Using old-fashioned steam power, two cubesats executed the first coordinated maneuver in low-Earth orbit. Some call it ‘talk’ – some call it ‘dance’.
The propulsive movement happened after one of the twin spacecraft — with help from the ground — commanded the other to close the 5.5-mile (8.85-kilometer) gap separating the cubesats. Each spacecraft carries fuel tanks filled with water, which thrusters converted to steam to help the cubesats move closer together.
Read more
https://www.space.com/steam-water-cubesats-dance-in-space.html
