Reference to Apollo 18 found in obscure document prepared by the National Space Science Data Center in 1988. The document entitled NASA Compendium of Meteorological Space Programs, Satellites, and Experiments provides information on all space missions, manned and unmanned, that carried out meteorological experiments.
Apollo 1-7, 9, and 18* were placed in earth orbit (1-3 were suborbital), and of these only the last three (7, 9, and 18) were manned. All of them were launched by the Saturn 1B configuration, with the exception of Apollo 4 and 6, for which the Saturn 5 was used. All of these flights were primarily to test and evaluate equipment to be used for the lunar flights, except for the scientific political flight of Apollo 18. Apollo 10-17 were all manned lunar flights. Apollo 8 and 10 were test flights with a test of the lunar module. Apollo 11-17 were planned lunar landing missions. Of these seven landers, only Apollo 13 failed to land due to an inflight explosion; however, the flight path circumnavigating the moon and returning to earth was successfully accomplished. An earth photography experiment was included on Apollo 6 – Apollo 18. All photographs were taken by means of hand-held Hasselblad 70-mm and Maurer 16-mm cameras with the exception of the unmanned Apollo 6, on which a fixed mount, sequencing camera was used.
*Apollo18 and Soyuz 19(1975-065A and 1975-066A), more frequently referred to as Apollo Soyuz,were launched independently and then docked in orbit. The crews jointly accomplished various observations and tests, undocked,and made their separate descents.