30
Apr 11

Swift and Hubble Probe Asteroid Collision Debris

Source: NASA News


Hubble Space Telescope image of (596) Scheila.
Image credits: NASA/ESA/D. Jewitt (UCLA).

Late last year, astronomers noticed an asteroid named Scheila had unexpectedly brightened, and it was sporting short-lived plumes. Data from NASA's Swift satellite and Hubble Space Telescope showed these changes likely occurred after Scheila was struck by a much smaller asteroid.

"Collisions between asteroids create rock fragments, from fine dust to huge boulders, that impact planets and their moons," said Dennis Bodewits, an astronomer at the University of Maryland in College Park and lead author of the Swift study. "Yet this is the first time we've been able to catch one just weeks after the smash-up, long before the evidence fades away."

Asteroids are rocky fragments thought to be debris from the formation and evolution of the solar system approximately 4.6 billion years ago. Millions of them orbit the sun between Mars and Jupiter in the main asteroid belt. Scheila is approximately 70 miles across and orbits the sun every five years. (read more)

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7
Apr 11

Dawn approaches asteroid Vesta

Source: NASA Science

NASA's Dawn spacecraft has entered the asteroid belt and it is closing in on giant asteroid Vesta. (read more)

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2
Feb 11

NASA's NEOWISE Completes Scan for Asteroids and Comets

Source: NASA/WISE


20 Comets discovered by the NEOWISE portion of the WISE mission.
Image Credit: Image credit: NASA/JPL-Caltech/UCLA

NASA's NEOWISE mission has completed its survey of small bodies, asteroids and comets, in our solar system. The mission's discoveries of previously unknown objects include 20 comets, more than 33,000 asteroids in the main belt between Mars and Jupiter, and 134 near-Earth objects (NEOs). The NEOs are asteroids and comets with orbits that come within 28 million miles of Earth's path around the Sun.(read more)

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30
Dec 10

Asteroid Itokawa Sample Return

Source: Science@NASA


Hayabusa photographs its own shadow on asteroid Itokawa in 2005.
Image credit: ISAS, JAXA

The Japanese Aerospace Exploration Agency's Hayabusa spacecraft returned to Earth with tiny pieces of asteroid Itokawa. In today's article from Science@NASA, a NASA specialist on the Hayabusa science team describes the nail-biting sample return and hints at new results from the ongoing analysis. (read more)

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17
Dec 10

NASA Discovers Asteroid Delivered Assortment of Meteorites

Source: NASA


Image credit: Andreus / Dreamstime.com.

An international team of scientists studying remnants of an asteroid that crashed into the Nubian Desert in October 2008 discovered it contained at least 10 different types of meteorites. Some of them contained chemicals that form the building blocks of life on Earth, and those chemicals were spread through all parts of the asteroid by collisions.

Chemists at Stanford University found that different meteorite types share the same distinct fingerprint of polycyclic aromatic hydrocarbons (PAHs). These complex organic molecules are distributed throughout the galaxy and form on Earth from incomplete combustion.

A research team from NASA's Goddard Space Flight Center in Greenbelt, Md., found amino acids in strongly heated fragments of the asteroid, where all such molecules should have been destroyed. Both PAHs and amino acids are considered building blocks of life.

Before landing on Earth, the 13-foot asteroid was detected by a telescope from the NASA-sponsored Catalina Sky Survey based at the University of Arizona in Tucson. Hours prior to its demise, astronomers and scientists around the world tracked and scanned the asteroid. It was the first time a celestial object was observed prior to entering Earth's atmosphere.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., created a search grid and impact target area. The data helped Peter Jenniskens, an astronomer at NASA's Ames Research Center in Moffett Field, Calif., and the SETI Institute of Mountain View, Calif., guide a recovery team from the University of Khartoum in Sudan to search the desert landscape. During four expeditions, approximately 150 students recovered nearly 600 meteorite fragments weighing a total of more than 23 pounds.

"Right from the start, the students were surprised to find so much diversity in meteorite texture and hue," said Muawia Shaddad, an astronomer at the University of Khartoum, who led the search effort. "We estimate the asteroid initially weighed about 59 tons, of which about 86 pounds survived the explosion high in the atmosphere."

Subsequently, scientists determined most of the fragments are a rare type of meteorite called ureilites. Less than 10 of the nearly 1,000 known meteorites are ureilites. The recovery team made history when they found the first-ever freshly fallen mixed-composition, or polymict ureilite. The majority of the remaining fragments are similar to the more common types of meteorites called chondrites.

Other Ames researchers showed the ureilite fragments contained widely varying amounts of the minerals called olivine and pyroxene. Carnegie Institute of Washington researchers found these minerals have the full range of oxygen atom signatures detected in previous ureilites. Scientists believe this is evidence all ureilites originated from the same source, called the ureilite parent body. Astronomers theorize the parent body experienced a giant collision approximately 4.5 billion years ago and caused iron-rich minerals to smelt into metallic iron. However, the olivine and pyroxene didn't melt, which allowed the oxygen atoms in them to stay in the same arrangement as when they first formed.

