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囊中羞涩的旅行者(NASA's funding shortfall means journey's end for Voyager probes)
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Mission to the edge of the Solar System may shut down in October to save cash.
美国国家宇航局(NASA)史上持续时间最长的使命——旅行者计划将因资金短缺而结束
背景知识：旅行者号探测器(Voyager)是美国于1977年发射的两颗行星探测器。它们巧妙地利用巨行星的引力作用，使它们适时改变轨道，从而达到同时探测多颗行星及其卫星的目的。旅行者号已经到达了太阳系的边缘，是迄今为止最深入宇宙的人类使者。两颗探测器将从不同方向飞出太阳系。它们都携带有一张特殊的镀金唱片“地球之音”，上面录制了有关人类的各种音像信息：60个语种向“宇宙人”的问候语、35种自然界的声音、27首古典名曲、115帧照片。预计唱片可在宇宙间保存10亿年之久。
On the edge: the Voyager spacecraft are on the verge of interstellar space.
旅行者号正接近太阳系边缘
NASA has told scientists working on some of the agency's longest-running space missions — including the twin Voyagers now speeding towards the edge of the Solar System — that they may have to shut down operations in October to save money.
美国宇航局(NASA)当局已告知旅行者计划的科学家说，为了节约资金，旅行者计划这项NASA历史上持续时间最长的空间探测使命将于今年10月结束。这意味着人们将中断与已飞近太阳系边缘的旅行者1号和2号探测器的联系。
The decision — which NASA officials say is not yet final — has angered scientists, who call it penny-wise and pound-foolish, and say that it is being made without the usual formal review by the science community.
NASA官员称这一决策尚未最终确定。此消息已经惹怒了有关科学家，他们称此决定目光短浅，而且没有经过科学共同体例行的正式评议。
The agency's Earth–Sun System division originally planned to spend $74 million next year to operate spacecraft that study the Sun's environment and to pay for data analysis. But the budget has since been cut to $53 million, as NASA struggles to fund all of its planned projects. Faced with the shortfall, division officials last month informed the managers of seven missions that are past their prime lifetime — Voyager, Ulysses, Polar, Wind, Geotail, FAST (Fast Auroral SnapshoT) and TRACE (Transition Region and Coronal Explorer) — that there is no money to keep them operating after the current fiscal year ends in October.
NASA的日地系统分部原计划于明年投入7400万美元，用于太阳环境研究的飞船控制和数据分析。但在NASA竭力为其所有计划项目提供资金的状况下，这项预算被削减到了5300万美元。由于这一削减，日地系统分部的官员上个月通知7项使命的管理者说，在本财政年度于今年10月结束后，将没有资金再维持这些项目的运作。这7个项目都已超过预定寿命，它们是：旅行者，太阳探测器尤利西斯(Ulysses)、太阳过渡区与日冕(TRACE,Transition Region and Coronal Explorer)，地球探测器极地(Polar)、风(Wind)、地球之尾(Geotail)和极光快照(Fast Auroral Snapshot Explorer)。
Launched in 1977, Voyagers 1 and 2 are now more than 14 billion and 11 billion kilometres from Earth, respectively. Having visited all the outer planets except Pluto, they are on their final quest — to locate the shifting boundary between the Sun's domain and the realm where interstellar space begins. Ground antennas are in daily contact with the spacecraft, which are expected to last until about 2020 before giving out. The Voyagers cost NASA about $4.2 million a year for operations and data analysis.
旅行者1号和2号于1977年发射，现在分别离地球140亿公里和110亿公里。它们访问了除冥王星之外所有的太阳系外层行星，目前正在进行最后的探索——确定太阳系与星际空间之间游移不定的边界在何处。地面天线每天与探测器联络，估计将持到2020年。每年旅行者探测器的操作与数据分析需要420万美元。
To afford new projects, NASA occasionally has to turn off spacecraft that are still working but that have exceeded their life expectancy. Every two or three years, a 'senior review' of outside scientists ranks the science value of currently operating missions to help the agency plan which ones should be extended and which shut down. The last such review for Earth–Sun System missions was in August 2003, and the projects now facing termination ranked lowest in that exercise.
