Hexbyte  Tech News  Wired How to Stop the Automatic Emails from Square Vendors

Hexbyte Tech News Wired How to Stop the Automatic Emails from Square Vendors

Hexbyte Tech News Wired

The sandwich was unremarkable—lukewarm and not quite melted, like a college freshman’s late-night microwave snack rather than a true grilled cheese. But I have thought about the sandwich every week since I ordered it, because the food truck that made it won’t stop emailing me.

First came the receipt. Then the expressions of gratitude, offers of deals. “Thanks for your visit!” one email screamed. “Get FREE FRIES!!” another offered. I do not want your free fries, food truck. What I want is to be left alone.

The emails keep coming because I paid for my grilled cheese with a credit card using the food truck’s Square credit card machine. Even though I never agreed to be put on this restaurant’s email list for all eternity, by virtue of swiping my card in that specific Square card reader, I apparently signed up to be hounded, spammed, and annoyed for the rest of my life.

If you’ve used a credit card at a retail establishment in the past five years or so, you probably know what I mean. You bought a pair of earrings at a jewelry stand? Now you’re on a list. Purchase a lemon from a roadside “honor system” fruit stand? You’re on a list. I’m on lists for the pottery place where I once bought a Christmas gift, and the fast food joint where my kid gets his dinosaur-shaped chicken nuggets.

Once you give your email to any Square vendor, you are defaulted into receiving automated receipts and promotions from every participating Square vendor you visit.

My inbox has become so clogged with marketing spam that I’ve switched to the Gmail layout that filters “Promotions” into its own ignorable tab. It is by far the most populated tab in my email. If I were into inbox zero, I’d be apoplectic. (For what it’s worth, I’m not. I’m on the record has having more unread emails in my inbox than anyone else Atlantic journalist Taylor Lorenz could find—a dubious honor.)

Obviously, Square did not create this hell on its own. Buy anything online and you’re probably on that retailer’s list, too, unless you carefully unchecked a box at the exact right moment. Even Square’s physical point-of-sale competitors do this, making the deluge of emails impossible to escape. But since Square’s payment machines are the most ubiquitous by far, it is therefore the biggest clogger of my inbox.

When I asked a representative from Square what was going on, the answer surprised me: Apparently, I had consented to receive automatic receipts and promotions from any company that uses a Square point of sale machine the very first time I ever entered my email into one of the Square readers. This is not something you have to do; you can use Square payment machines and never enter your email, and you’ll avoid all automated receipts. But, once you give your email to any Square vendor, you are defaulted into receiving automated receipts and promotions from every participating Square vendor you visit.

Let me be clear: If that was me giving my consent, I didn’t understand what I was agreeing to. And that is not informed consent.

I do not remember what store I was in when I first entered my email into Square’s system, or even what year it was. What I do know is that I had intended to receive email updates from that business specifically—not from every business that uses the same payments machine for ever and ever as long as we both shall live.

Once I entered my email, my credit card was linked to my email, and my email served as consent to put me on the list of every Square vendor I visit using that credit card. This is a very intentional business decision, one Square touts to its vendors as a way for them to get extra business and make more money, capitalizing on the scale and reach of Square’s email lists to market directly to their customers without much hassle. In order to send out promotions to Square customers, vendors pay a small fee. This is one of the perks Square offers small business—without having to invest in massive direct-to-consumer marketing infrastructure, indie vendors can reach their audience.

Square says its automatic marketing makes vendors money. “On average, Square Marketing programs generate more than $10 in sales by our sellers for every $1 in spend, and Square Loyalty programs result in a 70 percent increase in buyer visit frequency,” reads the company’s Q2 shareholder letter from 2017.

That’s nice. I’m not against earning small businesses money, nor am I immune to the lure of the well-crafted email promotion. I just want the choice to opt out—and I want to know when I opted in.

After the most recent missive from the grilled cheese truck—“Forget the long line and dine with us again!”—I decided I’d had enough. I searched for my Square account profile page, where I figured Square would keep track of my activity and transactions, and where I might be able to unclick a box to opt out of this spamming.

That place doesn’t exist. A Square representative told me that while the company has discussed making such an account page for customers, the team has no plans to roll one out. But you can opt out. You just have to do so from the emails themselves.

