NASA has clue to life's question
Meteorite found to have chemical building blocks
MARK CARREAU, Copyright 2006 Houston Chronicle
Published 6:30 am, Friday, December 1, 2006
A meteorite that fell on Western Canada nearly seven years ago has tiny globules that formed before the solar system appeared 4.5 billion years ago and contain the chemical building blocks for life, according to scientists from NASA's Johnson Space Center in Houston.The chemical compounds, which likely formed in the regions between stars, mixed with the swirling cloud of dust and gas that provided the brick and mortar for the sun and planets, according to their study.The findings, published in today's editions of the Journal Science, may help to strengthen the link between observations of key chemical building blocks for life in deep space with powerful telescopes and their migration to Earth and the other planets."This takes it one step further," said Mike Zolensky, a cosmic mineralogist and one of five study participants. "We knew the building blocks, the raw materials for life are out there in interstellar space. For the first time, we can actually see organic structures in a meteorite."The link was established by researchers Keiko Nakamura-Messenger and scientist husband Scott Messenger, who discovered and characterized microscopic globules in the Tagish Lake meteorite. Rich in carbon, the meteorite also contained specific kinds of the organic elements nitrogen and hydrogen that form only in the near absolute temperatures of deep space.The Tagish Lake meteorite gained fame on Jan. 18, 2000, when it streaked to Earth and exploded. Fragments fell onto a frozen Yukon landscape and were quickly collected.Estimates placed the meteorite at 25 feet across and about 250 tons before it exploded in the atmosphere. The stone is a rare kind of space rock called a carbonaceous chondrite that features carbon-bearing compounds that are essential to life.The age of the Tagish sample is similar to meteorites about 4.5 billion years old, the scientists said.The age of the globules is much older and more difficult to estimate.According to Zolensky, meteorites bearing similar globules likely transported chemical compounds essential to life throughout the solar system for billions of years. When they fell to Earth, the presence of water and warmth, in combination with other processes, fostered reactions that led to the more sophisticated forms of the chemicals required for biological