On 10 July, ESA’s Rosetta will fly past 21 Lutetia, the largest asteroid ever visited by a satellite. After weeks of manoeuvres and a challenging optical navigation campaign, Rosetta is perfectly lined up to skim by at 3162 km. Rosetta is expected to pass Lutetia at a relative speed of 54 000 km/hr, when both are located some 454 million km from Earth. As Lutetia is a major scientific target of Rosetta’s mission, most of the orbiter and lander instruments will be on for flyby, studying the asteroid’s surface, dust environment, exosphere, magnetic field, mass and density.