age temperature swings may have been caused by fluctuating Atlantic Ocean currents

1 July 2016
Science: During the last ice age, temperatures on Earth’s surface seesawed several times between the Northern and Southern Hemispheres: As the north got colder, the south grew warmer, and vice versa. Now researchers have found that the abrupt temperature changes in the two hemispheres may have been caused by a slowdown of the Atlantic Meridional Overturning Circulation (AMOC), an ocean current that drives shallower, warmer waters north and deeper, colder waters south. Studying a sediment core drilled from the Bermuda Rise in the Atlantic Ocean, Jerry McManus of Columbia University and colleagues say they saw at least four instances when the ratio of two radioactive daughter isotopes changed sharply, which indicated a weakening of the AMOC. Such slowdowns could have caused the north to receive less warm water and temperatures there to drop while the south heated up due to the backlog of warm water. What caused the slowdowns is still unknown, but one explanation is the breaking off of Canadian icebergs, whose melting would have increased the amount of freshwater in the North Atlantic and possibly disrupted ocean flow. Over some 1500 years, the freshwater would have dissipated, allowing the AMOC to increase once again in strength.

More than 100 Nobel laureates call for end to opposition of GMOs

1 July 2016

Washington Post: On 30 June more than 100 Nobel laureates, including 25 physics awardees, released a letter that called for the environmental activism group Greenpeace to end its opposition to the use of genetically modified organisms (GMOs) in agriculture. The letter primarily focused on Golden Rice, a form of rice that produces high levels of beta-carotene, a precursor of vitamin A. Golden Rice was developed as a potential crop for areas where the populations suffer from vitamin A deficiency. The letter says that Greenpeace has driven the resistance to the commercialization of Golden Rice and to GMOs in general, despite the lack of evidence that engineered crops are harmful. The signature campaign was organized by Richard Roberts of New England Biolabs, who shared with Phillip Sharp the 1993 Nobel Prize in Physiology or Medicine for the discovery of genetic sequences called introns.

Antarctic ozone hole appears to be shrinking

1 July 2016
Nature: Three decades after the introduction of the Montreal Protocol, the ozone hole over the Antarctic is beginning to disappear. The hole was first observed in the late 1970s, when scientists realized that the use of chlorofluorocarbons and similar substances in aerosol spray cans and cooling systems was having an adverse effect on Earth's ozone layer, which shields the planet from the Sun's UV radiation. Now Susan Solomon of MIT and colleagues, who have been monitoring polar ozone with weather balloons, say that since 2000 the Antarctic ozone hole has been shrinking in the month of September—a key time of year because it marks the beginning of the Antarctic spring and the return of more sunlight to the region. Although no measurable improvement has been seen in the hole over the Arctic, the researchers say the improvement in the Antarctic is a sign that the Montreal Protocol is having a positive effect. “We as a planet have avoided what would have been an environmental catastrophe,” says Solomon.

Tesla's Autopilot feature involved in fatal crash for first time

1 July 2016

Wired: On 7 May, a Tesla Model S driver, who was using the vehicle's semiautonomous Autopilot feature, died after the car crashed into a tractor trailer. In a statement Tesla indicated that the accident occurred when the tractor trailer made a left turn across a divided highway. The Model S went underneath the side of the trailer, which made contact only at the height of the windshield. Neither the vehicle's driver nor the Autopilot feature engaged the Tesla's brake. Tesla claims that the Autopilot (and the driver) failed to detect the white trailer, which would have been hard to see against the bright sky. The company says that its vehicles have accumulated more than 130 million miles using the feature without any other fatal accident. Autopilot, which must be activated by the driver, uses a combination of radar, cameras, GPS, and ultrasonic sensors to control the vehicle. When activated, it reminds drivers that they are supposed to keep their hands on the steering wheel and should be ready to assume complete control of the vehicle at any time.

NIF quest hobbled from the start

1 July 2016
Extra Dimensions: Any progress in the pursuit of laser-initiated fusion is overshadowed by the project’s failure to meet an absurdly ambitious deadline.

Emissions pledges may not be enough to meet climate goal

30 June 2016

Washington Post: Climate scientists have repeatedly found that if the global average temperature is kept from exceeding 2 °C over the preindustrial average, then many of the most significant effects of global warming will likely be avoided. However, according to a new study of the emissions-cutting pledges made in December 2015 by the 195 nations that gathered in Paris, those pledges are not going to be enough to keep global warming below the 2 °C threshold. Led by Joeri Rogelj of the International Institute for Applied Systems Analysis in Laxenburg, Austria, the researchers found that the pledged cuts will more likely limit the temperature increase to between 2.6 °C and 3.1 °C by 2100. According to the analysis, by 2030 humans will probably have released the maximum amount of emissions that could have limited warming to 2 °C.

The colors of radiative beta decay

30 June 2016
The energy distribution of photons produced in a rare neutron-decay mode has now been measured.

UK expected to remain committed to Paris climate accord

30 June 2016
BBC: Despite the UK’s decision to quit the European Union last week, the country's commitment to last year’s Paris climate negotiations appears to remain intact. Government ministers are expected to announce a 57% cut to the country’s carbon emissions from 1990 levels by 2032. That amount greatly exceeds the 40% agreed upon by the European Union. Once confirmed, however, the new target will require the introduction of new policies to overhaul the UK’s aging energy system and fund greener technologies.

