- Huge CCD Could Give Real-Time View of Dark Energy Hunt
- 70 Years of Telescopes Tuned to Cosmic Radio
- 1889 Pennsylvania Flood Was as Big as Mississippi River
Posted: 22 Oct 2009 09:22 AM PDT
The world's largest sky-survey telescope may deliver its 3,200-megapixel images of the universe to the public in near–real time.
The Large Synoptic Survey Telescope, scheduled to capture its first light at the end of 2014, might be able to incorporate real-time image processing that would deliver the project's photos to the web in minutes, not months.
It's a daunting computational task that even the researchers themselves aren't sure can be accomplished.
"We're really studying the problem and trying to understand how well these systems have to work to make it possible to put the images out in real time," Wayne State physicist David Cinabro told Symmetry magazine.
Current telescopes tend to do processing over time, painstakingly trying to produce the most accurate images of space possible. Often, they undergo transformations to eliminate problems with their cameras themselves, or random noise.
The LSST, though, may be able to calibrate its images in real time, thanks to a lot of processing power. Moore's Law, a computing rule of thumb, holds that computing power basically increases logarithmically. The amount of pixels that cameras have has been increasing at roughly the same rate, said Tony Tyson, an astronomer at the University of California, Davis, who built the first CCD camera for scientific applications in the late 1970s.
"Moore's Law drives the number of pixels per unit area. It also drives the computing capability — and you've got to have both to get somewhere," Tyson said. "You get all this data from an imager but you need to process it. And Moore's Law solves both problems. Or it creates the problem but solves it, too."
The LSST is a hotly anticipated telescope that could provide some answers to niggling little astrophysics questions such as, "What is this dark energy that composes 72 percent of the universe?" To do so, it will image the entire night sky every three days, generating huge maps of the mass distribution of the universe.
Enormous amounts of data will be produced by its massive 3,200-megapixel camera — and the team plans to share its real-time data with curious onlookers, not just scientists.
"Anyone with a computer will be able to fly through the universe, zooming past objects a hundred million times fainter than can be observed with the unaided eye," the telescope's website promises. "The LSST project will provide analysis tools to enable both students and the public to participate in the process of scientific discovery."
Posted: 21 Oct 2009 05:35 PM PDT
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Radio astronomy began with static. Bell Laboratories wanted to get rid of it and went looking for its causes. With a hand-built radio telescope, Karl Jansky discovered a clear signal of something else amidst the noise from thunderstorms near and far: a steady static that appeared to emanate from the center of the Milky Way.
The field of studying radio waves arriving at Earth from outer space was born. Jansky didn't know what could be causing the radio waves, and Bell Labs pulled him off the project soon after his big discovery. Still, he's considered the father of radio astronomy.
This gallery illustrates the progression of radio telescopes from Jansky's primitive 'scope to the huge arrays of antennas now installed in the world's deserts and perhaps, one day, on the moon.
Image: National Radio Astronomy Observatory
Posted: 21 Oct 2009 03:11 PM PDT
PORTLAND, Ore. — The devastating flow released when a dam burst upstream of Johnstown, Pa., in May 1889 transformed a small, normally tranquil river into a raging torrent that briefly rivaled the mighty Mississippi, a new study reveals.
Johnstown, which lies about 100 kilometers east of Pittsburgh, was a thriving coal- and iron-producing town in the years following the Civil War, says Carrie Davis Todd, a hydrologist at the University of Pittsburgh at Johnstown. Then, on the rainy afternoon of May 31, 1889, disaster struck: A dam about 23 kilometers upstream of the town burst, sending a wall of debris-filled water down the narrow valley of the Little Conemaugh River to ravage the town. More than 2,200 people died in the disaster — a death toll aggravated by the fact that even before the dam burst, flood waters filling the streets of Johnstown had trapped many residents in their homes, she reported here October 19 at the annual meeting of the Geological Society of America.
Despite the event's massive death toll, few detailed studies of the flood have been done, says Dan Ingram, curator at the Johnstown Area Heritage Association. "There's a ton of anecdotal information, but few people have ever looked at it in a scientific way," he notes.
Enter Davis Todd and her colleagues, who recently embarked on a project to analyze the Johnstown Flood. Using modern-day surveys of the area around the dam as well as archival photos, the researchers estimate that the 1.6-square-kilometer reservoir behind the dam held about 15 million cubic meters of water. The pressure of those accumulated waters, as well as erosion that occurred as water spilled over the top of the dam, triggered a sudden and catastrophic failure, says Davis Todd. Peak discharge through the 90-meter-wide, 13-meter-high breach in the dam exceeded 8,500 cubic meters per second — about three times the flow rate across Niagara Falls.
As devastating as that torrent would have been, the flow rate that slammed into Johnstown was even higher, the researchers estimate. Large amounts of rocks, trees and other debris swept along by the initial surge of floodwaters were temporarily trapped against a narrow bridge about four kilometers downstream of the dam. The deluge released by the dam's collapse carried more than 12,000 cubic meters of debris-filled water each second. Flow rates in the Mississippi River typically vary between 7,000 and 20,000 cubic meters per second, says Davis Todd.
Eyewitnesses in Johnstown said the mid-afternoon flood arrived as "a wall of black mist," says Ingram. That initial surge was quickly followed by a 10-meter-deep torrent chock-full of earth, trees, debris from hundreds of buildings and even the locomotives of trains swept off the rails running along the river's banks.
The new findings will help Ingram and his colleagues better explain the devastating force of the flood, as well as how the disaster unfolded. "This is one of those events that everyone's heard of but nobody knows the story behind," he notes.
Images: 1) Andrews, E. Benjamin. History of the United States, volume V. Charles Scribner's Sons, New York. 1912. 2) Johnstown Area Heritage Association.
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