Tag Archives: featured

Catching Them In The Act: Hyper Fast Camera Captures Atoms In Motion

An extremely fast “electron camera” at the Department of Energy’s SLAC National Accelerator Laboratory has produced the most detailed atomic movie of the decisive point where molecules hit by light can either stay intact or break apart.

The results could lead to a better understanding of how molecules respond to light in processes that are crucial for life, like photosynthesis and vision, or that are potentially harmful, such as DNA damage from ultraviolet light.

In the study, published in Science, researchers looked at a gas whose molecules have five atoms each. They watched in real time how light stretched the bond between two atoms in the molecules to a “point of no return,” sending the molecules on a path that either further separated the atoms and cleaved the bond or caused the atoms to vibrate while preserving the bond.

“The starting and end points of a chemical reaction are often obvious, but it’s much more challenging to take snapshots of the rapid reaction steps in between,” said postdoctoral researcher Jie Yang, the study’s lead author from SLAC’s Accelerator Directorate and the Stanford PULSE Institute.

“The crossroads where a molecule can do one thing or another are an important factor in determining the outcome of a reaction. Now we’ve been able to observe directly for the first time how the atomic nuclei of a molecule rearrange at such an intersection.”

Co-author Todd Martinez, a professor at SLAC and Stanford University and an investigator at PULSE, said, “The system we studied is a paradigm for the much more complex light-driven reactions in nature.” For example, the absorption of ultraviolet light can cause damage to DNA, but other mechanisms turn the light’s energy into molecular vibrations and minimize the harmful effect.

Ultra-High-Speed Snapshots of Atoms in Motion
The first steps in light-driven reactions are extremely fast. Molecules absorb light almost instantaneously, leading to a rapid rearrangement of their electrons and atomic nuclei. To see what happens in real time, researchers need ultra-high-speed cameras that can “freeze” motions occurring within femtoseconds, or millionths of a billionth of a second.

The camera used in the study was an instrument for ultrafast electron diffraction (UED), in which a high-energy beam of electrons probes the interior of a sample, generating snapshots of its atomic architecture at different points in time during a chemical reaction. Strung together, these snapshots turn into a movie of the speedy atomic motions.

At SLAC, the researchers flashed laser light into a gas of trifluoroiodomethane molecules and observed over the course of hundreds of femtoseconds how bonds between carbon and iodine atoms elongated to a point at which the bond either broke, splitting off iodine from the molecules, or contracted, setting off vibrations of the atoms along the bond.

“UED was absolutely crucial to seeing that point during the reaction,” said physicist Xijie Wang, head of SLAC’s UED program and the study’s principal investigator. “Other methods either don’t detect nuclear motions directly or haven’t reached the resolution necessary to make this kind of observation in gases.”

Mapping Energy Landscapes of Chemical Reactions
The observation is in agreement with calculations that provide a deeper understanding of what happens during the reaction.

The laser light “energizes” the molecules, elevating them from a low-energy ground state to a higher-energy excited state (see image below). Molecular states like these can be described by energy landscapes, with mountains of more energy and valleys of less energy. Like a golf ball rolling on a curved putting green, the molecules can follow reaction paths on these surfaces.

When the landscapes of different molecular states intersect, the reaction can proceed in several directions. Chemists call this point a conical intersection.

In fact, molecules at conical intersections exist in several states at once – an oddity rooted in the fact that molecules are tiny quantum systems, said co-author Xiaolei Zhu, a postdoctoral researcher at PULSE and Stanford. “We can predict this behavior in computer simulations,” he said. “Now we’ve also directly seen that the molecules behave exactly that way in the experiment.”

The team is now planning the next steps. “We’re continuing to develop the UED method so that we can look at similar processes in liquids,” Wang said. “This will bring us even closer to understanding light-driven chemical reactions in biological environments.”

First Space Tourist Flights Could Come In 2019

The two companies leading the pack in the pursuit of space tourism say they are just months away from their first out-of-this-world passenger flights — though neither has set a firm date.

Virgin Galactic, founded by British billionaire Richard Branson, and Blue Origin, by Amazon creator Jeff Bezos, are racing to be the first to finish their tests — with both companies using radically different technology.