Researchers at NASA's Johnson Space Center in Houston were able to deduce that much of the ureilite parent body was reduced to fragments measuring 30 to 300 feet during this giant collision. After the catastrophic collision, scientists believe the material that ended up making 2008 TC3 had a long history of violent collisions and impacts. These later collisions ground the fragments down into the smaller sand grain-sized pieces that gathered loosely together with many voids.

Researchers believe the amino acids were delivered to 2008 TC3 during the later impacts, or formed directly from trapped gases as the asteroid cooled following the giant collision. Other non-ureilite types of meteorites also became part of the asteroid. To date, ten different meteorite types have been identified, accounting for 20-30 percent of the asteroid's recovered remains.

"Asteroids have just become a lot more interesting," Jenniskens said. "We were surprised to find that not all of the meteorites we recovered were the same, even though we are certain they came from the same asteroid."

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28
Apr 10

Asteroid Ice May Be 'Living Fossil' With Clues to Oceans' Origins

Source:University of Central Florida


An artist conception of asteroid 24 Themis.
Credit: G. Pérez (Instituto de Astrofisica de Canarias, Spain)

The first-ever discovery of ice and organic molecules on an asteroid may hold clues to the origins of Earth’s oceans and life 4 billion years ago.

University of Central Florida researchers detected a thin layer of water ice and organic molecules on the surface of 24 Themis, the largest in a family of asteroids orbiting between Mars and Jupiter.

Their unexpected findings will be published Thursday, April 29 in Nature, which will feature two complementary articles by the UCF-led team and by another team of planetary scientists.

“What we’ve found suggests that an asteroid like this one may have hit Earth and brought our planet its water,” said UCF Physics Professor Humberto Campins, the study’s lead author.

Some theories suggest asteroids brought water to Earth after the planet formed dry. Scientists say the salts and water that have been found in some meteorites support this view.

Using NASA’s Infrared Telescope Facility in Hawaii, Campins and his team of researchers measured the intensity of the reflected sunlight as 24 Themis rotated. Differences in intensity at different wavelengths helped researchers determine the makeup of the asteroid’s surface.

Researchers were surprised to find ice and carbon-based compounds evenly distributed on 24 Themis. More specifically, the discovery of ice is unexpected because surface ice should be short lived on asteroids, which are expected to be too warm for ice to survive for long.

The distance between this asteroid and the sun is about three times greater than between Earth and the sun.

Researchers will continue testing various hypotheses to explain the presence of ice. Perhaps most promising is the possibility that 24 Themis might have preserved the ice in its subsoil, just below the surface, as a kind of “living fossil” or remnant of an early solar system that was generally considered to have disappeared long ago.

Campins’ team is made up of scientists from UCF, the University of La Laguna in Spain, University of Southern Maine, University of Maryland, Universidade Federal Do Rio De Janeiro in Brazil, NASA-Ames Research Center and NAIC-Arecibo Observatory in Puerto Rico.

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2
Feb 10

Hubble Sees Suspected Asteroid Collision

Source: NASA


NASA's Hubble Space Telescope has observed a mysterious X-shaped debris pattern and trailing streamers of dust that suggest a head-on collision between two asteroids. Astronomers have long thought that the asteroid belt is being ground down through collisions, but such a smashup has never been seen before.(read more)

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25
Jan 10

WISE discovers its first asteroid

Source: NASA/JPL


The red dot at the center of this image is the first near-Earth asteroid
discovered by NASA's Wide-Field Infrared Survey Explorer, or WISE.
Credit: NASA/JPL-Caltech/UCLA.

NASA's Wide-field Infrared Survey Explorer, or WISE, has spotted its first never-before-seen near-Earth asteroid, the first of hundreds it is expected to find during its mission to map the whole sky in infrared light.

The near-Earth object, designated 2010 AB78, was discovered by WISE Jan. 12. After the mission's sophisticated software picked out the moving object against a background of stationary stars, researchers followed up and confirmed the discovery with the University of Hawaii's 2.2-meter (88-inch) visible-light telescope near the summit of Mauna Kea. (read more)

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20
Jan 10

Comet might result of a collision between asteroids

Source: Skymania

Astronomers are watching what they believe is a remarkable collision between two asteroids deep in space. If they are right, it is the first time a high-speed crash has ever been witnessed between massive space rocks.

The cosmic hit-and-run is happening 250 million miles away in a band of debris lying between planets Mars and Jupiter - the main asteroid belt.

An automatic sky camera called LINEAR in New Mexico snapped a newly discovered object there that looks fuzzy with a tail like a comet rather than a dot of light like a normal asteroid. It has been labelled P/2010 A2.(read more)

Related Links:
Skymania
Sky and Telescope
Universe Today
Discovery News

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14
Jan 10

Asteroid 2010 AL30 passes close to Earth

Source: Space Weather

Is it an asteroid or a derelict spacecraft? Mystery object 2010 AL30 is flew past Earth last night only 1/3rd the distance to the Moon, and telescopes around the world were watching.


2010 AL30 is the faint object that comes down to the right.
This image was made in Colombia, using a 14-inch Meade LX200.
Credit: Alberto Quijano Vodniza (Amateur Astronomer)

Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time.

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