Engineers Could Heatproof Tech With New 3D-Printed Material

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<p>
  A new kind of 3D printed material could make technology more heat-resistant.
 </p>
<p>
  Unlike most naturally occurring solids, these manmade, mesh-like materials shrink when they’re heated up. By tweaking the materials’ chemical composition, the researchers could control how much they shrank at different temperatures. This work could apply to everything from circuitry to dentistry.
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/3d-heat-shrink.width-990_VhLafu1.jpg"/>
<figcaption>The design of this structure, coupled with its composition, allow it to shrink when heated.
        
    </figcaption>
</figure>
<p>
  Many devices warp or break at high temperatures because they’re made of metal, glass, or other normal solids that expand as they get hotter. Manufacturers can create sturdier devices if they incorporate some components that contract at higher heat, giving other pieces room to expand without breaking. But such shrinking solids are extremely rare. As a result, scientists have been trying since the mid-’90s to fabricate them in the lab.
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<p>
  The new 3D-printed “lattices” are grid-like structures mere millimeters across and are made up of tiny interlocking rods. Some of the rods are pure plastic; others are infused with copper nanoparticles. As they heat up, the pure-plastic beams swell faster than their copper-infused counterparts, bending in towards the center of the lattice and pulling the copper-reinforced rods along with them. This effectively causes the whole structure to crumple in on itself, said Qiming Wang, an engineer at the University of Southern California and lead author on the new study.
 </p>
<p>
  To test the lattices’ shrinkage, Wang’s team placed them inside a glass chamber and turned up the heat. As the chamber went from room temperature to 540 degrees Fahrenheit, the 3D-printed structures initially maintained their size and then gradually contracted. This work is described in
  <em>
   Physical Review Letters
  </em>
  .
 </p>
<p>
  The sugar-cube-sized lattices only shrink about the width of a human hair on each side, said Nick Fang, a mechanical engineer at the Massachusetts Institute of Technology and coauthor on the new study. But even this small change in size could make a big difference to engineers using these materials to build high-precision optical and mechanical devices. “This work is very innovative,” said Akihiro Takezawa, an engineer at Hiroshima University who is unaffiliated with the project.
 </p>
<p>
  According to Takezawa, these materials could be especially useful because of their tunable quality. Wang’s team could control how much the lattices shrank at different temperatures by changing how many nanoparticles they injected into the copper-infused rods. It’s also possible to fine-tune the lattices’ shrinkage by altering the width and orientation of their rods, Fang said.
 </p>
<p>
  Wang and his colleagues have proposed myriad uses for their new 3D-printed products. Take microchips, for example. When computers operate for a long time, they tend to heat up, which can cause their microchips to crack. Fashioning some microchip components that contract at higher temperatures could help computers withstand overheating. The researchers’ current 3D-printing method could construct samples less than a millimeter across, “so current technology is already good for microchip applications,” Wang said.
 </p>
<p>
  The lattices could similarly be used to build sturdier drone cameras, Fang said. If a drone flies up even 10 meters on a hot summer day, the increased temperature can cause the camera lens to expand. A contracting frame around the lens could act as a buffer that would keep a swelling lens from breaking the camera.
 </p>
<p>
  Fang said that the new 3D-printed materials could even be used to make something as simple as a dental filling. Unlike normal metal or plastic fillings, non-expanding fillings wouldn’t cause a toothache when the wearer drinks a hot beverage.
 </p>
<p>
  The lattices also might be used in ways that scientists haven’t even considered yet, said Jonathan Berger, a mechanical engineer at the University of California, Santa Barbara who was not involved in the study. It’s difficult to compile a full list of applications, he said, “for these materials that theoretically you can do completely new things with.”
 </p>
<p>
  The next step for Wang’s team is to devise a speedier method of manufacturing lattices. Some of the biggest structures printed for this study—each only a centimeter or so across—took 12 hours to make. But Wang hopes that eventually 3D-printing will provide a cheap, relatively easy way for designers and engineers to produce tunable materials for more heat-resistant tech.
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<p>
  “It’s a long road to travel to get these kinds of lattices into airplanes or circuit boards where there’s a huge established industry,” Berger said. “But it’ll be really exciting to see where this technology goes.”
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</section>
<p>
 Photo credit: Qiming Wang
</p>

