Scientists expect to confirm soon the presence of liquid water in a meteorite that landed in Morocco last year. Such confirmation would mark the second time that water has been discovered in a meteorite -- and would indicate that water may be more common in rocks from space than previously believed.
The meteorite, known as Zag (after the town it fell near), contains tiny droplets of fluid similar to those detected in the Monahans meteorite that landed in Monahans, Texas last year.
Zag broke into numerous pieces upon landing in a mountainous area of Morocco in August 1998. Weighing some 300 pounds, it was a far larger rock than Monahans, which broke into two pieces weighing less than three pounds each. Fragments of Zag were gathered by local people and sold to international collectors and researchers.
Unlike Monahans, Zag has not yet been subjected to definitive tests. However, scientists who have studied both meteorites are confident that the fluid in Zag is water.
"I'm 99.9 percent sure that it's water," says Robert J. Bodnar, a geochemist at Virginia Tech. Bodnar says there is a "miniscule chance" that the fluid may be something else, such as a carbon dioxide-based solution.
NASA scientist Michael Zolensky, who was the lead author on the Monahans study, says that Zag's fluid is "so similar" to that in Monahans that he is also "personally sure" that the Moroccan meteorite contains water.
Zolensky, Bodnar and others are collaborating on studies of Zag, and will conduct tests over the next week or two.
Both Zag and Monahans are ordinary chondrites, the most common type of meteorite that falls to Earth. Both are classified as H chondrites, indicating that they may have come from the same parent asteroid. In both meteorites, the fluid droplets were found inside the mineral halite, a type of salt.
Both meteorites were collected in dry regions shortly after they landed. This raises the possibility that many meteorites might contain water, but that the evidence is destroyed shortly after the rocks arrive on Earth. For example, rainwater might seep into a meteorite, diluting the salt crystals that could hold fluids.
Another danger, notes UCLA geochemist Alan Rubin, is that meteorite dealers may be inadvertently destroying evidence, by sawing into the rocks with water-lubricated tools. Such sawing results in nicely polished slices, but also could eliminate signs of extraterrestrial water.
The apparent presence of water is only part of Zag's interest to scientists. Rubin, who's about to conduct a detailed study of the meteorite, notes that Zag came from the surface of an asteroid, where it was exposed to meteoroid bombardments and particles of the solar wind. "Its been shocked quite a bit," he says.
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