The last time men walked on the moon was during the flight of Apollo 17, 43 Decembers ago. According to a Thursday story in Forbes, lunar soil and rock samples returned by the last moonwalkers are still yielding new insights into the history and nature of Earth’s nearest neighbor. In the meantime, the latest explorer to go to the moon, a Chinese robotic rover named Yutu, has made some discoveries of its own.
The first discovery, made over four decades ago by astronauts Gene Cernan and Harrison Schmitt, the later the first and thus far only geologist to walk on the moon, ran into orange soil near the landing site in the Taurus-Littrow highlands and valley area, remarkable since the moon had thus far been a universally gray world.
“What the analysis back on Earth revealed was fantastic: this was volcanic glass. What occurred was that molten lava from the interior of the Moon erupted, some 3 to 4 billion years ago, up above the airless surface and into the vacuum of space. As the lava became exposed to the vacuum, it separated out into tiny fragments and froze, forming tiny beads of volcanic glass in orange and black colors. (The tin in some of the fragments is what gives the orange color.)”
That finding was spectacular enough to the scientists who uncovered it. But, as a new generation of researchers found out, there was more.
“Over the decades after the Apollo missions concluded, technology continued to advance. In 2011, a team was able to analyze the samples that Schmitt and Cernan brought back, and found something spectacular: evidence that water was included during this volcanic eruption. The glass beads, based on the dryness of the Moon, should have had water concentrations of no more than 1 part-per-million (ppm), but instead exhibited water concentrations some 50 times as great. Moreover, there are olivine inclusions identified by the recent analysis, showing the presence of water in up to ~1,200 ppm concentrations.”
That concentration of water is the same amount as exist in the interior of the Earth, evidence that lunar rocks and Earth rocks have the same origin. The discovery was made because a human geologist was present, who was trained in what to look for where it came to soil and rock samples.
Meanwhile, separated from Apollo 17 in both time and space, the Chinese rover Yutu has made some discoveries that have scientists excited.
“When Yutu finally began sending back data, the mix of minerals the rover uncovered surprised planetary scientists. While the moon rocks uncovered during the American and Soviet moon missions in the 1960s and ‘70s contained either extremely high or low titanium levels, the samples Yutu dug up sat almost right in the middle. The rocks were also surprisingly rich in iron oxide and an igneous rock called olivine, Ferreira reports.
“While the Earth’s upper mantle is more or less made of consistent materials throughout, the regolith that makes up the moon’s surface varies greatly from region to region, planetary scientist Bradley Joliff, who was the only American member of the Chinese group that analyzed the rover’s findings, tells Radford.
“Plus, a smaller crater in Yutu’s range was created only about 100 million years ago, giving the plucky rover plenty of material to study rocks from different periods of the moon’s history.”
One can only imagine what insights will be had when a latter-day Harrison Schmitt arrives to make further exploration with the eye of a trained geologist.
The lesson therein is that among all of the other reasons for returning to the moon, reasserting space leadership, moon mining, and supporting the Journey to Mars, science is still among the arguments as to why there is unfinished business left over from Apollo.