'Biofinder' Bot Could Significantly Accelerate Search For Life on Mars

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<p>
  A new device could significantly speed up the search for life on Mars.
 </p>
<p>
  Using a green laser to scan surfaces for evidence of past or present life, the Stanoff Biofinder can, in less than a second, detect organisms as small as microbes from several feet away. The instrument, named for its fast, hands-off approach to finding life, is described in
  <a href="http://online.liebertpub.com/doi/abs/10.1089/ast.2015.1400">
   a paper
  </a>
  published in Astrobiology.
 </p>
<p>
  On a handful of previous Mars missions, the rovers’ life-seeking machines worked slowly—either because they had to collect samples for analysis or because they surveyed the landscape with lasers that only lit up a pinpoint of terrain at a time. The Standoff Biofinder can cover more ground because a special lens spreads its laser beam into a searchlight nearly ten inches across.
 </p>
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<img alt="Artist’s impression of Mars four billion years ago" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/mars-past_2048x1152.width-990_22JOapb.jpg"/>
<figcaption>An artist's impression of what Mars might have looked like four billion years ago
        
    </figcaption>
</figure>
<p>
  When the device showers a surface with laser light, molecules that absorb the radiation become excited and emit a faint fluorescent glow. Proteins, lipids, and other biologically produced substances only glow for a matter of nanoseconds, whereas the fluorescence given off rocks and minerals lasts thousands or millions of times longer. By recognizing only fluorescent blips less than 20 nanoseconds long, the Standoff Biofinder can pick out biological materials—dead or alive—against non-biological background materials.
 </p>
<p>
  A team of researchers led by Anupam Misra, a physicist at the University of Hawaii, recently put the Standoff Biofinder through the ringer to evaluate its life-perceiving prowess. In a series of lab experiments, researchers scanned various biological targets, such as crushed eggshells and algae-coated coral. The instrument was able to detect vestiges of life up to two meters (about 6.5 feet) away in one-tenth of a second. Misra was particularly impressed by the Biofinder’s ability to discern microbes among grains of Antarctic soil, which strongly resembles the Martian terrain.
 </p>
<p>
  “I’m really glad to see that this team has got [the Standoff Biofinder] up and running, and to see how well it performs with different examples of biological material,” said Lewis Dartnell, an astrobiologist and author of
  <em>
   Life in the Universe: A Beginner’s Guide
  </em>
  , who was not involved in the project.
 </p>
<p>
  According to Dartnell, this new gadget’s in-lab success does come with a caveat. Namely, any biological material on the surface of Mars has probably been so heavily degraded by the sun’s ultraviolet radiation that it would glow much more faintly than the organisms that Misra’s team used in their experiments. However, Dartnell said the new machine could work very well on freshly exposed material, like soil dug up from underground or rocks whose surfaces have been worn down with an abrasion tool.
 </p>
<p>
  Another limit to the Standoff Biofinder’s utility is that it can only recognize the presence of biological material—it can’t distinguish between different types of organisms. But this instrument could still be useful “in a triage function, scanning ahead of a Mars rover for any fluorescent signs of [life],” Dartnell said. The Standoff Biofinder would identify the most promising sites, and then other equipment on the rover could examine that terrain more closely.
 </p>
<p>
  Craig Marshall, a geologist at the University of Kansas who was not involved with the project, sees the instrument in a similar light. “I don’t think finding life on Mars is going to be as easy as point-and-shoot with the Standoff Biofinder within the first few minutes,” he said. “I do think it’s a good screening technique to find promising samples.”
 </p>
<p>
  The next step in getting the sensor to the Red Planet is building a much smaller version that would fit on a spacecraft, said Chris McKay, a planetary scientist at NASA Ames Research Center and co-investigator on the project. The current model resides on a dolly, and its fluorescence detector alone weighs over 13 pounds—about as much as a bowling ball. To send their device into space, McKay said, the team has to “shrink it down to the size of, maybe not a coffee cup, but a couple of coffee cups.”
 </p>
</section>
<p>
 Image credit:
 <a href="https://en.wikipedia.org/wiki/Mars#/media/File:Eso1509a_-_Mars_planet.jpg">
  European Southern Observatory / Wikimedia Commons (CC BY 4.0)
 </a>
</p>

