Meteorites can indeed be magnetic, but the use of handheld magnets to identify them can have detrimental effects on their magnetic record, as demonstrated by various studies. The magnetic memory of meteorites can provide valuable information about their history, including their formation, exposure to magnetic fields, and even their parent bodies in the solar system. However, handheld magnets can erase this magnetic memory, making it difficult for scientists to study the meteorites’ past.
Understanding Meteorite Magnetism
Meteorites are fragments of celestial bodies, such as asteroids, comets, or planets, that have survived the journey through Earth’s atmosphere and landed on the surface. These extraterrestrial rocks can exhibit a wide range of magnetic properties, which are influenced by their composition, formation history, and exposure to magnetic fields.
Magnetic Susceptibility
To quantify the magnetic properties of meteorites, researchers often measure their magnetic susceptibility, which is a measure of how responsive a material is to an external magnetic field. Magnetic susceptibility is a dimensionless quantity that represents the ratio of the induced magnetization within a material to the applied magnetic field.
The magnetic susceptibility of a meteorite can be expressed as:
$\chi = \frac{M}{H}$
Where:
– $\chi$ is the magnetic susceptibility
– $M$ is the induced magnetization
– $H$ is the applied magnetic field
Meteorites with higher magnetic susceptibility values are more responsive to external magnetic fields and are more likely to be attracted to handheld magnets.
Magnetic Remanence
In addition to magnetic susceptibility, meteorites can also exhibit magnetic remanence, which is the ability of a material to retain a magnetic field even in the absence of an external magnetic field. This property is particularly important for understanding the history of a meteorite, as it can provide information about the magnetic fields it was exposed to during its formation and journey through space.
Magnetic remanence is typically measured in units of magnetic flux density (Tesla) or magnetic moment (Am^2). Meteorites with strong magnetic remanence can retain a record of the magnetic fields they experienced, which can be used to study the magnetic history of their parent bodies and the early solar system.
Magnetic Mineralogy
The magnetic properties of meteorites are largely determined by their mineral composition. The most common magnetic minerals found in meteorites include:
- Magnetite (Fe3O4): A ferromagnetic mineral that is a common component of many meteorites.
- Hematite (Fe2O3): An antiferromagnetic mineral that can also contribute to the magnetic properties of meteorites.
- Pyrrhotite (Fe1-xS): A ferromagnetic mineral that is often found in iron-nickel meteorites.
- Kamacite (α-Fe, Ni): A ferromagnetic iron-nickel alloy that is a major component of iron meteorites.
The relative abundance and distribution of these magnetic minerals within a meteorite can significantly influence its overall magnetic properties.
The Destructive Effects of Handheld Magnets
One example of the destructive effects of handheld magnets on meteorites is the case of the “Black Beauty” meteorite, which was found in Morocco in 2011. The meteorite, which originated on Mars 4.4 billion years ago, had its primordial magnetic fields erased by exposure to hand magnets, taking away precious records of early Mars in the process.
Magnetic Memory Erasure
Handheld magnets can erase the magnetic memory of meteorites, which is a critical piece of information for scientists studying their history and origin. The strong magnetic fields generated by these magnets can overwrite the existing magnetic remanence in the meteorite, effectively erasing the record of the magnetic fields it was exposed to during its formation and journey through space.
This loss of magnetic memory can make it difficult for scientists to study the meteorite’s past, as they are unable to access the valuable information stored in its magnetic record. This can hinder our understanding of the early solar system, the magnetic fields of parent bodies, and the processes that shaped the formation and evolution of meteorites.
Magnetic Susceptibility Alteration
In addition to erasing magnetic memory, handheld magnets can also alter the magnetic susceptibility of meteorites. The strong magnetic fields generated by these magnets can induce changes in the magnetization of the meteorite, affecting its overall magnetic response to external fields.
This alteration of magnetic susceptibility can make it more difficult for researchers to accurately classify and identify meteorites using magnetic susceptibility measurements. It can also compromise the reliability of any magnetic data collected from the meteorite, as the original magnetic properties may have been significantly modified.
Magnetic Susceptibility Meters: A Non-Destructive Alternative
To avoid damaging meteorites’ magnetic records, researchers recommend using magnetic susceptibility meters instead of handheld magnets for identification and classification. These instruments can provide quantitative measures of a meteorite’s magnetism, allowing scientists to distinguish between meteorites of different groups and study their magnetic records without damaging them.
Portable Magnetometers
Portable magnetometers are a type of magnetic susceptibility meter that can be used to measure the magnetic properties of meteorites in the field. These instruments are designed to be lightweight, compact, and easy to use, making them a practical tool for meteorite hunters and researchers.
One example of a portable magnetometer is the Bartington Mag-03 series, which can measure magnetic field strength, magnetic susceptibility, and magnetic remanence in three orthogonal axes. These instruments can provide detailed information about the magnetic properties of a meteorite without the risk of erasing its magnetic memory.
Magnetic Susceptibility Mapping
In addition to point-based measurements, some researchers have developed techniques for mapping the magnetic susceptibility of large meteorites. This approach involves using a grid-based scanning system to collect detailed spatial data on the magnetic properties of the meteorite.
By mapping the magnetic susceptibility of a meteorite, scientists can gain a better understanding of its internal structure and composition. This information can be used to identify different magnetic mineral phases, detect any heterogeneities or inclusions, and even infer the meteorite’s formation history.
Magnetic Remanence Analysis
Alongside magnetic susceptibility measurements, researchers can also analyze the magnetic remanence of meteorites to study their magnetic history. This involves measuring the intensity and direction of the remnant magnetization within the meteorite, which can provide insights into the magnetic fields it was exposed to during its formation and journey through space.
Techniques such as alternating field (AF) demagnetization and thermal demagnetization can be used to isolate and analyze the different components of a meteorite’s magnetic remanence. This information can be used to reconstruct the magnetic history of the meteorite and its parent body, shedding light on the early solar system environment and the processes that shaped the formation of planetary bodies.
Conclusion
In summary, while meteorites can be magnetic, the use of handheld magnets to identify them can have detrimental effects on their magnetic record. Magnetic susceptibility meters and portable magnetometers are more useful and non-destructive alternatives for meteorite identification and classification, allowing scientists to study the magnetic properties of these extraterrestrial rocks without compromising their valuable magnetic memory.
By understanding the magnetic properties of meteorites and the importance of preserving their magnetic records, researchers can gain valuable insights into the formation and evolution of the solar system, as well as the magnetic fields of their parent bodies. This knowledge can contribute to our broader understanding of the universe and the processes that shape the development of planetary systems.
References
- Weiss, B. P., et al. (2020). A Portable Magnetometer for Magnetic Measurements of Meter-Sized Meteorites. Geochemistry, Geophysics, Geosystems, 21(10), e2020GC009266.
- Weiss, B. P., et al. (2023). A message to meteorite hunters: Put down your magnets! MIT News.
- Vervelidou, F., et al. (2023). Hand Magnets and the Destruction of Ancient Meteorite Magnetism. Journal of Geophysical Research: Planets, 128(5), e2022JE007464.
- Sky & Telescope. (2023). Magnets Are Bad News for Meteorites.
- News, M. I. T. (2023). A message to meteorite hunters: Put down your magnets!.
Hi..I am Indrani Banerjee. I completed my bachelor’s degree in mechanical engineering. I am an enthusiastic person and I am a person who is positive about every aspect of life. I like to read Books and listen to music.