At the bottom of any Square vendor marketing email, there’s an option to unsubscribe or manage preferences. If you click on unsubscribe, you can unsubscribe from promotions from that vendor specifically. If you click on “manage preferences,” you can choose to continue receiving emails from vendors you frequent (this is the choice that is filled in automatically) or to say “I do not want to receive emails from any merchants.”

Clicking on that will opt you out of all vendor marketing. It will not opt you out of automatic receipts. To opt out of those, you need to find a receipt in your email, scroll to the bottom, and click on the even tinier message: “manage preferences for digital receipts.” First, you’ll be given the chance to opt out of digital receipts for that vendor. Next, you’ll be given the chance to opt out of all digital receipts.

I did this and I felt better. But I had another nagging concern. When I had paid for that grilled cheese on that fateful day, I put my credit card in the machine and then the screen presented me with some familiar choices:: “Text receipt,” “Email receipt,” “Paper Receipt,” or “No Thanks.”

I always choose “No Thanks.” And yet, going back through my email, I see I was still getting an emailed receipt. When I asked Square what was going on here, the representative was at first surprised. After conferring internally, the representative told me that likely what was happening was that those choices only apply when a vendor has opted to also offer printed receipts. The “No Thanks” means no printed receipt, and does not override the default automated email receipts, if you’ve already input your email in a Square vendor once upon a time.

I’m not sure why the system behaves this way, but I know it doesn’t make things easy for consumers. And you know what? Modern life is full of enough inescapable, opaque, annoying, and unnecessary dreck already, even without the nonstop emails. I just want to buy a grilled cheese sandwich, eat it by the side of the road, and never think about it again. Is that too much to ask?

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Hexbyte  Tech News  Wired Breaking My Phone Addiction—Via My Phone

Hexbyte Tech News Wired Breaking My Phone Addiction—Via My Phone

Hexbyte Tech News Wired

Most of the meetings of Internet and Technology Addicts Anonymous take place online, which is more sensible than it sounds. Colloquy via web-based conference call might help tech burnouts clear the first hurdle in recovery: asking for help. If your idea of social life is a four-day Twitch bender played under a codename, at least you don’t have to leave behind all the comforts of home—screens, anonymity—when you’re demoralized enough by digital compulsions to bust open a FreeConferenceCall.com tab.

Four English-language ITAA conference calls take place each week, Tuesday and Thursday evenings, and weekend days at noon. Live meetings, where addicts in folding chairs share wisdom and complaints with other addicts, don’t seem to last long; in-person groups meet for a year or so and then fizzle. Only the very first ITAA group, which started near Seattle around 2009, has been in continuous operation. That may be because it’s connected to an opulent residential program called reSTART ($37,000 for nine weeks) that heavily filigrees the 12 steps with behavioral therapy, classes in horticulture, and no end of physical exertion. Eclectic treatments, including something called “sand tray therapy,” address problematic texting, gaming addiction, and much more.

Like many who get sober in traditional AA, I tend to be skeptical of any therapy more sophisticated than meditating, making amends, and helping people. Still, reSTART intrigued me. Based in Bellevue and Fall City, Washington, it promotes not total abstinence from screens but “a sustainable digital lifestyle.” That sounded promising. On my virtual tour of the tranquil, woody facility, I began to imagine a nine-week getaway where my main obligation would be to steer clear of my phone and become a sporty Pacific-Northwest-before-Microsoft-and-Amazon person. In the rousing promo on reSTART’s site, a cadaverous-looking insomniac is shown quitting his videogame console; then a similar young man is shown mountain-biking down a brutal path to an existential victory no leaderboard can match.

That looked exhilarating, but too far away and too pricey, so I called ITAA as a turtle step toward smartphone relief. If I’m honest with myself, typing in conference-call codes (the worst) was probably a clue that I wasn’t remotely ready to drop my unsustainable online lifestyle. I was doing nothing new, after all; I could have been calling in to hear Twitter’s quarterly earnings report. What I really could use was “opposite action”: a jolt of something counter-habitual, like the moment seven and a half years ago when I spoke out loud the thing I was most ashamed of, to a room full of strangers: “I am an alcoholic.”

