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A meteorite was found in a remote area of Botswana. The event is one of a kind because the meteor was identified before entering the atmosphere, and its fall and recovery have been documented. It's only the second time that happens. The Moina Spooner Conversation from Africa spoke to Fulvio Franchi and Alexander Proyer about their mission to recover the meteorite and why it is important.
Why is the find in Botswana so important?
Alexander Proyer: Meteorites are fragments of asteroids or comets fallen to the surface of the earth. Finding a new one is rare but what makes this case truly sensational is not the fall itself but the fact that we knew it was going to happen. Usually, people are taken by surprise, seeing a flash of light or a fireball when the asteroid enters the atmosphere. But this one was observed in the space eight hours before its collision with the Earth.
The asteroid was first detected by a network of observatories – NASA's planetary defense network – which searches the night sky for objects. In this case, it is Richard Kowalski of the Catalina Sky Survey in Arizona who discovered the extremely light light of an object moving in space.
It was the third time in history that such an observation and prediction was possible and only the second time that a fragment was recovered. The first discovery came from an asteroid called TC3 in Sudan
Fulvio Franchi: We can view this event as a free delivery of material from the space that would otherwise require a very space mission expensive.
Most meteorites are extremely ancient rocks, dating back to the birth of the solar system about 4.56 billion years ago, and coming from the asteroid belt – small objects and large consisting of stone, metal and carbon. in the space between Mars and Jupiter. These asteroids keep a "record" of the formation processes of the planet – such as growth by gravitational attraction, warming and fusion – a record that is no longer available on Earth because it has been overproduced by the processes tectonics operating on our planet.
Meteorites are fragments of our Moon or Mars, which have been catapulted into space by major events. They are even rarer than regular asteroids. One can appreciate the value of these asteroids by simply considering the costs of a space mission on the Moon, Mars or even the asteroid belt, to obtain such samples. This find is a real gift for the international consortium, in the process of training to perform lab badyzes of this and other fragments yet to be found during ongoing research.
What happened after it was detected?
: After seeing Kowalski in Arizona, he alerted other institutions that are part of NASA's planetary defense network, and they calculated the size and trajectory of the body, concluding that one asteroid 2 to 3 meters in diameter was about to hit the Earth – Botswana
Fulvio Franchi: Colleagues from South Africa and Finland contacted us, providing valuable information to locate fragments. We immediately realized the importance of this event and mobilized the first research team
The fragments of the 2018 LA asteroid – as it is called – have spread over a vast area in the Botswana Central Kalahari Nature Reserve, blown by the wind falling. Detailed calculations, by two independent groups, of the scattered field allowed our group of researchers to finally find a fragment of the asteroid.
What was the procedure for recovery and what were the challenges you faced?
Fulvio Franchi: There were a few factors to consider when recovering this meteorite in Botswana.
First, you can not just take a meteorite and possess it – at least not legally. Meteorites are considered vestiges by law and must be returned to the National Museum.
Secondly, the planned drop zone was in a national park, the Central Kalahari Game Reserve. This required permits to enter and to work.
Third, the Botswana Geoscience Institute is the one that has the mandate to act when unusual events like this occur. Naturally, he was involved in research.
The main technical challenges were to refine the search area. This was done using eyewitness observations and video equipment, mainly security cameras. Information on changes in direction and strength of winds, from 27 km above ground – where the meteorite exploded – to near the surface, was crucial.
The last challenge was to get off the road, days in the territory of lions and elephants, snakes and scorpions. We had Park Rangers with rifles that were walking and camping with us, and fortunately the only casualties were a number of blown tires. An unexpected challenge was to have at first sight millions of other objects resembling a generally dark meteorite: pieces of burned wood (from bush fires) or animal droppings. But the excitement of finding something of scientific interest, and the joy of adventure, kept us moving.
Why is it important to study meteorite?
Alexander Proyer:
Each meteorite is a piece of the puzzle to understand our solar system. The asteroids from which they originate represent different stages ranging from dust to small bodies via planetesimals (small planets), which have never reached the final stage of a single planet. One could say that different steps towards the formation of complete planets are preserved.
Some of them were broken again by collision with other asteroids and now expose their interiors. Samples of such depths are impossible to obtain on Earth or on any other untouched planet. They are absolutely unique and help us understand the inner workings of the Earth and other planets, which were built from very similar materials, but are now strongly differentiated into a core, mantle and crust.
In terms of planetary defense, we now have second case of remote observation of an asteroid linked to a recovered material from it. If we ever have to defend ourselves against larger asteroids in the future, it is essential to know what kind of asteroid enters and whether it is likely to disintegrate, at least in part, in the atmosphere or to be hit by a defense missile. By studying the meteorites of the 2018 LA asteroid, it will be possible to relate the properties of meteorites determined in the laboratory to remote observations before impact of the asteroid
Fulvio Franchi: Analysis more detailed, looking at the chemical composition of the rock and the possible content of the organic molecules, will also give us clues as to how life on earth has formed and, finally, on the big question: are there any there a life there?
The Conversation
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