A green space rock that some speculated was from Mercury may be too old to come from the planet, some scientists say. The meteorite is believed to be more than 4.5 billion years old, too old to have been able to survive the Late Heavy Bombardment without any evidence of damage, researchers say. "We don't have any 4.5-billion-year-old meteorites from the moon, because all of those rocks would have been bashed to smithereens during the Late Heavy Bombardment," said meteorite expert Randy Korotev. "...The same thing would have happened on Mercury, so the question is, How did this rock survive for that long?"
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