Life Ingredients Found in Superhot Meteorites—A First
New evidence that space rocks may have seeded life on Earth.
for National Geographic News
Published December 20, 2010
Hot on the heels of finding arsenic-loving life-forms, NASA astronomers have uncovered amino acids—the fundamental foundation for life—in a place where they shouldn't be.
The acids—precursors of proteins—have been unexpectedly found inside fragments of previously superheated meteorites that landed in northern Sudan in 2008, a new study says.
Amino acids have already been found in a variety of carbon-rich meteorites formed under relatively cool conditions. (See asteroid and comet pictures.)
But this is the first time the substances have been found in meteorites that had been naturally heated to 2,000 degrees Fahrenheit (1,100 degrees Celsius). That extreme temperature which should have destroyed any hint of organic material inside, said study leader Daniel Glavin, an astrobiologist at NASA's Goddard Space Flight Center in Maryland.
"Previously, we thought the simplest way to make amino acids in an asteroid was at cooler temperatures in the presence of liquid water," Glavin said in a statement. "This meteorite suggests there's another way involving reactions in gases as a very hot asteroid cools down."
The discovery also "provides additional support for the theory that life's ingredients were delivered to the Earth by asteroids," he said.
ET Amino Acids a "Big Deal"
The meteorites came from a 13-foot-wide (4-meter-wide) parent asteroid that entered an Earth-crossing orbit in 2008.
A collision about 15 million years ago sent the 59-ton asteroid closer to Earth—and provided scientists the first opportunity to observe a celestial object before it entered our atmosphere in October 2008.
(See "Meteorites in Africa Traced to Asteroid 'Parent.'")
During desert treks, scientists later recovered nearly 600 meteorite fragments from the meteor shower.
"Finding evidence for the extraterrestrial amino acids in this meteorite is a big deal," Glavin said, "since we can learn about the chemistry that took place in space prior to the origin of life on Earth."
Likewise, "these meteorites would have contributed to the amino acid inventory of the early Earth and other planets in our solar system, including Mars."
This may mean that organic compounds such as amino acids—delivered via asteroids—may have been much more pervasive throughout the solar system than thought, he said.
The new meteorite research is featured in 20 papers published this week in an issue of the Meteoritical Society's journal Meteoritics and Planetary Science.