Wednesday, October 5, 2011
Tuesday, October 4, 2011
You Built What?! A Seven-Foot-High 3-D Printer That Uses the Sun to Transform Sand Into Glass Objects
Marcus Kayser's Solar Sinter project turns desert sand into glass bowls
On Balance To keep the giant lens from tipping the whole printer over, Kayser filled water bottles with sand and affixed them to the arms near the solar panels as counterweights Amos Field Reid
When design student Markus Kayser wanted to test his sun-powered, sand-fed 3-D printer, he knew the gray skies outside his London apartment wouldn’t do. So he shipped the 200-plus-pound contraption to Cairo, Egypt, flew there himself, and haggled with officials for two days to get it out of customs. A few small “tips” and 11 hours of driving later, he finally made it to the Sahara. But soon the mercury hit 104 degrees, his components nearly overheated, and he was forced to improvise.
The idea for the printer first came to Kayser a few months earlier. He wanted to find a project in which the sun did more than just power a device. He researched possibilities online, talked to physics professors, and learned about a process in which sand, heated to its melting point, cools into solid glass. With enough sun, a large lens and an ample supply of sand, he figured he might be able to produce glassware.
Solar Art: Markus Kayser’s homebuilt 3-D printer created this glass bowl out of heated sand from the Sahara Amos Field Reid
For the printer to work efficiently, the focal point of the lens would have to be trained right onto the surface of the sand. He knew the sun would move and the focal point would shift during the process, so he ordered a single 4.5-foot-wide lens and built a motorized frame for it. The central sandbox, in which the objects are printed, shifts in all directions, and the entire machine rotates around its center. Two aluminum arms, holding the lens at one end and solar panels at the other, can pivot from straight overhead down to a 45-degree angle to chase the sun. directed by a CAD design from a connected laptop, the printer uses the concentrated beam of sunlight to slowly trace an object into the sandbox layer by layer. The sun melts the sand, which cools into glass.
When the electronics began overheating, Kayser cut open a soup can, sliced and bent its sides into fan blades, attached the creation to a spinning DC motor, and aimed it right at the circuit board. The sun melted only the sand, and, after more than four hours, he printed a glass bowl, and later several sculptures. He admits they’re not perfect; he says he could have used more-complicated optics. But, he adds, perfection wasn’t the point: “This is about showing the potential."
How It Works
Time: 8 weeks
Cost: $3,500
Cost: $3,500
Focal Point: After all the layers are done, Kayser digs the object out of the sandbox Amos Field Reid
TRACKING
Kayser attached a cylindrical sun tracker to the frame perpendicular to the lens. When the sun is directly in line with the lens, it shines straight through an opening in the top of the cylinder. As the sun shifts, the light comes in at an angle, creating shadows within the cylinder. Sensors inside detect the shadows and feed the data on their position to Kayser’s computer, which directs the motorized frame to adjust to properly align the lens.
Control Panel: The printer’s motors, the electronics, cameras and a laptop all run on batteries charged by the solar panels Amos Field Reid
PRINTING
Kayser first designs the object he wants to print in a CAd program. His computer sends instructions to the printer, which works from the bottom up. After a layer has cooled into glass, he adds more sand to the sandbox in the center of the machine and flattens it out, and the printer begins heating the next layer. Kayser’s first major piece, a bowl, took about four and a half hours to print.
POWER
Two photovoltaic panels, one on either side of the machine, keep the printer powered. since the panels are attached to the same arms as the lens, they also benefit from the sun tracking, which ensures that they always get direct light.
Five Reasons You Should Care About the New Ozone Hole Over the Arctic
Some answers from an atmospheric scientist
Two Poles, Two Holes These top two maps show total ozone, and the bottom show ozone deficit. The Arctic is in the left column and the Antarctic on the right. Nature/Manney et al.
A prolonged chill in the atmosphere high above the Arctic last winter led to a mobile, morphing hole in the ozone layer, scientists report in a new paper. It’s just like the South Pole hole we all studied in school, but potentially more harmful to humans — more of us live at northern latitudes. Here are five things you need to know about it.
1: THIS IS A NEW PROBLEM
Most of the public probably knows about the infamous ozone hole over the South Pole, which became one of the great environmental recovery efforts of the 1980s. The Arctic loses some ozone every year, too, but not like this, said Gloria Manney, who works at NASA's Jet Propulsion Laboratory and the New Mexico Institute of Mining and Technology in Socorro.
