美国宇航局计划使用特制宇宙飞船让国际空间站脱轨回收

The American space agency NASA has a new plan for deorbiting the International Space Station (ISS). The plan involves developing a new spacecraft to safely guide the ISS during its final reentry through Earth's atmosphere.
美国宇航局制定了一项新的国际空间站脱轨计划。该计划包括开发一种新的航天器，安全引导国际空间站最后一次重返地球大气层。

NASA cooperates with four other space agencies on the station. These include the Canadian Space Agency, the European Space Agency, Japan's Aerospace Exploration Agency and Russia's Roscosmos.
美国宇航局在空间站上与其他四个航天机构合作。其中包括加拿大航天局、欧洲航天局、日本宇宙航空研究开发机构和俄罗斯航天局。

The ISS began serving as a space research center more than 22 years ago. It has been widely praised as a scientific success. But, NASA and its international partners say the ISS has a limited technical lifetime. NASA has said it will keep operating and sending astronauts to the ISS until 2030.
国际空间站于22年前开始作为一个空间研究中心。它被广泛赞誉为科学上的成功。但是，美国宇航局及其国际合作伙伴表示，国际空间站的技术寿命有限。美国宇航局表示，将继续运营国际空间站并派遣宇航员，直到2030年。

After that, the U.S. space agency plans to use privately developed space laboratories for its space research needs. NASA says this will permit it to pay space station operators only for the goods and services it needs.
之后，美国航天局计划使用私人开发的太空实验室来满足其太空研究需求。美国宇航局表示，这将允许其仅为其所需的商品和服务向空间站运营商支付费用。

NASA has already chosen several American companies to develop future space stations. These privately-operated stations will aim to serve the science needs of NASA, as well as other nations' space agencies and other organizations.
美国宇航局已经选择了几家美国公司来开发未来的空间站。这些私人运营的空间站将致力于满足美国宇航局、其他国家的航天机构和其他组织的科学需求。

In a report to the U.S. Congress last year, NASA established its plans for the ISS. The report said the agency aims to make the station's final years its most productive. Among the goals NASA declared: "To support deep space exploration and continue to return medical and environmental benefits to humanity."
在去年提交给美国国会的一份报告中，美国宇航局制定了国际空间站的计划。该报告称，该机构的目标是使空间站的最后几年成为最富有成效的几年。美国宇航局宣布的目标之一是：“支持深空探索，继续为人类带来医疗和环境效益。”

The agency recently announced its new deorbiting plan for the ISS after considering other options to retire it. A past plan, or option, involved the use of several Russian spacecraft. But NASA officials rejected that plan and decided a new, specially designed spacecraft would better serve the needs of the deorbiting operation.
在考虑了退役国际空间站的其他选择后，该机构最近宣布了其新的国际空间站脱轨计划。过去的计划或选择涉及使用几艘俄罗斯航天器。但美国宇航局官员拒绝了这一计划，并决定建造一艘新的、专门设计的航天器来更好地满足脱轨操作的需要。

Other options included a plan to take apart the space station in space and transport its pieces back to Earth. Another plan would have seen the ISS sent to a higher orbit, where it would remain out-of-service. A third option involved a non-controlled reentry operation. NASA said none of these met its requirements for safety and effectiveness.
其他选择包括在太空中拆除空间站并将其部件运回地球的计划。另一个计划是将国际空间站送往更高的轨道，在那里它将停止服务。第三种选择涉及非受控再入操作。美国宇航局表示，这些都不符合其安全性和有效性的要求。

The agency recently released a request for proposals to companies interested in building the new the spacecraft. NASA calls it the U.S. Deorbit Vehicle (USDV). It says it can be a completely new vehicle or an existing design that is changed to meet all needs of the deorbiting process. The agency said it is seeking proposals now because the effort "will take years to develop, test, and certify."
该机构最近向有兴趣建造这种新航天器的公司发布了一份征求建议书的请求。美国宇航局称之为美国脱轨飞行器。美国宇航局称它可以是一种全新的载运工具，也可以是一种现有的设计，可以进行改造以满足脱轨过程的所有需求。该机构表示，目前正在寻求提案，因为这项工作“需要数年的时间来开发、测试和认证”。

NASA has said when it is time to retire the ISS, it will begin taking the first steps to slowly lower its operating altitude. This part of the process can likely be carried out by the ISS and its systems, without the need for additional spacecraft.
美国宇航局表示，当国际空间站退役时，它将开始采取第一步，慢慢降低其运行高度。这部分过程可能由国际空间站及其系统进行，而不需要额外的航天器。

But the final part of the operation, reentry, will center on guiding the ISS though Earth's atmosphere to a pre-chosen target in an unpopulated area in the ocean. NASA says this final part "is expected to require a new or modified spacecraft using a large amount of propellant."
但行动的最后一部分，即重返大气层，将聚焦于引导国际空间站穿过地球大气层，到达海洋中无人区的预定目标。美国宇航局表示，这最后一部分操作“预计需要一种使用大量推进剂的全新或改进的航天器”。

The targeted landing spot has been identified as a place called Point Nemo in the South Pacific Ocean. This is a stretch of open water between New Zealand and the southernmost part of South America. The U.S. National Ocean Service identifies Point Nemo as the point in the ocean that is farthest from land.
目标着陆点已被确认为南太平洋的一处名为尼莫角的地方。这是新西兰和南美洲最南端之间的一片开阔水域。美国国家海洋局将尼莫角确定为海洋中距离陆地最远的点。

NASA predicts that most ISS equipment will burn up or vaporize during the intense heating that happens during atmospheric re-entry. But it says some denser or more heat-resistant elements are expected to survive and land in the targeted ocean area.
美国宇航局预测，国际空间站的大多数设备在重返大气层期间发生的剧烈加热过程中将会烧尽或汽化。但它表示，一些密度更大或更耐热的元素有望残存下来，并落入目标海域。