This episode is sponsored by Ekster.

Ekster’s mission is to make people’s daily lives easier and that starts with their reimagined wallet that’s easier to use and harder to lose. Click our link in the description for 5% off your order. [♪ INTRO] What’s in a meteorite?

That which falls from space filled with anything else wouldn’t smell as sweet. Because it turns out there’s sugar in meteorites, and that’s about as sweet as it gets. But sugars don’t just taste delicious; they make up parts of some of the most important biological molecules in existence.

We would not be here if it weren’t for sugar. Our genetic code is made of it. So researchers have proposed that some of the starting materials for life as we know it could have come from serendipitous space rocks.

Researchers have suspected that there are sugars in meteorites since the 1960s. Since meteorites aren’t exactly living or reproducing organisms, you might not expect them to have some of the most essential stuff for life inside of them, like sugars. I mean, they’re mainly made of silicate, iron, and nickel.

But they also can contain carbon from dying red giant stars. Researchers suggested that carbon could take the form of sugar. Sugars are molecules made of carbon, hydrogen, and oxygen.

And biological processes use these molecules for all sorts of stuff, from breaking them down for energy to holding genetic information. DNA and RNA, the molecules that contain our genetic code, are made of nucleotides, and nucleotides are linked together by their phosphorus and oxygen, alternating with their sugars. Without this elaborate chain of sugars, DNA and RNA would not be able to store genetic information.

That chain of sugars is held together with covalent bonds. And ultimately, strong bonds are good because they prevent the chain of genetic information from getting damaged. So it is vital that this sugar does its job and does it well.

Since we’re not the only things in our universe with this essential sugary goodness inside us, researchers have suggested that these sweet meteorites could potentially help us learn more about how life on Earth originated. Back in the 1960s, researchers at the California Institute of Technology found some sugars inside meteorites called chondrites. But the tools they used weren’t sterile enough to rule out that they had contaminated the meteorites with Earthly sugars.

So in the 2000s, NASA researchers did further investigations to once and for all say that meteorites have come to Earth with sugars already on board. The sugars they discovered in chondrites ranged from sugar acids to formose sugars. Formose sugars are some of the first sugars thought to have been created from formaldehyde reacting with glycolaldehyde in space.

The NASA researchers concluded that those formose sugars in the meteorites they studied were extraterrestrial! They were able to determine that the reactions that make these sugars had happened at a specific temperature range too cold for Earth. In laboratories on Earth, these reactions happen around 50-100 degrees celsius, while the meteorite reactions were estimated to happen at temperatures as low as 0 degrees celsius.

This estimation came from the ratio of different oxygen isotopes in the sample. When there’s not enough water and heat available, the reaction doesn’t happen as efficiently, and so we get the same ratio that was found in the sampled chondrites. So they must have been in a cold environment.

But even still, none of the sugars analyzed so far from meteorites were the kind of foundational sugar that we use to stay alive. Until 2019, when a new study changed the sweet space rock narrative. A Japanese research group isolated ribose from meteorites.

That is the same sugar that we use to make RNA. Based on the mineral make-up of the meteorites, they think the sugar came from space and that at least some of the sugar pre-dates the meteorite. They found a larger amount of sugar in the meteorite than would likely be there today if it formed inside the meteorite.

If that were the case, the meteorite would likely have changed the sugars and maybe even broken them down with ammonia. So if the sugar was made before the meteorite, researchers only have ideas about how it would’ve been created. The sugar could have been made from ice that got light, chemical, and heat-treated by a solar nebula.

But that method for making space sugar is controversial. Still, it’s cool to think about. Because meteorites also have other compounds that are biologically important to us, like amino acids, phosphate, and nucleobases.

So it makes some scientists think our sugars could have evolved from space sugars. Now, it’s only one possibility of many, but our most central life-giving components could be extraterrestrially derived. Either way, it's pretty sweet to think about early Earth life moseying around with similar innards to meteorites flying through space.

So it is amazing that we found space sugar in rocks that conveniently brought it to our planet, and that some of that sugar is biologically relevant to us. But whether it influenced the development of life on Earth and other planets has definitely not been determined yet. Speaking of sweet things, Valentine’s Day is coming up pretty soon!

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