Antartica's Iron Meteorites Are Missing - The Atlantic
The Mystery of Antarctica’s Missing Meteorites
Hiding deep under the ice, iron meteorites could hold clues to the solar system’s past.
For about a month, Katherine Joy spent hours snaking up and down the Antarctic ice on a snowmobile, trying to spot gatherings of meteorites.
The bottom of the Earth is a jarringly alien realm—an “expansive place where the sky and ice seem to go on forever,” says Joy, a Royal Society University Research Fellow and meteorite hunter at the University of Manchester. And in some stretches of ice, “every rock you come across is from space.”
The majority of the world’s meteorites are discovered in Antarctica. A single dark rock would be easy enough to spot amid the white background, but the movements of the ice can also act as a conveyor belt, creating concentrated pockets of space debris. Meteorite-hunting expeditions over the past few decades have revealed, though, an enigmatic lack of iron meteorites in Antarctica compared with other locations around the world.
Though iron meteorites are falling through the atmosphere at equal rates across the planet, they simply weren’t showing up on the icy surface as often as they should be compared with their stony meteorite cousins. This raised an intriguing possibility: These missing iron meteorites were hiding beneath Antarctica’s ice.
To test this idea, Joy and her colleagues had come to Antarctica as part of the first-ever expedition to search for “lost meteorites.” They spent late December to early February scouting out accessible spots that might contain the best hauls. If they eventually find these missing meteorites on the full-blown expedition in a year’s time, they’ll have located new geochemical clues contained within that chronicle the early chaos of the solar system and its inner rocky planets, including our own.
Treacherously frigid conditions aside, finding meteorites buried beneath ice while scooting across a truly vast landscape will require plenty of serendipity, because buried meteorites can only be detected if you’re standing right above them. That’s why, to game the odds as much as it can, the team is bringing along some extremely fancy iron meteorite detectors: snowmobiles equipped with the sort of tech you’d normally find in war zones.
The hunt for lost meteorites began after a group of mathematicians and glaciologists started to wonder whether meteorites could burrow through Antarctic ice. The first test, in 2014, deployed a humble household freezer, a Pixar-like desk lamp, and “some small and cheapish meteorites,” says Geoffrey Evatt, a senior lecturer in applied mathematics at the University of Manchester.
The researchers shined the lamp on those discount meteorites, and nothing appeared to happen. Realizing that the lamp didn’t mimic the sun properly, they upgraded to a solar-simulator beam that provided the vital missing infrared spectrum.
That’s when they saw meteorites heat up and start to nestle down into the ice.
Iron meteorites generally come from the hearts of massive asteroids. Their composition is not dissimilar to that of Earth’s own core, which suggests that they can tell us much about the formation of rocky planets. They are rather shiny and typically have pronounced, sometimes crosshatched textures that catch the eye. Often, because of these properties, strange-looking rocks that the general public brings to meteorite researchers turn out to be iron meteorites, says Matthew Genge, a senior lecturer and meteorite expert at Imperial College London not involved in the expedition.
A meteorite sinking into ice (Katherine Joy)
Iron meteorites are also tougher than other meteorites, which means they survive atmospheric entry better than their relations. All things considered, we should be finding plenty of them, so it’s strange to encounter so few in Antarctica, an otherwise veritable wonderland for all things spaceborne.
This deficit matters. Joy notes that the handful of different meteorite groups we know of originate from at least 100 different sources, from the innards of long-lost annihilated planets to the inner reaches of asteroids.
“Any new meteorite we find could provide us with a previously unsampled asteroid type that tells us something new about how planets first formed and geologically evolve,” she says. The lack of iron meteorites means a key part of that cosmic puzzle is missing.
After those early desktop experiments, the researchers upped their game. Within a cloud-simulator contraption, which replicated real-world Antarctic environmental conditions, they carefully placed meteorites between two ice layers. Shining a solar lamp on the site, they noticed that the stony and iron meteorites sometimes caused melting above and below them, meaning they could move up and down in their icy prison an inch or two in just a few hours.