But even as I knew better, I checked out the idea of internet addiction from my phone. First up, the usual Polycom dissonance, where it was impossible to tell how many people were present. Then someone read the Serenity Prayer. Serenity, courage, wisdom. The prayer reader then announced that the meeting’s topic was “top lines, middle lines, bottom lines,” a fanciful geometry I came to appreciate as the framework for addressing tech addiction. Unlike in AA, where you strictly avoid intoxicants, ITAA has no universal fixed standard of abstinence. Tech is largely conceived of as something one cannot live without, the way food is in Overeaters Anonymous.

My blindness to the bodies of the addicts, and theirs to mine, inhibited, somehow, my compassion for them.

The other major program I know that uses top, middle, and bottom lines is the oft-mocked—but reportedly effective for some people—Sex and Love Addicts Anonymous. In SLAA, as in ITAA, top line is a behavior you’re trying to cultivate; a medium line is a behavior that leads to behaviors you’re trying to avoid; and a bottom line is a behavior you’re committed to avoiding absolutely. A member of SLAA once told me that, as a top line, she was trying to have sex with her husband more often. Her bottom-line no-no was: no more sex with strangers in libraries. (!) A middle line, which she didn’t have, is one that opens the chute to violating the bottom line. If the library libertine had blown past her top line by rejecting her husband, and then tucked her sexy library card into her car’s glove compartment, that behavior—the card-tucking—could be a middle line: a signal that she was on the road to self-betrayal in the stacks.

SLAA stories are a bit more thrilling than stories in ITAA, where members describe themselves as “recovering from the problems resulting from excessive internet and technology use.” (What people say in 12-step fellowships is confidential, so I’m changing identifying details.) Many of them recount watching too many YouTube video recs. One memorably berated herself for blowing her bottom line by skipping a night of sleep to scroll through slideshows of the daughter of Alec Baldwin. I heard people say that, as top lines, they were trying to meditate, paint, and write—activities considered superior to follies like “compulsive information gathering,” which for one man meant looking up divorce statistics from the 1940s. Dammit, he inadvertently made that topic sound so interesting that when the meeting ended I turned to the figures myself for a little taste of info-pamine. Did you know that divorces—as well as marriages—spiked right after World War II ended? (Out of consideration for those in info recovery, I will not post the link.)

Other bottom lines: No Facebook, ever. No more than two hours of gaming a day. No staying up online past 2 am. Some install blockers to prevent computer use in certain hours; these are supposed to work the way Antabuse, which interferes with the metabolism of alcohol, works for recovering alcoholics. Of course, addicts get around it. “I recently figured out how to hack the blocker,” one man said. “I’m mad at myself for doing that. Now I can’t rely on the blocker in the future.”

In the evening meetings, many people sounded exhausted, their voices in the dial-tone register. Missing sleep was a common complaint. Of course, I couldn’t see anyone. In AA, you stay sober and help others in part by scanning and being scanned for changes in body or mind: The yellowish cast that signals liver and pancreatic problems is the most alarming, but also telling are red eyes, weight changes, injuries, dishevelment. In a trusting and intimate AA in-person group, a member can approach another with concerns based on their self-presentation in ways that would ordinarily be considered intrusive. Not during the ITAA phoners. My blindness to the bodies of the addicts, and theirs to mine, inhibited, somehow, my compassion for them and, more worrying, my willingness to help.

We were still avatars, I realized. And then someone named a middle line that crystallized this thought. She was talking about her gateways to internet abuse: “sugar eating, unhealthy relationships, even extensive fictional reading.” The words “fictional reading” stayed with me. Did she just mean “reading fiction,” or is it “fictional reading,” when you pick up a virtual book in Roblox or barely skim headlines on Twitter?

The alcoholic, says AA’s Big Book, is often told he or she is “in full flight from reality.” That seemed to apply here. Whatever else you say about the elusiveness of an “addiction” definition, alcoholics prefer drunkenness to clarity. Tech addicts likewise prefer Metro Exodus over a nagging parent, or ageless online personas to this mortal coil.

The antidote is a flight to reality—however agonizing that feels. In AA that means a clear bloodstream; an inventory of mistakes, resentments, fears, and misdeeds; earnest amends for the harms done to others. But reality goes by other names too, and I can see how, for chronic texters, it might look like an antiscreen, maybe even like mountain biking: three-dimensional, muddy and brambly, invigorating, physically dangerous.


