

Cosmic background radiation provides a stable frame of reference for setting up a coordinate system. If the explorers have a main HQ base, it can be set as the origin (0,0,0). The location of an object in space can be communicated using a tuple like (10km, 30°, 30°), representing the radius (distance to the object), polar angle (angle between the positive z-axis and the line connecting the origin to the point), and azimuthal angle (angle between the positive x-axis and the line connecting the origin to the point on the xy-plane).
Alternatively, if only a general region is needed, grid coordinates can be used with any useful unit of measurement for the distance between grid lines.
When one member of the family has given up on joining clubs because their sister always joined the same clubs they did even if they hate that hobby and after a quiet word here and a quiet word there they get them kicked out of the club , which they then get bored with and decide it really is not that interesting after all and return to mocking that hobby.