These days, the Moon is a dry, rocky sort of place.   But 3 billion years ago, it was a little… different.   Back then, the Moon had active volcanoes, and they’d often erupt in what geologists call fire fountains, a type of volcanic eruption where escaping gas spews jets of lava out of the ground.   And in a new study published this week in the journal Nature Geoscience, researchers figured out that the exploding lava was probably propelled by carbon monoxide, adding another piece to the puzzle of how the Moon formed in the first place.   We’ve known for a long time that the Moon is full of extinct volcanoes. And when the Apollo 15 and 17 missions went to visit in the early 1970s, the astronauts brought back some samples of volcanic glass beads, which would have formed 3 billion years ago, as the lava cooled.   Scientists have been studying those beads ever since, but it’s only now that technology has advanced enough for researchers to accurately measure their carbon content.   And that turns out to be an important development, because the researchers found that the closer they got to the center of a bead, the more carbon there was.   That meant that a carbon-based gas probably drove the eruptions that formed them -- and according to the team’s simulation, it was most likely carbon monoxide, as opposed to the carbon dioxide in Earth’s eruptions.   But the carbon content showed up in concentrations similar to what we see here on Earth, in volcanic rock in the ocean.   The fact that volcanic rocks on Earth and on the Moon look similar makes a lot of sense, since both worlds probably started out as the same giant ball of stuff.   According to that theory, a Mars-sized object crashed into our young proto-Earth and knocked off a chunk that became the Moon.   But there’s one big difference between the Moon’s glass beads and the modern volcanic rock on Earth: the Moon rock is missing certain kinds of iron-containing compounds.   Scientists say it’s possible that while the lunar lava was still in the ground, chemical reactions occurred with something like graphite, that would’ve affected its iron content. But so far, no graphite has been detected in the lunar glass.   So, clearly, we still have a lot to learn about our closest celestial neighbor.   But not knowing exactly how the Moon got there hasn’t stopped us from visiting lots of times, either in person or by sending probes and landers.    And in 2016, you can send your very own message on the next vehicle that goes there!   A U.S. company called Astrobotic Technology is planning to send its Griffin Lander to the Moon, sometime next year, as part of Google’s Lunar XPRIZE challenge.    The idea behind the challenge is pretty simple: the first company to land a rover on the Moon and have it travel 500 meters, all while sending back HD images and video, wins 30 million dollars.   But actually completing the challenge is, obviously, a lot harder.   Astrobotic is going to try to do it by sending its rover, named Andy, on the Griffin Lander -- and Andy won’t be the only cargo.   A Japanese drink company is including a time capsule they’ve named Lunar Dream, which will contain titanium plates with messages from Earth. And they’re asking people to submit the messages that will be carved into the plates.    If hitchhiking a ride on a flying advertisement isn’t your thing, there’s a different way you can make your mark on another world.   In March 2016, NASA’s launching its InSight Rover to Mars. The mission’s main goal is to learn more about the planet’s geologic activity, like the Martian equivalent of earthquakes and heat flow from its core.   But it’ll also be taking a list of names, stored electronically.   If you want your name to fly to Mars, you have until September 8th to submit it.   So, if you’ve been meaning to scatter your name or a particular message through the solar system, now’s a really good time to do it.    Thanks for watching this episode of SciShow Space News, and thanks especially to our patrons on Patreon who help make this show possible. If you want to help us keep making episodes like this, just go to patreon.com/scishow. And if you want to keep getting smarter with us, just go to youtube.com/scishowspace and subscribe!