Hera hyperbolic arcs

The gravity levels of the Didymos asteroid pair are too low for the spacecraft to go into orbit in any traditional sense. Instead (borrowing a technique from ESA’s Rosetta comet-chaser) Hera will fly in ‘hyperbolic arcs’ – resembling a series of alternating flybys, reversed by regular thruster firings every three to four days. In the case of any normal mission, this amount of repeat velocity changes would soon exhaust its propellant tanks, but the gravity level around Didymos is so low that Hera will only be flying at a typical relative velocity of around 12 cm per second. See a visualisation here.