CYGNSS will give scientists a better idea of how tropical storms develop over short periods of time, as well as how they intensify. Image Credit: NASA

Eight New Eyes in The Sky

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<p></p><p>When Scott Gleason was a graduate student, he realized that GPS signals are good for more than just navigation—scattered GPS transmissions can be used to help monitor tropical storms. A decade later, Gleason’s idea just came to fruition with the launch of NASA’s Cyclone Global Navigation Satellite System (CYGNSS).</p><p>CYGNSS is a squad of small satellites that will use reflected GPS signals to monitor wind speeds over tropical oceans. “Because of the cell phone revolution and because of the GPS commercial uses on cars, GPS receivers have gotten really, really small [and] low-power,” said Chris Ruf, an engineer at the University of Michigan and principal investigator on the mission. What’s more, since the CYGNSS satellites don’t broadcast any of their own signals, they don’t have to carry the heavy transmission equipment that other weather satellites bear. As a result, each CYGNSS satellite is only about the size of a large microwave oven and weighs about 60 pounds—about a hundred times lighter than GOES-R, a typical weather satellite that NASA launched last month.</p><p>Because the CYGNSS satellites are so small, scientists could build a fleet of eight satellites more quickly and cheaply than a single traditional weather satellite. The whole CYGNSS set only cost $100 million to design, construct, and test, compared to the $1.4 billion that went into building the series of four full-size GOES weather satellites, though those larger satellites have multiple sensors that detect a range of meteorological activity, from flash floods to tornadoes and lightning.</p><p>The pint-size CYGNSS devices were also relatively cheap to send into space because they all fit on a single rocket, the Pegasus XL, which launched from a Lockheed L-1011 Stargazer airplane on December 15. Over the next few months, the CYGNSS satellites will disperse into a ring around the Earth that observes oceans between 35˚ north and 35˚ south, where tropical storms are most common. The system will start observations at the onset of 2017 Atlantic hurricane season.</p><h2>A Better Way to See Storms</h2><p>CYGNSS’s GPS observation technique isn’t just good for making satellites smaller. It could help scientists understand how tropical storms intensify—an area of atmospheric science that has been stalled out decades. Although scientists’ ability to predict hurricane paths has improved by about 50% since 1990, forecasts of storm severity haven’t improved at all since then. “We don’t know whether [a hurricane] is going to die out, or whether it’s going to ramp up to a Category Five,” said Gleason, who now works as the CYGNSS instrument scientist at Southwest Research Institute.</p><p>That’s because previous weather satellites couldn’t see into the eye of a hurricane, which scientists think is the engine that powers a storm. Traditional satellites measured sea-level winds by sending down radio waves and measuring the signal that bounced back, but those radio broadcasts couldn’t penetrate an eyewall—the heavy clouds and rain that cloak a storm’s core. GPS signals, on the other hand, consist of lower-frequency radio waves that easily cut through an eyewall’s cloud cover. So CYGNSS satellites will get a good look at what’s happening inside the eye that drives a hurricane.</p><p>There is one drawback to CYGNSS’s GPS vision: To gather enough reflected signal for each observation, a CYGNSS satellite has to take the average wind speed over an area between 6.2 and 15.5 miles across. The average diameter of a hurricane eye is only 30 to 60 kilometers across, which means that “if there’s an observation on the eyewall, you’re washing in the signal from inside and outside [the eye],” said Brian McNoldy, a University of Miami atmospheric scientist on the CYGNSS team. “That’s definitely a concern.” CYGNSS might not be able to get a clear picture of the peak wind speed inside smaller hurricane eyes, but tropical storms are usually hundreds of kilometers across. So this outfit of small satellites should be “excellent at [mapping] out the whole wind field of the storm,” McNoldy said.</p><p>CYGNSS will also give scientists a better idea of how tropical storms develop over short periods of time. Other satellites tasked with sea-level wind speed measurement only swing back around to observe the same spot on Earth approximately once or occasionally twice a day. But tropical cyclones can significantly intensify over a period of 12 hours or less. So more frequent observations are necessary to characterize the evolution of a storm, said Sharan Majumdar, a mission team member and atmospheric scientist at the University of Miami. Since CYGNSS has eight satellites evenly spaced around the Earth, the whole system will have eyes on the same spot at least every six hours.</p>
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/pegasus-takeoff_1024x576.width-990_qU0LUQZ.jpg"/>
<figcaption>An Orbital ATK L-1011 Stargazer aircraft carrying the NASA Cyclone Global Navigation Satellite System, or CYGNSS, takes off.
        
