China’s Chang’e 6 return capsule landed in Mongolia, carrying samples from the far side of the moon. Also, Paris has invested $1.5B in cleaning up the Seine for open-water swimming events, but recent tests indicate it’s not yet safe.A Sample From The Far Side Of The Moon Lands On EarthThis week, the return capsule from China’s Chang’e 6 lunar mission returned to Earth, touching down in a remote part of Inner Mongolia. Inside were dust and rock samples collected from the far side of the moon. Researchers hope that the samples could shed light on both the moon’s formation, and conditions in the ancient solar system.Rachel Feltman, host of the podcast “The Weirdest Thing I Learned This Week,” joins guest host Anna Rothschild to talk about the mission and other stories form the week in science, including a CDC warning about dengue fever, a trans-oceanic butterfly flight, and the possibility of seeing a stellar nova in the coming weeks.Will The Seine Be Clean Enough For Olympic Swimmers?The Paris Summer Olympics are fast approaching. Opening ceremonies for the games kick off on July 26. And all eyes are on the notoriously polluted River Seine. Due to aging infrastructure, sewage has sometimes flowed directly into it. For the past 100 years swimming in the river was banned. Now, the French government has spent roughly $1.5 billion to upgrade sewage treatment in Paris in order for athletes to be able to swim in the Seine.Earlier this week, Paris mayor Anne Hidalgo was set to take a dip in the river to prove its cleanliness. In protest some Parisians threatened to poop in the Seine to show their dislike of the disruptions and high price tag of the Games.The dip was postponed until after upcoming elections, but recent water quality tests indicate that the river is not yet safe to swim in.Guest host Anna Rothschild talks about the current state of the river with Dr. Dan Angelescu, founder and CEO of Fluidion, a water testing company based in Paris, France.Transcripts for each segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.