The ConversationMar 01, 2021 19:23:00 IST
NASA’s Perseverance rover made it down to Mars last month, and has already started retrieving images. But people may be surprised to learn that there are 48 other missions on the red planet so far. Of these, more than half failed at stages from take-off to use – with the introduction of the Mars Climate Orbiter in 1999, which was destroyed when they entered Mars from after someone failed to convert in imperial dimensions to metric. Successful missions include Mars Insight, which explores the interior through a series of “marsquakes”, and the Curiosity rover, which landed in 2012 and has studied geology. Mt Sharp.
While no missions have been returned, there is much we can learn without traveling to Mars – from more than 260 Martian meteorites that have fallen to Earth.
Images taken by orbiters show that Mars has more than 40,000 orbits, each created by an asteroid hitting the surface. You can explore these filters yourself by going to Google Earth, building Google Mars mode and navigating in.
If some of the debris from the massive impacts reached escape speeds (about 5 km / s on Mars), it would be able to leave the planet’s gravitational field. Eventually, some of the crushed Martian material has taken hold of the Earth ‘s path, shining through the atmosphere until it burns up or until it has come to rest on the surface.
Although Martian meteorites have been found all over the Earth, most have been collected from Antarctica or the deserts of northwestern Africa. In all cases, the black crust that is partly quartz burns up through the Earth’s atmosphere stands out clearly against ice or sand.
This interplanetary mode of travel is important because it raises the possibility that life may travel unnoticed from one planet to another. Back in 1996, one Martian meteorite, ALH84001, was controversially thought to contain fossil bacteria.
Some of the oldest landowners have certainly brought Earth’s bacteria to Mars, as they were not cleaned up before their launch.
Bubbles of Martian atmosphere
Small planets are rapidly cooling and there has long been a suspicion that the heart of Mars has largely collapsed. This means that Mars has lost most of its protective magnetic field which is lost to cosmic radiation.
But we are confident that Mars once had an ocean, which contains water as we know it. The temperature was above freezing and the conditions were ideal for life. Peeling off the magnetic field early in Mars’ history means that this ocean is long gone and the average temperature is now -65 ℃, but frost, clouds and caps- ice still there.
Not lucky enough to traverse the deserts of Africa or the frozen plateau of Antarctica, I discovered my first Martian meteorite sitting in a cabinet in a gem store in the New Zealand town of Akaroa.
Using a scanning electron microscope, my study showed that it was shergottite, one of the most common Martian meteorites – equivalent to what we know on Earth as basalt. If it is basalt, however, how do we know it is from Mars?
There are several ways to identify a Martian meteorite. One is from its gas content. When a meteorite hits the surface of Mars, the “target” rocks are under so much pressure that they partially melt and trap Martian atmosphere inside gas bubbles. Some of these rocks are then extracted from the planet – growing into the dragonflies themselves.
The gases in these meteorites can be measured back on Earth and compared to the known Martian atmosphere, which contains 95% carbon dioxide and a certain noble gas density.
The thousands of scallops that break the surface of Mars make it ancient. This was confirmed when the date of one meteorite was 4.4 billion years old. The features of some other Martian meteorites show Mars formed within 13 million years of the creation of the Solar System. This in turn means that some of the first planetary crust formed on Mars is still visible at the surface.
Old and cold – but not dead
This decision, along with some meteorite mineral and isotopic buildings, means that Mars was not designed with plate tectonics – the global process that created the continents, mountain ranges and ocean basins on Earth.
And, since most Martian meteorites are less than 1.5 billion years old, volcanism has continued throughout its history. Mars may be cold but not dead.
Martian meteorites also hold out how humans could one day survive on the planet.
While living in empty lava tubes in Martian basalt will appeal to some hopeful interplanetary settlers, we must eventually build shelters to protect us from cosmic radiation and major storms. dust that surrounds the planet.
Martian meteorites show that olivine, a magnesium-silicate mineral, is common. Experiments are underway to evaluate the use of a fracture component, magnesium carbonate, to create a concrete binder from which we could design buildings.
Martian meteorites show that large sights can be obtained from small rocks and reveal where Mars is made.
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