CWL

An illustration of the Chicxulub impact crater in the Yucatán Peninsula.

Located on the Yucatán Peninsula in Mexico, many scientists believe that the meteorite that left this crater caused or contributed to the extinction of the dinosaurs. Estimates of its actual diameter range from 106 to a whooping 186 miles (170 to 300 kilometers), which if proved right could mean it’s the biggest.

Gravity Map Reveals a Surprisingly Battered Lunar Surface

The moon and other rocky bodies in the inner solar system were pounded by long-ago impacts far more violently than previously thought, two NASA spacecraft have found.

NASA’s Gravity Recovery and Interior Laboratory (GRAIL) made this new high-resolution map of the moon’s gravity field. Credit: NASA/JPL-Caltech/MIT/GSFC

NASA’s twin Grail probes have created an ultra-precise gravity map of the moon, revealing that its crust is almost completely pulverized. The surprising find suggests that Earth, Mercury, Venus and Mars endured a similar beating billions of years ago, researchers said.

The discovery “really opens a window to this early stage of just what a violent place the surfaces of all terrestrial planets were early in their history,” Grail principal investigator Maria Zuber of MIT said during a press conference here today (Dec. 5) at the annual fall meeting of the American Geophyiscal Union.

jtotheizzoe:

What would happen if an meteor or asteroid the size of ______________, made of ______________, hit Earth at a speed of ______________? 

There’s a web app for that. Check out Purdue’s Impact: Earth!

Have fun destroying the planet!!! (And learning about asteroid impacts of various sizes and energies, of course)

Proof of Moon’s Birth in Giant Impact Found in Zinc: Study

Water on the moon boiled away in massive quantities in a cataclysmic evaporation event during the moon’s birth, bolstering the theory that a Mars-sized body collided with the Earth to form its only natural satellite, scientists say.

Image: This artist’s conception of a planetary smashup whose debris was spotted by NASA’s Spitzer Space Telescope three years ago gives an impression of the carnage that would have been wrecked when a similar impact created Earth’s Moon. A team at Washington University in St. Louis has uncovered evidence of this impact that scientists have been trying to find for more than 30 years. Image released Oct. 17, 2012. Credit: NASA/JPL-Caltech

Researchers examined rocks collected by astronauts during NASA’s Apollo lunar landing missions, as well as a meteorite that originated on the moon to make the find. They looked for traces of zinc, and found the ratios of heavy to light isotopes are greater than on Earth, which suggests the moon went through an intense evaporation event early in its formation.

The study is more evidence for the theory that the moon formed from a colossal impact, researchers said.

Early in the moon’s formation, the surface was hot enough to vaporize zinc – and a giant impact is one of the few things that would generate that much heat. Another prediction of the theory is that heavier isotopes would be more common, because they would condense at a higher temperature.

“What we found is that the depletion [of lighter isotopes] of Zinc is probably due to evaporation,” said study co-author Frédéric Moynier, assistant professor of Earth and planetary sciences at the Washington University in St. Louis.

source

On the Hunt for New Impact Craters

How exactly can we tell if an impact crater is new?

In this observation, we see a dark spot with a larger, rayed “blast zone” that was also apparent in a Context Camera image taken in 2011 (an instrument with a larger footprint than HiRISE and also on the Mars Reconnaissance Orbiter). However, a THEMIS image of the same area acquired in 2009 does not show the dark spot at all.

This is a great example of using three different instruments to view the same area not only to look for changes in the Martian landscape, but also to use the resolution of HiRISE to determine if this is indeed a new impact site.

Asteroid Crashes Likely Gave Earth Its Water

Illustration: Artist’s impression of a 6-mile-wide asteroid striking the Earth. Scientists think approximately 70 of these dinosaur killer-sized or larger asteroids hit Earth between 3.8 and 1.8 billion years ago. Credit: Don Davis

Asteroids from the inner solar system are the most likely source of the majority of Earth’s water, a new study suggests.

The results contradict prevailing theories, which hold that most of our planet’s water originated in the outer solar system and was delivered by comets or asteroids that coalesced beyond Jupiter’s orbit, then migrated inward.

