Space Cover #67, Testing the Saturn Engine
There are 1000s of non-descript covers without cachets in dealer dollar boxes. Collectors should check through them carefully as there are certainly treasures to be found. The cover pictured is like those typically found in the dollar boxes. It is cancelled on September 2, 1966 in Huntsville, Alabama with nothing more than a "S-IB Static Firing" typed cachet. Most dealers wouldn't know what "S-IB" stands for or what a "Static Firing" is... so in the dollar box it goes.
This "S-IB Static Firing" on September 2, 1966 cover is commemorating a test firing of the Saturn I-B engine developed by the Marshall Space Flight Center located in Huntsville, Alabama. While covers for the space shuttle engines are plentiful the covers for similar tests for the Mercury-Gemini-Apollo programs are very rare and highly sought after as the events were rarely publicly announced in advance and thus collectors had no way to service covers.
While many collectors have covers for the actual Saturn rocket launches having covers such as this one help tell the story of the many locations involved in the development efforts to land a man on the moon. So if you find one...