Chief Science Officer
This character is responsible for obtaining information, analyzing data, reporting and making recommendations to command concerning all scientific information that is needed to acheive mission objectives. This character should have a solid background in all the physical sciences: physics, chemistry, astronomy, biology, zoology, xenobiology. The player choosing to play a science officer deosn't need to have a background in science in real life, but it is wise to research a subject in order to write technobable that is believable and interesting.
The CSO maintains a science lab station on the bridge, and also has an office in the main science lab.
An example from Star Trek would be Spock.
This is a department leadership position that is heavily featured in most missions and will see activity frequently.