quarta-feira, 26 de dezembro de 2012

That meteorite which blew-up over California last April is one of the rarest ever found

This past April, a 100,000 pound (45,360 kg) meteorite exploded above the skies of Sutter's Mill, California. Streaking in at a speed of 64,000 miles per hour (103,000 km/hr or 28.6 km/s) — about twice the speed of typical meteorite falls — it hit with the energy of a quarter of a Hiroshima bomb, making it the biggest impact over land since a four meter-sized asteroid broke-up over Sudan four years ago. And now, after recovering and analyzing the ensuing meteorite fragments, scientists have realized that it's an incredibly ancient form of rock — one that may have brought compounds crucial for life to Earth.
After disintegrating over California in a 4-kiloton explosion, a team of scientists (including NASA researchers from Ames) scrambled to recover the fragments.

They managed to find a paltry 205 grams worth in the form of 77 pieces, but it was enough to conduct an analysis. They located the exact region where the fragments fell by using doppler weather radar — the first time this technique was used for such a purpose.

Based on photographs of the fireball, the object entered into Earth's atmosphere at an unusually low-inclined comet-like orbit that at one point reached the orbit of Mercury. Consequently, it passed closer to the sun than other recovered meteorites. But at the same time, it experienced an unusually short exposure to cosmic rays. The scientists suspect that it circled the sun three times during a single orbit of Jupiter, an important piece of insight into the object's point of origin.

The ensuing study, which was conducted by Peter Brown and colleagues at Western University and Peter Jenniskens of the SETI Institute, reveals that it was a rare carbonaceous chondrite meteorite — a so-called C-class asteroid that likely came from the Eulalia asteroid family. This is a very primitive class of asteroids that are very rarely discovered. Specifically, it's a regolith breccia that originated from near the surface of an ancient asteroid, possibly in the vicinity of Jupiter.

And importantly, the debris contained carbon. It's rocks like these, say the scientists, that contributed to the early organic chemistry on Earth — the same carbon atoms that can be found in biological matter.

Interestingly, NASA plans on sending astronauts to asteroids like these on future missions.

You can read the entire paper at Science.

Source: http://io9.com

segunda-feira, 17 de dezembro de 2012

Antarctic meteorite hunters

For more than 35 years, scientists from the Antarctic Search for Meteorites (ANSMET) program have been scouring glacial landscapes in search of meteorites. Since 1976, teams of physicists, meteorite specialists, and mountaineers have recovered thousands of untouched specimens from meteoroids, the moon and even Mars. Despite subzero temperatures and razor-sharp winds, scientists are lining up for the chance to experience the ultimate hunt for alien objects in the alien environment.

ANSMET teams either conduct systematic searches of a region or work as a scout teams making preliminary investigations of new sites that might be worth further exploration. Once discovered, the meteorites are carefully cataloged in the field and sent to the Smithsonian's National Museum of Natural History in Washington, D.C., where they are distributed to scientists for further research. What secrets will new specimens – locked away in the ice and yet to be discovered – hold about our solar system and the universe? Read the story online and find out at http://bit.ly/UtXc9R.

Read this story and more in the December issue of EARTH Magazine, available online now. Learn how mummification emerged from environmental change; discover the explosive combination of red giants and white dwarfs; and see what states are paying to dispose of low-level radioactive waste all in this month's issue of EARTH.

Keep up to date with the latest happenings in Earth, energy and environment news with EARTH magazine online at http://www.earthmagazine.org/. Published by the American Geosciences Institute, EARTH is your source for the science behind the headlines.

The American Geosciences Institute is a nonprofit federation of geoscientific and professional associations that represents more than 250,000 geologists, geophysicists and other earth scientists. Founded in 1948, AGI provides information services to geoscientists, serves as a voice of shared interests in the profession, plays a major role in strengthening geoscience education, and strives to increase public awareness of the vital role the geosciences play in society's use of resources, resiliency to natural hazards, and interaction with the environment.

Source: EARTH http://www.eurekalert.org

quarta-feira, 12 de dezembro de 2012

Meteorite ‘Tautetis’ to come closer to Earth today

Wednesday afternoon will be very special for astronomers when a large meteorite is predicted to pass closer to the earth. According to N Raghunandan Kumar, Director and secretary of Planetary Society of India, the asteroid, 4179 Tautetis, will pass very close from Earth at a distance of 69 lakh 31 thousand 175 kilometers from the blue planet.

Though, there is nothing to be scared of it. The meteorite will come closer to Earth on Wednesday afternoon. This meteorite is moving at a speed of 11.9 km per second. The meteorite comes from a region nearby Earth and it has its own orbit too. Given its large mass, it predicted that it could destroy some parts of the Earth.

The meteorite was discovered on January 4, 1989 and was named after tribal icon Tautetis. It is expected that it will come close to Earth again on December 16, 2016. Earlier it was viewed closer to the Earth on November 9, 2008. After December 16, 2016, it would not appear until 2069 in the vicinity of the Earth.

Source: http://post.jagran.com