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🔴 A Rock From Mars Just Filled a 2-Billion-Year Hole in the Planet’s History Scientists have dated an unusual Martian meteorite to 1.273 billion years old — placing it almost exactly inside a huge missing chapter in our geological record of Mars. The meteorite, called NWA 13441, was discovered in Algeria in 2019. Most Martian volcanic meteorites of its type are either younger than about 600 million years or around 2.4 billion years old. Until now, researchers had essentially no samples from the enormous interval between them. But its age may not even be the strangest part. The rock’s neodymium isotopes suggest that the magma it formed from came from a portion of the Martian mantle that had remained remarkably untouched since the earliest days of the Solar System. Mars formed very quickly and, unlike Earth, has no active plate tectonics constantly remixing its interior — potentially allowing ancient chemical reservoirs to survive for billions of years. In other words, a small rock blasted off Mars by an impact and eventually found in the Sahara may contain a chemical fingerprint preserved from almost the beginning of the planet itself. How much of Mars’s earliest history could still be locked inside rocks already lying somewhere on Earth? #Mars #Space #Meteorite #PlanetaryScience #Geology #Science Ссылка скрыта

🛰 We May Be Building Satellite Constellations Too Large for Earth’s Orbit A new analysis suggests that some satellite megaconstellations could cross a dangerous threshold where collisions create debris faster than Earth’s atmosphere can remove it — potentially triggering a runaway increase in space junk. The study introduces the idea of a “critical size” for a satellite constellation. Above that point, even if individual satellites follow good disposal practices and actively avoid collisions, the constellation as a whole may still generate an unstable debris environment. The model found that several planned, partially deployed and existing constellations exceed that threshold under some assumptions. The scale of what is being proposed is enormous. The paper notes that the number of active satellites in low-Earth orbit increased by nearly 12,000 in just five years, while applications submitted to the U.S. FCC in 2026 included proposed constellations totaling more than 1.2 million satellites. That would be over 78 times the current operational satellite population cited by the study. The feared endpoint is related to the Kessler syndrome: one collision produces fragments, those fragments cause more collisions, and eventually parts of low-Earth orbit become increasingly difficult to use safely. The important caveat: this is a modelling study and currently a preprint, not peer-reviewed research. It does not predict that a catastrophic debris cascade is about to happen tomorrow. But it raises a bigger question: should regulators evaluate satellites one by one — or the cumulative risk of entire constellations? Space may be enormous. Useful orbit around Earth is not. #Space #Satellites #SpaceDebris #Astronomy #SpaceTech #Science Ссылка скрыта