It is 4 billion years old and it travelled and landed safely on Earth about 13 000 years ago. The meteorite known as ALH84001 was discovered in the Allan Hills region of Antarctica in the year 1984. The geologists who picked it up at the time didn’t think much of the meteorite. It was only after 10 years of studying the rock that researchers realized that this was a specimen from Mars.
It is now commonly recognized by researchers that ALH84001 crystallized from magma on Mars 4.5 billion years ago. It then lived on Mars and gathered carbonate mineral grains in fractures that is thought to have been created from shocks that could have been caused by meteors or asteroids crashing into Mars. One of the later impacts must have been so devastating that it flung the piece of rock into a solar orbit of Mars. Eventually through other impacts and conditions the orbit of ALH84001 was altered so much that it set off on a course for Earth.
In 1996 ALH84001 became famous when scientists at NASA suggested that the meteorite from Mars contained evidence of life on the red planet. After careful examination researchers discovered what is called carbonate globules in the rock. This carbonate forms most likely in the presence of water. Inside these carbonates were something described as worm-like fossils.
After careful examination by Thomas Keprta and her team they discovered the mineral magnetite in the meteorite. It was a very chemically pure form of magnetite, a kind known to be created by bacteria. This would suggest that there was indeed life on Mars a long time ago. Even so, others suggested different ways the magnetite could have formed inside the rock and would not believe that there could actually have been life on Mars. The only problem is that nobody could recreate the magnetite with the same chemical and physical properties as it is in the rock.
Some other famous meteors never really got famous for what they contained but more for what they have done. In 1992 an unlucky car was hit by the Peekskill meteorite. Nothing significant was reported on the meteorite but there was plenty of video material that was used to study the behaviour of the meteorite before it hit. The Park Forest meteor shower was caused by a large meteor entering Earth’s atmosphere and bursting apart into smaller pieces which damaged several cars and houses in the area. The heaviest meteor ever found was the Hoba Meteorite. It lay undiscovered in Namibia for 80,000 years until 1920. It weighed in at 66 tons and is now a national monument in Namibia. The Vredefort Dome in South Africa is the largest impact crater on Earth. It is a whopping 300 kilometres wide and is estimated to be 2 billion years old.
Another famous meteorite is the Murchison meteorite. It is one of the most studied meteorites because it was seen falling from the sky and it contains amino acids. It came down in Australia on 28 September 1969. Similarly to ALH84001 which contain signs of life the Murchison contains amino acids. Something that is very important for the human body to live and to grow. The interesting thing about the amino acids found in the Murchison meteorite is that more than 50 of the amino acids are not found on Earth. Many of the protein amino acids found in Murchison can also be found in life on Earth but not all of them. Where would this meteorite have gotten these unearthly building blocks of life?
DNA – a necessary component in the human body. DNA is the key molecule that contains all the information on how to build a life form and how to keep the life form running. Signs of DNA were discovered in the Murchison meteorite.
When researchers examined larger chunks of the Murchison meteorite they already discovered traces of organic material. It was only a matter of time before they would discover DNA. The DNA and also amino acid components were found in a very small specimen of the rock. This discovery now makes researchers believe even more that life came from outside our planet. In a statement researcher Michael Callahan said that: “Despite their small size, these interplanetary dust particles may have provided higher quantities and a steadier supply of extraterrestrial organic material to early Earth.”
The sample in which life’s building blocks were found weighed only 360 micrograms, about a thousand times smaller than the sample researchers would normally use. This makes researchers a bit sceptical about how significant rocks from space really were in delivering life to Earth. Thing is, if traces of life’s building blocks were found on meteorites then surely they must have had some kind of influence, shouldn’t they?