From the Mojave to Phobos: PlanetVac rides with MMX

Sarah Al-Ahmed (0:03)

A Japanese spacecraft is about to set off on a journey to bring home a piece of a Martian moon. This week on Planetary Radio.

I'm Sarah Al-Ahmed of The Planetary Society, with more of the human adventure across our solar system and beyond. Japan's Martian Moon Exploration Mission, or MMX, is scheduled to launch next week on its journey to Phobos and Deimos, the two small moons of Mars. If all goes well, it will bring the first ever sample from the Martian system back to Earth, straight from the surface of Phobos. The Planetary Society's public outreach astronomer, Asa Stahl, joins me to explain why these small little moons are such a big mystery, and what those samples could reveal. Then, Kris Zacny, Vice President and Senior Research Scientist at Honeybee Robotics, returns to the show to talk about PlanetVac, a sampler that Planetary Society members get off the ground more than a decade ago. Its descendant will soon be on its way to Phobos. And in What's Up, Bruce Betts, our Chief Scientist, looks back at PlanetVac's history with the Society, from its first prototype test to a rocket launch in the Mojave Desert. If you love Planetary Radio and want to stay informed about the latest space discoveries, make sure you hit that subscribe button on your favorite podcasting platform. By subscribing, you'll never miss an episode filled with new and awe-inspiring ways into the cosmos and our place within it.

Mars is one of the most explored worlds in our solar system, but its two moons, Phobos and Deimos, are still keeping some of their biggest secrets. The Japanese Aerospace Exploration Agency, or JAXA, is about to launch its Martian Moon exploration mission to change that. For those of us in the United States, that's set for Monday, October 19, 2026 But for friends in Japan, because of the timezone difference, it's the next day, Tuesday, October 20 MMX is a true international effort, with contributions from NASA, the French Space Agency, CNES, the German Aerospace Center, DLR, and the European Space Agency. To help us understand what this mission is setting out to do and why it matters, I'm joined by Dr. Asa Stahl, the Planetary Society's Public Outreach Astronomer.

Hey, Asa.

Asa Stahl (2:24)

Hey, how's it going?

Sarah Al-Ahmed (2:25)

Man, I am so excited for this mission. We've been looking forward to this for so long, but finally, we're going to get to go out to the Martian Moons. Are you excited?

Asa Stahl (2:34)

Yes. I mean, it's so weird that we haven't been there already. I think it's the kind of thing where whenever I tell some about this mission, they're like, what? For real?

And that it doesn't get that much press. It's not as big in the news. Maybe it will be now that it's launching and getting there. But I think this one kind of snuck up on a lot of people.

Sarah Al-Ahmed (2:54)

I think, too, that people assume we understand what's going on with those moons, right? We've had so many spacecraft in the area that people would assume that we know more. But actually, it's a lot more complicated than that. So first off, this mission is actually launching next Tuesday. It's a little complicated. It's October 20th if you're on Japan time, but October 19th if you're in the United States. But for anyone who might be looking forward to this mission, might be looking forward to this launch, what is this mission actually going to do?

Asa Stahl (3:22)

It is going to bring back the first ever samples from Phobos, which is one of the two moons of Mars. You can picture it like a potato the size of Manhattan or so, covered in craters. It'll in general perform detailed remote measurements of both Phobos and Deimos. In doing so, hopefully teach us a bit about maybe giant impacts, maybe how asteroids get captured. We don't know what we're going to find, but it promises to teach us something about how planets form and the ancient history of the solar system.

It'll be a few years to get there, orbit Mars, or well, orbit Mars, but in doing so, it's going to orbit Mars in a way that also circles Phobos as a quasi-moon of Phobos, just like we've had some quasi-moons of Earth discussed on this show before. It won't land on Deimos, but it will touch down on Phobos, drop a rover, and then bring back some samples through a couple of different mechanisms to Earth, hopefully in 2031

The upside of all these sample return missions is that we get back samples and we're able to do amazing science with them. It's like some most impactful mission you could have as a sample return mission. The downside is you have to be patient.