IT IS not just on Earth that drones have uses (see article). Three experimental ones, 22cm across and known as Synchronised Position Hold, Engage, Reorient, Experimental Satellites, or SPHERES (even though they are actually truncated rhombic dodecahedrons), have been buzzing around the International Space Station since 2006 (see picture above). Now, a new and more advanced version, the Astrobee, is being designed at the Ames Research Centre, a NASA laboratory in Mountain View, California.

The Astrobee, which is scheduled for deployment in 2017, eschews geometric complication: it is a simple, 30cm cube. But it is otherwise a more complex beast than its predecessors. SPHERES can be used only in a designated area of the station, and they rely on beacons to know where they are. The Astrobee, by contrast, will use computer vision to orient itself and to navigate around.

It will be powered differently, too. A space drone does not need to work to keep itself airborne. Like the rest of the space station it is in free-fall and thus appears to float with respect to the station’s walls. But it does need motors of some sort to move itself around.

SPHERES use jets of carbon dioxide to propel themselves, and the canisters that this gas is stored in must be shipped to the station, changed by the astronauts and returned to Earth for refilling. The Astrobee, by contrast, will compress air on board, using battery power, and employ that for propulsion. To top up its batteries for this and other purposes, it will also be able to steer itself to one of several recharging docks.

Nor is the Astrobee intended to be a toy. Astronauts are busy people and the idea is that the new drone will be able to relieve them of several routine tasks, and also serve as a set of virtual eyes for ground controllers to see better what is going on in the station. Chris Provencher, the Astrobee’s project manager, observes, for instance, that astronauts must regularly check sound levels in various parts of the station, as it produces noise “like a factory”. Too much of this noise can damage the crew’s hearing. A full sound check takes a human being two hours to carry out, but is a task that could easily be automated.

The Astrobee could also help keep the station neat and tidy, by tracking down things that have floated away from their proper places. The station’s managers are planning to put radio-frequency identification (RFID) tags on every item on board, so that they can be found if they go missing, as thousands already have. The pressurised portion of the station, into which they vanish, is about the size of the interior of a Boeing 747. That means looking for missing items, even RFID-tagged ones, is time-consuming. The Astrobee should be able to lift this burden from the crew.

The new drone might also turn movie-maker. At the moment, flight controllers rely on camcorders held on fixed arms to see what is going on in the station. Sometimes these cameras need to be relocated—yet another tedious task for a busy crew. The Astrobee, though, will have its own high-definition camera that controllers can position at will, if they want to scrutinise something beyond the range of the fixed cameras. Not so much a fly on the wall as a bee off it.