Ranger IX Lunar Chart: Alphonsus.
– St. Louis: United States Air Force, 1966. (Lunar Charts and Mosaics, RLC-14).
The U.S. Air Force issued a series of charts in 1966 based on the Ranger missions. There were seventeen maps published in the RLC series; the first five show increasingly detailed maps of the Fra Mauro/Riphaeus region; maps 6-12 do the same with the Sabine/Ritter region, and maps 13-17 chart the crater Alphonsus.
Alphonsus was at one time slated for the Apollo 17 mission. It was of interest to selenologists because it was "pre-Imbrium," that is, formed of material that predated the impact that created the Imbrium Basin and showered much of the moon with debris. It was also thought at the time that many of the small craters on the Alphonsine floor were volcanic in origin, and sampling might give clues as to when tectonic activity ceased in the moon's interior. Apollo 16 raised doubts about lunar volcanism, however, and Alphonsus was finally replaced by Taurus/Littrow as the site for Apollo 17.