Astronauts should return to the Apollo 15 landing site on the moon and haul home some of its half-century-old poop and hardware, a panel told NASA on Wednesday.
A crew would land just north of the site at Mons Hadley — far enough away to avoid damaging it. From there, the astronauts would walk over to inspect the rover, lander base, instruments, and power systems the prior crew left behind in 1971.
That equipment has endured decades of space radiation and repeated heating and cooling as lunar days give way to nights. Scientists on Earth could study how the lunar environment impacts the hardware over time. A close look at the urine and feces in a lab could reveal how biological material changes and whether it affects the area around it.
That "would be foundational information [for] how we need to engineer the systems for lunar bases," said Dan Dumbacher, co-chairperson of the committee, "for anything humans take to the surface of the moon."
The mission proposal came from a National Academies of Sciences, Engineering, and Medicine committee, whom NASA asked to recommend future moon-landing sites away from the lunar south pole, where the agency already intends to build a long-term moon base. In a new report, members of the committee selected four non-polar sites — Bhabha Crater, Mons Hadley, Orientale Basin, and Aristarchus Plateau — where they believe Artemis astronauts should collect samples, make observations, and conduct experiments. They prioritized locations they believed would benefit from human explorers over uncrewed robots.
These so-called "sorties," the term NASA used when tasking the committee, would be short, one-time visits. Because the poles lack the volcanic terrain found elsewhere on the moon, as well as radioactive metals like uranium and thorium, the brief trips would complement the base, not replace it, according to the report.
Each mission would send a pair of astronauts to make one to four moonwalks within 2 kilometers — or 1.2 miles — of their lander. That distance is a previously established "walkback" limit NASA decided long ago that the committee thinks the agency should try to extend. The panel also chose landing sites that offered the most opportunities for geology, biology, human health, and physics research.
The top pick, Bhabha Crater, sits inside what may be the solar system's largest and oldest crater, and its rocks could pin down when that massive impact happened. Situated on the far side of the moon, the crew would have to land farther from home than any humans before, letting NASA test how astronauts cope with isolation.
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The site is also prime for a telescope, said James Day, the other chairperson of the committee.
"It's an almost unmatched location for doing radio astronomy, and the reason for this is because it's in the quiet zone on the far side of the moon. It is shielded from the noise that we produce here on Earth," Day said. "This will give us information on the very early universe before the first stars or galaxies had formed."
At Orientale, the moon's youngest large basin at roughly 3.8 billion years old, astronauts would collect boulders from deep in the crust that could show whether the moon was once entirely molten. They would also set up a detector for gravitational waves — ripples in spacetime. The instrument could alert astronomers months before distant neutron stars collide, the committee leaders said.
Finally, the Aristarchus Plateau, an Apollo destination that NASA never reached, holds volcanic deposits that may yield water. It spans about 60 miles, so crews there would gain the most from the simple open rover the committee thinks NASA should build.
Among its recommendations, the panel said NASA should keep mapping the moon in detail from orbit, build instruments that can run through the lunar night, and set up a communications system that keeps crews in constant contact with Earth, even on the far side.
NASA will decide when and in what order to fly the missions.
"All four of these sites will give us profound knowledge," Day said, "not just of our moon, but of our solar system, and frankly of ourselves."