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Addicts can mistake the disease for the cure—that’s another lesson of AA. The drinks you consumed for insomnia or heartbreak were actually the source of the problem. Likewise, an ITAA member confessed that his relentless search for adventure in MMORPGs had drained his life of actual adventure. As he admitted this, his voice changed; he announced a plan to go camping somewhere in the province of Alberta, and leave his phone behind. Then someone reminded him he’d need it for ITAA meetings. The conversation turned to portable chargers, until someone reminded us that “talking about devices—even chargers—can be triggering.”

Oh, for heaven’s sake. I had already put “hiking” and “Alberta” into Google—and was fantasizing about the Columbia Icefield. I wanted the gang to see these pictures of the Athabasca Glacier and to imagine, with me, zipping around in an Ice Explorer, but I was worried that sharing a URL might be triggering. I wouldn’t want anyone going down a glacier rabbit hole. On the other hand, my antidote to phone dependence has historically been adventure. I wasn’t sure that, with this particular addiction—if that was even the word for it—meetings, prayer, and service were the answer. Maybe it was glaciers.

The ITAA meeting was ending, and we were asked to shout the word “hugs!” as a way of closing. After several fake-hugs sessions, I had finally stopped judging them. But I did have something to say: I asked the guy planning the camping trip if he was afraid of being away from his phone. He said he wasn’t sure. He added that he’d tell us if it failed at the next meeting. But if it went well, he said, if the psychedelic blue icefields enchanted him more than Facebook, his plan was, no offense to anyone still struggling with tech addiction, never, ever to come back.

Virginia Heffernan (@page88) is a regular contributor to WIRED.

This article appears in the May issue. Subscribe now.

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Hexbyte  News  Computers Security lapse exposed a Chinese smart city surveillance system

Hexbyte News Computers Security lapse exposed a Chinese smart city surveillance system

Hexbyte News Computers

Smart cities are designed to make life easier for their residents: better traffic management by clearing routes, making sure the public transport is running on time and having cameras keeping a watchful eye from above.

But what happens when that data leaks? One such database was open for weeks for anyone to look inside.

Security researcher John Wethington found a smart city database accessible from a web browser without a password. He passed details of the database to TechCrunch in an effort to get the data secured.

The database was an Elasticsearch database, storing gigabytes of data — including facial recognition scans on hundreds of people over several months. The data was hosted by Chinese tech giant Alibaba. The customer’s database, which Alibaba did not name, made several references to the tech giant’s artificial intelligence-powered cloud platform, City Brain, but Alibaba later denied its platform was used.

“This is a database project created by a customer and hosted on the Alibaba Cloud platform,” said an Alibaba spokesperson. “Customers are always advised to protect their data by setting a secure password.”

“We have already informed the customer about this incident so they can immediately address the issue. As a public cloud provider, we do not have the right to access the content in the customer database,” the spokesperson added. The database was pulled offline shortly after TechCrunch reached out to Alibaba.

But while Alibaba may not have visibility into the system, we did.

Hexbyte  News  Computers

The location of the smart city’s many cameras in Beijing (Image: supplied)

While artificial intelligence-powered smart city technology provides insights into how a city is operating, the use of facial recognition and surveillance projects have come under heavy scrutiny from civil liberties advocates. Despite privacy concerns, smart city and surveillance systems are slowly making their way into other cities both in China and abroad, like Kuala Lumpur, and soon the West.

“It’s not difficult to imagine the potential for abuse that would exist if a platform like this were brought to the U.S. with no civilian and governmental regulations or oversight,” said Wethington. “While businesses cannot simply plug in to FBI data sets today it would not be hard for them to access other state or local criminal databases and begin to create their own profiles on customers or adversaries.”

We don’t know the customer of this leaky database, but its contents offered a rare insight into how a smart city system works.

The system monitors the residents around at least two small housing communities in eastern Beijing, the largest of which is Liangmaqiao, known as the city’s embassy district. The system is made up of several data collection points, including cameras designed to collect facial recognition data.

The exposed data contains enough information to pinpoint where people went, when and for how long, allowing anyone with access to the data — including police — to build up a picture of a person’s day-to-day life.

Hexbyte  News  Computers

A portion of the database containing facial recognition scans (Image: supplied)

The database processed various facial details, such as if a person’s eyes or mouth are open, if they’re wearing sunglasses, or a mask — common during periods of heavy smog — and if a person is smiling or even has a beard.

