SpaceX Brings Astronauts Home Safely in a Historic First

NASA astronauts Bob Behnken and Doug Hurley safely splashed down in a SpaceX Crew Dragon capsule off the Florida coast on Sunday after a two-month stay on the International Space Station. The two men made history earlier this summer when they became the first NASA astronauts to catch a ride to orbit on a private spacecraft as part of the SpaceX Demo-2 mission. It was a test flight to show NASA that the capsule is safe enough to fly humans, so the return of the astronauts concludes that mission.

“We completed all the objectives for the mission while we were docked and figured out if crew could live in Dragon,” Steve Stich, the program manager for NASA’s Commercial Crew Program, said during a press conference on Wednesday. “Now is the right time to bring this vehicle back.”

Behnken and Hurley landed under parachute in the Atlantic Ocean near Pensacola, Florida, one of seven landing sites pre-selected by NASA and SpaceX. They sheltered in the capsule until they were pulled from the water by Go Navigator, a ship operated by SpaceX. It was the first ocean recovery of a crewed spacecraft in 45 years. The last one was after the famous orbital rendezvous between the US and Soviet Union in 1975; since then, all crewed landings have been on terra firma (aside from one accidental lake landing by the Russians).

The Demo-2 splashdown marked the end of a long day for Behnken and Hurley, who spent nearly 20 hours in the capsule before they arrived back on Earth. After it left the ISS, the capsule autonomously executed a few short engine burns to put the spacecraft on a trajectory that would align it with its landing sites. Behnken and Hurley spent the next few hours drifting in orbit while NASA and SpaceX monitored weather conditions at the possible landing sites along the Florida coast. At least two of the sites had to be clear—so no rain, lightning, big waves, or strong winds—before the capsule could execute its final deorbit burn that would bring it down to Earth.

SpaceX mission control made the final decision to deorbit just an hour before Behnken and Hurley landed in the ocean. In the event that they decided to postpone the deorbit burn due to weather, the duo had enough air, water, and food for up to three days in the capsule. But once the decision was made to bring the astronauts back home it was a quick—and extreme—jaunt back to Earth.

During the descent, the capsule’s heat shield experienced temperatures above 3,500 degrees Fahrenheit as it used the atmosphere as a brake to reduce its speed from 17,000 to just 350 miles per hour. Once the capsule was about three miles above the surface—half the cruising altitude of a passenger jet—it deployed its small drogue parachutes as additional brakes. When it was only a mile above the waves, the capsule deployed its main chutes and drifted lazily to the surface.

“After splashdown, what I think of as the ‘SpaceX Navy’ go in and recover the crew,” Benji Reed, the director of crew mission management at SpaceX, said during a press conference last week. SpaceX deployed two boats—Go Navigator in the Gulf of Mexico and Go Searcher off the eastern coast of Florida—to lead the recovery effort; each boat is staffed with more than 40 crew members from SpaceX and NASA.

Once Behnken and Hurley are safely onboard Go Naviator, they will be subjected to a thorough medical screening. Within four hours of splashdown, a helicopter will drop them off at Kennedy Space Center where they’ll board a plane to fly to NASA’s astronaut headquarters at Johnson Space Center in Houston, Texas. As for the capsule itself, it will be restored at a SpaceX facility in Florida and used again for another crewed mission next spring. “We should be able to have Dragon refurbished and ready to go in just a matter of a couple months,” Reed said. “Almost all of the vehicle is totally reused and is designed for at least five reuses, possibly even more.”

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SpaceX splashdown replay: See NASA astronauts safely return to Earth – CNET

NASA astronauts Bob Behnken and Doug Hurley were strapped into Crew Dragon and ready to go prior to the launch scrub on May 27.


The first return of a commercially built and operated US spacecraft carrying two NASA astronauts from the International Space Station made waves Sunday when it splashed down in the Gulf of Mexico right as scheduled at 11:48 a.m. PT. 

The SpaceX Crew Dragon passengers -- NASA astronauts Bob Behnken and Doug Hurley -- fittingly named the history-making spacecraft Endeavour. The astronauts safely exited the spacecraft on Sunday afternoon after a recovery at sea.

NASA administrator Jim Bridenstine welcomed the astronauts home in a tweet

Crew Dragon undocked from the ISS at 4:35 p.m. PT on Saturday, kicking off the crucial final leg of the crewed test mission that's meant to prove SpaceX is ready to carry astronauts back and forth to the ISS on a regular basis. Crew Dragon had previously aced its uncrewed Demo-1 test flight back in March.

