This is the Dart portion of the solid-fuel Cajun-Dart sounding rocket. The Dart held the miniaturized payload for gathering weather data from the upper atmosphere. The small, low-cost, low-altitude Cajun-Dart was developed by the Space Data Corporation under contract to NASA. The first flight tests were made at Eglin Air Force Base, Florida, in 1964.
The rocket was meant for meteorological studies and designed to carry payloads to 60-80 km (50-60 miles) but it was used as a chaff rocket at Cape Kennedy. Chaff is shredded tin foil. The foil created artificial clouds that could be tracked by radar to study wind speed and direction at different altitudes.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.