When the world ends, it will probably be a rock from outer space that will. Climate disaster caused by the impact of an asteroid about six miles wide that killed the dinosaurs 65 million years ago. Other “planet killers” are definitely lurking there. That’s why a NASA spacecraft the size of a golf cart is currently about to crash into a 525-foot asteroid named Dimorphos, so we can watch the effect on Dimorphos’ trajectory. . It’s a first demonstration of how we could save the Earth from a really big asteroid strike.
Such examples of human ingenuity are the real stars of Greg Brennecka’s “Impact: How Rocks From Space Led to Life, Culture, and Donkey Kong.” Finding small asteroids, say about 50 meters wide, that could hit Earth is technically difficult. But it’s worth doing when you consider that in 1908 a rock of such modest size exploded about three miles above the ground, in what is called a meteorite explosion, and caused flattened 850 square miles of Siberian forest with the power of about 1,000 Hiroshima bombs. The 2013 Chelyabinsk meteor was just 20 meters in diameter, but its explosion damaged 7,000 buildings in six Russian cities. We didn’t see it coming because it was coming from the direction of the sun. A new NASA-funded asteroid tracking system, Atlas (which, rather ominously, stands for Asteroid Terrestrial-Impact Last Alert System), hopes to do better.
Chelyabinsk was officially a meteor because it was burning in the sky; any space rock that hits the ground is a meteorite. (It turns out that meteorite enthusiasts love to describe their miscalculations as “meteor errors.”) Mr. Brennecka is a cosmochemist, which means he studies the chemical makeup of things all over the universe, and he demonstrates with irrepressible enthusiasm how much we’ve learned about the universe by analyzing space rocks that fall to Earth. He calls them “time capsules”, many of which have been floating around the solar system since birth.
They have also, according to the author, been surprisingly important in human history. In the Bronze Age, before people figured out how to smelt iron from rock, the only widely available source of iron was meteoric – chunks of iron dropped from space. From these, people made jewelry or ceremonial knives, like the one that was buried with Tutankhamun. The Egyptians and Hittites of the second millennium BCE were fully aware of the origin of this substance, and a meteorite briefly became a Roman god under Emperor Elagabalus in the third century. Yet it took a surprisingly long time for authorities to credit everyday people’s stories of alien rocks falling from the sky. “The general consensus of ‘scholars’ as recent as the 1800s,” reports Mr. Brennecka, “was that there was no way something like this could happen.”
Impact: How Space Rocks Led to Life, Culture, and Donkey Kong
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Now we know this can happen, and does happen all the time. The history of the Earth is one of incessant bombardment. One hundred tons of space dust and space nuggets rain down on us every day. And a truly huge boulder – one the size of Mars – is thought to have collided with young Earth, creating our moon from the debris. This impact heated the planet to over 1,800 degrees Fahrenheit, killing any rudimentary life that might have existed and breaking down all of its chemical precursors. So where do the building blocks of life come from after that? One theory is that they came from meteorites. Modern research has found amino acids and even large DNA components on space rocks, so perhaps the bare young Earth received crucial organic enrichment from space. It’s not quite the panspermia hypothesis – that life itself is seeded throughout the universe by asteroids – but it’s an intriguing idea.
The possibility of living elsewhere has long been a primary motivation for space science. In 1996, for example, NASA announced that the Martian meteorite ALH 84001 showed signs of fossilized microbial life. Subsequent investigation of these microfossils showed that they were almost certainly formed by boring inorganic processes. But, says Mr Brennecka, this controversy has ensured that “enthusiasm for Mars research has grown exponentially” and has also motivated an increase in research into “extremophile” life on Earth, which can thrive under pressure. or hitherto unsuspected temperatures. “Life exists in toxic waste dumps and in hypersaline solutions like the Dead Sea,” observes the author. Whether it once existed on Mars is still an open question.
Meteorites are therefore messengers from other worlds that blur the boundaries between here and there. Intrepid meteor hunters spend weeks in Antarctica searching for them, and there is a healthy international trade in space rocks scavenged by desert nomads. Long before we could study them in such minute detail, these rocks could have had an outsized influence on human culture, as Mr. Brennecka’s joking speculations suggest. Were Sodom and Gomorrah Destroyed by Heavy Rain from an Intense Meteor Shower? Did the Pharisee Saul witness a meteorite fall on the road to Damascus? Writing as a converted Paul, he describes being blinded and then having scales falling from his eyes. According to a researcher, these phenomena could have resulted from burns on the surface of the cornea, among the symptoms that one could feel after seeing the intense light of a meteorite explosion. The global spread of a great religion could have been triggered by a humble rock from outer space.
Oddly enough, Mr. Brennecka never takes the time to explain the particular influence of meteorites on “Donkey Kong,” mentioned in its subtitle, but the video game’s predecessor, “Asteroids,” might hold a dark lesson for the Planetary Defense: In this game, if you just shoot straight at a large boulder to blast it, the resulting shower of fragments can still be dangerous. Hopefully NASA’s deflection experiment yields better results.
Mr. Poole is the author of “Rethinking: The Surprising History of New Ideas”.
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