NASA TV livestreamed the crew capsule's return and was scheduled to broadcast a follow-up news conference at 1:30 p.m. PT on Sunday.

Behnken and Hurley arrived at the ISS in late May after a smooth launch. The return schedule was initially uncertain due to the arrival of a major storm along the Florida coast.

Crew Dragon had seven potential splashdown sites in the Gulf of Mexico and Atlantic Ocean to choose from. A spot off the coast of Pensacola, Florida, won the honor. The weather held out nicely, giving the astronauts calm waters to land in.

A SpaceX recovery ship named GO Navigator was on location to retrieve the capsule, crew and parachutes. In a news conference on Friday, Behnken and Hurley said they would have bags ready in case they experienced seasickness while waiting for pickup by the recovery crew. The astronauts reported they were doing well after splashdown.

The splashdown followed a tense reentry process that put a lot of heat and stress on the spacecraft. Crew Dragon's parachutes deployed as it closed in on its target and brought it gently down into the sea. Scorch marks on the capsule were a testament to the rigors of its return journey.

There was a delay in opening the Crew Dragon hatch on board GO Navigator as the recovery crew purged toxic vapor fumes from around the capsule.

Hurley and Behnken were taken to a medical facility on the ship for initial checkups as part of the standard return procedures. They were scheduled for a helicopter ride back to shore. 

"To anybody who has touched Endeavour, you should take a moment to just cherish this day," said Hurley during the exit from Crew Dragon.

If the Demo-2 mission assessment goes smoothly, then NASA and SpaceX will move forward with the first operational Crew Dragon mission, which is scheduled to launch later this year. 

The safe return of Behnken and Hurley opens up a new future for US spaceflight. It fulfills the promise of NASA's Commercial Crew Program and its quest to end the space agency's dependence on Russian spacecraft to carry its astronauts to the ISS. 

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Egypt to Elon Musk: Aliens didn’t build the pyramids, come see for yourself – CNET

Aliens didn't build Egypt's famed pyramids, and the country is happy to prove that fact to SpaceX and Tesla CEO Elon Musk. Over the weekend, the country's minister of international cooperation responded to a Musk tweet by offering him a trip to investigate the real history of the enormous structures.

On Friday, Musk tweeted "Aliens built the pyramids obv," and whether he was serious or not, his tweet was liked more than 538,000 times and retweeted more than 85,000 times as of Sunday morning. 

On Saturday, Rania A. Al Mashat, Egypt's minister of international cooperation, invited Musk to come to her country and explore the pyramids' history, including the tombs of the non-alien humans who built them.

"I follow your work with a lot of admiration," she tweeted. "I invite you and SpaceX to explore the writings about how the pyramids were built and also to check out the tombs of the pyramid builders. Mr. Musk, we are waiting for you."

While Musk hasn't said if he'll accept the offer, he did dig into some online sources explaining the real history of the ancient structures.

"The Great Pyramid was the tallest structure made by humans for 3,800 years," Musk tweeted on Saturday -- note the "by humans" part. "Three thousand, eight hundred years." He followed up with a link to a BBC article that discusses how most archaeologists agree the Great Pyramid was built by 4,000 laborers supported by 16,000 to 20,000 secondary workers, who worked for 20 years or more.

Musk may not be thinking much about the pyramids on Sunday. His tweets have switched focus to the SpaceX Crew Dragon Demo-2 mission splashdown.

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Extend your desktop to a 15.6-inch portable monitor for just $149 – CNET


Whether you need a second monitor to extend your desktop across a second screen or just want an inexpensive display for your Nintendo Switch, a portable monitor is a great way to add the screen real estate you need. Right now, you can save $50 on a newly updated Lepow monitor that usually lists for $199. Specifically, you can get the Lepow Z1 for $149 when you click the coupon on the product page and apply discount code JGA7X76V at checkout, which makes this just about the cheapest full HD portable monitor you can buy today.

The Z1 is a full HD (1,920x1,080 pixels) 15.6-inch IPS display, but Lepow has upgraded the display to cover a full 100% of the Adobe sRGB color gamut. It's also slightly brighter than its predecessor, now 320 nits compared to 300 nits in last year's model. I doubt you'd ever notice those extra 20 nits in real-world use, but given that portable monitors are often a little dim, this is headed in the right direction.

