When it comes to space exploration, launching people into the final frontier is easier said than done. We haven't sent a human beyond low-Earth orbit since 1972.
That's why scientists rely on rovers to assist with celestial data collection. But the machines have their limits. Curiosity, for example, is starting to show its age — and the technology that works for a Martian rover won't necessarily work on other planets or moons.
As we push to make more world-specific robot explorers, scientists are kicking around ideas for bots that are even more specialized, depending on where they're sent.
Take NASA's Super Ball Bot. It's just a series of rods and cables and can be dropped from a spacecraft without breaking on impact. The lightweight machine collapses and expands itself to move across unknown but potentially hazardous surfaces, like those on Saturn's moon Titan.
Some scientists are creating flying rovers. The quadcopter Dragonfly, for example, is designed to survey Titan's surface from above. The moon's atmosphere is dense, and its gravity is low, which makes flight easy.
NASA even plans to make a Strandbeest-inspired rover that "combines steampunk with space exploration." Extreme temperatures on Venus and Mercury can melt sensitive electronics, so the Automaton Rover for Extreme Environments walks around on mechanical legs.