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Earth has had a complicated relationship with asteroids. Just ask the dinosaurs.

Oh, wait…. Still, it's not always fire and brimstone, and according to a new study, asteroids might actually benefit life on our planet sometimes. The paper was published last week in the journal Science Advances.

And in it, researchers suggest that a huge asteroid may have driven one of the largest increases in biodiversity in Earth's history. Almost five hundred million years ago, during what scientists call the Ordovician period,. Earth looked pretty different.

Back then, most life existed in the ocean, and most land was clumped together in a giant supercontinent. The climate was also warm, and the planet had nearly no ice, even at the poles. Then, around four hundred sixty-six million years ago, Earth began to enter an ice age.

Scientists have long wondered why this happened, and this new research suggests the cause may have been in space. See, around this time, an asteroid about one hundred fifty kilometers across broke apart between the orbits of Mars and Jupiter. It's not clear why it happened, but it was a big deal — perhaps the largest breakup since the solar system settled down more than three billion years ago.

In fact, even today, around a third of all meteorites falling on Earth seem to come from that one body. Researchers have suspected there might be a connection between this asteroid's destruction and the Ordovician ice age, but no one was able to provide detailed evidence until now. In this work, researchers measured the ages of ancient sediment layers and fossil meteorites: objects that hit Earth in the distant past and became part of that era's geologic record.

That allowed them to demonstrate that the timing of the asteroid breakup almost perfectly matched the start of that ice age. As for why this space rock had such an effect? Well, their evidence also showed that the breakup dumped a lot of dust into the inner solar system.

Every year, Earth gets hit by about forty thousand tons of interplanetary dust. But after the asteroid breakup of the Ordivician, that amount increased by a thousand or even ten thousand times. The paper suggests that this dust blanketed the Earth's upper atmosphere for about two million years, blocking some of the Sun's heat from reaching its surface.

And that likely resulted in a global cooling that transformed Earth's ecosystems. Before, habitats were all kind of just… “warm.” But after, the poles were cold, the equator warm, and the tropics somewhere in-between. We'll need more research to say exactly how and why this happened.

But one way or another, as life evolved to adapt to this new environment, it diversified dramatically. Seriously, the variety among groups of species quadrupled to something more like modern levels. Not all species could adapt to these changes, though, and the end of the Ordovician is also marked by the first recorded global extinction, in which eighty-five percent of species perished.

So it wasn't a good time for everyone. But one way or another, this study is a cool reminder that life on Earth isn't just influenced by what happens on our planet. It's part of a much larger system — one that sometimes involves asteroids millions of kilometers from here.

Now, while some researchers are studying the past, others are looking to the future. A future where humans are living on Mars. With recent advances in commercial spaceflight, sending humans safely to the Red Planet may soon be possible.

So it's not ridiculous to think that decades from now, we might want to start a big settlement there. If we do, one of our biggest challenges will be providing our own food, since shipping meals from Earth won't be practical for long. And it's a challenge scientists are already researching.

In a new paper, a pair of researchers at the University of Central Florida investigated what it would take to develop a food-independent Mars society with one million people. And they found it will take compromise — a whole lot of compromise. For one, they propose that there almost certainly won't be much farm-raised meat.

After all, raising livestock requires a ton of resources and lots of space, which isn't very scalable on a planet without breathable air. One substitute might be to develop lab-grown meat, which has many of the caloric benefits without all the “moo.” But that's really still in an experimental phase. So instead, the team suggests animal protein could come from insects, which are nutrient-rich and can be farmed in a small area.

This need to conserve space and find calorie-dense crops is a consistent theme in the paper. For example, it also proposes that corn, soybeans, and peanuts would make good staple crops. But then again, even once you figure out what to grow, you still need to figure out how to grow it.

And there are some challenges there, too. Like, the best long-term solution for farming on Mars is to grow crops in actual soil. But the authors note that would take time to convert the dead, poison-laden Martian regolith into something that can safely grow plants.

In the meantime, we'd likely need to use hydroponics, a method of growing plants in nutrient solutions instead of soil. Except, while that's more compact and would let you get started right away, it would require us to ferry more heavy equipment from Earth. Realistically, these aren't problems we'll need to worry about soon.

But overall, this paper makes a good point: An early Mars settlement will be really dependent on Earth. Whether it needs equipment or heaps of pre-packaged meals, it will require millions of tons of supplies to be shipped across the solar system. With today's tech, that would come at a staggering cost.

But maybe by the time we're ready to support a million people on Mars, we'll have figured this out. Thanks for watching this episode of SciShow Space News, and special thanks to our patrons on Patreon! If you're a patron, let us know what you think about this episode in our new Discord server.

And if not, we'd still love to hear your thoughts in the comments. If you do want to learn more about becoming a patron, you can head over to patreon.com/scishow. {♫Outro♫}.