The monitor itself looks more or less like a standard tablet -- it's 0.34 inches thick and weighs about 1.7 pounds. It stands on the included smart cover/screen protector that tents into a stand. You can connect it to virtually any device thanks to both a mini-HDMI and a USB-C connector on the side of the device, and there's even a small speaker built in to play audio from your source device. Lepow throws in a full set of cables: USB-C to USB-C, USB-C to USB-A and mini-HDMI to HDMI.

You'd be hard-pressed to find a 15.6-inch portable monitor for less than $150, and this one is an especially good deal given the full coverage of the sRGB gamut. This deal is available through Aug. 5. 

CNET's Cheapskate scours the web for great deals on tech products and much more. For the latest deals and updates, follow the Cheapskate on Facebook and Twitter. Find more great buys on the CNET Deals page and check out our CNET Coupons page for the latest promo codes from Best BuyWalmartAmazon and more. Questions about the Cheapskate blog? Find the answers on our FAQ page.

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Get the combo wireless Pandora portable power bank for $36 – CNET


Power banks are a dime a dozen (well, they're not that cheap, but they are that common), but I've been waiting for an innovative power bank to come along that offers more than a couple of USB ports and a built-in LED flashlight. My wait might be over: The Pandora Portable Power Charger is a wall charger, power bank with digital display and wireless Qi charger all in one. It has just debuted with a retail price of $60, but you can get the Pandora Portable Power Charger for $36 when you use the exclusive code CNET at checkout. The code buys you an additional 10% off the introductory discounted price of $40.

This pocket-size power bank plugs directly into the wall like a wall charger and while it tops off its 8,000-mAh battery, it can charge up to three devices at once: two via the USB-A ports and a third via USB-C. When you take it off wall power, it becomes a power bank that can charge up to four devices at once -- including a Qi-compatible wireless device. There's a digital display to keep you apprised of the battery level as well.

There's more. The USB-C port is bidirectional, so you don't have to plug it into the wall. You can charge the battery from any USB-C source, like a laptop or car charger. And Pandora supports fast charging -- 18 watts through the USB-C port and up to 10 watts on the Qi wireless pad.

The whole thing is roughly pocket-size (2.3 inches square and an inch thick) and weighs 9 ounces. If your junk drawer isn't already brimming with power banks, you might want to give this one a try.

This article was first published last week. 

CNET's Cheapskate scours the web for great deals on tech products and much more. For the latest deals and updates, follow the Cheapskate on Facebook and Twitter. Find more great buys on the CNET Deals page and check out our CNET Coupons page for the latest promo codes from Best BuyWalmartAmazon and more. Questions about the Cheapskate blog? Find the answers on our FAQ page.

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Best smart speakers of 2020: Amazon, Google and Apple offer hands-free help – CNET

AmazonGoogle and Apple all make good smart speakers, and the competition between these tech giants keeps making this category better and better. Amazon helped popularize smart home devices and smart speakers with the original Echo and the now-famous digital assistant known as Alexa, but today you have a bunch of options from several different companies, each with their own pros and cons. 

So how do you figure out the difference between them and pick the best smart speaker for your needs? Well, the key differences largely come down to hardware size, price and audio quality. If you don't need much oomph from your music and you're good with a little lower audio quality, you can save money and get the same smarts in a smaller smart speaker body.

Our favorites, the Amazon Echo Dot and the Google Nest Mini, are both awesome smart devices. Pretty much all of your options include multi-room audio and let you turn on the lights, play music, ask a question, set a reminder and more with simple voice commands. If that sounds appealing to you, it might be time to give in to the growing hype of this burgeoning category of devices and buy a smart speaker.

Now playing: Watch this: This is the best smart speaker


Read more: Best Sonos speakers from $100 and up | Best Wi-Fi speakers and music systems of 2020

If you have an affinity for one of those brands in particular, your job of picking a speaker is easy. Head here for help picking an Amazon smart speaker model. Here's a guide if you want a Google-equipped smart speaker. The $350 Apple HomePod is your only option if you want a Siri-enabled smart speaker, but the good news is it has great audio quality, which makes listening to music very enjoyable.

If you're platform-agnostic, and don't need to choose between Alexa or Google, the range of choices might seem intimidating at first. But picking the best smart speaker can be easy if you know what you're looking for. Here's our thoughts.

Note that the products discussed here are independently chosen by our editors.

Ben Fox Rubin/CNET

Naming the best smart speaker is really tough these days. Both Google and Amazon have very capable smart speakers at affordable prices. If you don't want to deal with the nitty-gritty of the category and just want to try out a smart speaker, get the 3rd gen Echo Dot. Amazon's voice assistant has more capabilities than Google Assistant and Apple's Siri.

