美国宇航局(NASA)的探测器刚刚着陆过的小行星原来是空心的,而且里面空心的部分非常大,这个小行星的自转可能最后会把自己给转没了。
翻译:涂博士
小行星贝努(Bennu)现在变得越来越离奇了。
当美国宇航局(NASA)决定发送探测器降落在一个太空中的岩石上并带回样本时,它选择了贝努(Bennu)小行星,因为这个小行星表面看上去比较光滑,是探测器降落的好地方。但是,当Osiris-Rex航天器飞了2亿英里的旅程到达贝努(Bennu)小行星后,航天器发回来的影像显示出小行星表面上到处是大小不同的砾石。
美国宇航局(NASA)最终选择了一个它能找到的相对最平坦的地点,在上个月探测器掠过这个行星的表面,趁机在表面上刮了一些东西下来,整个采样过程非常顺利。但是,让所有人感到惊讶的是:这颗小行星的表面的岩土非常的松软,当飞行器碰触到小行星的表面时,表面上的岩土随即垮塌了下去。
探测器的采样方式是对着小行星的表面喷射出一股氮气,通过氮气对小行星表面的冲击溅起一阵岩石和尘埃,然后采样器就可以把溅起的岩石和尘埃给收集起来。但科学家没有想到的是,用这个方法溅起的岩石和尘埃太多以至于把采样器里面塞满到门都关不紧,这样采样器里面好不容易收集的外星尘土随后又不断地泄漏到太空中去。
科学家们总算及时堵住了漏洞,所以样品损失还不算太大。不过这个问题解决后,科学家又发现了更大的惊奇。最近,科罗拉多大学的研究人员根据Osiris-Rex探测器在过去两年收集的数据得出结论,探测器一直绕着转的贝努(Bennu)小行星里面可能是空心的。
负责这项研究的大学航空航天工程学系教授丹尼尔·谢里斯(Daniel Scheeres)在新闻发布会上说:“就好像在这个小行星的中心里面有一个可以容纳几个足球场大小的空心地带。”
更重要的是,贝努(Bennu)行星的自转可能会把自己给转散架。
“整个东西都在散架”
当Osiris-Rex探测器在围绕着贝努(Bennu)小行星运行时,探测器测量了小行星对其的万有引力的大小。与此同时,贝努(Bennu)小行星的自转也会将一些弹子大小的碎石从地面上甩到空中去,进入到环绕小行星运行的轨道,然后其中的一些碎石会回落到小行星的表面上。通过跟踪这些碎石的运动轨迹,地面控制中心的人员能够计算出贝努(Bennu)小行星的重力强度。
由于重力来自于质量(译者注:如果不记得重力和质量的关系,可以复习一下初中物理里面的牛顿定律),因此通过这两组数据,谢里斯(Scheeres)团队可以计算出小行星内部物质的分布情况。
谢里斯(Scheeres)团队发现贝努(Bennu)小行星的质量分布远不是均衡的,贝努(Bennu)小行星自旋的力量似乎正在将其内部物质推向表面,小行星最薄的部分位于其凸起的赤道处。谢里斯(Scheeres)团队的这一研究结果发表于10月8日的《科学进展》杂志上(在Osiris-Rex探测器的短暂登陆之前)。
贝努(Bennu)小行星每四个小时完成一次自转,而且它的自转速度以后只会越来越快。
谢里斯(Scheeres)说:“你可以想象得到,在一百万年或更短的时间内,整个东西都会散架。”
贝努(Bennu)小行星可能会含有关于生命起源的秘密
根据Osiris-Rex探测器首席研究员丹特·劳雷塔(Dante Lauretta)的说法,贝努(Bennu)小行星是太阳系中最具潜在危险的小行星之一,因为它在22世纪撞击地球的概率“不能忽略不计”。不过,这个小行星本身的脆弱性可能对我们来说是个好消息。
对贝努(Bennu)小行星的研究可能会帮助到未来的科学家制定计划,以便在这颗小行星在将来威胁到地球时让它改变路径。该项研究还可能揭示有关小行星生命的新细节。在行星的形成过程中,那些没有加入到行星里面的原始的小块岩石聚集到一起就形成了小行星。这些物体可能隐含着我们的太阳系如何形成以及地球上的生命如何起源的秘密。
谢里斯(Scheeres)说:“我们希望经过一段时间的研究,我们能够发现这颗小行星过去到底经历了些什么,这可以让我们更好地了解所有这些小行星在数百万,数亿乃至数十亿年间的变化。我们现在的发现已经超出了我们当初的预期。”
科学家尚未梳理Osiris-Rex探测器收集的大量数据,探测器采集的样本有望在2023年返回地球。
美国宇航局(NASA)表示,如果装有采集样本的太空舱几年后能够按计划安全降落到犹他州的沙漠中,宇航局将保留一部分外星岩石,等将来开发出新的技术以后,再对其做进一步的研究,剩余的岩石将被送往世界各地的实验室做研究之用。
在Osiris-Rex探测器降落在小行星上之前,劳雷塔(Lauretta)介绍说:“这次任务的目的主要就是要了解我们的起源,解决了一些我们作为人类要问自己的最基本的问题,那就是我们来自哪里?我们在宇宙中是孤独的吗?”
