[♪ INTRO] You might have heard that  there’s an alien world out there populated only by robots. …Mars.

It’s Mars. Among that population are three rovers  on its surface, working hard right now to help humanity understand what our  planetary next door neighbor is like now… as well as what it used to be like in the past.

NASA has sent loads of missions  that have gotten loads of attention, from Sojourner in the 1990s, to its  newest roving expat, Perseverance. But there’s one mission you may not have heard of, one that has already spent over  a year on the Martian surface. It’s China’s Zhurong rover.

And it’s bringing us ever closer  to understanding the history of the fourth planet from the Sun. Tianwen-1 is China’s first  independent interplanetary mission, using an orbiter and rover  to explore the red planet. The orbiter is also named Tianwen,  which means “Questions to Heaven”, while the rover is Zhurong,  after the Chinese god of fire.

They launched together, back in July  2020, in the very same launch window as both Perseverance and the  United Arab Emirates’ Hope orbiter. Both orbiter and lander entered  Martian orbit the following February. Then in May, Zhurong broke  away and fell to the surface, landing in the Utopia Planitia basin.

That made China just the third country  to complete a soft landing on Mars, after the US and USSR, but the second  to have an operational spacecraft… because the Soviets lost communications  with theirs soon after landing. Utopia Planitia is the largest impact  basin in Mars’s northern lowlands, and Zhurong is the first craft to explore  the southern part of this region up close. While the exact origins of these  lowlands are still being debated, most of it looks like it formed  about 3.34 billion years ago.

When you’ve got a rocky body floating  out there in space, it’s going to get hit by debris over time. So the more craters  a patch of crust has, the older it is. Based on the low crater  count in Zhurong’s location, at least some of Utopia Planitia could  be as young as 700 million years old.

In other words, the surface may have  been wiped clean or renewed somehow. Originally slated for a three-month mission, Zhurong is still going strong as  of this writing, one year later. But over the past year, Zhurong has been  busy using its six scientific instruments to peel back the layers of the  Martian surface and subsurface.

In one case that’s metaphorical,  because it has ground penetrating radar. In another it’s more literal, because  it has a laser it uses to vaporize the outer layers of rock samples to  figure out what minerals they’re made of. The Tianwen orbiter, meanwhile, has the job of  relaying all that precious data back to Earth.

But it was also used to help confirm  exactly where Zhurong was going to land, and is also now doing some science of its own. And the results of all this  sciencing are slowly rolling out. Like based on how well the rover’s  wheels could traverse the surface, scientists were able to show that the surface acts basically like compact,  sandy soil does on Earth.

But overall, it looks like this region of  Utopia Planitia has a thin layer of dust and sand sitting on top of a layer of rock known  as duricrust: a hardened mix of silicon, aluminum, and iron-based minerals  that have cemented together. At least on Earth, this happens  after the minerals are deposited by a body of water, which then evaporates. In other words, it’s yet another piece of evidence  that Mars used to be swimming in liquid water.

But one study published in May 2022 using  Zhurong’s data revealed that that liquid water may have been in the area way more  recently than scientists thought it was. The research team identified a sample  of rocks which look to have come from the duricrust, and attempted to  work out what minerals they were made of. Unfortunately, they weren’t able to pin the  exact minerals down, but they did figure out that they had water molecules  incorporated into their structure.

Whether or not this duricrust material  is related to other geologic features in the area is currently unknown. We also don’t know exactly how  the duricrust in this area formed. One possibility is that it  was created by groundwater rising up from a lower layer, then evaporating.

Another is that the water came from  subsurface ice that melted due to a sudden change in temperature caused  by volcanism or meteoric impacts. Or the ice could have been melted by a  temporary infusion of local liquid water. In that case, the effect would  be a lot more limited in size, so an easy way to rule that out  would be to send Zhurong further away and see if the same duricrust  rocks formed over yonder.

Whatever the cause, the presence of this  kind of rock, in this much younger region of Utopia Planitia, suggests that Mars  was a bit wetter, at least for longer, than scientists have thought. While Zhurong continues its  investigation into Mars’s past, scientists on Earth are looking for ways  to keep in contact with the little rover while the Tianwen orbiter is busy sciencing. Last year, the European Space Agency tried linking  Zhurong up with their orbiter, Mars Express.

You might think that’d be as easy as  just dialing someone else’s phone number, but the two communications platforms  aren’t actually immediately compatible. Out of five tests, only one was  successful at sending non-corrupted data. So we’ll have to wait to hear  if these two space agencies make more progress on that collaboration.

Meanwhile, we can celebrate  this little guy’s achievements. And you can even take Zhurong home with  you as this month’s Pin of the Month! This year, our pins are celebrating  the best in solar system exploration, and this month only, you can pre-order  this pin to add to your collection.

We’ll take pre-orders all this month,  after which we’ll close orders, make the pins, and ship them to you. After that, you can never get this one again… but you can get next month’s awesome  pin, so keep your eyes peeled for that. [♪ OUTRO]