“It would be tantalizing to find microfossils of extraterrestrial forms of life on the moon. Even more exciting would be to find traces of technological equipment that crashed on the lunar surface a billion years ago, amounting to a letter from an alien civilization saying, “We exist,” speculated Harvard University astronomer, Avi Loeb, asking: can the moon provide clues for extraterrestrial life?
“The absence of a lunar atmosphere,” writes Loeb in “The Moon as a Fishing Net for Extraterrestrial Life”, “guarantees that these messengers would reach the lunar surface without burning up. In addition, the geological inactivity of the moon implies that the record deposited on its surface will be preserved and not mixed with the deep lunar interior. Serving as a natural mailbox, the lunar surface collected all impacting objects during the past few billions of years. Most of this “mail” comes from within the solar system.”
Apollo 14 Discovery –At the edge of Cone Crater
Less speculative than Loeb’s conjecture, was the discovery of a rock found by astronaut Astronaut Alan Shepard at the Apollo 14 landing site near the edge of Cone Crater, where it had rested for millions of years, and brought it back to Earth for analysis.
The ‘Apollo rock’ formed on the Earth and brought to the surface of the moon as a meteorite generated by a massive asteroid hitting Earth about four billion years ago –a period known as the Hadean Eon (image below) when impact craters, some flooded by shallow seas, cover large swaths of the Earth’s surface. The excavation of those craters ejected rocky debris, some of which hit the Moon. Apollo 14 was the last of NASA’s “H missions” –landings at specific sites of scientific interest on the Moon for two-day stays with two lunar extravehicular activities –EVAs or moonwalks.
In 2019 findings published in science journal Earth and Planetary Science Letters, confirmed that the sample collected during the 1971 Apollo 14 lunar mission contained traces of minerals with a chemical composition common to Earth and very unusual for the moon.
The sample was on loan from NASA to Curtin University, where it was investigated in cooperation with researchers from the Swedish Museum of Natural History, Australian National University and Lunar and Planetary Institute in Houston.
Research author professor Alexander Nemchin, from Curtin’s School of Earth and Planetary Sciences, said the 1.8 gram sample showed mineralogy similar to that of granite, which is extremely rare on the moon but common on Earth.
Similar to the oldest rocks on Earth
“The sample also contains quartz, which is an even more unusual find on the moon,” Nemchin said. “By determining the age of zircon found in the sample, we were able to pinpoint the age of the host rock at about four billion years old, making it similar to the oldest rocks on Earth. In addition, the chemistry of the zircon in this sample is very different from that of every other zircon grain ever analyzed in lunar samples, and remarkably similar to that of zircons found on Earth.”
Nemchin said the chemistry of the zircon lunar sample indicated that it formed at low temperature and probably in the presence of water and at oxidized conditions, making it characteristic of Earth and highly irregular for the moon.
“It is possible that some of these unusual conditions could have occurred very locally and very briefly on the moon and the sample is a result of this brief deviation from normality,” Nemchin said.
“However,” he concluded, “a simpler explanation is that this piece was formed on the Earth and brought to the surface of the moon as a meteorite generated by an asteroid hitting Earth about four billion years ago, and throwing material into space and to the moon.”
The Last Word
When asked about findings from the Apollo sample, planetary scientist David Kring, a Universities Space Research Association (USRA) scientist at the Lunar and Planetary Institute (LPI) who has worked extensively with the Chicxulub impact crater, told The Daily Galaxy: “The collisional environment was so violent during the first billion years of Solar System evolution that samples of Hadean Earth certainly peppered the lunar surface. Calculations with my colleague Dan Durda in 2002 indicated that 12% of the high-energy ejecta from the Chicxulub impact escaped Earth’s gravity and sped through the Solar System. Some of that material may have intersected the lunar surface.”
Mass-extinction expert, Peter Brannen in his book Ends of the World, noted the possibility of dinosaur fragments that might exist on the lunar surface from the massive Chicxulub asteroid impact 66 million years ago.
In an email to The Daily Galaxy, Marc Norman, a geophysicist at Australia National University, said about the sample collected during the 1971 Apollo 14 mission that was found to contain traces of minerals with a chemical composition common to Earth and very unusual for the moon, “that the Apollo 14 fragment. It is a provocative result but not definitive for delivery of bits of Earth to the Moon. An alternative might be that the Moon is more diverse than we thought. Either way, it is very interesting.
“Regarding mass-extinction expert, Peter Brannen’s conjecture in his book Ends of the World, about the possibility that dinosaur fragments that might exist on the lunar surface from the massive Chicxulub asteroid impact 66 million years ago, there is no evidence that I know of for fragments of dinosaur bone on the Moon,” Norman noted. “At the time of the Chicxulub impact, the Yucatan was a shallow sea overlying an igneous basement, so a high concentration of dinosaurs in the target would not be expected.
“In any case, the immediate target would have been vaporized,” Norman noted in his email. “While there are well-documented meteorites on Earth that came from the Moon and Mars, both of these are small bodies with thin atmospheres that make it easier to eject small (a few kg) fragments that eventually make their way to the Earth. Launching material off the Earth is theoretically possible but we have no direct evidence that this actually happened, so far. Also, the Moon has a very low gravity so any material that was launched off the Earth would have a small probability of landing on the Moon.
“An alternative,” Norman suggested in his email, “might be to look for traces of elements that are known to have been present in the target or the Earth’s atmosphere, such as sulfur and nitrogen. The isotopic compositions of these elements have been strongly modified on Earth by biological activity that did not happen on the Moon, but any signature in lunar soils would be very slight. Small bits of glass with the compositions of Earth’s crust might also have been delivered to the Moon but nothing like this has been documented, as far as I know.”
The research was supported by NASA’s Solar System Exploration Research Virtual Institute (SSERVI) through a cooperative agreement with the CLSE, a joint venture between the LPI and NASA’s Johnson Space Center.
Image credit top of page: NASA image via Shutterstock License. Hadean Earth, Simone Marchi.