Highlighted Research News on Micrometeorites and More

Recent Planetary News

  • Metsoc Brussels logo

    MetSoc Brussels 2024

    MetSoc is an international conference held each year in various countries across the globe, dedicated to the promotion of research and education in planetary science (particular those related to meteorites). This year the meeting was hosted by hosted by the Université libre de Bruxelles, the Vrije Universiteit Brussel, and the Institute of Natural Sciences in Brussels, Belgium. We had plenty of amazing talks given by early careers and experienced researchers in a full range of topics. Last year's winner of the Leonard Medal, which honors outstanding contributions to the science of meteoritics and closely allied fields, went to Professor Monica Grady (a British space scientist working at The OU). This year the winner goes to Dr Conel Alexander (an astrobiology researcher at the Carnegie Institution for Science, Washington)

  • Two scientists at the K-Pg boundary at Stevns Klint

    Fossil Micrometeorites Blog Post

    Isabelle Mattia has written a blog post describing the significance of finding fossil micrometeorites in sediments which are millions of years old. The blog is targeted to a general audience and provides introductory level explanations. You can find the blog here: Fossil Micrometeorites: Ancient Cosmic Dust and Where to Find Them

  • Ancient asteroid Ryugu with water geysers (artists drawing)

    Ancient asteroid Ryugu may have delivered the building blocks of life to Earth

    A study published in Nature Astronomy by Genge, et al., 2024 details the discovery of fractures within rocks brought back from the asteroid Ryugu. The identified fractures were filled with clay and sulfide minerals formed by water and seem to have been shaped by ice expanding and contracting as it melts and refreezes. How can the presence of water on asteroids help them deliver life-forming components? Well, Genge said: “Our calculations indicate that the pressure exerted by ice as it grows is sufficient to fracture asteroids to their core, allowing water to spread throughout them. Water then interacts with the minerals inside the asteroid to create essential organic matter – which would have been delivered to early Earth generating the oceans and the organic building blocks of life.” You can read the paper on Nature Astronomy, or a condensed version on the Imperial news page, or on NewScientist.

  • Artist rendition of an asteroid flying through space

    ESA's Hera Mission Takes Flight Toward the Asteroid Deflected by NASA's DART Probe

    The European Space Agency's Hera mission launched on 7 October 2024 aboard a SpaceX Falcon 9 rocket. Its objective is to journey several hundred million kilometres to the double asteroid system of Didymos, arriving in autumn 2026.

    This mission follows NASA's DART probe, which intentionally impacted Dimorphos, the smaller body of the Didymos system in an attempt to alter its trajectory, providing crucial data on how such impacts can modify the paths of asteroids. Early findings suggest success, thanks to a combination of DART's onboard camera and observations from ground-based telescopes, as well as space-based assets like Hubble and the James Webb Space Telescope.

    Hera's mission is to gather data regarding the current state of Didymos and Dimorphos post-impact. Hera aims to enhance our understanding of the effects of the DART impact, ultimately contributing to planetary defense strategies against future asteroid threats. You can read more about this mission on ESA's website or on PhysOrg.

In the 1990s, Love and Brownlee computed a numerical simulation on the atmospheric entry of micrometeoroids which had large implications on cosmic dust research. Previous studies had their own coded models, but this was the first uniform simulation of entry which took into consideration effects such as the angle at which a particle enters Earth’s atmosphere from space, its entry velocity, the mass lost due to evaporation, etc. Some of their conclusions show:

1) Only 1% of micrometeoroids above 300 microns will survive atmospheric heating.
2) Most spherules come from asteroids because they produce dust which enters Earth at high enough angles and low velocities to not undergo total evaporation. Smaller particles likely come from bodies with eccentric orbits and high velocities such as comets.
3) The majority of cosmic dust will only be be above melting temperatures for about 2 seconds at altitudes of 85 to 90km!

Highlighted Papers

Heating and Thermal Transformation of Micrometeoroids Entering the Earth's Atmosphere

Love and Brownlee (1991) - Icarus

The Classification of Micrometeorites

Genge, et al. (2008) - Meteorit. Planet. Sci.

With the cosmic dust field growing in the early 2000s and new particles being discovered, researchers needed a unified naming system to better describe their samples in a simple manner. Queue “The Classification of Micrometeorites” - a comprehensive paper detailing the textures and geochemical and isotopic properties expected for various micrometeorites based on Antarctic samples. Now we identify cosmic spherules, even under an optical microscope, following these protocols.

Ancient Micrometeorites Suggestive of an Oxygen-rich Archaean Upper Atmosphere

Tomkins, et al. (2016) - Nature

The Earth’s oxygen levels were thought to be much lower than present a few billion years ago during a geological period called the Archaean. However, spherules acquired from Archaean limestone show that the upper atmosphere was just as oxygenated as it is today! Previous evidence of low oxygen levels at the surface acquired from analysing sediments may imply that there was minimal mixing between the lower and upper atmosphere during this time. This paper introduced the successful capability fossil micrometeorites have for being paleoclimate indicators - a great way in better understanding our ancient atmospheric compositions. 

Micrometeorite Collections: a Review and Their Current Status

Van Ginneken, et al. (2024) - Royal Society

Cosmic dust falls everywhere on Earth’s surface (and other planets too)! So, micrometeorites can be found in various locations from the sea floor, Antarctic ice, sandy deserts, and even your own roof! This recently published paper details some major collections of all types of micrometeorites (not just cosmic spherules), providing information on collection sizes, locations, and contacts for further collaborative research. Interestingly, their conclusions state “future micrometeorite collections should focus on fossil micrometeorites to provide clues to the flux of cosmic dust in the distant past, its variability through time, as well as act as effective paleoclimatic proxies.”

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