The people who opened up the study of micrometeorites
From Victorian oceanographers to a jazz guitarist, a small number of people turned space dust from a curiosity into a major field of planetary science.
Micrometeorites were first recognised in deep-sea mud in the 1880s. Fred Whipple explained how they survive in 1950. Donald Brownlee pioneered collecting them in the stratosphere and on the seabed, Michel Maurette led the polar collections, and later researchers built the classification, measured the flux and showed they can be found in cities.
The pioneers
- John Murray (1841–1914), a Canadian-born Scottish oceanographer on the Challenger expedition of 1872–1876, and Alphonse Renard (1842–1903), a Belgian geologist, described black magnetic and brown crystalline spherules in deep-sea clay and argued that they came from space.
- Fred Whipple (1906–2004), an American astronomer best known for describing comets as dirty snowballs, coined the word micrometeorite and showed in 1950 that small particles can be slowed in the upper air without melting. He also designed the shield that protects spacecraft from dust impacts.
The space age
- Donald Brownlee (born 1943), an American astronomer, pioneered the collection of interplanetary dust in the stratosphere in the 1970s, so that such particles are sometimes called Brownlee particles. He led deep-sea spherule collections, and was principal investigator of NASA's Stardust mission, which brought back dust from comet Wild 2 in 2006.
- Michel Maurette, a French physicist, opened up polar collecting, first from meltwater lakes in Greenland in the 1980s and then from Antarctic blue ice. His collections showed how abundant unmelted micrometeorites are, and he championed the idea that they delivered water and organic matter to the early Earth.
- Susan Taylor, an American geologist working on cold regions, led the South Pole water-well collection in the 1990s, which gave one of the first reliable measurements of how many micrometeorites reach the ground.
Building the modern field
- Matthew Genge, a British planetary scientist at Imperial College London, led the 2008 classification scheme used worldwide, and in 2016 confirmed the first urban micrometeorites with Jon Larsen.
- Jean Duprat and Cécile Engrand, French researchers, led the collections of clean snow near the Concordia station on the Antarctic plateau, described the ultracarbonaceous micrometeorites in 2010 and, with colleagues, measured the flux of about 5,200 tonnes a year published in 2021.
- Luigi Folco, an Italian planetary scientist, led the discovery of very old micrometeorite traps on summits of the Transantarctic Mountains, which yielded unusually large particles and microtektites.
- Andrew Tomkins, an Australian geologist, led the 2016 study of 2.7-billion-year-old iron micrometeorites from the Pilbara, which opened a new way to study the ancient atmosphere.
- Birger Schmitz, a Swedish geologist, has spent decades tracing fossil meteorites and extraterrestrial chromite through ancient limestones, revealing the dust shower that followed the asteroid break-up about 466 million years ago.
- Kenneth Farley, an American geochemist, used helium-3 in deep-sea sediments to track the dust supply over millions of years, including the pulse from the Veritas asteroid break-up.
Citizen science
- Jon Larsen (born 1959), a Norwegian jazz guitarist and self-taught naturalist, spent years learning to tell space dust from industrial particles and found the first convincing urban micrometeorites. His photographs, books and outreach have encouraged thousands of people to look for micrometeorites themselves. See micrometeorites in towns and cities.
A field built by teams
Each of these names stands for a team of colleagues, students, engineers and expedition staff. Collecting dust from Antarctic snow or the deep-sea floor takes ships, aircraft, field camps, clean rooms and years of patient work, and new researchers continue to join the field from every continent.
Did you know?
Donald Brownlee also co-wrote a well-known book arguing that complex life like ours may be rare in the universe.
Michel Maurette wrote a popular book about his micrometeorite hunts in the polar ice.
The Challenger expedition's reports were so extensive that they filled 50 volumes and took about 20 years to complete.