The third-generation Amazon Echo Dot looks and sounds better than previous versions and still only costs $50. Plus, there's a $60 version with a practical LED clock for timers, temperature and alarms. The Echo Dot offers all of the same digital assistant smarts as more expensive Echo devices. You sacrifice some audio quality for the size and price, but it plugs into your own speakers, so you can easily make up for that difference. Read the Amazon Echo Dot review.

Sarah Tew/CNET

The $200 Sonos One allows you to pair two units to play stereo sound or multiroom audio, but even a single speaker sounds awesome playing a wide variety of music genres and it costs significantly less than other smart speakers with premium sound quality such as the Google Home Max and the Apple HomePod.

Better yet, the Sonos One has both Alexa and Google Assistant built in -- simply pick which one you'd like to use for your voice commands during setup. Plus, Sonos has Apple's AirPlay 2 so you can control it with any Siri-enabled device, including your iPhone

Add it up and the Sonos One is a great-sounding, reasonably priced smart speaker that can fit into households centered around Alexa, Google Assistant or Siri. That's a tough pitch to beat. Read the Sonos One review.

James Martin/CNET

Amazon used to be the unquestioned ruler of the smart speaker world, but Google has done an admirable job of catching up its digital assistant in the sound race. At this point, picking between the lowest-price smart devices from the two companies -- the Amazon Echo Dot or the Google Nest Mini -- comes down to splitting hairs. The Dot is still our favorite overall, but by a small margin. 

Google Assistant now has almost as many capabilities as Alexa, making the $50 Google Nest Mini a solid alternative to the Amazon Echo Dot in your quest to find the best smart speaker. Plus, Google Assistant is a little smarter voice assistant than Alexa. It responds more flexibly to voice commands if you can't remember the exact name of your smart home devices, and Google's grouped commands, called routines, work with more types of smart devices than Amazon's similar routines. Google Assistant can recognize multiple voices, so it'll give you and your spouse different answers if you each ask about your calendars, though Alexa can now do this too.

Overall, Google still has the edge in assistant intelligence, and the Google Nest Mini is a great, low-cost way to take advantage of those smarts. Read the Google Nest Mini review.

Chris Monroe/CNET

Deciding which assistant you want at the center of your smart home is a tough call. Both Alexa and Google Assistant work with lots of devices. Both help you organize and control them easily. While Google Assistant is a little smarter, Alexa works with more smart home devices and makes setup with voice commands easier. 

Ultimately, we'll give the smart-home edge in the best smart speaker category to Amazon thanks to Alexa and the $150 Echo Plus. Alexa can send alerts if your smart speaker hears glass breaking or a smoke detector blaring. The Echo Plus combines the usual Alexa smarts with a speaker that sounds good and has a smart-home hub built in so you can sync your small sensors with it instead of needing to buy more gear.  Read the Amazon Echo Plus review.

Tyler Lizenby/CNET

Siri's first smart speaker adapts its sound to the room you're in and sounds fantastic playing all genres of music. Its sound quality outclasses the Sonos One and even squeaks by the similarly priced Google Home Max. Thanks to Siri, you can also use an Apple HomePod to control your smart home products with the sound of your voice, ask for help as you would with the other smart speakers and answer phone calls coming to your iPhone.

The HomePod is more limited than the rest, however. You can only play music from Apple's music service with voice commands. Other smart speakers give you a few popular streaming options to pick from, like Pandora or Spotify. As for the smart home, you're limited to devices that work with Apple's smart home platform, HomeKit. So the HomePod has a few limitations the rest don't have, but that shouldn't matter to you if you've already invested in Apple products and just want great sound quality. Read the Apple HomePod review.

Best portable smart speaker

JBL Link 20

Sarah Tew/CNET

Given the wide array of smart speakers, it's surprising how few are portable. Fortunately, the JBL Link 20 checks all of the right boxes to qualify as a good smart speaker, and it's battery-powered. It has decent battery life and solid sound quality, and it has Google Assistant built in, like the Google Nest Mini.

Even better, the wireless speaker is fully waterproof, so you can play music outside, and can connect to your home's Wi-Fi network or you can stream audio with it through your phone's Bluetooth. $200 is a little pricey. It's often on sale for $150 and it's sold out at the moment, but JBL representatives reassured us it'll be back in stock soon. 