为了省出资金给新项目，NASA有时会放弃一些仍在运作但已经超出预期寿命的探测器。每两三年，由外部科学家进行的“高级评议”将对目前运作中的使命的科学价值进行评估，帮助NASA确定哪些使命应该延长、哪些该中止。上一次对日地系统使命的此类评估，是2003年8月进行的，现在将被中止的一些项目在那些评议中级别最低。
Out of time 超出时限
But the panel never suggested that the low-ranking missions should be shut down this year. For example, Ulysses, launched in 1990 to explore the Sun's polar regions for the first time, was recommended to continue until 2008, and Wind until 2007. The Voyagers were recommended for funding until at least 2006, after which they would have to be reviewed again.
但评议小组并未提议将今年就停止那些级别低的使命。例如1990年发射的尤利西斯是第一个研究太阳两极地区的探测器，评议者建议将该项目执行到2008年，并建议将“风”至少维持到2006年，届时重新评议。
Stephen Keil of the National Solar Observatory, who chaired the 2003 review, says his panel assumed a budget of $74 million for 2006, and although their rankings might have been the same given a lower budget, their advice on how to allocate resources would probably have been different. Voyager project scientist Edward Stone of the California Institute of Technology says that instead of holding another review (the next one is scheduled for spring 2006), NASA "just worked up the old list until they matched the lower budget. But that really defeats the purpose of the senior review, which at the time was predicated on a certain level of funding."
国家太阳观测站的Stephen Keil主持了2003年的评议，他说，评议小组假定2006年至少有7400万美元的预算；如果预算减少，小组的评级结果可能相同，但对如何分配资源的建议将会有所不同。旅行者计划的科学家、加州理工学院的Edward Stone说，NASA并没有举行新的评议（下次评议预定于2006年春天进行），只是“整理了一下旧表格，直到其与低预算相配。但这违背了高级评议的宗旨，因为评议结果是根据特定资金水平作出的”。
Lennard Fisk, a University of Michigan space scientist who chairs the National Academy of Sciences Space Studies Board and is a former head of NASA space science, calls the threatened cuts "an extremely foolish thing to do". Voyager, he says, is entering one of the most interesting scientific phases of its long life as its particle detectors approach the edge of the Solar System. "There is no replacement for Voyager," he adds — no other working spacecraft have travelled so far from Earth, and no new ones are being built to follow them. Similarly, says Fisk, it "doesn't make sense" to turn off Ulysses just as the Sun comes to the end of a 22-year magnetic cycle.
曾任国家空间科学院研究委员会(National Academy of Sciences Space Studies Board)主席、NASA空间科学负责人的密歇根大学空间科学家Lennard Fisk说，这个削减计划“极其愚蠢”。他说，随着旅行者的粒子检测器接近太阳系边缘，它们正在进入其漫长生涯中最有趣的科研阶段。“旅行者是无可替代的，”他还说，没有任何其它飞行器曾经飞到离地球这么远的地方，目前它们也没有后继者。与此相似，此时关闭尤利西斯也“毫无意义”，因为太阳正迎来其22年磁周期的终结。
Scientists from the threatened missions are already lobbying their congressional delegations to try to get the money restored, and Fisk thinks NASA could easily solve the budget problem by shifting funds within its $2-billion budget for the Earth–Sun System.
那些即将终止的项目的科学家正在游说他们在国会中的代表，努力使预算恢复到原有水平。Fisk认为，通过在日地系统20亿美元的资金中进行调整，NASA可以很容易地解决预算问题。
That may, in fact, happen. "There's been no final decision at NASA headquarters to terminate any of these missions, despite what budget figures may imply," says NASA spokeswoman Gretchen Cook-Anderson. But for now, project scientists say they have no choice but to take the threat seriously. Having been told by NASA that there is no money available after October, Stone says, "we are currently developing a plan for shutdown".
这是有可能的。NASA女发言人Gretchen Cook-Anderson说：“不管预算数字意味着什么，目前NASA总部尚未作出终止这些使命的最终决定。”不过在眼下，相关项目的科学家说他们别无选择，只能认真对待这一威胁。Stone已被NASA告知10月份以后将没有资金来源，“我们正在制订终止计划。”
【原载Nature/译文载三思科学杂志◎52EN.Com】
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