On one side of the Orbiter is a 2.2 metre-diameter
communications dish – the steerable high-gain antenna – while the Lander is attached to the opposite face. Two enormous solar wings extend from the other sides. These panels, each 32 square metres in area, have a total span of about 32 m tip-to-tip. Each of them comprises five panels,
and both may be rotated through ±180 degrees to catch the
maximum amount of sunlight.
In the vicinity of Comet Wirtanen, the scientific instruments
will almost always point towards the comet, while the
antennas and solar arrays point towards the Sun and Earth (at large distances, they are looking more or less in the same direction).
In contrast, the Orbiter's side and back panels are in shade for
most of the mission. Since these panels receive little sunlight, they are an ideal location for the spacecraft's
radiators and louvers. They will also face away from the comet, so damage from comet dust will be minimised.
