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Only a week after InSight landed on Mars, another one of humanity’s space-exploring robots arrived at its destination. This Monday, after traveling for more than two years and two billion kilometers,.

NASA’s OSIRIS-REx finally entered orbit around the asteroid Bennu! Whoo!!! Because they’ve been around since the dawn of the solar system, asteroids are really useful for understanding how our neighborhood formed, and Bennu is especially valuable.

For one, it’s closer to us than the main asteroid belt past Mars, which makes it easier to get to. But it also has an important chemical composition. Bennu is what’s called a B-type asteroid, which means it’s full of carbon and hasn’t changed much in the billions of years our solar system’s been around.

This means it could teach us what our corner of space was like all those years ago, as well as how small, rocky bodies were able to clump together and grow into full-sized planets. Bennu might even contain minerals or water for future asteroid miners, or basic hydrocarbons, molecules that are the building blocks for life. OSIRIS-REx was built to learn more.

The spacecraft launched in 2016, and it’s spent the last two years traveling through space and, for a couple of weeks, looking for other nearby asteroids. It snapped its first photo of Bennu in August of this year, and on Monday, it finally arrived. This mission may not have been as much of a nail-biter as last week’s Mars landing, but getting a spacecraft to orbit a tiny asteroid billions of kilometers away is pretty impressive

in a whole different way.

Now, OSIRIS-REx will spend the next year or so scanning Bennu’s surface. This will partly be to study the asteroid and partly to find the best place to take a sample of its regolith, or its surface dust and rock. But to get that sample, the spacecraft isn’t going to, like, reach down with an ice cream scoop and just yank up some dust.

Instead, and I love this, it will shoot out a jet of nitrogen gas to kick up bits of regolith, and some of those bits will fly into the spacecraft’s collector. OSIRIS-REx will take up to 2 kilograms of Bennu, the largest sample of space regolith since the Apollo program brought back all those Moon rocks. Then, it’s going to head back towards Earth, and in 2023, it will drop those samples in to a protective canister before heading into a stable orbit around the Sun.

After that, scientists will spend a couple of years studying Bennu’s regolith, storing lots of leftovers for future research, too. The spacecraft’s arrival is just one step in a long process. But we’ve been talking about this mission since before it launched, so we are all very excited here at SciShow.

Someday, we might discover the building blocks of life on Bennu. But based on other research published this week, those building blocks might also be different than we used to think. According to a new paper in PNAS, scientists may have found a different chemical recipe for RNA, one of biology’s most important molecules.

RNA, or ribonucleic acid, is responsible for helping our cells making proteins, both by acting as a messenger and by actually constructing them. It’s also usually at the center of the scientific debate about the origin of life. Some scientists say it was the first code for life.

Others say life was originally run on smaller molecules and that RNA came along later. Either way, figuring out how RNA showed up is important for understanding the history of the world, and it’s also important for astrobiologists, who are hunting for life elsewhere. One of the big questions in this research is what molecules could have originally formed RNA’s four chemical bases: adenine, guanine, uracil, and cytosine.

We’ve already made a lot of progress finding predecessors to uracil and cytosine, but scientists are still working on the origins of the other two. Except now, they might need to start investigating a fifth base. Because this new paper suggests that, early on, guanine may not have been as important as we thought.

Instead, later in history, it may have actually replaced a different base called inosine. We already knew about inosine, it’s found occasionally in some modern RNA, but until now, scientists didn’t realize its potential importance in the first life on Earth. Previous work had even dismissed it as a possible early base.

This new discovery was just kind of a happy coincidence, because the researchers weren’t even directly studying inosine when they figured this out. Instead, they were attempting to verify a previous hypothesis about a special version of the chemical called 8-oxo-inosine, trying to see if RNA made with it could self-replicate like it would have to in a lifeform. As part of that study, though, they had to run tests comparing their experimental RNA with a control RNA made with regular inosine.

Ultimately, they found that the experimental molecule didn’t work that well, but the control molecule did. In fact, it worked just as well as modern RNA made with guanine. So, this team hypothesized that inosine could have been a perfectly suitable RNA base for early life.

As for how inosine could have come into existence, they suggest it could have been derived from another compound containing adenine, another one of those four traditional bases. So if adenine existed but guanine didn’t, the inosine could have served as a sort of surrogate. We’ll need more research to back up these results, but if they’re accurate, it could mean big things in our search for life.

We’ll be able to widen the field of what compounds to look for on worlds we think might have had or currently have life. And if nothing else, we’ll probably learn a lot about life on our planet, too. Thanks for watching this episode of SciShow Space News!

It’s amazing how much stuff happens in space research every week, and we’re really thankful for the chance to explore it with you. If you want help us keep making episodes like this and join our little community, you can go to patreon.com/scishow. [ ♪ Outro ].