In the meantime, the similar JBL Link 10 is a solid and cheaper, if slightly less impressive, alternative.  Read the JBL Link 20 review.

Other options

Those smart speakers are our favorites, but you still have lots of other options if you're looking for something specific. Read our breakdown of Alexa versus Google Assistant versus Siri if you'd like to learn each one's pros and cons and decide by platform.

Note that neither the original Amazon Echo nor the original Google Home made an appearance above because you can get the same capabilities for less with the smaller (Dot and Mini) versions. That said, if you want a smart speaker that splits the difference between affordability and premium sound, both are still solid options.

If you like the idea of always-listening help but want something more visual, check out our smart display best list. Smart displays essentially combine a smart speaker with a touchscreen so you can watch videos on YouTube, make video calls, scroll through pictures and control your smart home gadgets with a touch. Amazon and Google both have several options in this booming smart display category of smart home tech. 

There are also lots of third-party devices with Alexa built in, and a growing number of third-party speakers with Google Assistant. Check out the Amazon Tap or the UE Megablast if you want Alexa in a portable body. The TicHome Mini is another, more compact choice if you want a portable smart speaker with Google Assistant. You can also buy add-ons from a company called Ninety7 if you want to make your Google or Amazon smart speaker portable. 

Finally, the Harman Kardon Invoke uses Microsoft's assistant Cortana. It's competent enough if you're a Windows fan but otherwise doesn't have enough going for it to stand out from the crowd. Samsung even has a much-delayed smart speaker, the Galaxy Home with Samsung's assistant Bixby

Figure out what platform or features you'd like, and you should be able to quickly narrow down your options and find the best smart speaker for you and your family.

Regularly updated with new products as we review them.

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Archaeologists Have Found the Source of Stonehenge’s Boulders

The huge slabs of stone that make up the most iconic structures at Stonehenge came from about 25km away, according to chemical analysis. Since the 1500s, most Stonehenge scholars have assumed the 6- to 7-meter tall, 20-metric-ton sarsen stones came from nearby Marlborough Downs, and a recent study by University of Brighton archaeologist David Nash and his colleagues has now confirmed that.


This story originally appeared on Ars Technica, a trusted source for technology news, tech policy analysis, reviews, and more. Ars is owned by WIRED’s parent company, Condé Nast.

Recent studies have traced Stonehenge’s bluestones to quarries in the Preseli Hills of western Wales, about 300km (200 miles) away. When another group of archaeologists studied the chemical isotope ratios in the cremated remains of people once buried beneath the bluestones, those researchers found that many of those people may have come from the same part of Wales between 3100 and 2400 BCE. Ancient builders set up the sarsen stones a few centuries after the arrival of the bluestones. Modern scholars have only been able to speculate about where the huge boulders came from—until now.

Sarsen, also called silcrete, is a sedimentary rock mostly made up of quartz sand cemented by silica (quartz is just silica in crystal form), formed in layers of sandy sediment. Thanks to erosion, sarsen boulders are now scattered in clumps all over southern England. Prehistoric Britons built monuments like Stonehenge and Avebury with sarsen boulders, Roman settlers used sarsen bricks to build their villas, and medieval people built sarsen churches and farm buildings. But the largest sarsen boulders we know of in Britain today are the ones at Stonehenge.

About 99 percent of the average sarsen boulder is silica, but the other 1 percent contains trace amounts of other elements, like aluminum, calcium, iron, potassium, magnesium, and others. That extra material is different in different sarsen sources, as it depends on the minerals in the ground where the rock formed. Nash and his colleagues used those trace elements as a geochemical fingerprint to match the Stonehenge sarsens to their most likely source.

The largest concentration of sarsen in the UK is at Marlborough Downs, an area of round, grassy hills 25 to 30km (17 miles) north of Stonehenge. Centuries of archaeologists and antiquarians have assumed the Stonehenge sarsens came from the Marlborough Downs, mostly because the area is nearby and full of the right material. But that idea hadn’t been scientifically tested, and the bluestones demonstrate that the Neolithic people who built Stonehenge had a far-flung and complex supply network—and their own reasons for doing things, often inscrutable to modern researchers.

To track down the source of the sarsens, archaeologists first had to solve a more recent mystery: what happened to three missing chunks of Stonehenge?

One of the trilithons (arch-like structures made of two upright stones supporting a horizontal lintel stone) in the central horseshoe fell down in 1797. A century and a half later, in 1958, a restoration project set the massive stones in place again—but one of the uprights, called Stone 58, had cracked along its length. To help hold the cracked stone together so it could stand and support its half of the lintel stone, restorers drilled three holes through the stone and inserted metal ties. After the project, the three stone cores they’d drilled out seemed to vanish into thin air.

