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美国宇航局确认“旅行者1号”探测器离开太阳系超过一年

来源：人民网  2013年09月13日

　　人民网纽约9月12日电 （记者 徐澍）美国宇航局NASA在本周四确认，“旅行者1号”探测器已经离开太阳系，到达太阳系外各恒星之间空旷的恒星际空间超过一年时间。
　　NASA的发言人表示：“旅行者号已经到达了从来没有探测器到达过的空间，这是人类的科学发展史上的里程碑。”一系列相关数据证明了旅行者号已经脱离了包裹着太阳系的由炽热而活跃的粒子组成的太阳圈顶层，进入了寒冷黑暗的恒星际空间。旅行者号探测器脱离太阳系的日期大约为2012年的8月25日。
　　自今年以来，科学家一直就旅行者号目前到达的位置展开着激烈的争论。数据显示该探测器经受过越来越频繁的宇宙射线和来自太阳圈内部脱落的高能粒子的威胁。但NASA一直表示，在不能确定旅行者号周边的磁场环境发生改变之前，无法就其是否已经离开太阳系做出判断。目前，NASA已经承认磁场变化并不是做出结论的必要条件。
　　确认旅行者号是否离开太阳系的一个关键因素，是探测器上装有的探测空间等离子体电子密度装置的数据结果。当数据显示电子密度大大增加，意味着探测器已经离开活动频繁、电子密度较低的太阳系。但这个实验需要太阳耀斑爆发的一个类似触发机制，在太阳活动不活跃的时期，需要很长时间的等待。幸运的是，科学家分别在去年的11月和今年的5月的捕捉到两次有效的实验数据，两次数据都显示旅行者号处于寒冷、高密度的环境中，意味着旅行者号到达了恒星际空间。
　　旅行者1号探测器在1977年9月5日发射，历经36年的旅行，终于成为第一个离开太阳系的人造物体。科学家也希望同时发射的旅行者2号探测器可以沿着另外的轨迹在若干年后同样到达恒星际空间，更加丰富人类对于太阳系和太阳系以外空间的认知。

“旅行者1号”飞出太阳系

《 人民日报 》（ 2013年09月14日   11 版）

　　
本报驻美国记者 陈一鸣

　　美国航天局喷气推进实验室9月12日证实，“旅行者1号”探测器已于去年8月底离开太阳系，成为首个跨入星际空间大门的人造物体。目前，这颗探测器与太阳的距离约为190亿千米。
　　9月12日出版的美国《科学》杂志刊登了艾奥瓦大学研究人员唐·格尼特及其团队发表的一份报告，认为“旅行者1号”现在处于太阳系以外地带，但来自太阳的影响仍然明显。
　　让科学家确定“旅行者1号”已经进入星际空间的证据，源自去年3月的一次太阳日冕物质爆发。当时释放的太阳风和磁场物质在今年4月抵达“旅行者1号”所在位置，使其周围的等离子体像琴弦一样颤动。4月9日，“旅行者1号”的等离子波探测仪感受到了这一振动。科学家通过对振动强度进行分析，发现“旅行者1号”周边的等离子体密度比太阳风层的最外层高了40倍，表明它已经处于星际空间。
　　“当我们从数据中看到了振幅，都从椅子上跳了起来。这些数据告诉我们，这颗探测器已经处在一个与太阳风层完全不同的新区域。”唐·格尼特说：“很明显，‘旅行者1号’已经穿越了太阳风层最外层，那里是科学界长期公认的、来自太阳的等离子与外层空间的等离子交界的地带。”
　　去年8月25日“旅行者1号”测到来自太阳的高能带电粒子密度突然发生持续性改变，因此“旅行者”号项目团队现在一致认定，“旅行者1号”在那一天前后进入了星际空间。
　　“旅行者1号”探测器于1977年9月5日在佛罗里达州卡纳维拉尔角发射升空，最初的目标是对木星、土星、天王星和冥王星进行观测。当观测任务在1989年完成后，美国航天局令其朝着银河系中心的方向进发。
　　如今，美国航天局已没有负责“旅行者”号项目的专职科学家，只有大约20名专家轮流进行数据接收和分析工作。目前，“旅行者1号”发出的信号大约要经17个小时抵达地球，但对这些数据进行分析和判断，往往要花费数月至数年时间。预计“旅行者1号”上的两颗钚电池只能继续工作到2025年，此后“旅行者1号”将再也不会向地球发回任何数据。
　　在美国航天局喷气推进实验室工作的“旅行者”号项目经理苏珊娜·多德表示，项目团队期待“旅行者1号”上的科学仪器至少在2020年前仍能传回数据。“我们都急着想看到‘旅行者1号’上的仪器将给我们展现什么样的深空。”多德说。
　　（本报洛杉矶9月13日电） 