在开始阅读英文原文之前,请先复习下列核心词汇:
asteroid - n. 小行星
land on - 着陆
turn out - 结果是
hollow - adj. 中空的,空心的
void - n. 真空,空虚
spin - n. 旋转,自转
spacecraft - n. 航空器
sample - n. 样品
probe - n. 探测器
landscape - n. 景观
boulder - n. 巨石,砾石
touch-and-go - 刚接触到地面就立刻拉升
scoop up - (敏捷地)抱起,捡起
smoothly - adv. 平稳地
nitrogen - n. 氮气
dust - n. 尘埃
swirl - v. 旋动
measure - v. 测量
gravity - n. 重力
pull - v. 拉
fling - v. 扔,抛
track - v. 追踪
strength - n. 强度
bulging - adj. 鼓起的,凸出的
equator - n. 赤道
hazardous - adj. 危险的
primordial - adj. 原生的,原始的
pile - n. 堆
coalesce - n. 合并,结合
capsule - n. 太空舱,胶囊
parachute - v. 伞降,空投
address - v. 处理,从事
在复习了以上词汇后,请将下面的英文原文一口气读完,不要在中途停下来去查那些不认识的单词。有了上面的核心单词打底,你完全可以将整篇文章读完并且理解里面的大致意思。记住,你只要做到大致明白就可以了。
阅读能力和阅读量成正比,要提高阅读量,必须是大量的泛读,如果要对每个不懂的单词都去查字典,那么就不可能通过大量的泛读来提高你的阅读量。
这篇英语原文是《涂博士原版听读写辅导课》直播班上用来训练学员快速阅读的文章之一。能够快速阅读各个领域的原版文章并找出文中的核心内容,是真正学好英语的最最基础的技能之一,另一个最最基础的技能就是听得懂原版的广播。有了这两个最最基础的技能打底,学员就可以利用好网上大量的原版英语文章和听力资源,不出国就可以把自己沉浸在英语的环境当中。在建立起强大的语感之后,口语和写作能力都会自然成长起来。
如果你对某篇泛读文章特别喜欢,可以在泛读一遍以后再慢慢地精读。如果在精读的过程中对某些句子不是太明白需要讲解,或者你希望以后多看到哪方面的双语阅读,请直接联系涂博士。
The asteroid NASA just landed on turns out to be hollow, with a large 'void' at its center. It may be spinning itself to death.
Morgan McFall-Johnsen
Business Insider
The asteroid Bennu just keeps getting more bizarre.
When NASA decided to send a probe to land on a space rock and bring back samples, it picked Bennu for its seemingly smooth surface — perfect landing ground. But once the Osiris-Rex spacecraft had made the 200-million-mile journey to Bennu, the images it beamed back revealed a landscape covered in boulders and rock fields.
NASA eventually chose the flattest spot it could find to land, and the touch-and-go operation to scoop up material went smoothly last month. But then came the next surprise: Bennu's rock turned out to be incredibly soft, crumbling under the spacecraft as it touched the surface.
The probe fired a blast of nitrogen to send rock and dust swirling — that way it could catch some in its sample-collection tool. But yet again, scientists were caught off-guard when the maneuver turned out to have yielded so much material that dust and rock were propping the sample-collection tool open, allowing precious alien dust to leak into space.
They managed to stow the sample before losing too much, but that wasn't the last of the shocks. Recently, University of Colorado researchers concluded based on data Osiris-Rex has collected in the two years it's been circling Bennu that the asteroid is probably hollow.
"It's as if there is a void at its center, within which you could fit a couple of football fields," Daniel Scheeres, a professor in the university's Department of Aerospace Engineering Sciences who led the research, said in a press release.
What's more, Bennu could be spinning itself to pieces.
'The whole thing flying apart'
While Osiris-Rex has been orbiting Bennu, the probe has measured how much the asteroid's gravity pulled on it. At the same time, Bennu was also flinging marble-sized bits of rock away from its surface. Those crumbs entered orbit around the asteroid, then some of them fell back to its surface. By tracking their motions, mission managers were able to make calculations about the strength of Bennu's gravity.
Since gravity comes from mass, these two sets of data allowed Scheeres' team to calculate how material is distributed through the inside of the asteroid.
Their findings, published in the journal Science Advances on October 8 (before Osiris-Rex's brief landing), show that it's far from even. The force of the Bennu' spinning seems to be pushing its material outward towards the surface. Some of the thinnest parts of the asteroid are at its bulging equator.
Bennu completes one rotation every four hours, and it's only getting faster.
"You could imagine maybe in a million years or less, the whole thing flying apart," Scheeres said.
Bennu could hold secrets about the origins of life
Bennu is one of the most potentially hazardous asteroids in our solar system, according to Osiris-Rex principal investigator Dante Lauretta, since it has a "non-negligible chance" of crashing into Earth during the 22nd century. Its fragility could be good news, though.
Studying Bennu could help future scientists make a plan to pert the asteroid if it ever threatens to impact Earth. The research could also reveal new details about the lives of asteroids — primordial piles of rock that coalesced from the leftover bits that didn't make it into planets. Such objects could hold secrets to how our solar system formed and how life arose on Earth.
"We were hoping to find out what happened to this asteroid over time, which can give us better insight into how all of these small asteroids are changing over millions, hundreds of millions, or even billions of years," Scheeres said. "Our findings exceeded our expectations."
Osiris-Rex has collected heaps of data that scientists have yet to comb through. The sample it collected is expected back on Earth in 2023.
Assuming that the capsule holding the sample safely parachutes into the Utah desert as planned in a few years, NASA has said it will preserve a portion of the alien rock for future study with technologies not yet developed. The agency will ship the rest to laboratories all over the world.
"This is all about understanding our origins, addressing some of the most fundamental questions that we ask ourselves as human beings," Lauretta said before Osiris-Rex landed on the asteroid. "Where did we come from? And are we alone in the universe?"