Powered by Wind: World’s Tiniest Windmills

tiny_windmillWind turbines are one of the fastest growing industries thanks to their ability to provide clean, renewable energy. And while most designs are trending towards larger and larger sizes and power yields, some are looking in the opposite direction. By equipping everyday objects with tiny windmills, we just might find our way towards a future where batteries are unnecessary.

Professor J.C. Chiao and his postdoc Dr. Smitha Rao of the University of Texas at Arlington are two individuals who are making this idea into a reality. Their new MEMS-based nickel alloy windmill is so small that 10 could be mounted on a single grain of rice. Aimed at very-small-scale energy harvesting applications, these windmills could recharge batteries for smartphones, and directly power ultra-low-power electronic devices.

tiny_windmill1These micro-windmills – called horizontal axis wind turbines – have a three-bladed rotor that is 1.8 mm in diameter, 100 microns thick, and are mounted on a tower about 2 mm tall mount. Despite their tiny size, the micro-windmills can endure strong winds, owing to being constructed of a tough nickel alloy rather than silicon, which is typical of most microelectromechanical systems (MEMS), and a smart aerodynamic design.

According to Dr. Rao, the problem with most MEMS designs is that they are too fragile, owing to silicon and silicon oxide’s brittle nature. Nickel alloy, by contrast, is very durable, and the clever design and size of the windmill means that several thousands of them could be applied to a single 200 mm (8 inch) silicon wafer, which in turn makes for very low cost-per-unit prices.

tiny_windmill2The windmills were crafted using origami techniques that allow two-dimensional shapes to be electroplated on a flat plane, then self-assembled into 3D moving mechanical structures. Rao and Chiao created the windmill for a Taiwanese superconductor company called WinMEMS, which developed the fabrication technique. And as Rao stats, they were interested in her work in micro-robotics:

It’s very gratifying to first be noticed by an international company and second to work on something like this where you can see immediately how it might be used. However, I think we’ve only scratched the surface on how these micro-windmills might be used.

Chiao claims that the windmills could perhaps be crafted into panels of thousands, which could then be attached to the sides of buildings to harvest wind energy for lighting, security, or wireless communication. So in addition to wind tunnels, large turbines, and piezoelectric fronds, literally every surface on a building could be turned into a micro-generator.

Powered by the wind indeed! And in the meantime, check out this video from WinMEMS, showcasing one of the micro-windmills in action:


Source: news.cnet.com, gizmag.com

News From Space: 200 km Water Jets on Europa

europa-landerAs the prime candidate for extra-terrestrial life, the Jovian moon of Europa has been the subject of much speculation and interest over years. And while our understanding of the surface has improved – thanks to observations made by several space probes and the Hubble space telescope – what lies beneath remains a mystery. Luckily, Europa may yet provide Earth scientists with a chance to look at its interior.

Earlier this month, data collected from the Hubble space telescope suggested that enormous jets of water more than 200 kilometers tall may be spurting intermittently from the moon’s surface. The findings, presented last week to the American Geophysical Union, await independent confirmation. But if the jets are real, the frozen world would join the tiny number of others known to have active jets, including Saturn’s moon Enceladus and Neptune’s moon Triton.

europa-lander-2What’s more, should these newly observed water plumes be tapping into some Europan sea, they could be bringing material to the surface that would otherwise stay hidden. Follow-up observations from Earth or with probes around Europa could sample the fountains, hunting for organic material and perhaps finding the evidence need to prove that living organisms exist beyond Earth.

Scientists spotted the plumes thanks to ultraviolet images taken by Hubble in December 2012. The research team, which hails from the Southwest Research Institute in Texas, then published their research in Science magazine. In the paper, astronomer and co-author Lorenz Roth explained their findings:

We found that there’s one blob of emission at Europa’s south pole. It was always there over the 7 hours we observed and always at the same location.

Previous observations from NASA’s Galileo mission, which visited the Jupiter system in the 1990s and early 2000s, suggest that Europa’s south pole is full of ridges and cracks quite similar to features called tiger stripes on Enceladus that spew water.

europa_chaosterrainLorenz and his team looked back through previous Hubble data to see if the plumes could have been spotted earlier but saw nothing, suggesting that they are likely transient. At the time, Europa was at its farthest from Jupiter, which could explain why the jets appeared only then. Researchers recently determined that Enceladus’ plumes are weakest when the moon is closest to Saturn, likely because the ringed planet’s gravity squeezes the tiger stripes shut.

