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A short time later, Schmitt will probably be seen carrying off the familiar dumbbell-shaped package of scientific gear called ALSEP (for Apollo Lunar Surface Experiments Package). At a site some 300 ft. west of Challenger, Geologist Schmitt, with Cernan's help, will set up the five ALSEP experiments, giving space scientists their fifth automatic observatory on the moon (see Lunar Science, page 44). The ALSEP experiment that the scientists are particularly eager to monitor involves two probes that measure the flow of heat from the moon's interior. During Apollo 16, that $1,200,000 experiment was ruined when Astronaut John Young tripped over one of the cables connecting the probes to the central transmitter and ripped the wire loose. To avoid the possibility of a similar accident, all of ALSEP'S external leads have been fitted with stress absorbers—folded tucks in the leads that will come undone if they are tugged too hard.
After buckling themselves into the rover the astronauts will continue their first EVA by driving southeast for about one mile to the edge of a 2,000-ft.-wide crater called Emory. It is here that Schmitt hopes to recover fine-grained dark material, called pyroclastics (literally, broken up by fire), which may be a sign of relatively recent volcanic eruptions. If Schmitt's trained eye happens to spot any interesting material between scheduled stops, he will be able to pick it up without leaving his seat in the rover; at hand will be an extension pole with a device similar to a Dixie cup holder at its far end. After he scoops up a rock or dust with the topmost cup in the holder, Schmitt will remove the cup and its contents, seal the little container and stow it away.
During this EVA, the astronauts will plant the first three of the eight small packages of explosives that NASA calls "the world's safest land mines." Equipped with radio receivers and timers, the packages will be ignited by signals from earth after the astronauts leave the moon. Their blasts—which will register on the ALSEP'S geophones and thus provide data about the moon's interior—may well be seen on earth through the remote-controlled TV camera atop the abandoned rover.
Volcanic Eruption. Refreshed after an eight-hour sleep period, the astronauts are scheduled to start their second EVA at 5:03 p.m. Tuesday, Dec. 12. Heading southwest, they will drive nearly four miles to the base of South Massif and collect samples from a rock-strewn region that scientists believe was formed by a huge landslide from the upper slopes of that mountain billions of years ago. Scientists hope that the rocks consist largely of highland material far older than the relatively young rock of the valley floor. En route back to the LM, the astronauts will stop at a 300-ft.-wide crater called Shorty, which may yield entirely different material: deep-lying rock that was either ejected by a meteor impact or a volcanic eruption that occurred after the landslide covered the area.