By 23rd and 24th centuries, it was generally accepted that brain activity could have a significant influence on the environment or on other individuals. The exact means by which this occurs varies and was not always well understood. Examples of measurable effects of neurological activity are the psionic and bioelectric fields, although psychological effects were also observed in relation to warp bubbles, the Great Barrier and some extreme areas of space.
April 1966: Further modifications for regular series run (TOS: "The Corbomite Maneuver" onwards). (1966)
1974: The model arrives at the Smithsonian NASM in a crate, with minor damage and missing parts. It's restored.
1984: NASM renovation
1991: NASM renovation, adding very visible weathering and hull lining that were not present on the original model. This is the current state of the model.
For TOS: "Mirror, Mirror", a variation of the model was created to represent the Imperialstarship Enterprise. It was based on the first configuration of the eleven foot model, and had a darker, metallic grey hull.