“No previous year rivals 2011, when the evolution of Arctic ozone more closely followed that typical of the Antarctic,” Manney and colleagues write in the Oct. 2 online issue of Nature. For the first time, the Arctic loss was enough to be considered a hole.
Both holes are driven by chemical reactions involving chlorine. In cold air and sunlight, chlorine is converted into compounds that break down ozone (itself a harmful substance at the surface, but a protective one at stratospheric altitudes). Antarctica experiences an annual ozone hole as a result. The Arctic is cold, too, but usually not as cold as the Antarctic, and not for as long. But winter 2010-2011 was different. Scientists aren’t sure why.
“The processes that control temperatures in the stratosphere in the winter are so complex; it depends on various factors,” Manney said in an interview. “In December, we couldn’t have told you we were going to have this unusually long cold period.”
2: IT COULD HAPPEN AGAIN
Without ozone, more radiation would get through to interfere with our DNA, and that of other life forms on Earth.The planet’s climate is an extremely complex system, so it’s hard to say what will happen if global surface temperatures rise as expected. But it’s generally accepted that an increase in surface temperatures will translate to a chill in the upper atmosphere, Manney said. So as the Arctic loses more of its ice sheet in the summer, the air will get even colder up above, meaning more of the chlorine reactions will take place.
“If the stratosphere cools as a result of the changing climate, we might see severe ozone depletion more often in the future,” she said.
3: IT'S TOO LATE TO STOP
Humans have already emitted enough chemicals to seed the process. The Montreal Protocol, which took effect in 1989, prohibits production of chemicals involved in ozone destruction. But human activity belched out plenty of those chemicals before international governments ever started noticing, let alone signing treaties. There’s still enough in the atmosphere for this effect to persist for decades, Manney said.
4: PEOPLE NEED OZONE
The air over the Arctic is extremely mobile and turbulent, forming a vortex that covers the entire region. It’s a massive area, equivalent to maybe five Californias, and it churns and moves about the Arctic Circle. In April 2011, the vortex — and the hole — moved over northern Russia and Mongolia, Manney said. The climate-monitoring scientists didn’t notice it at the time, but ground-level ultraviolet radiation monitors started to spike.
The ozone layer’s main utility is in protecting Earth from the sun’s UV rays. Without ozone, more radiation would get through to interfere with our DNA, and that of other life forms on Earth. A mobile ozone hole in the northern latitudes thus poses a risk to lots of people.
5: WE NEED MORE DATA
International groups of scientists monitor the Arctic with a suite of Earth-observing satellites, balloons, ground stations and more. But some of their instruments, especially the satellites, are not designed to last for much longer. The instruments onboard NASA’s Aura spacecraft, whose trace gas and cloud measurements were key to this study, were designed to last about 5 years and they’re now about 7, Manney said.
And as we’ve seen before, it’s tough to get a polar-observing satellite approved.
“There aren’t immediate plans for other satellites that give us the same kind of comprehensive measurements. So it is a concern as to whether and how much capability we’ll have to monitor not just ozone, but the other chemicals that contribute to destroying ozone,” Manney said.
... AND NOW FOR SOME GOOD NEWS
Combating greenhouse gas emissions and reversing global warming will help — if surface temps don’t rise dramatically, the stratosphere may not cool dramatically, and the chemical reactions that cause ozone depletion may not occur over the Arctic. What's more, humans have already made some progress with the Montreal Protocol, Manney said.
“Having done that, we expect that we are now on a path to where eventually, in several decades, we will stop having enough chlorine to form ozone holes,” she said. “And things we might be able to do to mitigate climate change would also decrease our odds of seeing more severe future ozone loss.”
As a scientist, Manney wouldn’t speculate about other possible solutions — like geoengineering or cloud-seeding projects that would warm up the stratosphere and prevent more ozone depletion, which we'll just go ahead and throw out there. But she does believe with better data and better models, she and others will eventually be able to predict where and when it happens, leading to better warning systems for people on the ground.
“There is the possibility of saying, ‘We’ve had severe ozone loss this winter, and the ozone vortex is expected to be here [in Russia or elsewhere], so you guys should put your sunscreen on,'” she said.
Subscribe to:
Comments (Atom)