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<p>The official mission life for CYGNSS is two years. According to McNoldy, it’s difficult to say how many tropical storms the satellites might observe in that time, but the odds are good that CYGNSS’s line of sight will pass over the eyewall of a hurricane a couple times each month. This should give scientists a significant stockpile of data to characterize tropical storm intensification in unprecedented detail.</p>
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<h2>For Better Forecasting</h2><p>The data gathered during the CYGNSS mission isn’t expressly intended for use in real hurricane forecasts. “This is not an operational mission, it’s an experiment,” said W. Linwood Jones, a satellite communications expert at the University of Central Florida who is not involved in this mission. Officially, CYGNSS is just a “proof of concept mission” to demonstrate that such small satellites can use the new GPS technique to make useful observations, Jones said. But he noted that “CYGNSS has the potential for significant impact right out of the box,” because scientists at the National Oceanic and Atmospheric Administration (NOAA) might use data from this mission in forecasts anyway.</p><p>“There’s a large computer system that the [NOAA] hurricane center uses to forecast the weather for real,” Ruf said. The computer model accounts for temperature, pressure, humidity, and other variables measured by aircraft and satellites, and its forecasts show up on the nightly news. NOAA researchers have now built a modified version of the program that can incorporate CYGNSS data, and they plan to test it out when the satellites start making observations next year. If CYGNSS data helps make more accurate weather predictions, NOAA might use it for official forecasts, Ruf said.</p><h2>More Small Satellites to Come</h2><p>CYGNSS may be the first small satellite mission launched by NASA’s Earth Science division, but it’s only one set of miniature machines coming down the NASA pipeline. A handful of other missions, which will use satellites ranging in size from a loaf of bread to a small washing machine, are planned to observe phenomena like Earth’s carbon cycle, atmospheric pollution, and weather. Gleason and McNoldy both expect to see more squadrons of small satellites in the future. “There have certainly been a lot of very large, very expensive [satellites] that have served us well,” McNoldy said. “I don’t think that’s going to end any time soon. But we might gradually see fewer of those in exchange for more missions like this.”</p><p>Jones agrees. He says the era of small satellites is “just in its infancy,” and envisions a future NASA mission that might have 20 or 30 small satellites performing CYGNSS-type observations to be used in NOAA forecasting. But of course, he said, “nothing happens overnight.”</p><p>Watch the Orbital ATK Pegasus XL rocket launch</p>
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Exotic New Atom Discovered in Nine Year Old Data

