Oamenii de stiinta chinezi au identificat un nou tip de piatra pe luna. Un lander lunar chinezesc fără pilot, lansată în 2013, a explorat un flux antic de lavă vulcanică și a compoziției minerale identificate în întregime, spre deosebire de orice colectate de către astronauți americani între 1969 și 1972, sau de către ultimul sovietic în sonda 1976.
Stirile, expediate dintr-un crater de impact în Imbrium Mare, este un alt memento că explorare planetară nu mai este apanajul rușilor este, americanii sau Agenția Spațială Europeană: Japonia, India și China au lansat toate Orbiter lunar pe propriile lor rachete. Marea Britanie a lansat propriul satelit, Prospero, pe cont propriu rachetei, săgeata neagră, de la propriul site-ul său de lansare în Woomera, Australia, în 1971 și apoi s-au retras din cursa spațială.
Since the end of the Apollo programme, US scientists have conducted their lunar research mostly from orbiters. Chang’e-3, China’s unmanned lunar mission, put down a rover called Yutu or “Jade Rabbit” on a comparatively young lava flow. This rover proceeded to identify a mineralogical mystery on the moon, a basalt with “unique compositional characteristics.”
The study, reported in Nature Communications, is expected to enhance readings from satellite instruments, and to throw new light on the origins of Earth’s nearest neighbour.
The moon is thought to have formed when a Mars-sized object crashed into planet Earth early in the history of the solar system. The debris from the collision coalesced and cooled, but radioactive elements deep in the interior heated up the rock beneath the crust, și 500 million years later, volcanic lava slurped into impact craters on the moon to form the so-called “seas” or maria.
The Yutu rover’s instruments started examining lava that probably flowed about 3 billion years ago. What they found won’t keep ordinary citizens wide awake at night, but it is a surprise for planetary scientists. Geochemists can reconstruct a rock flow’s history from the telltale mix of minerals in the cooled lava. Basalts sampled by astronaut expeditions or collected by a Soviet Luna probe tended to be distinguished in two ways: either high in titanium, or low.
But the latest find reported from the first soft landing on the Moon in 40 years is both intermediate in titanium content and rich in iron oxide.
“The diversity tells us that the Moon’s upper mantle is much less uniform in composition than Earth’s. And correlating chemistry with age, we can see how the moon’s volcanism changed over time,” said Bradley Joliff of the Washington University of St Louis, the only American partner in the Chinese team.
The mix of minerals in magma tells a story: that is because minerals in molten rock characteristically crystallise at different temperatures. So rock on the surface delivers clues to the deep interior of a planet.
“The variable titanium distribution on the lunar surface suggests that the Moon’s interior was not homogenised,” Professor Joliff said. “We’re still trying to figure out how this happened.”
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