Moon Robots, a Cosmic Cold Case, and a 24-Mile Icelandic Slog: This Week in Space Got Wild

Picture two robots the size of baseballs, dropped on the moon. The second they land, they crack open like eggs — and the two halves of each shell turn into wheels. Then they wobble off across the lunar dirt on their own, no one steering. That's not a movie. That's Tuesday for NASA's favorite podcast, Short Wave, which this week stacked up three space stories that each mess with what you thought you knew: shape-shifting moon robots, a nearly 30-year-old argument about the universe that still hasn't been settled, and a brand-new moon astronaut who just trained by walking 24 miles across Iceland. All three are worth your time. Let's go.

This Robot Is Not Optimus Prime — and That's the Whole Point

Host Regina Barber opens with a tease — "Transformers on the moon" — then immediately deflates her own joke: "It's not about Optimus Prime. They're very different." The three hosts spend a minute arguing about who's actually seen the Transformers movies. Scott Detrow has. Producer Berly McCoy has seen "some," but thinks they're "kind of forgettable" (her words — and she begs, "no hate mail, please"). Barber has seen exactly zero.

The real robots are less Hollywood, more genius. A pair of them, each about the size of a baseball and weighing roughly half a pound, hitched a ride on Japan's first successful moon landing. On touchdown, each sphere splits open — half becomes a spinning wheel, and a little camera pokes out of the middle. Part waddle, part roll, they navigate entirely on their own across the bumpy lunar surface. A study published just last week in the journal Science Robotics dug into how they actually performed up there. Their job isn't glamorous: no fancy instruments, no deep science experiments. They just take pictures of the ground and the lander, and scout terrain that the bigger, pricier rovers can't reach yet.

Here's the actual wow moment. Roger Weems, a planetary scientist who wasn't involved in the project, says the biggest advantage of these robots isn't that they're advanced — it's that they're cheap: "These are not expensive devices. You can have several of them. And if one or two fails, then you still have others." That's a genuinely backwards way to design a space mission: instead of building one flawless, irreplaceable machine, build a pile of cheap, disposable little dummies, and don't sweat it if a couple break. The moon's gravity is only one-sixth of Earth's, which is why these robots visibly bounce as they move — and Weems thinks that same low-gravity design could eventually work on asteroids or even Mars. (Side note: McCoy compared the waddling gait to her toddler — "always exploring, always expanding" — which Detrow called "a really smooth transition" into the next story.)

Is the Universe Speeding Up or Slowing Down? The Case Isn't Closed

Almost 30 years ago, astronomers discovered something that became a textbook fact: the universe isn't just expanding, it's expanding faster and faster. But over the past few years, a group of scientists has been arguing the opposite — that expansion is actually slowing down. Last week, a new paper in the Monthly Notices of the Royal Astronomical Society pushed back hard, insisting the old "acceleration" framework still holds up. The scientists behind the slowdown claim — a team at Yonsei University in South Korea — already posted a rebuttal, standing firm that the standard way of measuring cosmic expansion has a hidden flaw.

How do you even measure how fast the universe is expanding?

Astronomers use a special kind of exploding star called a supernova as a cosmic ruler: they measure how bright it looks, then work backward to figure out how far away it is and how fast it's moving — after correcting for things like how long the explosion lasts and how much dust is blocking the light. The Yonsei team's argument is that this correction has always been missing one variable: the age of the galaxy the star lives in. Add that in, they say, and the math flips — the universe is slowing down, not speeding up. If that's true, it would be a massive deal.

Most other astronomers aren't convinced. The supernova method has been fine-tuned by the scientific community for almost 30 years, and several completely independent measurement techniques still point to acceleration. Yale astrophysicist Priyamvada Natarajan, who also wasn't involved in this research, is skeptical too — but she says that's exactly how science is supposed to work: "Scientists by nature are skeptical. And even for an idea that has been validated and accepted, if there is a new argument, we do take it seriously and we interrogate it."

What's riding on this argument is nothing less than the ultimate fate of the universe. If the acceleration is real and keeps going, galaxies drift farther and farther apart until everything goes cold and dark, alone. If the slowdown is real, the universe could eventually collapse back in on itself — what astronomers call the Big Crunch. Barber doesn't hesitate to pick a side: "I'm team cold death." (She's also squarely with the acceleration majority: "Right. Like me.") Nobody's won this argument yet. The honest ending here is: still unresolved.

Training for the Moon Means Walking 24 Miles Across Iceland — Blind

NASA just announced the crew for Artemis III. On the day his selection was announced, Detrow sat down with the newest astronaut, Andre Douglas, who'd previously served on the backup crew for Artemis II and trained right alongside them — including a brutal trip to Iceland: "We did a 24-mile hike in two days in Iceland, just to go through a hard challenge of land navigation, as if we're learning how to be really good operators."

Why Iceland, of all places? Because its rocky terrain and rock composition are eerily close to the moon's — Apollo-era astronauts trained there too, and called it the closest thing to the lunar surface they'd ever seen on Earth. Two more NASA astronauts head back to Iceland this July for another round. And this kind of training isn't just moon prep: NASA also sends astronaut candidates hiking the lava fields of Hawaii Volcanoes National Park under heavy packs, doing geology fieldwork while dealing with deliberately limited, badly delayed communications — a dry run for what a Mars mission's comms lag would actually feel like. Right now, there's also a live simulated Mars mission underway at NASA's Johnson Space Center in Houston: four researchers have been living inside a 3D-printed habitat since last October, running experiments as if they were actually on Mars, for a stay of just over a year.

The episode wraps with the hosts joking about taking a Spacing Out field trip to Iceland to chase the Northern Lights — and the whole show closes on one last callback: Detrow jokes "I'm floating away," McCoy asks "accelerating or decelerating?", and Barber answers, "decelerating — he stopped."

So, what's the actual story here?

These three stories aren't really three separate stories — they're the same idea, three times over. Space exploration doesn't run on single flashes of miracle technology. What actually powers it is a pile of wheeled robots so cheap nobody cries if one breaks; a group of scientists still arguing after 30 years over a measurement error worth a few percentage points; and an astronaut earning his spot on the moon one gravel step at a time across Iceland. Next time someone tells you the universe's fate is a done deal, remember that Yonsei team's rebuttal paper is still sitting out there, unanswered. This case is not closed.