Trailblazer was an American series of rockets used between 1959 and 1973 for research on atmospheric reentry.
Both vehicles were tested at the Wallops Flight Facility on Wallops Island, Accomack County, Virginia and were located under the NASA Langley program (itself located at the Langley Research Center near Hampton, Virginia).
In each test, a different material was used, and ground workers could observe the spectral density and luminance of the artificial "meteorites" that had been created.
Thus, a reference was provided for the luminance of the trails of the artificial meteorites resulting from later tests.
Also, due to the sheer size of it, Trailblazer 2 could hold instruments for measuring and sending data to the ground, greatly enhancing its utility to researchers.