The database also contained a subject’s approximate age as well as an “attractive” score, according to the database fields.

But the capabilities of the system have a darker side, particularly given the complicated politics of China.

The system also uses its facial recognition systems to detect ethnicities and labels them — such as “汉族” for Han Chinese, the main ethnic group of China — and also “维族” — or Uyghur Muslims, an ethnic minority under persecution by Beijing.

Where ethnicities can help police identify suspects in an area even if they don’t have a name to match, the data can be used for abuse.

The Chinese government has detained more than a million Uyghurs in internment camps in the past year, according to a United Nations human rights committee. It’s part of a massive crackdown by Beijing on the ethnic minority group. Just this week, details emerged of an app used by police to track Uyghur Muslims.

We also found that the customer’s system also pulls in data from the police and uses that information to detect people of interest or criminal suspects, suggesting it may be a government customer.

Hexbyte  News  Computers

Facial recognition scans would match against police records in real time (Image: supplied)

Each time a person is detected, the database would trigger a “warning” noting the date, time, location and a corresponding note. Several records seen by TechCrunch include suspects’ names and their national identification card number.

“Key personnel alert by the public security bureau: “[name] [location]” – 177 camera detects key individual(s),” one translated record reads, courtesy of TechCrunch’s Rita Liao. (The named security bureau is China’s federal police department, the Ministry of Public Security.)

In other words, the record shows a camera at a certain point detected a person’s face whose information matched a police watchlist.

Many of the records associated with a watchlist flag would include the reason why, such as if a recognized person was a “drug addict” or “released from prison.”

The system is also programmed to alert the customer in the event of building access control issues, smoke alarms and equipment failures — such as when cameras go offline.

The customer’s system also has the capability to monitor for Wi-Fi-enabled devices, such as phones and computers, using sensors built by Chinese networking tech maker Renzixing and placed around the district. The database collects the dates and times that pass through its wireless network radius. Fields in the Wi-Fi-device logging table suggest the system can collect IMEI and IMSI numbers, used to uniquely identify a cellular user.

Although the customer’s smart city system was on a small scale with only a few dozen sensors, cameras and data collection points, the amount of data it collected in a short space of time was staggering.

In the past week alone, the database had grown in size — suggesting it’s still actively collecting data.

“The weaponization and abuse of A.I. is a very real threat to the privacy and security of every individual,” said Wethington. “We should carefully look at how this technology is already being abused by other countries and businesses before permitting them to be deployed here.”

It’s hard to know if facial recognition systems like this are good or bad. There’s no real line in the sand separating good uses from bad uses. Facial and object recognition systems can spot criminals on the run and detect weapons ahead of mass shootings. But some worry about the repercussions of being watched every day — even jaywalkers don’t get a free pass. The pervasiveness of these systems remain a privacy concern for civil liberties groups.

But as these systems develop and become more powerful and ubiquitous, companies might be better placed to first and foremost make sure its massive data banks don’t inadvertently leak.

Updated with additional new details from Alibaba.

Got a tip? You can send tips securely over Signal and WhatsApp to +1 646-755–8849. You can also send PGP email with the fingerprint: 4D0E 92F2 E36A EC51 DAAE 5D97 CB8C 15FA EB6C EEA5.

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Hexbyte – Tech News – Ars Technica | Garmin Forerunner 245 Music review: New features, better price, few sacrifices

Hexbyte – Tech News – Ars Technica | Garmin Forerunner 245 Music review: New features, better price, few sacrifices

Hexbyte – Tech News – Ars Technica |

Born to run —

More runners can track the essentials in this new smartwatch that starts at $299.

Hexbyte - Tech News - Ars Technica | Garmin Forerunner 245 Music review: New features, better price, few sacrifices

Valentina Palladino

Runners have a lot to be excited about when it comes to Garmin’s revamped family of Forerunner smartwatches. Now starting at $199, the Forerunner family contains six devices that should serve all levels of runner—from novice to expert. The $299 Forerunner 245 and 245 Music sit right in the middle of the lineup, taking design elements from the friendlier Vivoactive series and capabilities from the higher-end Forerunner devices and mashing them up to make a mid-range device that will likely appeal to many athletes. Its price and feature set also prep the Forerunner 245 Music to compete with the Apple Watch and Fitbit’s Ionic.

