2023年02月06日 VOA慢速英语：最近的小行星飞越表明行星防御存在“盲点”

 

A small asteroid was discovered recently, just days before it passed close to Earth. The object was never considered a real threat to our planet. But the discovery has raised questions about whether current systems used to identify possibly threatening objects might leave a blind spot for some objects.
最近发现了一颗小行星，就在它接近地球的前几天。该物体从未被视为对我们星球的真正威胁。但这一发现引发了一些问题，即当前用于识别可能具有威胁性物体的系统是否会为某些物体留下盲点。
 
NASA and its international partners continuously search the skies for what scientists call near-Earth objects. Such objects include asteroids and comets that come within 50 million kilometers of Earth's orbit.
NASA 及其国际合作伙伴不断在天空中搜寻科学家所说的近地天体。这些物体包括距离地球轨道 5000 万公里以内的小行星和彗星。
 
The American space agency NASA announced January 25 that an asteroid about the size of a large truck would pass very close to Earth the very next day. The agency said the object, called 2023 BU, was expected to make one of the closest trips past Earth ever recorded.
美国宇航局 NASA于 1 月 25 日宣布，一颗大卡车大小的小行星将在第二天非常接近地球。该机构表示，这个名为 2023 BU 的物体预计将成为有史以来最接近地球的旅行之一。
 
NASA said the asteroid was discovered January 21 by an amateur astronomer based in the Russian-occupied Ukrainian territory of Crimea. The astronomer, Gennady Borisov, is a telescope maker and operates his own observatory. He is credited with discovering an interstellar comet in 2019.
美国国家航空航天局表示，这颗小行星是 1 月 21 日由一名位于俄罗斯占领的乌克兰克里米亚领土的业余天文学家发现的。天文学家根纳季·鲍里索夫 (Gennady Borisov) 是一名望远镜制造商，并经营着自己的天文台。他因在 2019 年发现一颗星际彗星而受到赞誉。
 
Additional observations of 2023 BU were then reported to an internationally recognized organization, the Minor Planet Center, which records the current positions of near-Earth objects. The data was added to the Near-Earth Object Confirmation Page.
对 2023 BU 的额外观测随后被报告给国际公认的组织小行星中心，该组织记录了近地天体的当前位置。数据已添加到近地天体确认页面。
 
NASA said that in the days leading up to the asteroid's flyby, a number of observatories around the world were able to confirm the position of the object. This helped astronomers follow 2023 BU's orbit.
美国宇航局表示，在小行星飞越前几天，世界各地的许多天文台都能够确认该物体的位置。这有助于天文学家追踪 2023 BU 的轨道。
 
Davide Farnocchia is an engineer and planetary defense expert at NASA's Jet Propulsion Laboratory in California. He said in a statement that the agency was quickly able to rule out an asteroid strike.
Davide Farnocchia 是位于加利福尼亚州的 NASA 喷气推进实验室的工程师和行星防御专家。他在一份声明中说，该机构很快就排除了小行星撞击的可能性。
 
NASA said the asteroid passed within 3,600 kilometers of Earth, above the southern tip of South America. That distance is 10 times closer than numerous satellites orbiting Earth.
美国国家航空航天局表示，这颗小行星在距地球 3,600 公里的范围内掠过，位于南美洲南端上方。这个距离比绕地球运行的众多卫星近 10 倍。
 
Scientists said that even if the space rock came a lot closer to Earth, it would have burned up in the atmosphere. In that case, a few bigger pieces might have fallen to Earth as meteorites.
科学家表示，即使太空岩石离地球更近，它也会在大气层中燃烧殆尽。在那种情况下，一些更大的碎片可能会以陨石的形式落到地球上。
 
In general, NASA believes the probability of Earth being struck by a space rock is very low. Astronomers estimate that a space rock of 5-meters in length targets Earth once a year. And a 50-meter rock is estimated to target Earth once every 1,000 years.
总的来说，美国宇航局认为地球被太空岩石撞击的可能性非常低。天文学家估计，一块 5 米长的太空岩石每年以地球为目标一次。据估计，一块 50 米的岩石每 1000 年就会瞄准地球一次。
 
But existing systems used to identify near-Earth objects have difficulty finding smaller ones. Asteroid 2023 BU was on the smaller end of a grouping of objects between 5 to 50 meters. Scientists say objects that size are difficult to identify until they get much closer to Earth. This makes it difficult to prepare for an object that might be heading for a populated area.
但是用于识别近地天体的现有系统很难找到更小的天体。小行星 2023 BU 位于 5 到 50 米之间的一组物体的较小端。科学家们说，这种大小的物体在离地球更近之前很难识别。这使得很难为可能前往人口稠密地区的物体做准备。
 
"We don't know where most of the asteroids are that can cause local to regional devastation," Terik Daly told Reuters news agency. He is a planetary scientist at the Johns Hopkins Applied Physics Laboratory in Maryland.
“我们不知道大多数可能造成局部到区域破坏的小行星在哪里，”泰里克戴利告诉路透社。他是马里兰州约翰霍普金斯应用物理实验室的行星科学家。
 
Some astronomers have proposed using new tools to identify near-Earth objects rather than depending on probability estimates and existing asteroid populations.
一些天文学家提议使用新工具来识别近地天体，而不是依赖概率估计和现有小行星数量。
 
Daly noted that new identification tools could help scientists deal with a possibly dangerous asteroid event. "How many natural hazards are there that we could actually do something about and prevent for a billion dollars? There's not many," he said.
戴利指出，新的识别工具可以帮助科学家应对可能存在危险的小行星事件。“有多少自然灾害是我们实际上可以做点什么并用 10 亿美元来预防的？没有多少，”他说。
 
NASA is already planning to launch a new infrared space telescope designed to support current planetary defense efforts. The Near-Earth Object Surveyor is currently still in development and is set to launch in 2026. NASA officials have said the telescope promises a major improvement over existing ground-based models limited by daytime light and the effects of Earth's atmosphere.
NASA 已经在计划发射一种新的红外太空望远镜，旨在支持当前的行星防御工作。Near-Earth Object Surveyor目前仍在开发中，计划于 2026 年发射。NASA 官员表示，该望远镜有望对受白天光线和地球大气影响限制的现有地面模型进行重大改进。
 
Last year, NASA carried out the first-ever planetary defense test when it crashed a spacecraft into an asteroid. The test successfully changed the path of an asteroid named Dimorphos.
去年，美国宇航局将航天器撞向小行星，进行了有史以来的首次行星防御测试。该测试成功地改变了一颗名为 Dimorphos 的小行星的路径。