Mars touches down in Toulouse

For its "Explore Mars" exhibition, the Cité de l'Espace has a Martian meteorite on display! Ejected from the Red Planet several million years ago, then several decades ago it eventually "fell" to Earth, landing in the Sahara desert.

 

Meteorite NWA 2990 that is on display at the Cité de l'Espace: a piece of Mars! The opportunity to get closer than ever to the Red Planet. Credit: Luc Labenne Météorites.

 

Our planet is constantly bombarded by small rocks from space. These meteorites enter our atmosphere leaving a fleeting, bright trail across the sky, incorrectly called a "falling star". Those that survive the intense heat, hit the ground. Most of these meteorites are fragments from asteroids in our solar system. However, a very small percentage come from the Moon and Mars.

Pieces of Mars on Earth
But how can fragments from our natural satellite and many others from the Red Planet be found on Earth? Due to impacts! When large meteorites strike the Moon or Mars, the shock of the collision results in pieces of the affected body being thrown into the air. Just like a splash when a stone is thrown into a lake for example. The strength of the meteoric impact can sometimes be such that pieces are ejected into space! Then, they float around for millions of years before eventually being pulled towards a planet like Earth where they are tracked down by "meteorite hunters". Among the various small rocks from space, lunar and Martian meteorites are considered as the rarest and most precious.
Thanks to the renowned collector Luc Labenne, the Cité de l'Espace features a Martian meteorite as part of its "Explore Mars" exhibition. So, visitors to the Toulouse-based space park can admire a piece of the Red Planet. This 252 g meteorite, called NWA 2990 was discovered in the Saharan desert in late 2010. A Shergottite type meteorite (so, the same type as a meteorite that fell in Shergotty in India in 1865), it has been estimated that the impact causing its ejection from Mars took place several millions of years ago. It fell to Earth several decades ago.

From Mars to the Moon in just a few steps!
But how do we know that this meteorite is from Mars? By analysing it: in addition to the composition of the meteorite itself, it contains elements of the Martian atmosphere trapped through vitrification (due to the intense heat of the impact). This "signature" is then compared with the composition of the Martian atmosphere as determined by the American spacecraft, Viking I and II, the first to be successfully landed in 1976. If the comparison is positive, the meteorite then receives its "Martian label", like the meteorite on display at the Cité de l'Espace from Saturday 11 August 2012.

The Viking lander (here a scale model on Earth). In 1976, Viking I and II landed on Mars and analysed its atmosphere. Certain meteorites suspected of coming from Mars could then be authenticated through a comparison because they contained "trapped" elements of the Martian atmosphere. Credit: NASA

In fact, the Cité de l'Espace enables its visitors to look directly at fragments from two legendary celestial bodies. Mars, as we have just explained, but also the Moon since, we must remember that the space adventure park in Toulouse has also exhibited a lunar rock since it opened. However, this did not arrive in the form of a meteorite, but was one of the rocks collected by the astronauts of the Apollo 15 mission. So, at the Cité de l'Espace, you can walk from the Moon to Mars.

The Moon rock at the Cité de l’Espace. Credit: Cité de l’espace/Alexandre Pietcha Photographe

Published 11 August 2012