Mission commander Alan Shepard assembles a double core tube. Astronauts Shepard and lunar module pilot Edgar D. Mitchell, who took this photograph, explored the lunar surface while astronaut Stuart A. Roosa, command module pilot, orbited the moon.
Credit: NASA

Apollo sample 14321 is a specimen collected during the Apollo 14 moonwalking mission in 1971 – and it may have a new story to tell.

Apollo 14 rock sample: 14321
Credit: NASA/LPI

As the third lunar landing, Apollo 14 touched down in the Fra Mauro highlands on February 5, 1971. Commander Alan Shepard and Edgar Mitchell, lunar module pilot, made the mission’s moonwalks.

Last week, Australia’s Curtin University announced that the lunar rock sample gathered by astronauts almost 50 years ago may be originally from Earth, thrown into space when an asteroid struck our planet billions of years ago.

Credit: NASA/Curtin University

Mineral traces

The sample was found to contain traces of minerals with a chemical composition common to Earth and very unusual for the Moon. The lunar collectible 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 Alexander Nemchin, from Curtin’s School of Earth and Planetary Sciences, said the 1.8 gram sample showed mineralogy similar to that of a granite, which is extremely rare on the Moon but common on Earth.

The sample also contains quartz, which is an even more unusual find on the Moon, reports Nemchin.

The research has been published in the journal Earth and Planetary Science Letters.

Cone crater site.
Credit: USGS

 Earth characteristics

By determining the age of zircon found in the sample, scientists 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,” Nemchin adds, “and remarkably similar to that of zircons found on Earth.”

In a Curtin press statement, Nemchin says 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.

Round-trip rock

“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 points out.

“However, 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,” Nemchin says.

Further impacts on the Moon at later times would have mixed the Earth rocks with lunar rocks, at the Apollo 14 landing site too, where Apollo sample 14321 was collected by moonwalkers and hauled back to the Earth – perhaps making a celestial round-trip.

Location of rock sample 14321.
Credit: NASA

Big Bertha

Lunar Sample 14321, a breccia, was collected during the second EVA at Station C1, near the rim of Cone Crater. It was the largest sample returned during the Apollo 14 mission and was also known as “Big Bertha.” This sample is the third largest sample returned by any Apollo mission. The sample was returned in bag 1038.

According to transcripts of the two moonwalkers, Shepard collected sample 14321, a 20-pound (9.0-kilogram) breccia.

The research, Terrestrial-like zircon in a clast from an Apollo 14 breccia, can be found online in Earth and Planetary Science Letters, Volume 510, 15 March 2019, pages 173-185 here:

https://www.sciencedirect.com/science/article/pii/S0012821X19300202?via%3Dihub

For detailed information regarding the geology of the Apollo 14 landing site, go to:

Geological Survey Professional Paper 880 (Swann et al., 1977) here:

https://pubs.usgs.gov/pp/0880/report.pdf

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