Astronomer Kurt Retherford, also of SwRI and another co-author, claimed that the case of Enceladus helped them to make a connection with what they were observing:

We actually saw this press release on Enceladus. And we thought, ‘Oh my god! This is the explanation’” for why Europa’s plumes might only appear when it’s far from Jupiter.

In the past, scientists have looked for evidence of jets coming from Europa’s surface. When the Voyager probes flew by in the 70s, one image showed a fuzzy spot that some thought to be a plume, though most considered it an artifact of imaging. Galileo also saw a row of dark spots on a ridge of Europa which looked similar to spots seen on planet Earth before an eruption begins.

europaBecause of these previous false positives though, scientists are likely to be cautious when interpreting these newest results. But even with these reservations, Robert Pappalardo – who leads the planning team for the Europa Clipper Pre-Project (a proposed mission to Europa) – said that he’s already discussing with other scientists how these new results should affect their study priorities.

For instance, some future orbiter headed to Europa could carry detectors specifically designed to search for heavy organic molecules that could be indicative of life in the subsurface. When it passed over the geyser’s spray, it would be bathed in material from the moon’s interior, giving scientists a window into Europa’s ocean. Pappalardo also hopes that the finding will help push Europa to a place of high priority in NASA’s exploration agenda.

Due to budget constraints, a manned mission is not yet feasible, but NASA has indicated that it would be willing to send a robot lander there in the near future. In addition, recent computer models provided from the University of Texas showed that the ice is likely to be thinnest at the equator. Between the possibility that the oceans might be most accessible in this region, and the likelihood that some of that water escapes into space, unlocking the mysteries of the Jovian satellite might be easier than previously thought.

europa_gieserSources: wired.com, science.jpl.nasa.gov

News from Space: The Search for Life on Europa

europa-landerJupiter’s moon of Europa is one of the best and most intriguing candidates for extra-terrestrial life in our Solar System. For many decades, scientists have known that beneath its icy outer-shell, a warm, liquid ocean resides. Due largely to interaction with Jupiter’s strong magnetic field – which causes heat-generating tidal forces in Europa’s interior – these warm waters may host life.

And now, new models suggest that its ice-covered waters are turbulent near the lower latitudes. This is what gives rise to its chaotic equatorial landscapes, but intriguingly, may also make it easier for life to make it to the surface. This contradicts previously held beliefs that Europa’s life was contained beneath it’s outer shell, and will mean that any missions mounted to Europa may have an easier time spotting it.

europa_chaosterrainThanks to ongoing observation of the planet’s surface – especially the Galileo and New Horizons space probes which provided comprehensive and detailed images – it has been known that Europa’s surface features are not consistent. The landscape is marked by features of disrupted ice known as chaos terrains, geological features that are characterized by huge chunks of ice that have broken away and then re-froze into chaotic patterns.

These models were produced by University of Texas geophysicist Krista Soderlund and her colleagues. Based on computer simulations, Soderlund and her colleagues have theorized that turbulent global ocean currents move Europa’s internal heat to the surface most efficiently in regions closest to the moon’s equator. This is likely causing the melting and upwelling at the surface, and why regions further north and south appear to be smoother.

europa_modelIn addition, the models indicate that given Europa’s spin, heat flow, and other factors, it likely percolates upward at about 1m per second or so — which is remarkably fast. This would explain why the equatorial regions appear to be so fragmented. But it also means that these areas are also likely yo be relatively fragile and soft, which means that upward currents could bring nutrients and even living organisms to the surface.

Hence why any potential search for signs of life on this moon would now appear to be considerably easier. If missions are indeed mounted to Europa in the not-too-distant future, either involving probes or manned missions (most likely in that order), their best bet for finding life would be to land at the equator. Then, with some drilling, they could obtain core samples that would determine whether or not life-sustaining nutrients and organic particles exist beneath the ice.

Hopefully, these missions won’t run afoul of any life that doesn’t take too well to their presence. We don’t want a re-enactment of Europa Report on our hands now do we?

Source: IO9.com