美国宇航局发现火星的磁场比预期强10倍
美国宇航局发现火星的磁场比预期强10倍
Part of the reason why Earth is a world teeming with life while Mars is a barren wasteland is due to the presence of our planet’s magnetic field. This invisible barrier shields the atmosphere from the harmful effects of the solar wind.
地球是一个充满生命的世界，而火星是一片贫瘠的荒地，部分原因是地球磁场的存在。这个看不见的屏障使大气免受太阳风的有害影响。
But, that’s not to say Mars doesn’t have a planetary magnetic field at all — it’s just tiny relative to Earth’s. Now, NASA’s InSight lander has found it’s actually 10 times stronger than expected.
但是，这并不是说火星根本就没有行星磁场，只是相对于地球来说，磁场很小。现在，美国宇航局的InSight登陆器发现它实际上比预期的强10倍。
Unlike other NASA missions to the Martian surface, InSight isn’t a rover — it’s a static lander.
与美国航天局其他火星表面任务不同，“InSight”不是一个探测器，而是一个静态着陆器。
It touched down on the red planet surface about a year and a half ago with two major goals. One is understanding how rocky planets formed and evolved by measuring the interior structure and processes of Mars. The other is figuring out just how tectonically active Mars is today, and how often meteorites impact it.
它在一年半前降落在这颗红色星球的表面，有两个主要的目标。一个是通过测量火星的内部结构和过程来了解岩质行星是如何形成和演化的。另一个是计算出今天的火星在构造上有多活跃，以及陨石撞击它的频率。
NASA
InSight was the first mission to measure seismic activity on Mars. It also has a magnetic sensor that allows InSight to measure the strength of the magnetic field at the lander location, a hallow crater called “Homestead hollow”, found in a flat region called Elysium Planitia.
InSight是第一个测量火星地震活动的任务。它还具有一个磁传感器，该传感器使InSight能够测量着陆器位置上的磁场强度，该着陆器是一个称为“Homestead hollow”的空心陨石坑，位于一个名为“极乐空间”(Elysium Planitia)的平坦地区。
Previously, the only reliable measurements of Mars’ magnetic field were performed by orbiting satellites that were hovering hundreds of kilometers from the red planet’s surface.
以前，对火星磁场的唯一可靠测量，是由离火星表面数百公里远的轨道卫星进行的。
According to the measurements reported in Nature Geosciences, Mars’ magnetic field is actually 10 times stronger than scientists were led to believe from satellite readings. This would make Mars’ magnetic field, while still very weak compared to Earth’s much stronger than initially thought.
根据《自然地球科学》报道的测量结果，火星的磁场实际上比科学家从卫星读数中得出的磁场强10倍。这将使火星的磁场，尽管与地球相比要比最初想像的要强大得多，但仍然非常弱。
Earth’s magnetic field is generated by the motion of molten iron alloys in its outer core, which acts as a planetary dynamo, generating a massive magnetic field called the magnetosphere. It extends for several tens of thousands of kilometers into space, well above the atmosphere, sheltering the planet from charged particles of the solar wind and cosmic rays that would otherwise strip away the upper atmosphere, including the ozone layer that protects life from harmful ultraviolet radiation.
地球的磁场是由其外核中的熔融铁合金运动产生的，其作用就像行星发电机，产生一个称为磁层的巨大磁场。它延伸数万公里进入太空，远远高于大气层，保护地球免受太阳风和宇宙射线的带电粒子的影响，否则这些粒子会剥去上层大气，包括保护生命免受有害紫外线辐射的臭氧层。
Earth isn’t unique in this respect. Jupiter has masses of liquid metallic hydrogen in its outer mantle, creating the largest planetary magnetic field in the solar system. Uranus generates a global magnetosphere closer to the surface, which leads to some very strange quadrupole field effects — rather than just a north and a south, there are another two poles. Mars also used to have a magnetic field, but it suddenly switched off around four billion years ago.
地球在这方面并不独特。木星的外地幔中有大量液态金属氢，形成了太阳系中最大的行星磁场。天王星产生了一个更接近地表的全球磁层，这导致了一些非常奇怪的四极场效应，而不仅仅是南北两极。火星过去也有磁场，但在大约40亿年前突然关闭。
Scientists aren’t sure how the red planet lost its magnetosphere but there are currently two leading theories. The first says that its core shut down, deactivating the dynamo and consequently Mars’ global magnetic field. The other leading hypothesis suggests that massive heat generated by large asteroid impacts warmed the outer layer of the planet to such a degree that it shut down convection from the hot core to the mantle.
科学家不确定这颗红色行星是如何失去其磁层的，但目前有两种主要的理论。第一个说它的核心关闭，使发电机失活，从而导致火星的全球磁场。另一种主要的假说认为，大型小行星撞击地球所产生的大量热量使地球外层温度升高到一定程度，以至于停止了从地核到地幔的对流。
The new measurements of the red planet’s magnetic field change nothing about the prospects of finding life on Mars.
对这颗红色行星磁场的新测量丝毫没有改变在火星上发现生命的前景。
