Friday, January 28, 2011
NASA says private-sector spaceships will have to satisfy safety standards that the space shuttle can’t meet — and the companies building those spaceships say they'll rise to the challenge. January 28 was the 25th anniversary of the Challenger shuttle explosion and it has space enthusiasts focusing fresh attention on the issue of spaceflight safety -- with good reason.
The loss of the shuttle and its crew of seven, including educator-astronaut Christa McAuliffe, dramatically highlighted the risks associated with the world's most complex flying machine.
Those risks were brought home again with the catastrophic breakup of the shuttle Columbia in 2003. Once again, seven astronauts were lost, due to inherent problems with the space shuttle's design as well as lapses in NASA's "safety culture."
The Challenger and Columbia disasters led risk analysts to estimate that flying the space shuttle carried a roughly 1-in-100 chance that the crew and the spaceship would be lost during a given mission. In the wake of the Columbia tragedy, NASA and the White House decided to retire the shuttle fleet and move on to a simpler, safer launch system.
When NASA was working on plans for its own crew launch system to replace the shuttle and service the International Space Station, the agency set standards that lowered the chance of crew loss to 1-in-1,000.
"Neither the shuttle nor the Russian Soyuz could meet these standards," said John Logsdon, former director of the Space Policy Institute at George Washington University and a member of the NASA Advisory Council's Exploration Committee.
Over the past year, the White House and NASA decided to go with a different approach, with the space agency purchasing services from commercial spaceship ventures. NASA is paying out hundreds of millions of dollars for the development of cargo ships such as SpaceX's Dragon capsule, which passed its first flight test last month. If the spaceships work as advertised, commercial companies would be in line for billions of dollars worth of contracts.
NASA eventually hopes to use commercial craft to ferry astronauts back and forth to the space station as well.
Posted by Discovery Student Adventures at 4:29 PM
Wednesday, January 19, 2011
Fish can distinguish between larger and smaller quantities, with an additional ability to “count” up to three, according to research on tropical angelfish. Angelfish are regarded as being one of the world’s most intelligent fish, but scientists believe other fish species also possess the math-related skills outlined in a new Animal Cognition paper.
Doing something akin to counting up to three might sound underwhelming, but math itself is a very human-centric concept that may need reconsideration if comparisons are to be made with the abilities of non-human species.
“We all think we know what we mean by 'counting,' but do we really?” asked co-author Robert Gerlai. “Is recounting a series of 1 to 100 counting? Is 2+3=5 counting? Is calculating the square root of a number counting, or perhaps is the mathematics necessary for quantum physics counting?”
Gerlai and Luis Gomez-Laplaza of the University of Oviedo in Spain exploited the previously determined tendency of angelfish to seek protection in unfamiliar environments by joining the largest possible fish group, called a shoal. To rule out possible confounding effects arising from sexual interactions, the researchers only used juvenile angelfish for their experiments.
Test fish placed in special compartmentalized tanks were given a simultaneous choice between shoals containing different numbers of fish. The angelfish were always able to select the larger of two groups so long as the ratio between the shoals was 2:1 or above. Below that ratio, their choices were less predictable, suggesting a limit to their quantity estimation abilities.
After the findings were published, the researchers, according to Gerlai, “have already collected new data suggesting that angelfish can discriminate much more precisely than this. That is, angelfish can tell the difference between 3 and 2, for example.”
Posted by Discovery Student Adventures at 10:24 AM
Monday, January 17, 2011
Scientists have taken their first, vicarious journey to the center of the moon, thanks to a fresh look at 30-year-old moonquake data from the Apollo era. What the researchers found deep in the lunar interior: a solid iron ball 300 miles across, wrapped in molten iron another 56 miles thick, topped with a 93-mile layer of partially molten material.
The effort represents the first direct observation of the moon's core and the depths of its various layers, says Renee Weber, a lunar scientist at the Marshall Spaceflight Center in Huntsville, Ala., who headed a international team of scientists on the project.
The notion that the moon has an iron core with a layer of molten iron surrounding it isn't new. But evidence so far has been indirect.
The new look confirms that picture. But also appears to be breathing new life into data once thought to be poorly suited for detailed studies of the deepest portions of the lunar interior.
“I think there's a lot more that can be done with these data,” Dr. Weber says.
During the Apollo program, astronauts left four seismographs on the lunar surface. The instruments returned their last data to Earth in 1977, five years after the Apollo program ended.
The goal was to use seismic waves generated by moonquakes to probe the moon's structure, just as geologists on Earth use earthquakes to study Earth's interior structure and astrophysicists use acoustic waves from “star quakes” to study the interiors of stars.
But the heavy pummeling the moon has taken throughout its history has severely fractured the region between the crust and core, meaning that seismic waves were degraded, making them too difficult to interpret.
But new ways of analyzing less-than-ideal seismic data, developed for use on Earth, plus the rapid increase in computing power since the days of Apollo, prompted Weber and her collaborators to give the Apollo data a fresh look.
Posted by Discovery Student Adventures at 12:05 PM
Thursday, January 13, 2011
Arguably the most widely recognized structure in the world, the Eiffel Tower was designed to stand for only 20 years—and some predicted it would collapse long before then. Even as it was being built for the 1889 Universal Exhibition, a professor of mathematics sagely calculated that when the tower was two-thirds complete, its legs would buckle and the whole thing would come tumbling down, crushing workers and houses alike.
Today, the Eiffel Tower is not only standing but remains in rude health, testifying to the soundness of Gustave Eiffel's design and the strength of “puddle iron,” the hand-made wrought iron of the late 19th century, say engineers.
Specialists at the Technical Centre for Mechanical Industries have put together a high-powered computer model based on the 18,000 pieces that comprise the world's greatest iron edifice and the emblem of Paris.
On screen, the tower has been exposed to hurricane-force winds, lashing rain, extreme heat, cold and thick snow, and each time emerges unbowed, they say.
“We have applied the most demanding test standards currently set in Europe and have found that the tower is in excellent shape,” said Stephane Roussin, a former French naval officer in charge of structural safety at Eiffel Tower Operating Co. “We have even doubled its weight to see what happens. The tower moves but is not destroyed.”
Posted by Discovery Student Adventures at 3:35 PM
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