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Cosmic dust sheds light on Earth's past climate EARTH INSTITUTE NEWS RELEASE Posted: August 3, 2006 Each year nearly 40,000 tons of cosmic dust fall to Earth from outer space. Now, the first successful chronological study of extraterrestrial dust in Antarctic ice has shown that this amount has remained largely constant over the past 30,000 years, a finding that could help refine efforts to understand the timing and effects of changes in the Earth's past climate. The same study also used an improved analytical technique to show that dust carried to Antarctica from continental sources changed depending on climate. The study, which appears in the July 28 issue of the journal Science, involved researchers from the Lamont-Doherty Earth Observatory, a part of The Earth Institute at Columbia University, and the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany. The depth of the core they examined corresponded to the period between 6,800 and 29,000 years before the present day--a span that includes the height of the last glacial period, and the transition to warm conditions similar to today. The scientists collected particulate matter from the EPICA (European Project for Ice Coring in Antarctica) ice core and measured the concentration of helium-3 (3He), a rare isotope that is plentiful in the sun's solar wind and is carried to Earth imbedded in cosmic dust particles measuring just a few thousandths of a millimeter in diameter. These dust particles carry their exotic helium load to the Earth's surface where they are preserved in the snow and ice of the polar ice caps, among other places. Because ice cores from the polar caps provide a high-resolution temporal record of the past, the researchers were able to measure fine variations in the rate of cosmic dust accumulation between glacial and interglacial periods as well as the helium isotope characteristics of these rare particles. They found that the accumulation of cosmic dust did not change appreciably as the Earth emerged from the last great Ice Age and entered the current warm period, a fact that is likely to bolster the use of cosmic dust measuring techniques in future climate studies. In addition, this was the first study to examine both cosmic and terrestrial dust using the same helium-isotope technique. As a result, they also found that the composition of mineral dust particles carried by wind from the southern continents to Antarctica changed considerably as the Earth's climate changed. "The terrestrial dust coming down on Antarctica during the Ice Age obviously is not the same as that during warm periods," said Gisela Winckler, a Doherty associate research scientist at Lamont-Doherty and lead author on the study. "This may be due to the mineral dust originating from different regional sources or to changes in the process responsible for producing the dust." The project was supported by the Comer Science and Education Foundation. The Earth Institute at Columbia University is the world's leading academic center for the integrated study of the Earth, its environment and society. The Earth Institute builds upon excellence in the core disciplines--earth sciences, biological sciences, engineering sciences, social sciences and health sciences--and stresses cross-disciplinary approaches to complex problems. Through research, training and global partnerships, The Earth Institute mobilizes science and technology to advance sustainable development, while placing special emphasis on the needs of the world's poor. The Lamont-Doherty Earth Observatory, a member of The Earth Institute at Columbia University, is one of the world's leading research centers seeking fundamental knowledge about the origin, evolution and future of the natural world. More than 300 research scientists study the planet from its deepest interior to the outer reaches of its atmosphere, on every continent and in every ocean. From global climate change to earthquakes, volcanoes, nonrenewable resources, environmental hazards and beyond, Observatory scientists provide a rational basis for the difficult choices facing humankind in the planet's stewardship. |
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Space shuttle Atlantis is delivered to Kennedy Space Center's launch pad 39B on August 2 to begin final preparations for blastoff on the STS-115 mission to resume construction of the International Space Station.
Just after 1 a.m. local time August 2, the crawler-transporter began the slow move out of the Vehicle Assembly Building carrying space shuttle Atlantis toward the launch pad.
Astronauts Jeff Williams and Thomas Reiter will conduct a U.S.-based spacewalk outside the International Space Station on August 3. To preview the EVA and the tasks to be accomplished during the excursion, station managers held this press conference from Johnson Space Center in Houston.
The long voyage of exploration to Jupiter and its many moons by the Galileo spacecraft began on October 18, 1989 with launch from Kennedy Space Center aboard the space shuttle Atlantis. The crew of mission STS-34 tell the story of their flight to dispatch the probe -- fitted with an Inertial Upper Stage rocket motor -- during this post-flight presentation film.
Space shuttle Atlantis is transported to the cavernous Vehicle Assembly Building where the ship will be mated to the external fuel tank and twin solid rocket boosters for a late-August liftoff.
A camera was mounted in the front of space shuttle Discovery's flight deck looking back at the astronauts during launch. This video shows the final minutes of the countdown and the ride to space with the live launch audio included. The movie shows what it would be like to launch on the shuttle with the STS-121 crew.
A high-altitude WB-57 aircraft flying north of Discovery's launch trajectory captures this incredible aerial footage of the space shuttle's ascent from liftoff through solid rocket booster separation.
This is the full launch experience! The movie begins with the final readiness polls of the launch team. Countdown clocks then resume ticking from the T-minus 9 minute mark, smoothly proceeding to ignition at 2:38 p.m. Discovery rockets into orbit, as seen by ground tracker and a video camera mounted on the external tank. About 9 minutes after liftoff, the engines shut down and the tank is jettisoned as the shuttle arrives in space.
MiTEx -- an experimental U.S. military project to test whether the advanced technologies embedded in two miniature satellites and a new upper stage kick motor can operate through the rigors of spaceflight -- is launched from Cape Canaveral aboard a Boeing Delta 2 rocket.