Meteorite that hit Earth 200 years ago upends theories about Mars

Meteorite that landed on Earth more than 200 years ago upends previous theories of how Mars formed

  • Analysis shows interior chemical make-up of Mars largely came from meteorites
  • Suggests Mars got volatile elements hydrogen and oxygen from these collisions
  • It had been thought they came from a large cloud of gas called the solar nebula
  • Experts analysed sample of Chassigny meteorite, which hit Earth 200 几年前
  • A meteorite that hit Earth more than 200 years ago could fundamentally change our understanding of how 火星 was formed.

    Most of what we know about the Red Planet’s interior comes from three space rocks that landed on our planet after being blasted off Mars by impacts.

    They include the Chassingy meteorite, which came down in north-eastern 法国 在 1815, and two others known as Shergotty and Nakhla.

    New analysis of Chassingy suggests that the interior chemical make-up of Mars largely came from meteorite collisions, rather than from a giant cloud of gas called the solar nebula as previously thought.

    It contradicts current thinking about how rocky planets like the Earth and Mars acquire volatile elements such as hydrogen, carbon, 标志着他开始转变为今天的样子, nitrogen and noble gases as they form.

    Mars is of special interest because it formed relatively quickly — solidifying in about 4 million years after the birth of the Solar System, while the Earth took 50 至 100 million years to form.

    发现: New analysis of the Chassingy meteorite (图为) suggests that the interior chemical make-up of Mars largely came from meteorite collisions, rather than from a giant cloud of gas called the solar nebula as previously thought

    发现: New analysis of the Chassingy meteorite (图为) suggests that the interior chemical make-up of Mars largely came from meteorite collisions, rather than from a giant cloud of gas called the solar nebula as previously thought

    MARS: THE BASICS

    Mars is the fourth planet from the sun, with a ‘near-deaddusty, 寒冷的, desert world with a very thin atmosphere.

    Mars is also a dynamic planet with seasons, polar ice caps, canyons, extinct volcanoes, and evidence that it was even more active in the past.

    It is one of the most explored planets in the solar system and the only planet humans have sent rovers to explore.

    One day on Mars takes a little over 24 hours and a year is 687 木星和卫星等矮行星.

    Facts and Figures

    Orbital period: 687 天

    Surface area: 144.8 million km²

    Distance from Sun: 227.9 万公里

    到目前为止,人们已经参加了测验: 3.721 m/s²

    Radius: 3,389.5 公里

    月亮: Phobos, Deimos

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    Scientists had thought that the newly-forming worlds first collected these volatiles from the nebula around a young star, before the elements initially dissolve into a magma ocean and then degass back into the atmosphere while the planet is still a ball of molten rock.

    The theory assumes that later on, chondritic meteorites crashing into the young planet deliver more volatile materials.

    It had been believed that the volatile elements in the interior of the planet should reflect the composition of the solar nebula, or a mixture of solar and meteoritic volatiles, while the volatiles in the atmosphere would come mostly from meteorites.

    This was supported by previous research into Chassingy which looked at isotopes of xenon, a chemically inert gas which can survive unchanged for millions of years.

    The isotope ratios from the meteorite seemed to match those of both Mars’s atmosphere and the solar nebula, which led to the assumption that its volatile elements, such as hydrogen, carbon and oxygen, came from the solar nebula and that additional elements came from meteorites later.

    然而, the new study by researchers at the University of California, Davis disputes this.

    They analysed a sample from Chassigny but this time looked at isotopes of krypton — a different inert gas which allows for more precise measurements.

    ‘With xenon isotopes, it’s difficult to distinguish the precise source of volatiles, but that’s not the case with krypton,’ one of the study’s authors Sandrine Péron told the New Scientist.

    ‘With krypton, you can better see the difference between potential sources like from solar or meteorites… but krypton isotopes are more difficult to measure than xenon isotopes, so that’s why it had not been previously done.

    The researchers found that the isotopes came from meteorites rather than from the solar nebula.

    That means that meteorites were delivering volatile elements to the forming planet much earlier than previously thought, and in the presence of the nebula, reversing conventional thinking.

    Mars is of special interest because it formed relatively quickly — solidifying in about 4 million years after the birth of the Solar System, while the Earth took 50 至 100 million years to form

    Mars is of special interest because it formed relatively quickly — solidifying in about 4 million years after the birth of the Solar System, while the Earth took 50 至 100 million years to form

    ‘The Martian interior composition for krypton is nearly purely chondritic, but the atmosphere is solar,’ Péron said. ‘It’s very distinct.

    The results show that Marsatmosphere cannot have formed purely by outgassing from the mantle, as that would have given it a chondritic composition.

    The planet must have acquired atmosphere from the solar nebula, after the magma ocean cooled, to prevent substantial mixing between interior chondritic gases and atmospheric solar gases.

    The new results suggest that Marsgrowth was completed before the solar nebula was dissipated by radiation from the sun.

    But the irradiation should also have blown off the nebular atmosphere on Mars, suggesting that atmospheric krypton must have somehow been preserved, possibly trapped underground or in polar ice caps.

    '然而, that would require Mars to have been cold in the immediate aftermath of its accretion,’ Mukhopadhyay said.

    ‘While our study clearly points to the chondritic gases in the Martian interior, it also raises some interesting questions about the origin and composition of Marsearly atmosphere.

    该研究已发表在该杂志上 科学.

    由于它在黄昏前位于东南地平线上的低位置,因此在最接近的地方: 由于它在黄昏前位于东南地平线上的低位置,因此在最接近的地方, 由于它在黄昏前位于东南地平线上的低位置,因此在最接近的地方

    一个 小行星 由于它在黄昏前位于东南地平线上的低位置,因此在最接近的地方. 大多数位于主带火星和木星之间.

    一种 彗星 是一块被冰覆盖的岩石, 甲烷和其他化合物. 它们的轨道使它们远离太阳系.

    一种 流星 当碎片燃烧时,天文学家称之为大气中的闪光.

    这种碎片本身被称为 流星体. 大多数都太小了,它们在大气中蒸发了.

    如果有任何流星体到达地球, 它被称为 陨石.

    流星, 流星体和陨石通常起源于小行星和彗星.

    例如, 它们的轨道使它们远离太阳系, 它们的轨道使它们远离太阳系, 它们的轨道使它们远离太阳系.

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