“旅行者1号”与地球人送给“外星人”的礼物

2010年12月22日  来源：北京日报

  
　　……。
　　于1977年10月发射的“旅行者1号”探测器，考察目标和“先驱者11号”一样，都是木星和土星。但由于它携带的仪器更先进，所以它一经过木星，就发现了一个新东西——木星光环，这是“旅行者1号”的最大成就。
　　先于“旅行者1号”一个半月发射的“旅行者2号”，其业绩更值得一说。它一次飞行先后掠过了木星、土星、天王星和海王星，分别对它们进行了探测，因此人们把这次探测叫做“大旅行”。
　　地球人送给“外星人”的礼物
　　由于四个探测器都要飞出太阳系，到茫茫银河系中去旅行，科学家们就想到，为什么不顺便给可能存在的外星文明带去一点有关人类文明的信息呢？
　　于是，人们在“先驱者10号”和“先驱者11号”上放进了一张地球人给外星人的“名片”——一张能保存10亿年的镀金铝版。上面的辐射线代表14颗脉冲星，反映地球在银河系中的方位；下面是太阳和它的九大行星；左上方两个用横线连接的圆圈，表示地球上第一号元素氢的分子结构；右边是先驱者号探测器和男女地球人的图形。
　　两个“旅行者”探测器携带的人类“名片”，是一张直径30.5厘米的镀金铜质音像光碟，密封在一个铝盒里。在这张镀金光盘上，一面录制有116张照片，一面录有联合国秘书长和美国总统的致辞，55种语言的问候语，27首世界古今乐曲和35种自然界声响。
　　光碟上录制的相片，反映了太阳系的方位、地球人的细胞组成、男女性别、家庭构成和风土人情等。其中包括一张中国万里长城和一张中国人全家聚餐的相片。
　　光碟上录制的55种语言的问候语中，汉语部分包括普通话、广东话、厦门话和江浙一带的吴方言。先是一位小姐用广东话向“外星人”问候：“各位都好吗？祝各位平安、健康、快乐！”接着是一位厦门妇女的声音：“太空朋友，你们好，你们吃饭了吗？有空请来这儿坐坐。”吴方言的问候是：“祝你们大家好！”最后是一位男子用普通话说：“各位都好吧！我们都很想念你们，有空请到这儿来玩！”
　　光碟上的35种地球自然界声响，包括火山爆发声，滂沱大雨声，海浪波涛声，火车、飞机和汽车轰鸣声，火箭发射声，婴儿第一次啼哭声，鸟啼虫鸣声等。27首世界名曲中则包括中国的京剧唱段和古琴演奏的《高山流水》乐曲等。

