Kaidun
A small stone that fell on a military base in Yemen in 1980 and turned out to be a jigsaw of many different worlds.
Key facts
- Type
- Breccia (mostly carbonaceous chondrite material; ungrouped)
- Fell or found
- Fell (witnessed)
- Year
- 1980 (3 December)
- Country
- Yemen
- Mass
- about 2 kg
- Official name
- Kaidun
On 3 December 1980, a stone weighing about 2 kilograms fell on a Soviet military base near the village of Kaidun in what was then South Yemen. Because it landed at a Soviet base, the meteorite was taken to Moscow, where scientists at the Vernadsky Institute of the Soviet Academy of Sciences began to study it. They soon realised that this small, dark stone was one of the strangest meteorites ever to fall.
A meteorite made of meteorites
Most meteorites are made of material from a single kind of parent body. Some are breccias, rocks made of broken fragments cemented together, often mixing material of the same type. Kaidun is a breccia too, but its fragments come from an astonishing variety of sources. Detailed study, led for many years by the Russian scientist Andrei Ivanov, has identified pieces resembling several groups of carbonaceous chondrites, along with fragments of enstatite chondrites, which formed in very different, oxygen-poor conditions. There are also unusual igneous fragments, formed from molten rock, and minerals rarely or never seen in other meteorites.
Think of it as a jigsaw puzzle assembled from pieces of many different boxes. Somewhere in space, a parent body gathered and welded together fragments from widely separated parts of the early Solar System. Carbonaceous fragments that were altered by water sit side by side with enstatite-chondrite fragments that formed with almost no oxygen at all, materials that, as far as scientists can tell, came from very different environments.
Where did it come from?
That diversity makes Kaidun hard to explain. Its main mass appears to be carbonaceous chondrite material, so its parent body was probably a dark, primitive object. One intriguing suggestion is that Kaidun might come from Phobos, the larger of Mars's two moons, which is dark like carbonaceous asteroids and lies in a position where it could collect debris from many sources, including material blasted off Mars. Some fragments in Kaidun have been compared with Martian rocks. This idea remains a hypothesis rather than an established fact, and other researchers favour an origin from a large, primitive asteroid that collected a wide range of debris over its history.
A rare witnessed fall
Kaidun's value is enhanced by the fact that it was seen to fall and collected immediately. Many unusual meteorites are found in deserts after long periods of weathering, which can alter their delicate minerals. Kaidun reached scientists fresh. Even so, because the whole meteorite is so small, every fragment of it is precious. Ivanov and colleagues in other countries, including the United States, have published studies of it over several decades, examining it in great detail with microscopes and microprobes, down to grains just a few thousandths of a millimetre across.
Why it matters
Kaidun shows that the Solar System's small bodies did not stay neatly separated. Material moved around, collided and mixed, sometimes ending up in surprising combinations. By studying it, scientists can sample materials from many sources at once, including types that might not otherwise survive as separate meteorites. It also raises fascinating questions about where in the Solar System such mixing could happen.
For anyone interested in meteorites, Kaidun is a reminder that even a stone weighing just a couple of kilograms can be a treasure chest of discoveries, and that some of the most important meteorites are small and unassuming to look at. Today the main mass is held in Moscow, where it continues to be studied.
As scientists send spacecraft to explore Phobos and to collect samples from asteroids, they may finally learn whether this extraordinary jigsaw came from the moon of Mars or from some other body that has been collecting debris for billions of years.
Did you know?
Kaidun fell on a Soviet military base in Yemen and was taken to Moscow for study.
It contains fragments of several very different types of meteorite in a single stone.
Some scientists have suggested that it could come from Phobos, the larger moon of Mars, though this is unproven.