What is the Kaidun meteorite?
Kaidun is an extraordinary meteorite that fell in Yemen in 1980, containing a mixture of many different meteorite types in one stone.
On 3 December 1980, a meteorite fell near a Soviet military base at Al-Hudaydah in Yemen. It was named Kaidun. Only a single stone of about 2 kilograms was recovered.
A mixture. Kaidun is a breccia containing fragments of many different meteorite types, more than any other known meteorite. Studies have identified clasts resembling CM and CR carbonaceous chondrites, CV chondrites, enstatite chondrites of both EH and EL types, ordinary chondrites, and fragments of unusual melted rocks. Some fragments have never been found as separate meteorites. Its main host material is carbonaceous.
Unusual minerals. Kaidun contains many rare and unusual minerals, including some first discovered in it.
Origin. How did so many different materials come together in one rock? One suggestion is that it comes from a body that collected debris from many different asteroids over a long period, such as a moon of Mars. Some researchers proposed that Kaidun might come from Phobos, Mars's larger moon, which has been showered with material from many sources, including possibly Mars itself. Others suggest it formed on a large carbonaceous asteroid that collected impact debris.
Comparison. Kaidun resembles Almahata Sitta, which fell in Sudan in 2008 and contained many meteorite types, though Almahata Sitta was mainly ureilitic.
Significance. Kaidun shows that material moved between asteroids in the Solar System and suggests that some bodies acted as collectors of debris. Japan's MMX mission to Phobos may help test whether Kaidun-like material exists there.