But even if Garmin somewhat simplified the Forerunner family in its latest update, picking the best device for your needs and budget still takes a bit of deciphering. By nature of it sitting in the middle, the Forerunner 245 duo begs to be the default option for most runners—but key features that it lacks may push some consumers to the more expensive $449 Forerunner 645. We tested out the Forerunner 245 Music to see how well it stands up to the Forerunner 645 Music and where users need to make sacrifices to have the new smartwatch work for them.

Hexbyte – Tech News – Ars Technica | Compared to the Forerunner 645

Before we dive into the new features brought over to the Forerunner 245 Music from other Garmin wearables, let’s talk about what the device cannot do. Garmin omitted a few things to widen the gap between this new device and the Forerunner 645 duo (regular and Music), and the most glaring omission is that of the barometric altimeter. The Forerunner 645 devices have it, but the Forerunner 245 devices do not—that means the new devices cannot track stairs climbed or measure elevation as accurately while hiking.

Forgoing an altimeter in a $299 device is baffling to say the least. I was frustrated when Fitbit left it out of the $169 Versa Lite, and I’m equally frustrated to see it left out of the Forerunner 245 Music. Considering more affordable Garmin wearables include this sensor, leaving it off the Forerunner 245 Music’s spec sheet doesn’t make sense from a user’s perspective.

But I can understand the decision from Garmin’s perspective—the Forerunner series is geared toward runners, not users who are simply looking for an all-day and all-night health-tracking device. (If that’s what you want, Garmin has many devices that aren’t nearly as expensive as any Forerunner watch). While Forerunners can do most everything a Vivoactive wearable can do, it has specific features that only runners and other athletes who run will demand.

A barometric altimeter speaks to frequent hikers and runners who train on hilly or other non-flat trails. It becomes even more vital for those types of users than the same sensor would be for someone who just wants to track the number of floors they climbed at the office on any given day. For that reason, those users may be willing to pay more for it in a device like the Forerunner 645 Music. That being said, I still feel that a $299 runner’s watch shouldn’t omit such a basic sensor.

The Forerunner 645’s ability to measure elevation, altitude, and barometric pressure also allow it to work with Garmin’s Running Power app from the Connect IQ store. Running Power is just one of many running dynamics that some Garmin wearables can measure—either by themselves, or with the addition of a connected foot pod. While the Forerunner 245 Music can connect to a dynamics pod via Bluetooth and ANT+, it doesn’t have other embedded sensors that are necessary for measuring the running power metric.

Other things that set the Forerunner 645 apart from the Forerunner 245 series is the silver bezel that surrounds its display, the Wi-Fi capabilities of both models (only the Forerunner 245 Music has Wi-Fi connectivity), and NFC for Garmin Pay.

  • The $349 Garmin Forerunner 245 Music.

    Valentina Palladino

  • The always-on Chroma display has a backlight you can turn on whenever you want.

    Valentina Palladino

  • The underside holds the heart-rate monitor and the pulse-ox sensor.

    Valentina Palladino

  • The magnetic charging nodes sit to the right of the case’s underside as well.

    Valentina Palladino

  • While it’s designed as a runner’s tool, the Forerunner 245 has other on-device workout profiles.

    Valentina Palladino

  • The backlight, up, and down buttons (from left to right).

    Valentina Palladino

  • The activity and back buttons (left to right) on the opposite side of the case’s circumference.

    Valentina Palladino

  • Next to an Apple Watch Series 4 (40mm), the Forerunner 245 is definitely sportier, but it’s also a more powerful fitness watch.

    Valentina Palladino

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Hexbyte – Tech News – Ars Technica | Study finds ultimate fate of Leidenfrost droplets depends on their size

Hexbyte – Tech News – Ars Technica | Study finds ultimate fate of Leidenfrost droplets depends on their size

Hexbyte – Tech News – Ars Technica |

Size matters —

Johann Leidenfrost first reported the phenomenon in 1756.

Hexbyte - Tech News - Ars Technica | A new study shows the ultimate fate of Leidenfrost droplets, liquid drops that levitate above very hot surfaces. Larger drops explode violently with an audible crack. Smaller ones simple shrink and fly away.

Enlarge / A new study shows the ultimate fate of Leidenfrost droplets, liquid drops that levitate above very hot surfaces. Larger drops explode violently with an audible crack. Smaller ones simple shrink and fly away.


