"The findings appear to trace CR2 meteorites' origin to to cosmochemical regimes where ammonia was pervasive," the authors write.
Researchers spent three years developing the Zafirro Iridium, which has a handle made of 99.9 per cent pure iridium - the most corrosion-resistant platinum metal, found only in meteorites.
Such meteorites look like igneous rocks from earth-hence the belief that Vesta has a mantle.
The theory that has developed is that asteroids in the the Asteroid Belt between Mars and Jupiter may have produced smaller meteorites which have shot off into space and landed on Earth.
The only sources? Rare lunar meteorites, soil from Soviet probes, and the 842 pounds of rubble carted back by Apollo astronauts from 1969 to 1972.
So like all natural phenomena, meteorites deserve our respect, but not our fear.
The researchers examined Martian meteorites here on Earth to determine that the sulfur and chlorine likely resulted from ancient volcanic explosions.
