Guardian staff and agencies
guardian.co.uk, Wednesday 22 March 2000 11.26 EST
Weird gases from outer space arrived on Earth during a dinosaur-killing asteroid strike 65 million years ago, and survive in molecular cages called buckyballs, researchers reported on Tuesday.
Buckyballs probably drifted into the solar system early on, bringing carbon and other material from far away.
"Most of the carbon in our bodies came from outside the solar system," said Ted Bunch of Nasa’s Ames Research Centre in California. "We’re all aliens."
Buckyballs, lacy-looking molecules made up of carbon atoms, are also known as fullerenes and are named in honour of Buckminster Fuller because they are shaped like the geodesic dome he invented.
They can form on Earth but also are born outside our solar system, in hot areas of the universe such as the gas envelopes around embryonic stars. The buckyballs in question came in on the killer asteroid.
The gas-carrying buckyballs were found in various parts of the globe, from North America to New Zealand to Denmark, in a layer of sediment laid down after an ancient asteroid impact.
"The buckyballs containing the gases arrived on Earth about 65 million years ago during an asteroid impact that scientists theorise ended the age of the dinosaurs," said Bunch.
The impact of the big space rock may have killed the dinosaurs and most earthly life with its globe-girdling dust cloud, but the sturdy little buckyballs survived with their gaseous cargo intact, Bunch and his colleagues reported in the March 28 edition of the Proceedings of the National Academy of Sciences.
The article was available to subscribers on the Internet on Tuesday.
Inside the buckyballs was a strange type of cosmic helium, along with other gases, Bunch said in a telephone interview.
Helium created on Earth usually has four sub-atomic particles in its nucleus, while cosmic helium generally has only three, the scientists said.
“They’re enriched helium 3,” Bunch said. “We know by the helium signature that it was formed probably outside the solar system… they’ve trapped them inside (the buckyballs) at the site of formation.”
This weird helium shows, as no other evidence has, that buckyballs can transport extraterrestrial gases without letting them escape on the way. Future research may focus on other gases that might have come to Earth in this fashion.
This research also supports the theory that gases that make up Earth’s atmosphere and organic compounds came to Earth’s surface during the so-called age of bombardment, some 3.8 billion to 4.5 billion years ago, when “asteroids were running wild in their orbits,” as Bunch put it.
This was the period when the Moon’s craters were gouged out by asteroids, comets and meteors, which also slammed into Earth, Mars and other celestial bodies.