Solo operations of Apollo 15
During the 1971 Apollo 15 mission to the Moon, and its three days of exploration on the lunar surface by David Scott and James Irwin, Command Module Pilot (CMP) Al Worden had a busy schedule of observations.
The Metric Camera took square frames of film, covering about 27,000 km2 of the lunar surface, with a resolution of about 20 m. Using the stellar camera, Réseau plates (which added the familiar crosses to Apollo photographs), and other data provided by the laser altimeter, it was possible to identify the exact position on the lunar surface of the photograph taken.
This was of great help to mission planners as it would help them further refine the planning of the traverses by Scott and Irwin, and also help with photographic interpretation from the surface.
During the 17th near side pass, while Worden was eating his dinner, the spacecraft was oriented so that its radio signal would reflect off the Moon and be received by the Earth.
Before going to sleep, Worden orientated the spacecraft best for the various experiments of the SIM bay, specifically the spectrometers.
As the gamma ray passed through a cylinder of doped sodium iodide, it would emit light that would be detected by a photomultiplier tube.
Another photomultiplier tube detected charged particles that passed through a plastic shield around the cylinder.
He spent much of his time switching various experiments on and off and acquiring photographs of targets of interest on the lunar surface.
Ideally for scientists, a mission would be placed in a polar orbit for a month, from where it could observe the entire lunar surface.
Lunar scientists were particularly interested in rocks that had higher concentrations of samarium, uranium, thorium, potassium and phosphorus.
They gave these rocks the acronym KREEP (potassium (atomic symbol K), rare earth elements (REE), and phosphorus (P)).
It is believed that KREEPs represent the last chemical remnants of the "magma ocean" after the lunar crust formed.
KREEPs floated to the surface because their component elements are "incompatible", that is, they did not incorporate into compact crystal structures.
In the late 1990s, results from Lunar Prospector's gamma ray spectrometer shows that KREEP-containing rocks are concentrated in the Mare Imbrium rim, the near side maria and highlands near Imbrium and the Mare Ingenii South Pole-Aitken basin and are distributed at a lower level in the highlands.
He and Farouk El-Baz had decided to use the phrase "Hello Earth; Greetings from Endeavour" but in different languages, ranging from Arabic to Spanish.
It had been found on even the short duration flights, the crews became weakened due to the lack of gravity.
This was composed of orange glass beads which were sprayed while molten from a fumarole or lava fountain 3.64 billion years ago.
146 hours after launch, Worden position the spacecraft so that he could take photographs of the region of the 'sky' opposite the Sun, in hopes of seeing the gegenschein.
This faint glow is thought to be caused by tiny particles in the interplanetary medium reflecting light back at the observer.
However he had difficulty due to the Sun having risen higher, making the relief much less and the surface much brighter.