– Moments of weightlessness –

Neither Virgin nor Blue Origin’s passengers will find themselves orbiting the Earth: instead, their weightless experience will last just minutes. It’s an offering far different from the first space tourists, who paid tens of millions of dollars to travel to the International Space Station (ISS) in the 2000s.

Having paid for a much cheaper ticket — costing $250,000 with Virgin, as yet unknown with Blue Origin — the new round of space tourists will be propelled dozens of miles into the atmosphere, before coming back down to Earth. By comparison, the ISS is in orbit 250 miles (400 kilometers) from our planet.

The goal is to approach or pass through the imaginary line marking where space begins — either the Karman line, at 100 kilometers or 62 miles, or the 50-mile boundary recognized by the US Air Force.

At this altitude, the sky looks dark and the curvature of the earth can be seen clearly.

– Virgin Galactic –

With Virgin Galactic, six passengers and two pilots are boarded onto SpaceShipTwo VSS Unity, which resembles a private jet.

The VSS Unity will be attached to a carrier spacecraft — the WhiteKnightTwo — from which it will then detach at around 49,000 feet (15,000 meters.) Once released, the spaceship will fire up its rocket, and head for the sky.

Then, the passengers will float in zero-gravity for several minutes, before coming back to Earth.

The descent is slowed down by a “feathering” system that sees the spacecraft’s tail pivot, as if arching, before returning to normal and gliding to land at Virgin’s “spaceport” in the New Mexico desert.

In total, the mission lasts between 90 minutes and two hours. During a May 29 test in California’s Mojave desert, the spaceship reached an altitude of 21 miles, heading for space.

In October 2014, the Virgin spaceship broke down in flight due to a piloting error, killing one of two pilots on board. The tests later resumed with a new craft.

The company has now also reached a deal to open a second “spaceport” at Italy’s Tarente-Grottaglie airport, in the south of the country.

Branson in May told BBC Radio 4 that he hoped to himself be one of the first passengers in the next 12 months. About 650 people make up the rest of the waiting list, Virgin told AFP.

– Blue Origin –

Blue Origin, meanwhile, has developed a system closer to the traditional rocket: the New Shepard.

On this journey, six passengers take their place in a “capsule” fixed to the top of a 60-foot-long rocket. After launching, it detaches and continues its trajectory several miles toward the sky. During an April 29 test, the capsule made it 66 miles.

After a few minutes of weightlessness, during which passengers can take in the view through large windows, the capsule gradually falls back to earth with three large parachutes and retrorockets used to slow the spacecraft.

From take-off to landing, the flight took 10 minutes during the latest test.

Until now, tests have only been carried out using dummies at Blue Origin’s West Texas site.

Company officials were recently quoted as saying the first tests with Blue Origin astronauts would take place “at the end of this year,” with tickets for the public expected to go on sale in 2019.

But in comments to AFP Friday, the company struck a more cautious note.

“We have not set ticket pricing and have had no serious discussions inside of Blue on the topic,” the firm said. “We have a flight test schedule and schedules of those types always have uncertainties and contingencies. Anyone predicting dates is guessing.”

– What’s next? –

SpaceX and Boeing are developing their own capsules to transport NASA astronauts, most likely in 2020, after delays — a significant investment that the companies will likely make up for by offering private passenger flights.

“If you’re looking to go to space, you’ll have quadruple the menu of options that you ever had before,” Phil Larson, assistant dean at the University of Colorado, Boulder’s College of Engineering and Applied Science, told AFP.

Longer term, the Russian firm that manufactures Soyuz rockets is studying the possibility of taking tourists back to the ISS. And a US start-up called Orion Span announced earlier this year it hopes to place a luxury space hotel into orbit within a few years — but the project is still in its early stages.

U. S. F-22 Stealth Fighters Arrive In Korea

American F-22 stealth fighter jets have arrived in South Korea ahead of a joint air force drill, Seoul said Wednesday, despite a recent diplomatic thaw with Pyongyang.

