In 2014, NASA sent 800 ants to the International Space Station to study how they search without gravity; some spent seconds tumbling through the air

Ants may look like simple insects, but their colonies can solve surprisingly complex problems without anyone directing them. In 2014, NASA and BioServe Space Technologies at the University of Colorado Boulder sent 800 common pavement ants to the International Space Station to find out whether that ability would survive in microgravity.

The experiment, known as “Ants in Space,” divided the insects among eight chambers aboard the ISS. Researchers could open barriers between sections, giving the ants progressively larger areas to explore. Cameras recorded their movements so scientists could compare their behavior with ants conducting the same searches on Earth.

The researchers were particularly interested in how ants determine how crowded their surroundings are. On Earth, ants effectively use their interactions with one another as a measure of density. When they encounter other ants frequently, they can infer that they are in a confined area. When encounters become less frequent, they tend to travel in straighter paths, allowing them to cover more territory.

Microgravity complicated that system

The ants could no longer rely on gravity to keep them attached to the floor or walls of their enclosure. Some lost their footing and floated through the chamber, sometimes tumbling for three to eight seconds before regaining contact with a surface.

Yet the insects didn't simply stop searching.

They were often able to recover after losing their footing. Some grabbed onto other ants, while others managed to flatten themselves against the surface and continue moving. Researchers found that the ants could still conduct collective searches in microgravity, although they were less effective than ants on Earth.

The problem was partly mechanical. An ant that was floating wasn't available to interact with other ants, making it harder for the colony to use encounters as a measure of how densely populated its surroundings were. The effort required to hold onto surfaces also slowed the insects and interfered with their ability to thoroughly explore their territory.

That mattered because the experiment wasn't really just about ants.

Scientists studying collective behavior are interested in how groups can make decisions without a central leader. Ant colonies use local interactions between individual workers to accomplish tasks such as searching for food and exploring unfamiliar territory.

Deborah Gordon, a Stanford biologist who helped develop the experiment, argued that the strategies ants have evolved over millions of years could provide ideas for designing systems in which individual robots coordinate without relying on a central controller.

"We have devised ways to organize the robots in a burning building, or how a cellphone network can respond to interference, but the ants have been evolving algorithms for doing this for 150 million years. Learning about the ants' solutions might help us design network systems to solve similar problems," Gordon was quoted as saying by phys.org.

That could eventually have applications ranging from search-and-rescue robots to autonomous networks.

The space experiment also revealed something more basic: an ability that works remarkably well on Earth doesn't necessarily work the same way when gravity disappears.

For ants, losing gravity meant that even something as ordinary as walking across a surface could become a problem. Yet despite repeatedly falling away from the walls and floor, the colony still managed to search its environment collectively.

And that's arguably the most interesting part of the experiment: NASA didn't send the ants into space to teach them how to build something. It sent them there to see whether a system that evolved on Earth could still function when one of Earth's most fundamental forces was taken away.