Mars - Alh84001

During the 1980s NASA was busy running the space shuttle program. There was no money to send spacecraft to Mars. Luckily a piece of Mars turned up on Earth. On December 27, 1984, a meteorite hunter found a 4-pound rock on the Allan Hills ice field in Antarctica (the South Pole). The rock was grayish-green and covered with pits and gouges. It was given the designation ALH84001.

The National Science Foundation (NSF) conducts annual searches in Antarctica looking for meteorites (rocks that have traveled through space to Earth). Each possible candidate is collected and assigned a tracking code. The letters in the tracking code represent the location of the find (Allan Hills). The first two numbers stand for the year of the find (1984). The last digits indicate the order in which rocks were processed by the NSF that year. ALH84001 was recognized immediately as a significant find, so it was the first rock investigated during that sampling year. In fact, the person who found it wrote "Yowza-Yowza" across the sample notes.

Scientists also got excited when they examined the rock, because they found gas trapped within it that matched the known atmosphere of Mars. They concluded that the rock formed on Mars 4.5 billion years ago. About 16 million years ago an asteroid probably slammed into the planet and sent the rock hurtling through space. Scientists believe that the rock arrived on Earth 13,000 years ago.

The rock contains a small amount of carbonate (a carbon-containing compound). Some scientists believe that the carbonate formed inside the rock in the presence of liquid water. This would mean that liquid water existed on Mars billions of years ago. The exact origin of the carbonate is still under debate.

Rocks determined to be meteorites are kept in special laboratories at NASA or the Smithsonian Institute. In all there have been twelve known Martian meteorites found on Earth since 1815. ALH84001 is the oldest meteorite in the collection.