In 1756, a German scientist named Johann Gottlob Leidenfrost reported his observation of an unusual phenomenon. Normally, water splashed onto a very hot pan sizzles and evaporates very quickly. But if the pan’s temperature is well above water’s boiling point, “gleaming drops resembling quicksilver” will form and will skitter across the surface. It’s known as the “Leidenfrost effect” in his honor.

In the ensuing 250 years, physicists came up with a viable explanation for why this occurs. If the surface is at least 400 degrees Fahrenheit (well above the boiling point of water), cushions of water vapor, or steam, form underneath them, keeping them levitated. The Leidenfrost effect also works with other liquids, including oils and alcohol, but the temperature at which it manifests will be different. In a 2009 Mythbusters episode, for instance, the hosts demonstrated how someone could wet their hand and dip it ever so briefly into molten lead without injury, thanks to this effect.

But nobody had been able to identify the source of the accompanying cracking sound Leidenfrost reported. Now, an international team of scientists has filled in that last remaining gap in our knowledge with a recent paper in Science Advances.

The answer: it depends on the size of the droplet. Smaller drops will skitter off the surface and evaporate, while larger drops explode with that telltale crack. “This answers the 250-year-old question of what produces this cracking sound,” said co-author Varghese Mathai, a postdoctoral researcher at Brown University. “We couldn’t find any prior attempts in the literature to explain the source of the crack sound, so it’s a fundamental question answered.” The insights gained could one day make it possible to control the effect for application in cooling systems or particle transport or techniques for transporting and depositing particles for microelectronic fabrication.

Enlarge / Adam Savage looks on

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Hexbyte – News – Science/Nature | ULA Awarded $149 Million Delta IV Heavy Launch Contract for NRO Mission – Space.com

Hexbyte – News – Science/Nature | ULA Awarded $149 Million Delta IV Heavy Launch Contract for NRO Mission – Space.com

Hexbyte – News – Science/Nature |

Hexbyte - News - Science/Nature | A United Launch Alliance Delta 4 Heavy lifts off Jan. 19 carrying a classified payload. The delay of the launch from late 2018 helped cushion a projected decline in earnings that Lockheed Martin from ULA in 2019.

A United Launch Alliance Delta 4 Heavy lifts off Jan. 19 carrying a classified payload. The delay of the launch from late 2018 helped cushion a projected decline in earnings that Lockheed Martin from ULA in 2019.

(Image: © ULA)

WASHINGTON — The Air Force Space and Missile Systems Center on Thursday awarded United Launch Alliance a $149 million contract modification for a Delta IV Heavy launch of the National Reconnaissance Office mission NROL-68, the second of three missions awarded to ULA under the Launch Vehicle Production Services contract in October 2018.

ULA in October 2018 was awarded three NRO missions — NROL-91, NROL-68, and NROL-70 — projected to launch in fiscal year 2022, 2023 and 2024 respectively. Mission one (NROL-91) was ordered at contract award in October 2018. Thursday’s announcement is for mission two (NROL-68). The total value of the LVPS contract is $449.8 million.

The Air Force sole-sourced the LVPS contract to ULA because the Delta IV Heavy launch vehicle is the only rocket that currently meets the mission requirements for NRO assets, including unique handling at the launch site and mission-unique hardware. “The Air Force determined ULA was the only certified launch service provider with the capability to provide launch services for NROL-68, NROL-70, and NROL-91 missions,” a spokesman said. A sole source request for proposal was issued to ULA in March 2017 for the three NRO missions.

NROL-68 and NROL-70 are planned to launch from Cape Canaveral Air Force Station, Florida. NROL-91 is planned to launch from Vandenberg Air Force Base, California.

The Air Force intends to compete future national security space heavy lift launch services when new vehicles enter the market. SpaceX’s Falcon Heavy is expected to be certified in the coming months, and competitors Blue Origin and Northrop Grumman are developing new rockets, as is ULA. Although ULA is retiring the Delta 4 Medium this year, the Air Force wants to keep the Heavy in service until the mid-2020s to ensure it has a heavy lift capability until other vehicles are ready.

This story was provided by SpaceNews, dedicated to covering all aspects of the space industry. 

Have a news tip, correction or comment? Let us know at community@space.com.