NASA Spacecraft Embarks on Historic Journey Into Interstellar Space

Sept 12, 2013

PASADENA, Calif. -- NASA's Voyager 1 spacecraft officially is the first human-made object to venture into interstellar space. The 36-year-old probe is about 12 billion miles (19 billion kilometers) from our sun.
New and unexpected data indicate Voyager 1 has been traveling for about one year through plasma, or ionized gas, present in the space between stars. Voyager is in a transitional region immediately outside the solar bubble, where some effects from our sun are still evident. A report on the analysis of this new data, an effort led by Don Gurnett and the plasma wave science team at the University of Iowa, Iowa City, is published in Thursday's edition of the journal Science.
"Now that we have new, key data, we believe this is mankind's historic leap into interstellar space," said Ed Stone, Voyager project scientist based at the California Institute of Technology, Pasadena. "The Voyager team needed time to analyze those observations and make sense of them. But we can now answer the question we've all been asking -- 'Are we there yet?' Yes, we are."
Voyager 1 first detected the increased pressure of interstellar space on the heliosphere, the bubble of charged particles surrounding the sun that reaches far beyond the outer planets, in 2004. Scientists then ramped up their search for evidence of the spacecraft's interstellar arrival, knowing the data analysis and interpretation could take months or years.
Voyager 1 does not have a working plasma sensor, so scientists needed a different way to measure the spacecraft's plasma environment to make a definitive determination of its location. A coronal mass ejection, or a massive burst of solar wind and magnetic fields, that erupted from the sun in March 2012 provided scientists the data they needed. When this unexpected gift from the sun eventually arrived at Voyager 1's location 13 months later, in April 2013, the plasma around the spacecraft began to vibrate like a violin string. On April 9, Voyager 1's plasma wave instrument detected the movement. The pitch of the oscillations helped scientists determine the density of the plasma. The particular oscillations meant the spacecraft was bathed in plasma more than 40 times denser than what they had encountered in the outer layer of the heliosphere. Density of this sort is to be expected in interstellar space.The plasma wave science team reviewed its data and found an earlier, fainter set of oscillations in October and November 2012. Through extrapolation of measured plasma densities from both events, the team determined Voyager 1 first entered interstellar space in August 2012.
"We literally jumped out of our seats when we saw these oscillations in our data -- they showed us the spacecraft was in an entirely new region, comparable to what was expected in interstellar space, and totally different than in the solar bubble," Gurnett said. "Clearly we had passed through the heliopause, which is the long-hypothesized boundary between the solar plasma and the interstellar plasma."
The new plasma data suggested a timeframe consistent with abrupt, durable changes in the density of energetic particles that were first detected on Aug. 25, 2012. The Voyager team generally accepts this date as the date of interstellar arrival. The charged particle and plasma changes were what would have been expected during a crossing of the heliopause.
 "The team’s hard work to build durable spacecraft and carefully manage the Voyager spacecraft's limited resources paid off in another first for NASA and humanity," said Suzanne Dodd, Voyager project manager, based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We expect the fields and particles science instruments on Voyager will continue to send back data through at least 2020. We can't wait to see what the Voyager instruments show us next about deep space."
Voyager 1 and its twin, Voyager 2, were launched 16 days apart in 1977. Both spacecraft flew by Jupiter and Saturn. Voyager 2 also flew by Uranus and Neptune. Voyager 2, launched before Voyager 1, is the longest continuously operated spacecraft. It is about 9.5 billion miles (15 billion kilometers) away from our sun.
Voyager mission controllers still talk to or receive data from Voyager 1 and Voyager 2 every day, though the emitted signals are currently very dim, at about 23 watts -- the power of a refrigerator light bulb. By the time the signals get to Earth, they are a fraction of a billion-billionth of a watt. Data from Voyager 1's instruments are transmitted to Earth typically at 160 bits per second, and captured by 34- and 70-meter NASA Deep Space Network stations. Traveling at the speed of light, a signal from Voyager 1 takes about 17 hours to travel to Earth. After the data are transmitted to JPL and processed by the science teams, Voyager data are made publicly available.
“Voyager has boldly gone where no probe has gone before, marking one of the most significant technological achievements in the annals of the history of science, and adding a new chapter in human scientific dreams and endeavors,” said John Grunsfeld, NASA’s associate administrator for science in Washington. “Perhaps some future deep space explorers will catch up with Voyager, our first interstellar envoy, and reflect on how this intrepid spacecraft helped enable their journey.”
Scientists do not know when Voyager 1 will reach the undisturbed part of interstellar space where there is no influence from our sun. They also are not certain when Voyager 2 is expected to cross into interstellar space, but they believe it is not very far behind.
JPL built and operates the twin Voyager spacecraft. The Voyagers Interstellar Mission is a part of NASA's Heliophysics System Observatory, sponsored by the Heliophysics Division of NASA's Science Mission Directorate in Washington. NASA's Deep Space Network, managed by JPL, is an international network of antennas that supports interplanetary spacecraft missions and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected Earth-orbiting missions.
The cost of the Voyager 1 and Voyager 2 missions -- including launch, mission operations and the spacecraft’s nuclear batteries, which were provided by the Department of Energy -- is about $988 million through September.

For a sound file of the oscillations detected by Voyager in interstellar space, animations and other information, visit:
http://www.nasa.gov/voyager .
For an image of the radio signal from Voyager 1 on Feb. 21 by the National Radio Astronomy Observatory's Very Long Baseline Array, which links telescopes from Hawaii to St. Croix, visit:
http://www.nrao.edu .
Jia-Rui C. Cook/D.C. Agle 818-354-0850/818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
jccook@jpl.nasa.gov
Dwayne Brown 202-358-1726
Headquarters, Washington
dwayne.c.brown@nasa.gov
2013-277