Optical instruments are sometimes put in on an articulated, powered appendage for the spacecraft bus called a scan platform, which points in commanded directions, letting optical observations being taken independently in the spacecraft's Angle. This is the situation on Voyager and Galileo. Most more recent spacecraft are created without scan https://edwineggfc.theideasblog.com/29324898/a-secret-weapon-for-lab-testing-equipment-suppliers