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Have you ever wanted to know what it would be like to have an army of hopping robots? NASA might bring that dream to life as we explore our solar system.

Hosted by: Caitlin Hofmeister
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Caitlin: Some day this is how we might explore Mars! And asteroids. And comets. And moons! At least, that’s what a European team of planetary scientists and engineers is proposing in a paper being published in the journal Acta Astronautica. The idea is that instead of using robots to roll around these worlds the old-fashioned way... they’d jump. And it could work really well! In the past, when we’ve sent unmanned missions -- all of which are technically robotic -- to the surface of one of these places, it’s pretty much been one of two types.

First, there are the landers. Landers don’t have any way of moving around, so while they can do a whole bunch of interesting science, they have to stay in one spot. We also have rovers, which can do interesting science and move around, but they have to be really careful about where they go. Their wheels degrade over time, and going over the wrong terrain could make the whole rover flip over -- which would mean the end of the mission, since tow trucks don’t usually come to Mars. Rovers also can’t drive on small bodies like asteroids and comets, where there just isn’t enough gravity to pull the rover down to the surface and create the kind of friction they need to move.

But the researchers think that instead of rolling around the surface, our robots could jump around on top of it. And they’re calling these hopping robots hopters, which is short for Highland Terrain Hoppers -- and is also really fun to say. Hopters are still very much in the concept stage, but the idea is that they’d jump using pieces that act like pistons or springs, which would quickly expand to propel the hopter upwards and in a certain direction.

Robots jumping across the surface of an asteroid might seem like a weird idea at first, but it’s actually super convenient. Astronauts on the Moon, for example, noticed that the lunar regolith -- the fine surface rocks and dust -- made it tough to walk normally. But they could hop around just fine. In the same way, robots that jump across the surface of a planet or moon might have an easier time and might have a better chance of not getting stuck than rovers do. Durable hopters that could flip themselves over wouldn’t have to worry about terrain in the same way rovers do, either. Plus, unlike with rovers, where smaller worlds with less gravity are a problem, less gravity would just mean farther jumps for a hopter.

But one of the main advantages of hopters would be their size. A fully functioning hopter could be as light as 35 kilograms, since all it has to do is be able to jump and hold an instrument or two. Compare that to Curiosity’s 900 kilograms, with its big wheels and whole set of instruments. The smaller and lighter hopters are, the easier it would be to send a bunch of them somewhere -- like our own little roving army of robotic rabbits. And the farther they could jump.

The jumps would also depend on what kind of hopter you’re talking about, because there could be all different kinds of jumping robots, meant to explore different places. Mopters, for example, would be designed for places like the Moon, Mars, and Mercury -- hence the ‘M’ in the name -- where there’s plenty of sunlight to recharge their batteries and the surface gravity is fairly high. These little guys might be able to jump as high as four meters on Mars, which would get them higher than Curiosity’s cameras can even see.

Then there are the phopters, designed for smaller moons and asteroids farther out in the solar system. These places have much lower gravity, so a phopter’s jump would take much less power than a mopter’s. But phopters would also operate much farther from the Sun, which would make it harder to recharge their batteries with solar cells -- which scientists would have to plan for.

Finally, there are the kbopters. The “KBO” at the beginning is a reference to Kuiper Belt Objects, the clumps of rock and dust out around and past Pluto -- which is where kbopters would be exploring. Since the Kuiper belt is so far from the Sun, kbopters would need to bring their power with them. They’d also need some other special adaptations to be able to handle the extreme cold out there. Any of these kinds of hopters might be able to go a thousand hops without recharging, which would give them a range of at least 5 kilometers no matter where they landed. And while they’re hopping around, they might as well do some science.

Hopters wouldn’t each be able to bring along a whole set of fancy instruments like Curiosity, but they’d be cheap enough to launch that we could send a whole team at once, each with different main instruments. Then, they could hop along together, each testing something different about whatever surface they’re on. Or, they could all have the same instruments, and do a giant sweep of the surface. So many possibilities!

Again, hopters are still just concepts -- there are no definite plans to build an army of robotic space rabbits any time soon. But still, it’s nice to know we have the, uh, hop-tion.

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