Debate Over Meteorite Continues
Oct. 09, 1997
ALBUQUERQUE, N.M. (AP) _ University of New Mexico scientist Adrian Brearley and his peers are debating whether a football-size meteorite fragment at UNM records the dawn of the solar system.
The violent formation of the sun and planets 4.5 billion years ago left only rudimentary clues on Earth about the conditions of those turbulent times.
But asteroids _ rocky material orbiting between Mars and Jupiter _ remain largely unaffected by time. Occasionally, one is knocked out of orbit and chunks collide with Earth.
The UNM specimen is among meteorites that fell near Pueblito de Allende in northern Mexico on Feb. 8, 1969.
Because different minerals form under different temperatures and pressures, scientists can look at the Allende fragment and infer what it was like when the rock was formed.
A number of scientists, including Brearley, now believe some of its minerals were changed by heat and chemistry later, after the material had coalesced to become an asteroid.
That would mean the fragment does not record the heat of the cloud of gas that formed the solar system.
``We're almost 30 years down the line from that (Allende's discovery) and we know that the story is a lot more complicated,'' Brearley said.
Brearley's findings were published in May in the journal Science.
Not all scientists agree with his conclusions.
In July, Brearley was one of about 100 scientists who debated the issue in Hawaii. No clear consensus emerged.
``It would be inaccurate to say that the differences ... were completely resolved and everyone went home happy,'' Brearley wrote in a report on the conference published last week in Science.
He said the debate doesn't mean the fragment is no longer useful in understanding the solar system's formation, but that more research will be needed to settle the questions.