S͢T͢R͢A͢N͢G͢E͢ ͢S͢T͢O͢N͢E͢S͢ ͢F͢R͢O͢M͢ ͢O͢U͢T͢E͢R͢ ͢S͢P͢A͢C͢E͢ ☄
“Meteorites are, by almost any measure, far more diverse than any rocks formed on Earth.”
This line from Appendix 1 of Greg Brennecka’s 𝙄𝙢𝙥𝙖𝙘𝙩 struck me. Here’s a visual array of the April additions to the FV collection to illustrate the point. Which is your favorite? +More quotes from the book:
“Meteorites represent the origins of Earth and humanity. Meteorites are ancient and largely unchanged — certain types have never been melted since they formed over 4.5 billion years ago, and thus are excellent time capsules for the genesis of the Solar System. The most primitive types of meteorites are so pristine we essentially sample an unadulterated version of our parent molecular cloud from which the Solar System formed.”
– Starting composition of the Sun and planets
– Ancient clocks and thermometers, embedded in stone
– “Diamonds older than the sun among the cosmic dust and galactic garbage”
– Amino acids, DNA and RNA base pairs, and large amounts of water
– “the texture and minerals present in many meteorites are essentially impossible to re-create on Earth.”
– Paleomagnetism: the sun had an intense magnetic field in the early years
– “Meteorites record a gradient in their isotopic compositions related to how far out from the sun they formed.”
Luna launch: “The moon exists because of a really, really big meteorite. When the Earth was a mere toddler, less than 150 million years after the birth of the Solar System, the impact flash-melted the entire surface of the Earth and large portions of its mantle. The impactor itself, a Mars size body that have been names Theia, was completely obliterated as it violently introduced itself to a fledgling Earth. The material that was ejected from this collision eventually coalesced into what we call the Moon, producing a brilliantly tidally locked, lower-density-than-Earth extra-large satellite for us to marvel at 4 billion+ years later.”
– Sterilized Earth and reset the atmosphere to be rich in hydrogen, carbon monoxide and water (the source of our abundant water remains unknown; it may have come from Theia, liberated from the Earth’s mantle from Theia’s impact, or delivered by subsequent comets and water-rich meteorites. Or all three).
– “Four billion years ago, Earth was spinning much faster and the Moon was much closer to us. These differences caused much larger tide fluctuations to happen more frequently: up to ~50m changes every five hours.”
– “Ocean tides produce local differences on a repeated basis, which happens to be the perfect mechanism for concentrating organic material. Without the Moon and the tides it creates, this crucible for carbon concentration would barely exist.”
Dino-busting: “One moment there were creatures as big as 100 tons strutting their stuff around, and then, in a blink of geologic time, no living animal on Earth was larger than a basset hound.”
Ongoing nourishment: “Every day in our modern world, an average of more than 100 metric tons of meteoritic material is added to Earth.”
– “Living things use only 21 amino acids to perform their daily functions, and many amino acids discovered in meteorites were previously unknown to exist. More than 80 types of amino acids have been identified in a single primitive metworite.”
– “The realization that organic molecules exist at all in meteorites is mind-bending enough, but the fact that such a complex and highly diverse suite of molecules — including life-essential things like sugars, alcohols and amino acids— exist in abundance in many kinds of meteorites is almost incomprehensibly thought provoking.”
– Other essential ingredients for our biology, like reactive phosphorous and soluble iron may have come from meteorites, as it is in “vanishingly short supply, particularly in places like the ocean, where organisms get a lot of the nutrients they require from seawater.”
– “The well documented increased influx of extraterrestrial material around 450 million years ago caused a global increase of marine productivity (seeding the oceans with iron). If such a productivity bump was intense enough, it would have caused a significant drawdown of global CO2 levels, lowering global temperatures. As such, increased meteoritic delivery may have been the indirect cause of the most intense ice age of the last 500 million years, the Ordovician-Silurian extinction event, which wiped out ~85% of marine species at the time.”
Free Sample Return from Mars: Martian meteorites could not have been launched by volcanos on Mars, as some initially thought. The escape velocity is 11,000 MPH “so the only realistic way they got off Mars was from large impacts to the surface of the planet” — more meteorites, hitting Mars.
– “It is only through the study of Martian meteorites that we can quantify the amount of water that was present in the past, and how much has been lost over time.”
– We have 300 samples “from 4.1 billion years old to a scant 160 million years ago; in other words, for nearly the entirely of Mars’s history.”
– No plate tectonics remixing and melting the surface
– “With the recent space exploration interest success by private companies such as SpaceX, and the continued interest and accelerated collaboration between governmental space agencies, the possibility of returning samples from Mars is becoming ever more tangible” and they will be chosen rocks from chosen locations, like old lakebeds and riverbanks.
Book: https://www.amazon.com/Impact-Rocks-Space-Culture-Donkey/dp/0063078929 and on twitter, the author confirmed my hypothesis about the appendices: https://twitter.com/GregBrennecka/status/1519472829292457984
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