The “Raptor” fighters previously flew to the South in December when Seoul and Washington staged their largest-ever joint air exercise, days after North Korea test-fired a missile believed capable of hitting the US mainland.

The North customarily reacts with anger to the deployment of American stealth fighters, which it fears could be used for surgical strikes against its leadership and strategic facilities.

The confirmation came after local newspapers said eight F-22 jets arrived Sunday at a military airbase in the southern city of Gwangju.

The “Max Thunder” drill will kick off on May 11 for a two-week run, with the reported participation of some 100 aircraft from both countries.

“Max Thunder is a regular exercise that has been on the docket long before a planned US-North Korea summit”, the South’s Defence Ministry said in a statement.

It urged news media to refrain from producing “speculative reports” about the intention of the deployment aside from the routine exercise.

That request came after the conservative Chosun Ilbo daily claimed the aircraft deployment was apparently aimed at heaping pressure on Pyongyang ahead of a planned summit between North Korean leader Kim Jong Un and US President Donald Trump.

The Panmunjom truce village in the demilitarised zone between North and South, where a rare inter-Korean summit successfully convened last week, has emerged as a possible venue for the Kim-Trump meeting.

Chosun suggested the arrival of F-22 jets could also be aimed at bolstering security in case the North Korea-US summit takes place at Panmunjom.

Supreme Court Hears States Beg For Your Bucks

Online shoppers have gotten used to seeing that line on checkout screens before they click “purchase.” But a case before the Supreme Court could change that.

At issue is a rule stemming from two, decades-old Supreme Court cases: If a business is shipping to a state where it doesn’t have an office, warehouse or other physical presence, it doesn’t have to collect the state’s sales tax.

That means large retailers such as Apple, Macy’s, Target and Walmart, which have brick-and-mortar stores nationwide, generally collect sales tax from customers who buy from them online. But other online sellers, from 1-800 Contacts to home goods site Wayfair, can often sidestep charging the tax.

More than 40 states are asking the Supreme Court to reconsider that rule in a case being argued Tuesday. They say they’re losing out on “billions of dollars in tax revenue each year, requiring cuts to critical government programs” and that their losses compound as online shopping grows. But small businesses that sell online say the complexity and expense of collecting taxes nationwide could drive them out of business.

Large retailers want all businesses to “be playing by the same set of rules,” said Deborah White, the president of the litigation arm of the Retail Industry Leaders Association, which represents more than 70 of America’s largest retailers.

For years, the issue of whether out-of-state sellers should collect sales tax had to do mostly with one company: Amazon.com. The online giant is said to account for more than 40 percent of U.S. online retail sales. But as Amazon has grown, dotting the country with warehouses, it has had to charge sales tax in more and more places.

President Donald Trump has slammed the company, accusing it of paying “little or no taxes” to state and local governments. But since 2017, Amazon has been collecting sales tax in every state that charges it. Third-party sellers that use Amazon to sell products make their own tax collection decisions, however.

 

The case now before the Supreme Court could affect those third-party Amazon sellers and many other sellers that don’t collect taxes in all states — sellers such as jewelry website Blue Nile, pet products site Chewy.com, clothing retailer L.L. Bean, electronics retailer Newegg and internet retailer Overstock.com. Sellers on eBay and Etsy, which provide platforms for smaller sellers, also don’t collect sales tax nationwide.

States generally require consumers who weren’t charged sales tax on a purchase to pay it themselves, often through self-reporting on their income tax returns. But states have found that only about 1 percent to 2 percent actually pay.

States would capture more of that tax if out-of-state sellers had to collect it, and states say software has made sales tax collection simple.

Out-of-state sellers disagree, calling it costly and extraordinarily complex, with tax rates and rules that vary not only by state but also by city and county. For example, in Illinois, Snickers are taxed at a higher rate than Twix because foods containing flour don’t count as candy. Sellers say free or inexpensive software isn’t accurate, more sophisticated software is expensive and that collecting tax nationwide would also subject them to potentially costly audits.

“For small businesses on tight margins, these costs are going to be fatal in many cases,” said Andy Pincus, who filed a brief on behalf of eBay and small businesses that use its platform.

