Hess, MSC Director of Science and Applications, reviewed the Group for Lunar Exploration Planning (GLEP) meeting in Washington December 8 and 9, which had examined potential sites for lunar exploration beyond Apollo based on scientific objectives and not operational considerations. He pointed out that during the GLEP group study at Santa Cruz, Calif., in the summer, scientists had strongly recommended a manned orbital mission be flown before manned landings, to gain additional photographic information for more effective mission planning and to make remote-sensing measurements to detect anomalies on the lunar surface. Hess said this position had changed to some extent.
Hess pointed out that lunar exploration was the responsibility of the new Lunar Exploration Office at NASA Hq. The office had further been subdivided into the Lunar Science Office, responsible for science and experiment planning, and the Flight Systems Office, responsible for modifications in the Apollo spacecraft to increase capability for developing advanced support systems such as mobility units and for developing the advanced ALSEP packages. Hess felt that dual launches, if conducted at all, would be carried out in the far distant future and therefore directed his group to select sites for nine single-launch missions, three of which should be planned without the aid of mobility and be limited to one-and-a-half kilometers; and the other six sites limited to five-kilometer maximum mobility radius.
Ground rules used in reduction of the proposed 39 lunar exploration sites were:
- landing accuracy would be improved so the LM would land within a one-kilometer radius circle around the target point;
- Lunar Orbiter high-resolution photography must cover any site considered;
- science payload including mobility devices would be limited to 340 kilograms and
- the lunar staytime would be limited to three days to include four extravehicular (EVA) periods totaling 24 hours.
Hess mentioned new criteria which would affect mobility on the lunar surface. He said that MSC's Director for Flight Crew Operations Donald K. Slayton stated he would permit a single roving vehicle to go beyond walk-back distance if the vehicle had two seats so that both astronauts could simultaneously and if the unit carried two spare back-packs. Hess said, "This new criteria, however, would result in a roving vehicle weight of well over 227 kg when the backpacks were induced and thus could not be carried on a single launch mission."