Scientists have recovered water delivered from outer space trapped inside a meteorite. The rock fell from the sky on March 1998 and was found by boys near Monahans, Texas.
Details of the find were reported in the current issue of the journal, Science, by Dr Michael Zolensky and colleagues. The meteorite was taken to the Johnson Space Centre in Houston, Texas, where it was cut open to reveal purple salt crystals carrying tiny pockets of liquid water.
The rock was thought to have come from an asteroid and the water itself is believed to date back to the dawn of the solar system, but the authors were unclear how it might have got into the meteorite. One theory holds that the water arose from water flowing within the original asteroid, and another suggests that the asteroid might have been hit by a comet containing water.
The authors pointed out, however, that water had never been confirmed in a meteorite before, and that "fluid inclusions" could be found in other extraterrestrial samples.
The find was described as "astonishing" in a related article by geophysicist, Dr Robert Clayton of the University of Chicago. The discovery indicated that water molecules must have been a major constituent of the solar nebula from which the planets in our solar system formed, Dr Clayton suggested.
While most of this early water condensed on the giant outer planets such as Saturn and Jupiter, some remained to accumulate on the stoney inner planets including the Earth.