In Horizon, each of the stellarnauts have their own PAL, a ball-shaped personal assistant that hovers in the zero G environment using small fans and allows the stellarnauts to talk to each other via video and audio link as well as acting as a recorder.
It's a cool concept and, like pretty much everything in the novel, it's based on actual scientific development.
In 2006, DARPA and NASA began developing football sized SPHERES (Synchronized Position Hold Engage Re-Orient Experimental Satellites), which were upgraded in 2013 to be controlled by a smartphone on the ISS.
The latest news is that, like the PALs, they will soon be capable of autonomous movement following the installation of a wi-fi network on the ISS. Each SPHERES robot is powered by 16 AA batteries and moves using jets of compressed CO2.