Full story at site
The Mystery of Antarctica’s Missing Meteorites
Hiding deep under the ice, iron meteorites could hold clues to the solar system’s past.
For about a month, Katherine Joy spent hours snaking up and down the Antarctic ice on a snowmobile, trying to spot gatherings of meteorites.
The bottom of the Earth is a jarringly alien realm—an “expansive place where the sky and ice seem to go on forever,” says Joy, a Royal Society University Research Fellow and meteorite hunter at the University of Manchester. And in some stretches of ice, “every rock you come across is from space.”
The majority of the world’s meteorites are discovered in Antarctica. A single dark rock would be easy enough to spot amid the white background, but the movements of the ice can also act as a conveyor belt, creating concentrated pockets of space debris. Meteorite-hunting expeditions over the past few decades have revealed, though, an enigmatic lack of iron meteorites in Antarctica compared with other locations around the world.
Though iron meteorites are falling through the atmosphere at equal rates across the planet, they simply weren’t showing up on the icy surface as often as they should be compared with their stony meteorite cousins. This raised an intriguing possibility: These missing iron meteorites were hiding beneath Antarctica’s ice.
To test this idea, Joy and her colleagues had come to Antarctica as part of the first-ever expedition to search for “lost meteorites.” They spent late December to early February scouting out accessible spots that might contain the best hauls. If they eventually find these missing meteorites on the full-blown expedition in a year’s time, they’ll have located new geochemical clues contained within that chronicle the early chaos of the solar system and its inner rocky planets, including our own.
Treacherously frigid conditions aside, finding meteorites buried beneath ice while scooting across a truly vast landscape will require plenty of serendipity, because buried meteorites can only be detected if you’re standing right above them. That’s why, to game the odds as much as it can, the team is bringing along some extremely fancy iron meteorite detectors: snowmobiles equipped with the sort of tech you’d normally find in war zones.
The hunt for lost meteorites began after a group of mathematicians and glaciologists started to wonder whether meteorites could burrow through Antarctic ice. The first test, in 2014, deployed a humble household freezer, a Pixar-like desk lamp, and “some small and cheapish meteorites,” says Geoffrey Evatt, a senior lecturer in applied mathematics at the University of Manchester.
The researchers shined the lamp on those discount meteorites, and nothing appeared to happen. Realizing that the lamp didn’t mimic the sun properly, they upgraded to a solar-simulator beam that provided the vital missing infrared spectrum.
That’s when they saw meteorites heat up and start to nestle down into the ice.
Iron meteorites generally come from the hearts of massive asteroids. Their composition is not dissimilar to that of Earth’s own core, which suggests that they can tell us much about the formation of rocky planets. They are rather shiny and typically have pronounced, sometimes crosshatched textures that catch the eye. Often, because of these properties, strange-looking rocks that the general public brings to meteorite researchers turn out to be iron meteorites, says Matthew Genge, a senior lecturer and meteorite expert at Imperial College London not involved in the expedition.
A meteorite sinking into ice (Katherine Joy)
Iron meteorites are also tougher than other meteorites, which means they survive atmospheric entry better than their relations. All things considered, we should be finding plenty of them, so it’s strange to encounter so few in Antarctica, an otherwise veritable wonderland for all things spaceborne.
This deficit matters. Joy notes that the handful of different meteorite groups we know of originate from at least 100 different sources, from the innards of long-lost annihilated planets to the inner reaches of asteroids.
“Any new meteorite we find could provide us with a previously unsampled asteroid type that tells us something new about how planets first formed and geologically evolve,” she says. The lack of iron meteorites means a key part of that cosmic puzzle is missing.
After those early desktop experiments, the researchers upped their game. Within a cloud-simulator contraption, which replicated real-world Antarctic environmental conditions, they carefully placed meteorites between two ice layers. Shining a solar lamp on the site, they noticed that the stony and iron meteorites sometimes caused melting above and below them, meaning they could move up and down in their icy prison an inch or two in just a few hours.
Full story at site
