Subscribe free to our newsletters via your
. 24/7 Space News .

Meteorite experiment deals blow to 'bugs from space' theory
by Staff Writers
Paris (AFP) Sept 25, 2008

A novel experiment has dealt a setback to a theory that life on Earth was kickstarted by bacteria that hitched a ride on space rocks.

The "pan-spermia" hypothesis is that cells were transported to the infant Earth on rocks that were bumped off other planets or even came from another star system.

The theory gained a boost in 1996 when a group of US scientists proposed that a famous meteorite found in Antarctica may have held traces of fossilised bacteria that once lived on Mars.

Seeking to find out more, European scientists have devised "artificial meteorites" to see what happens when rocks bearing fossil traces and living bacteria are exposed to the fiery heat of entering Earth's atmosophere.

In research to be unveiled on Thursday, they attached small rocks two centimetres (0.8 of an inch) thick to a Russian unmanned Foton M3 capsule that was launched in September 2007 and returned to Earth 12 days later.

The samples were imbedded on the capsule's heat shield, which reached a peak velocity of 7.6 kilometres (4.75 miles) per second (17,000 miles, or 27,200 kms, per hour) during the controlled descent.

One sample comprised a 3.5-billion-year piece of sedimentary rock from Pilbara, Australia, that contained carbonaceous microfossils.

The other was a piece of lake sedimentary rock from the Orkney Islands, Scotland, containing chemical traces of past organisms.

The back of both rocks was smeared with a living bacterium called Chroococcidiopsis -- a hardy, primitive species that lives on the underside of stones in the desert, surviving on tiny droplets of moisture.

Some scientists have considered it, or a relative of it, to be a good candidate for a Martian germ.

Recovered and analysed after the return, the Pilbara sample was found to be covered with a creamy-white fusion crust about half a millimetre (0.02 of an inch) thick but, underneath, its microfossils were intact.

The Orkney samples lost nearly a third of its mass, but otherwise survived, as did its biomolecules.

But there was bad news for the Chroococcidiopsis. The bugs were burnt to a crisp, although their carbonised outline remained intact.

"The STONE-6 experiment suggests that, if Martian sedimentary meteorites carry traces of past life, these traces could be safely transported to Earth," said investigator Frances Westall, of the Centre of Molecular Biophysics in Orleans, France.

"However, the results are more problematic when applied to pan-spermia," she said a press release.

"STONE-6 showed at least two centimetres (0.8 of an inch) of rock is not sufficient to protect the organisms during [atmospheric] entry."

The study was scheduled to be presented on Thursday at the European Planetary Science Congress in Muenster, western Germany.

So far 39 meteorites have been found on Earth that have been attributed, through their chemical signature, to a Martian origin.

The notion is that they were knocked off the planet in the distant past by an asteroid impact. They then wandered in space before landing here.

But all of these meteorites are of basalt, or volcanic origin.

None is sedimentary, a term for rocks that are laid down in beds or strata as a result of wind, water or gravity. This has perplexed scientists, as there is abundant evidence for sediments on the Red Planet.

The outcome of the STONE-6 experiment, though, shows that Martian sedimentary rocks could survive entry through Earth's atmosphere.

The Foton capsule generated temperatures of around 1,700 degrees Celsius (927 degrees Fahrenheit), although its speed was somewhat slower than that of a meteorite.

Meteorites normally attain a velocity of 12-15 kms per second (26,800-33,500 mph, 42,800-53,600 kph) depending on their angle of descent.

A third piece of rock, a control sample of basalt, was lost during the descent.


Related Links
Life Beyond Earth
Lands Beyond Beyond - extra solar planets - news and science

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

Drilling Down To Alien Oceans
Moffett Field CA (SPX) Aug 29, 2008
Some of the most interesting places in our solar system are also the most difficult to reach. Areas hidden under thick layers of ice such as the polar caps of Mars, Saturn's moon Enceladus and Jupiter's moon Europa are prime examples. Drilling through ice on Earth is complicated enough, but on another world the task becomes almost impossible. ... read more

Diving For The Moon

Science By The Light Of The Moon

Chang'e-1 Sends Back Verbal Wishes

Russian Water Detector To Ride Piggyback On U.S. Lunar Orbiter

Spirit's Warming Up On Mars

Rock Moved By Phoenix Lander Arm

Growing Library Of Mars Spectrometer Images

Mars Polar Cap Mystery Solved

Commercial space ventures ready for lift-off

NASA at 50: still taking science to the limit

Reaching for the stars: a space travel timeline

Facts about NASA, the world's biggest space agency

China Astronauts Return From Historic Spacewalk Mission

Penpix of Chinese astronauts to blast off on historic mission

In desert city, crowds keen to see China space mission

China's astronauts spend first day in orbit

Europe's "space truck" heads for Pacific breakup

Russia's Space Agency Confirms 18th ISS Expedition

The US Has No Option But To Use Russia's Soyuz Craft

Resupply spacecraft docks with International Space Station

Sea Launch Successfully Delivers Galaxy 19 To Orbit

Sea Launch Countdown Underway For The Galaxy 19 Mission

ArianeSpace Buys 10 Soyuz Rockets For Kourou Spaceport

Telesat Launches Nimiq 4 Broadcast Satellite

US astronomers discover inter-planetary collision

NASA's Kepler Spacecraft Baked And Ready For More Tests

TNO Star Separators Help ESO With Detection Of Exoplanets

First Picture Of Likely Planet Around Sun-Like Star

Oracle, HP unveil computer to cope with digital explosion

Microsoft courts Chinese consumers with slashed software price

Study Spotlights Anti-satellite And Space Debris Threats

LockMart Demos New Radiator Tech For TSAT Program

The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights 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 Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement