Meteorite is 'hard drive' from space ~ Researchers decode ancient recordings from asteroid ~ BBC

The Esquel meteorite consists of gem-quality crystals embedded in metal.

They found tiny “space magnets” in meteorites which retain a memory of the birth and death of the asteroid’s core.

Like the data recorded on the surface of a computer hard

drive, the magnetic signals written in the space rock reveal how Earth’s

own metallic core and magnetic field may one day die.

The work appears in Nature journal.

Using a giant X-ray microscope, called a synchrotron, the

team was able to read the signals that formed more than four-and-a-half

billion years ago, soon after the birth of the Solar System.

They represents the left-over fragments of a planet that

failed to form. The magnetic recording within it traps a signal of the

precise moments when an iron-rich core formed in the asteroid as well as

when it froze, killing its magnetic field.

The new picture of metallic core solidification in the

asteroid provide clues about the magnetic field and iron-rich core of

Earth.

Core values
“Ideas about how the Earth’s core evolved through [our

planet’s] history are really changing at the moment,” lead researcher Dr

Richard Harrison, from the University of Cambridge, told BBC News.

“We believe that Earth’s magnetic field is linked to core

solidification. Earth’s solid inner core may have started to form at

very interesting time in terms of the evolution of life on Earth.

“By studying an asteroid we get to see this in fast forward.

We can see the start of core solidification in the magnetic records as

well as its end, and start to think about how these processes work on

Earth.”

The Earth’s magnetic field will likely die off when the core completely freezes

The meteorites studied by the team originally fell to Earth in

Argentina, and are composed of gem-quality crystals enclosed in a

metallic matrix of iron and nickel. 

Tiny particles, smaller than one thousandth the width of a

human hair, trapped within the metal have retained the magnetic

signature of the parent asteroid from its birth in the early Solar

System.

“We’re taking ancient magnetic field measurements in

nano-scale materials to the highest ever resolution in order to piece

together the magnetic history of asteroids – it’s like a cosmic

archaeological mission,” said Dr James Bryson, the paper’s lead author. 

“Since asteroids are much smaller than Earth, they cooled

much more quickly, so these processes occur on a shorter timescales,

enabling us to study the whole process of core solidification.”

Prof Wyn William, from the University of Edinburgh, who was

not involved in the study, commented: “To be able to get a time stamp on

these recordings, to get a cooling rate and the time of solidification,

is fantastic. It’s a very nice piece of work.”

The key to the long-lived stability of the recording is the

atomic-scale structure of the iron-nickel particles that grew slowly in

the asteroid core and survived in the meteorites. 

Making a final comment on the results, Dr Harrison said: “In

our meteorites we’ve been able to capture both the beginning and end of

core freezing, which will help us understand how these processes

affected the Earth in the past and provide a possible glimpse of what

might happen in the future.” 

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Meteorite is 'hard drive' from space ~ Researchers decode ancient recordings from asteroid ~ BBC