ArXiv prepares for multimillion-dollar redesign

30 June 2016
Nature: This week arXiv, the preprint server for papers in physics, mathematics, and computer science, released the results of an expansive survey regarding what the site's users would like to see change or improve. The 25-year-old site is still running more or less on its original architecture, which is straining under the 1.1 million papers in the database and the 139 million yearly downloads. The advisory team that oversees the site is hoping to raise $2.5 million to $3 million to modernize the system. About 95% of survey respondents were very satisfied or satisfied with the site, with most asking for basic modernizations and small tweaks. Larger changes that would make the site into a more social forum for commentary and ratings had the support of only 34% of respondents. The advisory board will meet in September to draw up plans for the site and for fundraising.

NASA responded well to SpaceX’s failed ISS resupply mission, report says

30 June 2016
SpaceNews: One year after the failure of a SpaceX cargo resupply mission to the International Space Station, NASA’s Office of Inspector General has issued a report reviewing the agency's response to the failure. It found that NASA compensated for the loss of $112 million worth of cargo by sending additional supplies via several subsequent resupply launches and by compressing the launch schedule for 2016 and 2017 to increase the number of resupply missions. Furthermore, NASA successfully negotiated with SpaceX to receive discounted prices for several future cargo missions. Having learned from its contract with Orbital ATK, which also experienced a launch failure, NASA “has effectively managed its contract with SpaceX to reduce cost and financial risk,” the report concluded.

Extracurricular activities drive this teacher—and his students

29 June 2016
From dripping faucets to Dubai friendships, Mark Vondracek puts his energy into teaching.


29 June 2016

US, Canada, and Mexico agree to produce half their energy from renewables by 2025

29 June 2016

Guardian: At a meeting in Ottawa, Canada, this week, Barack Obama, Justin Trudeau, and Enrique Peña Nieto will commit to a plan to have the US, Canada, and Mexico produce half their electricity from hydropower, wind, solar, and nuclear plants by 2025. That represents a large increase from the current collective clean power levels of about 37%. The agreement will also include plans for carbon capture and storage and energy efficiency measures. Because the US accounts for 75% of the three countries' energy production and only one third of its production is from clean energy, it will have the most work to do to reach the stated goal. A Supreme Court ruling earlier this year halted Obama's attempt to reduce coal plant emissions to meet emissions targets set at the 2015 Paris climate conference. Although Mexico currently produces less than 20% of its electricity from clean sources, Canada gets 81% of its power from renewables.

Traversing a hypothetical tunnel through the center of the Earth

29 June 2016
Science News: In a recent thought experiment, Thomas Concannon and Gerardo Giordano of King’s College in Pennsylvania explore what it would be like to fall down a hole through Earth’s center to the other side. Because of the complexity of the problem, researchers in the past have simplified the calculations by making some broad assumptions, including that Earth has a uniform density and doesn’t rotate and that there is no drag from air resistance or friction along the tunnel’s sides. To create a more realistic model, Concannon and Giordano have now included drag forces in their calculations. They found that it would take at least 1.8 years just to reach Earth’s center through an air-filled tunnel. By evacuating the air, the total trip time to Earth’s center could be shaved down to just 19 minutes. But because of friction, it would never be possible to overcome gravity’s pull and make it to the other side.

Virginia R. Brown

29 June 2016

VW faces largest US civil settlement ever

29 June 2016
Bloomberg: Because of Volkswagen’s attempt to rig environmental tests on its diesel vehicles, the car manufacturer may have to pay out some $15 billion to settle all the lawsuits in the US alone. Up to $10.03 billion is to cover costs including buying back vehicles and compensating the owners. Some $2.7 billion will be paid as fines to the US Environmental Protection Agency and the California Air Resources Board, and about $2 billion will be invested in clean-emissions technology. Another $400 million will go to settlements with states, including New York. Whether VW has set aside enough money to cover all the fallout remains to be seen, as the company still faces civil and criminal actions in other countries spanning three continents.

NASA performs test-fire of SLS rocket booster

29 June 2016 On 28 June, NASA successfully test-fired its Space Launch System (SLS) rocket booster engine in Promontory, Utah. The two-minute burn of the 3.6-million-pound-thrust engine is the last live firing for the booster until NASA performs its first SLS rocket launch in 2018. On that Exploration Mission 1, the SLS will carry an uncrewed Orion capsule on a flight around the Moon and back to Earth. For launches, the SLS will use two booster engines alongside the rocket's core stage.

Nighttime blue-light LEDs cause health problems, AMA warns

28 June 2016
The shift to LEDs for residential street lighting is creating a host of medical and environmental problems, a new report says.

NASA prepares for <em>Juno</em> spacecraft’s arrival at Jupiter next week

28 June 2016
New York Times: On 4 July the US will celebrate not only Independence Day but also the arrival of NASA’s Juno spacecraft at Jupiter. Launched five years ago, Juno has traveled nearly 3 billion kilometers. Whereas the Galileo spacecraft, launched in 1989, spent eight years exploring Jupiter and its moons, Juno will concentrate on the planet itself, particularly on what lies beneath its dense cloud cover. Besides abundant hydrogen and helium, Jupiter is thought to contain small amounts of heavier elements, such as carbon, lithium, and nitrogen. The data gathered should provide insight into how the solar system and the planets formed.