Thanks to Skillshare for supporting this episode of SciShow Space.

The first thousand people to click the link in the description can get a two-month free trial of Skillshare's Premium membership. [ ♪INTRO ]. Most of the time, it's not great when an expensive spacecraft slams into an extraterrestrial body.

But now and then, mission control crashes a spacecraft on purpose. And while a smoldering hunk of broken machinery might not look like cutting edge science, sometimes that's exactly what it is. In the early days of space exploration, we often crash landed because that was the best we could do.

We didn't have technology to make soft, controlled landings. So, for instance, in 1959, the Soviet Union crashed the Luna 2 probe into the Moon for the sake of becoming the first country to make contact with another celestial body. A few years later, a series of NASA's Ranger spacecraft crashed into the Moon, too.

Their goal was to capture a bunch of close-up photographs on the way down so that engineers could later use those to plan the Apollo missions. But as technology advanced and we started landing spacecraft all around the solar system… sometimes we've still intentionally crashed them. Like, in 1970. once the Apollo 13 crew got into orbit around the Moon, NASA sent the empty rocket booster crashing onto the lunar surface.

And NASA wasn't just tossing out their garbage — they did it for science! They used this impact to calibrate seismometers that would give them a way to study the Moon's interior. At that point, we didn't know much about the Moon beyond what we could see on the surface.

But scientists knew that we could explore it the same way we explore the interior of the

Earth: through its seismic activity. The Moon doesn't have big earthquakes like we have here — mainly because it doesn't have any major tectonic activity. But moonquakes do happen. Since the Moon has no atmosphere to burn up space rocks, meteoroids often strike the surface, sending shockwaves through the Moon's layers.

Based on how quickly those shockwaves travel, and how strong they are, scientists can make some inferences about the materials they're traveling through — just like on Earth. But to do that on the Moon, scientists needed to be able to measure that seismic activity. On various Apollo missions, scientists deployed seismometers at the different landing sites.

But they couldn't calibrate those instruments because no one knew the precise timing or location of objects hitting the Moon. So they decided to crash something into it themselves. The third stage of the rocket that had launched the mission was massive and moving fast, so.

NASA scientists could be sure it would make a decent crash. Plus, they could control the timing and location. So they sent it plummeting into the Moon.

Afterward, they were able to measure the timing and strength of the seismic waves as they hit different seismometers, and they used that information to calibrate the network. Since then, these instruments have used vibrations to reveal that the Moon is made up of a crust, mantle, and core, just like Earth, and they've given us a way to study the Moon's different layers — without even drilling beneath the surface. One stop closer to the Sun, our neighbor Venus is also home to its fair share of wrecked spacecraft.

They include four probes from the Pioneer Venus 2 mission that NASA intentionally crashed into the planet in 1978. By then, scientists were well aware that there was little point in trying to build a spacecraft that could survive Venus. The Soviet Union had tried a few times, starting in the 1960s, and they had numerous probes destroyed by the extreme heat, pressure, and sulfuric acid in the planet's atmosphere.

So, with Pioneer Venus 2, NASA's goal was just to record a bunch of atmospheric data on the way down, for as long as possible, and then crash into the surface. Of the mission's four probes, the largest floated down with a parachute, while three smaller probes just plunged freely through the clouds so that they could get farther before being destroyed. Together, these probes taught us about the structure of Venus's atmosphere and showed us that night is almost as warm as day beneath all those clouds.

Which is kind of remarkable considering a Venus night lasts almost half its year! Now, most of the time, we've intentionally crashed spacecraft in an attempt to learn something we couldn't learn otherwise. But in the case of the Galileo spacecraft that we sent plummeting into Jupiter, it was the opposite: It was because of something we learned that we had to crash it.

Galileo orbited Jupiter between 1995 and 2003. It gave us an incredible, close-up look at the giant planet as well as its moons. And one of the things it found was that Jupiter's moon Europa happened to have all of the key ingredients needed for life.

Because of that, when Galileo was nearly out of fuel, engineers decided they couldn't risk just letting it orbit Jupiter forever. There was always a chance that it could crash into Europa and contaminate any life there. And as small as it was, that wasn't a chance scientists were willing to take.

So, on September 21, 2003, Galileo crashed into Jupiter's atmosphere at about 48,000 meters per second and vaporized in its clouds. There were definitely no microbial survivors. In the end, as sophisticated as our forays into other worlds can be, sometimes the right move is just a good old-fashioned crash.

And, If you like learning — whether it's through a crash into an extraterrestrial world or through something less dramatic, like an online course, you might like Skillshare. Skillshare is an online community full of resources to help you develop creative skills. For instance, if you have a passion for language and art and want to make your content stand out in an online world, you might like a class called The Art of the Story, taught by Debbie Millman.

In this class, you can learn how to bring together art and language and craft a narrative that's designed to be visual. You can get access to this and unlimited other classes with a Premium membership, which is less than $10 a month. And if you're one of the first 1,000 people to click the link in the description, you can try it out free for two months. [ ♪OUTRO ].