Fairy tale inspiration could help rovers explore risky places

Sensors dropped like Hansel and Gretel’s bread crumbs could send back collected data

Self-driving rovers could one day leave sensors behind them while exploring other worlds (illustrated). The dropped sensors would communicate through Wi-Fi to pass any data collected by the scout rover back to a central rover.


In the classic fairy tale, Hansel and Gretel dropped bread crumbs while walking through a forest to avoid losing their way. Rovers may one day use a similar trick to traverse other planets without losing their data.

Typically, if a rover loses contact with Earth for good, all the data it has gathered is lost. To avoid this, researchers suggest using a multi-rover system.

In that setup, a small rover would piggyback on a larger “mother rover.” The small rover would then hop off the mother rover to explore any uncertain territory. Such places might include caves or lava tubes. The small rover would drop sensors like bread crumbs behind it as it drove. And those sensors could wirelessly pass any collected data back to the mother rover.

a photo of a small rectangular rover. It has treads on the long side of the rectangle. On the short side of the rectangle, facing the viewer, two cameras are mounted looking forward, they alost look like eyes.
Fink’s team used experimental rovers like this one, equipped with cameras and other sensors, to test the technology for self-driving rover exploration.W. Fink/University of Arizona

Wolfgang Fink and his colleagues proposed this idea in Advances in Space Research. The work appeared February 11. Fink is a theoretical physicist at the University of Arizona in Tucson.

To show the concept could work, his team built prototype “bread crumb” sensors that communicate via Wi-Fi. Each is about as big as an AirPods case.

The small rover wouldn’t be following these “bread crumbs” back the way it came, Fink notes. Instead, the sensors would help data gathered in the field make its way back to the mother rover. “To get to the real exciting science,” he says, “you most of the time have to go to exotic places. Hard-to-get-to places.”

The breadcrumb strategy could also be useful here on Earth. Imagine a natural disaster, such as an earthquake. A sensor-dropping rover could be sent into rubble that’s too dangerous for people to navigate. Even if the rover gets broken, its trail of sensors could still return its observations to search-and-rescue teams.

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