In 2018, one of the restorers, Robert Phillips, returned a broken but complete core from Stone 58 to the UK. Part of a second core turned up in the Salisbury Museum in 2019, but one and a half of the stone cores are still out there somewhere. Samples from the Phillips core gave Nash and his colleagues the chance to compare the chemical makeup of Stone 58 to sarsen boulders from sites all over Britain.

The match turned out to be exactly what various researchers had assumed for the last 500 years. The only boulders that matched Stone 58 came from one site in the southeastern Marlborough Downs: West Woods, in Wiltshire, about 25km (16 miles) north of Stonehenge and just 3km (2 miles) south of where most studies had looked for Neolithic sarsen quarries. West Woods is a six square kilometer (four square mile) plateau, partially wooded and dotted with large sarsen boulders and pits from millennia of quarrying.

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I Bought the Duffel Bag That’s in ‘The Expanse’—and Loved It

My husband and I have shared an ancient Mountain Hardwear expedition duffel for years (similar to this one) to keep our snowboarding, surfing, and camping gear together in the car. With the arrival of our two children, we needed another one to haul their tiny camping chairs, tiny sleeping bags, and three thousand stuffed animals.

Image may contain Clothing and Apparel
Photograph: OnSight

Enter OnSight’s Tarmac duffel. It comes in sizes ranging from a 50-liter to a 140-liter size. The 100-liter version can fit everything that my 4-person family needs for shelter, like a stand-up tent, vestibule, sleeping pads, and sleeping bags.

It’s light—under 3 pounds for the 50-liter version—and has reinforced seams, a yawning D-shaped opening, comfortable padded grab handles, and fitted, padded backpack straps. I’m 5’2” and I can cinch the backpack straps tight enough for me to wear it comfortably while hiking.

Most importantly, the bag is also environmentally-friendly. It’s made from Cotec EPO, which is a tarpaulin material that’s polyvinyl chloride (PVC)-free. When it’s inhaled as a gas—mostly during the manufacturing process—PVC can have dangerous side effects that include liver, lung, and kidney damage.

“PVC is not something we’re not comfortable having in our product or in our supply chain,” said Ourum. “When [Cotec EPO] is combusted, it’s entirely inert and non-toxic. Even if you were to put flame to it, it wouldn’t create any toxic materials.”

Because it’s water-resistant and the zippers are covered, I’ve been using it as a paddle-packing dry bag. I’ve loaded it up in canoes and on paddleboards, and all our gear—including our full-sized pillows—has stayed dry. It can also withstand pretty extreme temperature environments; the tarpaulin is designed to stay flexible even around -40 degrees Celsius, so I’m looking forward to loading it up with snowboarding gear once the weather turns.

It’s pretty durable, too. I’ve only taken ours out on two camping trips so far, but so far it’s withstood pretty harsh treatment. “That’s the most sustainable thing you can do, is to build a bag that will really last,” said Ourom.

People Problems

I Bought the Duffel Bag That's in The Expanseand Loved It
Photograph: OnSight
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Why Are Plants Green? The Answer Might Work on Any Planet

From large trees in the Amazon jungle to houseplants to seaweed in the ocean, green is the color that reigns over the plant kingdom. Why green, and not blue or magenta or gray? The simple answer is that although plants absorb almost all the photons in the red and blue regions of the light spectrum, they absorb only about 90 percent of the green photons. If they absorbed more, they would look black to our eyes. Plants are green because the small amount of light they reflect is that color.

Original story reprinted with permission from Quanta Magazine, an editorially independent publication of the Simons Foundation whose mission is to enhance public understanding of science by covering research develop­ments and trends in mathe­matics and the physical and life sciences.

But that seems unsatisfyingly wasteful because most of the energy that the sun radiates is in the green part of the spectrum. When pressed to explain further, biologists have sometimes suggested that the green light might be too powerful for plants to use without harm, but the reason why hasn’t been clear. Even after decades of molecular research on the light-harvesting machinery in plants, scientists could not establish a detailed rationale for plants’ color.

Recently, however, in the pages of Science, scientists finally provided a more complete answer. They built a model to explain why the photosynthetic machinery of plants wastes green light. What they did not expect was that their model would also explain the colors of other photosynthetic forms of life too. Their findings point to an evolutionary principle governing light-harvesting organisms that might apply throughout the universe. They also offer a lesson that—at least sometimes—evolution cares less about making biological systems efficient than about keeping them stable.

