The items brought back to Earth by astronauts in 1972 may contain “fossils” of a world from 4.36 billion years ago.
According to Live Science, a new study led by Professor John Tarduno, an Earth scientist from the University of Rochester (USA), suggests that lunar rocks could be a priceless treasure that allows us to “travel back in time” to understand the early Earth.
Specifically, the oldest evidence of Earth’s ancient atmosphere may be hidden within the rocks on its own satellite.
Overview of Plum Crater, with Apollo 16 Commander John Young standing on the left. The sample “Big Muley” they brought back was taken right next to where Young is standing – (Photo: NASA)
Professor Tarduno’s team reanalyzed the lunar rocks that astronauts from NASA’s Apollo 16 mission brought back to Earth in 1972.
When the samples were first returned, scientists discovered magnetic traces locked within the rocks, indicating that these rocks must have originated from a celestial body with a magnetic field.
This was quite puzzling because the Moon’s core is too small to possess its own magnetic field. Therefore, scientists had previously suspected that the Moon once had a magnetic field in some way.
After 50 years, the new study confirms that the Moon was only protected by a magnetic field for the first 140 million years after its formation, meaning it has not had a magnetic field for the past 4.36 billion years.
Instead, the ancient data captured by scientists over half a century ago represents traces of the ancient magnetic field of Earth!
Without a protective magnetic field, the Moon could capture ions from Earth’s atmosphere. These ions left behind magnetic signatures and may represent chemical traces of the ancient atmosphere of Earth.
Cross-referencing the timelines, it is clear that the lunar rocks influenced by Earth’s magnetic field occurred around 4.36 billion years ago. The ions it captured are likely representative of the atmospheric composition at that time.
According to Professor Tarduno, one of the mysteries surrounding Earth and its evolutionary process is the composition of the planet’s first atmosphere.
The Sun, a relatively young star at that time, was less luminous. Therefore, to avoid existing as a barren ice sphere, Earth had to possess the ability to warm itself.
This capability could have been provided by the necessary greenhouse gases in the atmosphere. This is what helped “reshape” the planet, paving the way for life to evolve.
However, we cannot find traces of this first atmosphere on Earth itself.
Very few types of rocks older than 3.5 billion years remain on Earth. The rare remnants that do exist have been significantly altered by ongoing tectonic activity.
In contrast, the Moon is geologically quiet, Tarduno notes, and has a regolith (lunar soil) that may not have been disturbed for billions of years, making it an excellent place to study what it has unintentionally preserved about early Earth.
The study has just been published in the scientific journal Communications Earth & Environment.
