美國宇航局發(fā)現(xiàn)火星的磁場比預(yù)期強(qiáng)10倍

美國宇航局發(fā)現(xiàn)火星的磁場比預(yù)期強(qiáng)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.

地球是一個(gè)充滿生命的世界，而火星是一片貧瘠的荒地，部分原因是地球磁場的存在。這個(gè)看不見的屏障使大氣免受太陽風(fēng)的有害影響。

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，這并不是說火星根本就沒有行星磁場，只是相對(duì)于地球來說，磁場很小。現(xiàn)在，美國宇航局的InSight登陸器發(fā)現(xiàn)它實(shí)際上比預(yù)期的強(qiáng)10倍。

Unlike other NASA missions to the Martian surface, InSight isn’t a rover — it’s a static lander.

與美國航天局其他火星表面任務(wù)不同，“InSight”不是一個(gè)探測器，而是一個(gè)靜態(tài)著陸器。

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這顆紅色星球的表面，有兩個(gè)主要的目標(biāo)。一個(gè)是通過測量火星的內(nèi)部結(jié)構(gòu)和過程來了解巖質(zhì)行星是如何形成和演化的。另一個(gè)是計(jì)算出今天的火星在構(gòu)造上有多活躍，以及隕石撞擊它的頻率。

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是第一個(gè)測量火星地震活動(dòng)的任務(wù)。它還具有一個(gè)磁傳感器，該傳感器使InSight能夠測量著陸器位置上的磁場強(qiáng)度，該著陸器是一個(gè)稱為“Homestead hollow”的空心隕石坑，位于一個(gè)名為“極樂空間”(Elysium Planitia)的平坦地區(qū)。

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，對(duì)火星磁場的唯一可靠測量，是由離火星表面數(shù)百公里遠(yuǎn)的軌道衛(wèi)星進(jìn)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.

根據(jù)《自然地球科學(xué)》報(bào)道的測量結(jié)果，火星的磁場實(shí)際上比科學(xué)家從衛(wèi)星讀數(shù)中得出的磁場強(qiáng)10倍。這將使火星的磁場，盡管與地球相比要比最初想像的要強(qiáng)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.

地球的磁場是由其外核中的熔融鐵合金運(yùn)動(dòng)產(chǎn)生的，其作用就像行星發(fā)電機(jī)，產(chǎn)生一個(gè)稱為磁層的巨大磁場。它延伸數(shù)萬公里進(jìn)入太空，遠(yuǎn)遠(yuǎn)高于大氣層，保護(hù)地球免受太陽風(fēng)和宇宙射線的帶電粒子的影響，否則這些粒子會(huì)剝?nèi)ド蠈哟髿?，包括保護(hù)生命免受有害紫外線輻射的臭氧層。

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.

地球在這方面并不獨(dú)特。木星的外地幔中有大量液態(tài)金屬氫，形成了太陽系中最大的行星磁場。天王星產(chǎn)生了一個(gè)更接近地表的全球磁層，這導(dǎo)致了一些非常奇怪的四極場效應(yīng)，而不僅僅是南北兩極。火星過去也有磁場，但在大約40億年前突然關(guān)閉。

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.

科學(xué)家不確定這顆紅色行星是如何失去其磁層的，但目前有兩種主要的理論。第一個(gè)說它的核心關(guān)閉，使發(fā)電機(jī)失活，從而導(dǎo)致火星的全球磁場。另一種主要的假說認(rèn)為，大型小行星撞擊地球所產(chǎn)生的大量熱量使地球外層溫度升高到一定程度，以至于停止了從地核到地幔的對(duì)流。

The new measurements of the red planet’s magnetic field change nothing about the prospects of finding life on Mars.

對(duì)這顆紅色行星磁場的新測量絲毫沒有改變在火星上發(fā)現(xiàn)生命的前景。