 

The case now before the Supreme Court involves South Dakota, which has no income tax and relies heavily on sales tax for revenue. South Dakota’s governor has said the state loses out on an estimated $50 million a year in sales tax that doesn’t get collected by out-of-state sellers.

In 2016 the state passed a law requiring those sellers to collect taxes on sales into the state, a law challenging the Supreme Court precedents. The state, conceding it could win only if the Supreme Court reverses course, has lost in lower courts.

South Dakota says the high court’s previous decisions don’t reflect today’s world. The court first adopted its physical presence rule on sales tax collection in a 1967 case dealing with a catalog retailer. At the time, the court was concerned in part about the burden collecting sales tax would place on the catalog company. The court reaffirmed that ruling in 1992.

It’s unclear how the justices might align on the question this time. But three justices — Neil Gorsuch, Clarence Thomas and Anthony Kennedy — have suggested a willingness to rethink those decisions. Kennedy has written that the 1992 case was “questionable even when decided” and “now harms states to a degree far greater than could have been anticipated earlier.”

“Although online businesses may not have a physical presence in some states, the Web has, in many ways, brought the average American closer to most major retailers,” he wrote in suggesting the days of inconsistent sales tax collection may be numbered. “A connection to a shopper’s favorite store is a click away regardless of how close or far the nearest storefront.”

SpaceX Set To Launch Planet Hunter TESS On Monday

With the crippled Kepler orbital equipment almost out of fuel, NASA is preparing the launch of its newest planet-hunting spacecraft, TESS.

TESS, short for Transiting Exoplanet Survey Satellite, will be carried into space by SpaceX’s Falcon 9 rocket on April 16. With a little help from the moon’s gravity, the satellite will achieve a high Earth orbit, offering the probe wide, unobstructed views of the night sky. The probe will orbit Earth twice for every one lunar orbit.

While TESS’s scientific mission is largely the same as Kepler’s — image transiting exoplanets — the probe will use a different approach. Whereas Kepler focused on small fields of view for long periods of time, TESS will take a wider, more comprehensive view.

“TESS is designed to image almost all of the night sky — using four wide angle cameras — in long vertical strips called sectors,” Natalia Guerrero, MIT scientist and researcher on the TESS mission, told UPI.

TESS scientists have divided the sky into long strips called sectors. Each hemisphere contains 13 sectors, and over the next three years, TESS will survey, sector by sector, the Southern Hemisphere and then the Northern Hemisphere.

During each sector scan, TESS’s four cameras will capture 30-minute exposures. The four images will be stacked on top of each other by the satellite’s computer and transmitted back to Earth.

In addition to organizing the sky into sectors, TESS scientists have identified 200,000 especially bright stars likely to host transiting exoplanets. Each stellar target is highlighted by a so-called postage stamp.

Exposures of each postage stamp will be stacked on top of each other every two minutes and beamed back to Earth. These postage stamp observations are expected to identify planetary systems located much closer to Earth than those found by Kepler.

Data captured by TESS will go through the same image-processing pipeline used for Kepler observations. Basic algorithms will process images and identify the dimming patterns created when exoplanets pass across the face of their host star.

Scientists will review the transit events identified via computer analysis and highlight targets for follow-up observations.

“From the depth of the transit and the frequency light curve, we can back out the size of the planet and distance from its host star,” Guerrero said.

But, like Kepler, TESS is designed to survey the sky, not carry out in-depth investigations. Scientists will rely on other telescopes, both ground and space-based, to observe transiting objects in greater detail. Through follow-up investigations, astronomers will be able to estimate an exoplanet’s mass and the composition of its atmosphere, as well as its habitability.

TESS scientists will focus much of their analysis on the two-minute cadence of images of postage stamped targets, but the satellite’s biggest surprises may be more likely to be revealed by the full frame images. In addition to capturing transits, the full-frame images will record observations of thousands of stars.

“The full frame images will serve as really rich repositories of data,” Guerrero said. “They will be made public and will be a wonderful opportunity for the astronomical community and really any interested parties.”

“We’re very excited about the citizen science efforts that will be inspired by these images,” Guerrero said.