Has the Moon been volcanically active in the geologically recent past? Selenography, or moon research, is a relatively young field. Astronomers work with less than six decades’ worth of planet samples, whereas geologists (who study the earth’s forms) work with centuries of material.
“We’re just at the beginning of understanding the Moon,” says Associate Professor of Physics and Astronomy Jonathan Levine.
To find answers to his question, Levine will participate in an upcoming through NASA’s recurring Payloads and Research Investigations on the Surface of the Moon (PRISM) program.
PRISM works like this: A team proposes a plan for research on a specific place on the Moon, and, and if selected, receives funding from NASA and flies to the Moon aboard a future Commercial Lunar Payload Services delivery. Levine’s team, which is led by Scott Anderson at the Southwest Research Institute, has homed in on Ina, a lunar region that Levine describes as “about the size of the village of Hamilton.”
Levine’s team called its proposal the “Dating an Irregular Mare Patch with a Lunar Explorer” (DIMPLE) mission. Ina is their irregular mare patch, or peculiarly young lunar region, of choice. It’s her small craters and their smooth appearance that suggest recent volcanic activity.
But Ina’s appearance could mislead us — if the team discovers that her composition is a foamy mass made of cooled magma, the region may form craters differently than its neighbors. This would mean the region’s small size is due to its make-up and does not indicate its young age.
Thus, the DIMPLE team provided two hypotheses to NASA: “One is that Ina is 3 billion years old or more, like the volcano where it sits. Or, we can take the crater density on these mounds at face value and conclude that Ina is really only about 33 million years old.”
A different, valuable conclusion can be made, regardless of the outcome: “If Ina is very old, then we can’t know the ages of planetary surfaces without also checking on their rock textures,” said Levine. “If Ina is one of the youngest rocks on the moon, we have no idea how the moon could have been holding on to so much heat in the interior to melt rocks relatively recently.”
What’s more, “If the Moon was active 33 million years ago, then maybe the Moon is still warm enough in its interior to produce melt today,” said Levine.
Levine’s mission could thus open a new conversation in the scientific community.
“Either the Moon has been volcanically active much more recently than they taught me about when I was in school, or Ina doesn’t experience the cratering process like other rocks,” said Levine.
The answer requires analyzing rocks from Ina. When it gets there,
DIMPLE will have with it all the tools to examine the local rocks, and radio its findings back to the waiting scientists on Earth. “Our understanding of lunar history is at a stage where we’re still learning how to ask good questions,” said Levine. “The [lunar] rocks tell the story.”