The mystery of the color of plants is one that Nathaniel Gabor, a physicist at the University of California, Riverside, stumbled into years ago while completing his doctorate. Extrapolating from his work on light absorption by carbon nanotubes, he started thinking of what the ideal solar collector would look like, one that absorbed the peak energy from the solar spectrum. “You should have this narrow device getting the most power to green light,” he said. “And then it immediately occurred to me that plants are doing the opposite: They’re spitting out green light.”

Nathaniel Gabor
Nathaniel Gabor, a physicist at the University of California, Riverside, and his colleagues have developed a model for light collection in photosynthetic organisms that optimizes the reduction of “noise” over efficiency.Courtesy of UC Riverside

In 2016, Gabor and his colleagues modeled the best conditions for a photoelectric cell that regulates energy flow. But to learn why plants reflect green light, Gabor and a team that included Richard Cogdell, a botanist at the University of Glasgow, looked more closely at what happens during photosynthesis as a problem in network theory.

The first step of photosynthesis happens in a light-harvesting complex, a mesh of proteins in which pigments are embedded, forming an antenna. The pigments—chlorophylls, in green plants—absorb light and transfer the energy to a reaction center, where the production of chemical energy for the cell’s use is initiated. The efficiency of this quantum mechanical first stage of photosynthesis is nearly perfect—almost all the absorbed light is converted into electrons the system can use.

But this antenna complex inside cells is constantly moving. “It’s like Jell-O,” Gabor said. “Those movements affect how the energy flows through the pigments” and bring noise and inefficiency into the system. Quick fluctuations in the intensity of light falling on plants—from changes in the amount of shade, for example—also make the input noisy. For the cell, a steady input of electrical energy coupled to a steady output of chemical energy is best: Too few electrons reaching the reaction center can cause an energy failure, while “too much energy will cause free radicals and all sorts of overcharging effects” that damage tissues, Gabor said.

Gabor and his team developed a model for the light-harvesting systems of plants and applied it to the solar spectrum measured below a canopy of leaves. Their work made it clear why what works for nanotube solar cells doesn’t work for plants: It might be highly efficient to specialize in collecting just the peak energy in green light, but that would be detrimental for plants because, when the sunlight flickered, the noise from the input signal would fluctuate too wildly for the complex to regulate the energy flow.

an infographic showing predictive model of color on plants
Illustration: Samuel Velasco/Quanta Magazine
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iPhone 8 vs. iPhone 8 Plus: Specs and features compared – CNET

If you're looking for a new iPhone at the lowest price possible, the iPhone 8 and 8 Plus from 2017 are viable options. (They're still so viable, in fact, that the US Census Bureau is using the iPhone 8 specifically to conduct the 2020 Census.) Though Apple discontinued selling them, you can still nab the devices from third-party retailers like Walmart and Best Buy. Prices will vary depending on the retailer and the phone's model and capacity, but from what we've seen so far, the iPhone 8 (64GB) averages about $350 and the iPhone 8 Plus (64GB) averages about $450. You can get them refurbished for about $100 less. (You tend to only see refurbished or "renewed" stock in the UK and Australia, starting at about £260 or AU$400 for the iPhone 8, and £430 or AU$600 for the iPhone 8 Plus.)

Unlike current iPhones, the iPhone 8 phones sport an intuitive home button and familiar design. If those are the main draw for you though, we suggest the iPhone SE 2020. Like the iPhone 8, it doesn't have a headphone jack, but as the newer phone, it has better hardware, more software support and a more robust Apple return policy and trade-in value. (For more information, read our comparison piece, iPhone SE vs. iPhone 8: The differences that matter to the budget-conscious.)

Nevertheless, if you are committed to an iPhone 8, but don't know which model you should get, we'll walk you through their main differences to help you make a more informed decision.

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At about $100 cheaper than the iPhone 8 Plus, we prefer the iPhone 8 largely due to the money you'll save. Though its screen isn't as big and sharp as the iPhone 8 Plus, nor does it have a telephoto lens, for most people the iPhone 8 has enough to satisfy your most casual phone needs. But if you do have more money to spend, we once again suggest the newer iPhone SE, which starts at $399 (£419 and AU$749). At about $50 more you'll get a better camera, a faster processor and dual-SIM capabilities. Read our Apple iPhone 8 review.