“Our results provide important new constraints for the origin of volatiles in the inner solar system, including the Earth,” lead author Conel Alexander, of the Carnegie Institution of Washington, said in a statement. “And they have important implications for the current models of the formation and orbital evolution of the planets and smaller objects in our solar system.”

Full Article..

Oldest Impact Crater on Earth Discovered

The world’s oldest meteorite crater —a giant impact zone more than 62 miles wide — has been found in Greenland, scientists say.

Scientists think it was formed 3 billion years ago by a meteorite 19 miles (30 kilometer) wide — which, if it hit Earth today, would wipe out all higher life. The crater is so wide that it would reach the edge of space 62 miles (100 km) above Earth if stood on end.

The crater was “discovered” at an office in Copenhagen by scientist Adam Garde as he pored over maps showing nickel and platinum abundance in the target region of West Greenland. Garde, a senior research scientist with the Geological Survey of Denmark and Greenland, saw a both simple and extreme explanation for several strange geological features in this region: an impact from a meteorite that may have contained valuable metals.

Asteroids Battered Young Earth Longer Than Thought

A giant ancient barrage of asteroids striking Earth may have lasted much longer than previously thought, with some collisions perhaps even rivaling those that created the largest craters on the moon, researchers say.

Scientists think untold numbers of asteroids and comets pummeled Earth, the moon and the inner planets during an era known as the Late Heavy Bombardment about 4.1 billion to 3.8 billion years ago. Investigators continue to debate the precise nature of this epoch in terms of what happened and how long it lasted.

To learn more about the Late Heavy Bombardment, scientists would like to analyze the most obvious evidence cosmic impacts leave behind, their craters. However, while such craters are preserved well in the vacuum of the moon environment, they disappear quickly on Earth due to erosion and tectonic activity.

Instead, researchers analyzed other evidence of asteroid impacts — millimeter- to centimeter-thick layers of rock droplets known as spherules.

Asteroids Smacked Moon Stronger & Faster 4 Billion Years Ago

The moon, which has been pummeled by a barrage of asteroids and debris throughout its lifetime, experienced a strong uptick in the energy and speed of incoming rocks around 4 billion years ago, new research suggests.

A team of researchers from the NASA Lunar Science Institute (NLSI) at the Ames Research Center in Moffett Field, Calif., tracked the history of crater formation on the moon using digital maps, and found evidence of a dramatic shift in the velocity and energy of the asteroid bombardment during a period called the “lunar cataclysm” that occurred 4 billion years ago.

The timing of this shift could coincide with disturbances in the solar system’s main asteroid belt caused by changes in the movement of the outer planets, the researchers said.

Detailed maps of the lunar surface from the United States Geological Survey previously identified ancient regions on the moon to look for clues about the bombardment. The new study combined these observations with new data from NASA’s Lunar Reconnaissance Orbiter to study the impact craters found on these ancient surfaces.

Spherule From Earth’s Moon

Credit: Timothy Culler (UCB) et al., Apollo 11 Crew, NASA

How did this spherule come to be on the Moon? When a meteorite strikes the Moon, the energy of the impact melts some of the splattering rock, a fraction of which might cool into tiny glass beads.

Many of these glass beads were present in lunar soil samples returned to Earth by the Apollo missions. Pictured above is one such glass spherule that measures only a quarter of a millimeter across. This spherule is particularly interesting because it has been victim to an even smaller impact.

A miniature crater is visible on the upper left, surrounded by a fragmented area caused by the shockwaves of the small impact. By dating many of these impacts, astronomers can estimate the history of cratering on our Moon.

In 1984 NASA Dryden Flight Research Center and the Federal Aviation Administration (FAA) teamed-up in a unique flight experiment called the Controlled Impact Demonstration (CID), to test the impact of a Boeing 720 aircraft using standard fuel with an additive designed to supress fire. The additive FM-9, a high molecular-weight long chain polymer, when blended with Jet-A fuel had demonstrated the capability to inhibit ignition and flame propagation of the released fuel in simulated impact tests.

(NASA FAA)