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<p>
  Researchers recently discovered evidence of a rare quirk of matter buried in data almost a decade old—the πK atom. Observations of these manufactured atoms could help scientists understand how some particles lose their electric charge.
 </p>
<p>
  Physicists have long suspected that pion (π) and kaon (K) particles could stick together to form πK atoms, but no one had ever seen such an exotic particle pairing. It’s rare enough to spot pions and kaons on their own—scientists have only ever witnessed these exotic particles in high-energy radiation inside atom smashers or from outer space.
 </p>
<p>
  “You can’t buy a bottle of pions or kaons in any store,” said Gerald Miller, a physicist at the University of Washington who was not involved in the new study.
 </p>
<p>
  Physicists first thought they’d glimpsed πK atoms splintering out of particle collisions in 2007. The researchers were working on the Dimeson Relativistic Atom Complex (DIRAC) experiment at CERN, shooting protons into metal foil at nearly the speed of light.
 </p>
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/dirac_0.width-990_9uXXsPX.jpg"/>
<figcaption>The DIRAC experiment is fed by CERN's Proton Synchrotron.
        
    </figcaption>
</figure>
<p>
  But the scientists analyzed the data “quickly by using only part of the detectors,” said Juerg Schacher, a physicist at the University of Bern and co-author on the new study, so they weren’t certain of their discovery.
 </p>
<p>
  Now, CERN researchers have re-examined the data from 2007 as well as data collected in similar experiments between 2008 and 2010. This time around, using observations from all of DIRAC’s sub-detectors and a more sophisticated method of data analysis, the scientists saw clear evidence of hundreds of πK atoms. Their work is described in a
  <a href="http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.112001">
   paper
  </a>
  recently published in
  <em>
   Physical Review Letters
  </em>
  .
 </p>
<p>
  “Of course, we were excited to be able to demonstrate in a sophisticated experiment the existence of such [an] exotic atom,” Schacher said.
 </p>
<p>
  Now that they have found πK atoms lurking in near-decade-old data, physicists want to see what these particle duos reveal about a fundamental theory of nature called quantum chromodynamics (QCD).
 </p>
<p>
  QCD is a mathematical theory that describes how quarks—the building blocks that construct pions and kaons, as well as familiar particles like protons and neutrons—stick together to form matter in the universe. That is, if the complete picture of how quarks behave in nature is a puzzle, then QCD is the box cover that tells physicists what the finished puzzle should look like. Unfortunately, the math of QCD is so gnarly that physicists have trouble using it to make testable predictions about the natural world. In other words, the QCD box cover is pretty much unreadable.
 </p>
<p>
  Still, each observation of a new quark composite gives experimental physicists another puzzle piece to work with. And now that they have the πK piece in hand, the next step is to study the πK’s characteristics to see what it contributes to the full picture of quark interaction.
 </p>
<p>
  One key characteristic they hope to measure is the πK atom’s lifetime. When a πK atom is born in a particle collision, electromagnetic force binds the pion and the kaon together because one is positively charged and one is negatively charged. But because pions and kaons are made of quarks, they have the curious ability to shed their electric charge and go neutral, said Eric Swanson, a physicist at the University of Pittsburgh who was not involved in the new study. When that happens, the electromagnetic force no longer holds the pion and kaon together, and the atom falls apart.
 </p>
<p>
  Theories that explain how pions and kaons lose their charge are based on QCD, Swanson said. Measuring how quickly the πK atom falls apart provides physicists with new insight into how pions and kaons—and thereby the quarks that compose them—behave.
 </p>
<p>
  “By collecting observations like this, we can learn something about how QCD manifests itself in nature,” Swanson said.
 </p>
</section>
<p>
 Photo credit: CERN
</p>

Maria Temming

Articles

Engineers Could Heatproof Tech With New 3D-Printed Material

'Biofinder' Bot Could Significantly Accelerate Search For Life on Mars

Eight New Eyes in The Sky

Exotic New Atom Discovered in Nine Year Old Data

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