Sarah Tew/CNET

If you prioritize having a bigger screen to watch videos or play games, and a telephoto camera to capture beautiful portrait shots of your friends and family, then go for the iPhone 8 Plus. Everything else about the phone though, except for a slightly longer battery life (and the additional $100 price tag), is pretty much the same as the iPhone 8. Read our Apple iPhone 8 Plus review.

iPhone 8 and 8 Plus design: Choose your size

As counterparts to one another, the iPhone 8 and 8 Plus look nearly identical, except for the fact that the iPhone 8 Plus is bigger and has a higher resolution. It has a 5.5-inch, 1080p LCD display while the iPhone 8 has a 4.7-inch, 750p screen. 

Despite the obvious size difference though, you still have to consider how the size will affect your everyday interaction with the phone. If you have a smaller grip, for example, the iPhone 8 is more comfortable to hold and fits into pockets easier. If you watch a lot of video and play games, the larger iPhone 8 Plus is more immersive. And even though you might not be able to discern it with the naked eye, given the iPhone 8 Plus' greater resolution and pixel density, images are a tad sharper (at least on paper anyway).

Other than that though, the devices are similar. They come in three colors (white, black and gold), but phones this old means limited inventory, so retailers may stock fewer options. They are both water resistant and have wireless charging. But they also don't have headphone jacks and -- instead of swiping gestures for navigating or Face ID, like in newer phones -- they have a physical home button that houses the fingerprint reader. 

iPhone 8 Plus' second telephoto camera

While both phones have the same 12-megapixel standard camera with the same f1.8 aperture, only the 8 Plus has a second telephoto camera. With this second camera you can take portrait shots with a depth-of-field, bokeh effect that adds a lot of drama. Apple also added five lighting tools that you can apply to portraits, which include studio and stage lighting.

In addition to portraits, the telephoto camera adds some extra zoom. While the iPhone 8 only has digital zoom up to 5x, the telephoto offers a clearer 2x telephoto or optical zoom that does not degrade the photo's quality. The iPhone 8 Plus' digital zoom also goes up to 10x.

iPhone 8 and 8 Plus battery

Because the iPhone 8 and 8 Plus both have the Apple A11 Bionic processor, expect them to perform as reliably and quickly as each other. As for their batteries, Apple never releases those specs, but third-party teardowns have reported that the iPhone 8 has a 1,821-mAh battery and the 8 Plus has a 2,675-mAh battery. The phones clocked in similar times for our lab tests for continuous video playback on Airplane mode. The iPhone 8 lasted 13.5 hours while the 8 Plus lasted slightly longer at 13.75 hours. All in all, expect similar battery lives for both phones.

iPhone 8, 8 Plus and SE spec comparison

iPhone 8 iPhone 8 Plus Apple iPhone SE (2020)
Display size, resolution 4.7-inch; 1,334x750 pixels 5.5-inch; 1,920x1,080 pixels 4.7-inch; 1,334x750 pixels
Pixel density 326 ppi 401 ppi 326 ppi
Dimensions (Inches) 5.45x2.65x0.29 in 6.24x3.07x0.3 in 5.45x2.65x0.29 in
Dimensions (Millimeters) 138.4x67.3x7.3 mm 158.4x78.1x7.5 mm 138x67x7.3 mm
Weight (Ounces, Grams) 5.22 oz; 148g 7.13 oz; 202g 5.22 oz; 148g
Mobile software iOS 11, can update to iOS 13 iOS 11, can update to iOS 13 iOS 13
Camera 12-megapixel (wide-angle) 12-megapixel (wide-angle), 12-megapixel (telephoto) 12-megapixel (wide-angle)
Front-facing camera 7-megapixel 7-megapixel 7-megapixel
Video capture 4K 4K 4K
Processor Apple A11 Bionic Apple A11 Bionic Apple A13 Bionic
Storage 64GB, 128GB, 256GB 64GB, 128GB, 256GB 64GB, 128GB, 256GB
RAM 2GB 3GB Not disclosed
Expandable storage None None None
Battery 1,821 mAh (Apple doesn't confirm this) 2,675 mAh (Apple doesn't confirm this) 1,821 mAh (Apple doesn't confirm this)
Fingerprint sensor Home button Home button Home button
Connector Lightning Lightning Lightning
Headphone jack No No No
Special features Water resistant (IP67); wireless charging Water-resistant (IP67); wireless charging Water resistant (IP67); dual-SIM capabilities (nano-SIM and e-SIM); wireless charging

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