24/7 Space News  





. South African Meteorite Makes Deep Impact On Space Rock Theory

Satellite photo of Morokweng (M) and Vredefort (V) meteorite craters in Northwest South Africa. Image courtesy of Morokweng Consortium.
by Staff Writers
Paris, May 10 (AFP) May 11, 2006
A remarkable meteorite the size of a beachball, found in heat-forged crystals in one of the world's largest impact craters, may push back the boundaries of knowledge about space rocks, a study due to be published on Thursday says.

The 25-centimetre (10-inch) fragment has been found in the Morokweng impact crater in northwest South Africa, where a massive object slammed into Earth around 145 million years ago.

The find is unique, for large asteroids or comets are believed to vaporise or melt completely within a few seconds after they hit the Earth, so enormous is the energy of their impact.

As a result, their composition is identified indirectly, by looking at chemical telltales left in the crater soil.

The Morokweng rock falls into the category of a "stony" meteorite. But it is chemically quite unlike other meteorites of this type, which are of a far more recent vintage. The South African rock is rich in iron silicates and iron-nickel sulphides yet poor in metal.

More work is needed to see if there could be other meteorites around the world that match this unusual signature, say the authors, led by Wolfgang Maier of the University of Quebec in Chicoutimi, Canada.

But the implication is that the composition of space rocks that have reached the Earth differs over the timescale of impact.

This, in turn, raises the question that there may be a bigger than suspected variety in the chemistry of rocks circling the Sun or perhaps some alteration to the rocks themselves that occurs during the aeons in orbit.

The study appears on Thursday in Nature, the weekly British science journal.

The Morokweng crater measures more than 70 kilometres (44 miles) across. It lay unidentified until 1996 because the distinctive crater ring had been worn away by the millions of years or lay hidden under sand.

The impact coincided with the end of the Jurassic era 145 million years ago, when there was a mass extinction among marine life and reptiles.

This has caused some scientists to draw a parallel with an impact that occurred in modern-day Mexico around 65 million years ago that is believed to have ended the long reign of the dinosaurs.

Impacts by very large asteroids or comets, according to this theory, can deliver so much energy that clouds of dust can be kicked into the atmosphere, cooling the heat from the Sun and killing off species of vegetation and the chain of animals that depend on them.

Meteorites are the remains of meteors -- rubble that collides with Earth and show up as streaks of light as they burn up through friction with atmosphere.

These remnants can be very big, but until now they have only been found in craters with a diameter of four kilometres (2.5 miles) or less. The smaller the rock, the less energy is released, which means there is less risk that the object will be consumed upon impact.

Source: Agence France-Presse

Related Links
Morokweng - Earth Impact Database




Tempur-Pedic Mattress Comparison

Newsletters :: SpaceDaily Express :: SpaceWar Express :: TerraDaily Express :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News


hello world
Deflecting Asteroids Difficult But Possible
Moscow, Russia (RIA) Apr 23, 2006
Col. Gen. Vladimir Popovkin, commander of the Russian Military Space Forces, told a news conference Friday that the national satellite network lacked a spacecraft capable of preventing an asteroid strike.

.
Get Our Free Newsletters Via Email
  



  • NASA Awards Boeing S-3B Viking Modification Contract
  • NASA Cannot Accommodate Indian Astronaut Aboard Shuttle
  • Aquanauts Learn About Teamwork And Task Performance For The Moon And Mars
  • UP Aerospace Offers Round-trip Payload Space Flights Directly to the Public

  • Spirit Takes A Winter Break From Travels But Remains Busy
  • Opportunity Within Sight Of Victoria
  • Mars Drilling Tests Will Seek Knowledge And Resources
  • Spirit Looks Back Up Husband Hill

  • Zenit Rocket Will Power AsiaSat 5 Launch
  • Defence Minister Expedites Preparations For Launching Military Satellite
  • Successful Launch Of Swedish Maxus 7 Sounding Rocket
  • Sea Launch Contracts To Launch Intelsat Americas-9

  • Tibet Provides Passage For Chemicals To Reach The Stratosphere
  • Raytheon Tests Advanced Space-Based Weather Sensor
  • African Wetland Managers Armed With New Technology
  • ESA To Host Atmospheric Science Conference

  • New Horizons Taking Exploration To Edge Of Sol
  • Xena Poses A Bright Mystery
  • Tenth Planet Only Slightly Bigger Than Pluto
  • New Horizons Payload Gets High Marks on Early Tests

  • Earth Deemed Safe From Gamma-Ray Bursts
  • XMM-Newton Reveals Chemical Signatures Of Galaxy Clusters
  • Astronomers Find Two New Milky Way Companions
  • ESO Detects Most Distant Hydrogen Cloud

  • China To Launch Satellites For Lunar Surveying
  • India Hoping To To Unveil Space Prowess Before NASA
  • Scientists Working To Help Astronauts To Breath Moon Dust
  • NASA Announces Lunar Lander Analog Competition Agreement

  • Iridium Will Supply Satellite Links For ARGO Tracker
  • Spirent Federal GPS Simulation System Selected by Naval Air Systems Command
  • Novariant And Wenco Deliver New Positioning Applications For Open Cut Mines
  • Magellan RoadMate First To Offer Traffic RDS Capabilities

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement