A new instrument mounted atop a telescope in Arizona has aimed its robotic array of 5,000 fiber-optic “eyes” at the night sky to capture the first images showing its unique view of galaxy light.
美国亚利桑那州的一架望远镜上安装了一种新仪器，它将5000只光纤“眼睛”组成的机器人阵列对准夜空，以捕捉到第一批显示其独特星系光视野的图像。
It was the first test of the Dark Energy Spectroscopic Instrument, known as DESI, with its nearly complete complement of components. The long-awaited instrument is designed to explore the mystery of dark energy, which makes up about 68 percent of the universe and is speeding up its expansion.
这是对被称为DESI，拥有完成组成部分的暗能量光谱仪器的首次测试。这个期待已久的仪器旨在探索暗能量的奥秘，占宇宙的68%的暗能量正在加速膨胀。
Connie Rockosi, professor and co-chair of astronomy and astrophysics at UC Santa Cruz, serves on the DESI Leadership Team. As the commissioning scientist, she has the job of planning and coordinating the work of a team of scientists and engineers from throughout the DESI collaboration to demonstrate that the instrument is ready to start scientific observations.
加州大学圣克鲁斯分校（UC Santa Cruz）天文学和天体物理学教授兼联合主席Connie Rockosi是DESI领导团队的成员。作为调试科学家，她的职责是规划和协调整个DESI合作的科学家和工程师团队的工作，以证明该仪器已经做好了开始科学观测的准备。
“It’s a real thrill to be part of making everything come together as a working instrument that will do exciting science. This is a milestone achievement of many years of work by many people in DESI,” Rockosi said.
“把所有的东西作为工作工具组合在一起，做一个令人兴奋的科学研究真是一件激动人心的事。这是为DESI工作多年的人们取得的一个里程碑式的成就。”Rockosi说。
DESI’s components are designed to automatically point at preselected sets of galaxies, gather their light, and then split that light into narrow bands of color to precisely map their distance from Earth and gauge how much the universe expanded as this light traveled to Earth. In ideal conditions, DESI can cycle through a new set of 5,000 galaxies every 20 minutes.
DESI的组件被设计成自动指向预先选定的星系集，以便收集它们的光，然后将这些光分成窄色带，以精确地绘制它们到地球的距离，并测量当这些光到达地球时宇宙膨胀了多少。在理想的条件下，DESI每20分钟可以穿过5000个星系。
The latest milestone marks the opening of DESI’s final testing toward the formal start of observations in early 2020.
最新的里程碑标志着DESI的最终测试开始，正式开始观测将在2020年初。
Time machine
时光机
Like a powerful time machine, DESI will peer deeply into the universe’s infancy and early development—up to about 11 billion years ago—to create the most detailed 3-D map of the universe.
就像一台强大的时光机，DESI将深入观察宇宙的婴幼期和早期发展——大约110亿年前——以创建最详细的宇宙三维地图。
By repeatedly mapping the distance to 35 million galaxies and 2.4 million quasars across one-third of the area of the sky over its five-year run, DESI will teach us more about dark energy. Quasars, among the brightest objects in the universe, allow DESI to look deeply into the universe’s past.
5年里，DESI不断地在三分之一的天空中绘制出3500万个星系和240万个类星体的距离图，这将使我们对暗能量有更多的了解。类星体是宇宙中最明亮的天体之一，这使DESI得以深入研究宇宙的过去。
DESI will provide very precise measurements of the universe’s expansion rate. Gravity had slowed this rate of expansion in the early universe, though dark energy has since been responsible for speeding up its expansion.
DESI将提供非常精确的宇宙膨胀率测量数据。尽管暗能量是加速膨胀的原因，但引力减缓了早期宇宙的膨胀速度。
“After a decade in planning and R&D, installation and assembly, we are delighted that DESI can soon begin its quest to unravel the mystery of dark energy,” said DESI Director Michael Levi of the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), the lead institution for DESI’s construction and operations.
“在经历十年的规划，研发，安装和组装之后，我们很高兴DESI可以很快开启探索暗能量秘密之旅,”DESI总负责人Michael Levi说道，他来自美国能源部劳伦斯伯克利国家实验室(Berkeley Lab)，DESI建设和运营的领导机构。
"Most of the universe’s matter and energy are dark and unknown, and next-generation experiments like DESI are our best bet for unraveling these mysteries,” Levi added. “I am thrilled to see this new experiment come to life.”
“宇宙中的大部分物质和能量都是黑暗和未知的，像DESI这样的下一代实验是我们解开这些谜团的最佳选择，”Levi补充说。“看到这个新实验获得成功，我很激动。”
The DESI collaboration has participation from nearly 500 researchers at 75 institutions in 13 countries. At UC Santa Cruz, Alexie Leauthaud and J. Xavier Prochaska, both professors of astronomy and astrophysics, are involved in the collaboration along with Rockosi. Leauthaud serves on the DESI Science Committee.
来自13个国家，75个机构的近500名研究人员参与了DESI的合作。在加州大学圣克鲁斯分校(UC Santa Cruz)，天文学和天体物理学教授Alexie Leauthaud和J. Xavier Prochaska与Rockosi进行了合作。其中Leauthaud是DESI科学委员会的成员。
Installation
安装
Installation of DESI began in February 2018 at the Nicholas U. Mayall Telescope at Kitt Peak National Observatory near Tucson, Arizona. “With DESI we are combining a modern instrument with a venerable old telescope to make a state-of-the-art survey machine.” said Lori Allen, director of Kitt Peak National Observatory at the National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory.
DESI的安装工作于2018年2月在亚利桑那州图森市（Tucson, Arizona）附近的基特峰国家天文台（Kitt Peak National Observatory）的Nicholas U. Mayall望远镜开始。“通过DESI，我们把现代仪器和古老的望远镜结合起来，制造出了最先进的测量仪器。”美国国家科学基金会国家光学-红外天文研究实验室（National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory）基特峰国家天文台主任Lori Allen说。
Over the past 18 months, a bevy of DESI components were shipped to the site from institutions around the globe and installed on the telescope. Jiani Ding, an astronomy graduate student from UC Santa Cruz, has been on site to help with the installation.
在过去的18个月里，一组DESI组件从世界各地的机构运至现场，并安装在望远镜上。来自加州大学圣克鲁斯分校的天文学研究生Jiani Ding一直在现场帮助安装。
Among the early arrivals was an assembly of lenses packaged in a large steel barrel, together weighing in at three tons. This corrector barrel sits over the 4-meter primary mirror of the Mayall Telescope and provides an expansive field of view. The lenses, each measuring about a meter across, were successfully tested in April.
在最早到达的组件中，有一组镜头被包装在一个大钢桶里，总共重达3吨。这个校正筒位于Mayall望远镜的主镜上方，主镜高4米，提供了广阔的视野。今年4月，这两款直径约1米的柔性焦距透镜组测试成功。
DESI’s focal plane, which carries 5,000 robotic positioners that swivel in a choreographed “dance” to focus individually on galaxies, is at the top of the telescope.
DESI的焦平面位于望远镜的顶部，它可以承载5000个机器人定位器，这些定位器可以按照精心设计的“舞蹈”旋转，以单独聚焦于星系。
These little robots—which each hold a light-gathering fiber-optic cable that is about the average width of a human hair—serve as DESI’s eyes. It takes about 10 seconds for the positioners to swivel to a new sequence of targeted galaxies. With its unprecedented surveying speed, DESI will map over 20 times more objects than any predecessor experiment.
这些小机器人——每个机器人都有一根平均宽度约人类头发的聚光光纤——充当DESI的眼睛。定位器旋转到一个新的目标星系序列大约需要10秒钟。以其前所未有的测绘速度，DESI将会比之前的任何实验多绘制20多倍的物体。
The focal plane, which is comprised of a half-million individual parts, is arranged in a series of 10 wedge-shaped petals that each contain 500 positioners and a little camera to help the telescope point and focus.
焦平面由50万个独立部分组成，由10个楔形花瓣组成，每个花瓣包含500个定位器和一个小相机，帮助望远镜瞄准和聚焦。
The focal plane, corrector barrel, and other DESI components weigh 11 tons, and the Mayall telescope’s movable arm that DESI is installed on weighs 250 tons and rises 90 feet above the floor in the Mayall’s 14-story dome.
焦平面、校正筒和其他DESI组件重11吨，安装在Mayall望远镜的移动臂上，在Mayall 14层的圆顶上，重达250吨，高出地面90英尺。
Among the more recent arrivals at Kitt Peak is the collection of spectrographs that are designed to split up the gathered light into three separate color bands to allow precise distance measurements of the observed galaxies across a broad range of colors.
在最近到达基特峰的光谱仪器中，有一种仪器是将收集到的光分成三个不同的色带，以便在大范围的颜色范围内对观测到的星系进行精确的距离测量。
These spectrographs, which allow DESI’s robotic eyes to “see” even faint, distant galaxies, are designed to measure redshift, which is a shift in the color of objects to longer, redder wavelengths due to the objects’ movement away from us. Redshift is analogous to how the sound of a fire engine’s siren shifts to lower tones as it moves away from us.
这些光谱仪可以让DESI的机器眼睛甚至能“看到”微弱的遥远星系，它们的设计目的是测量红移。红移是由于物体远离我们时物体颜色向更长的、更红的波长转变。红移类似于消防车的警笛声在远离我们时转为较低的音调。
There are now eight spectrographs installed, with the final two arriving before year-end. To connect the focal plane with the spectrographs, which are located beneath the telescope, DESI is equipped with about 150 miles of fiber-optic cabling.
目前已经安装了八台光谱仪，最后两台也将在年底前到达。为了将焦平面与位于望远镜下方的光谱仪连接起来，DESI配备了大约150英里长的光纤电缆。
“This is a very exciting moment,” said Nathalie Palanque-Delabrouille, a DESI spokesperson and an astrophysics researcher at France’s Atomic Energy Commission (CEA) who has participated in the selection process to determine which galaxies and other objects DESI will observe.
“这是一个非常激动人心的时刻，”DESI发言人、法国原子能委员会(CEA)天体物理学研究员Nathalie Palanque-Delabrouille说。
“The instrument is all there. It has been very exciting to be a part of this from the start,” she said. “This is a very significant advance compared to previous experiments. By looking at objects very far away from us, we can actually map the history of the universe and see what the universe is composed of by looking at very different objects from different eras.”
“设备都在那儿。从一开始就参与其中的我感到非常兴奋，”她说。“与之前的实验相比，这是一个非常重要的进步。通过观察离我们很远的物体，我们可以绘制出宇宙的历史，通过观察不同时代的不同物体，我们可以看到宇宙是由什么组成的。”
Palanque-Delabrouille’s institution, CEA, contributed a specialized cooling system to optimize the performance of the light sensors (known as CCDs or charge-coupled devices) that enable DESI’s broad color-sampling range.
palque - delabrouille的机构，CEA，贡献了一个专门的冷却系统，用来优化光传感器（称为CCDs或电荷耦合设备）的性能，使DESI有广泛的颜色采样范围。
Gregory Tarlé, a physics professor at the University of Michigan (UM) who led the student teams that assembled the robotic positioners for DESI and related components, said it’s gratifying to reach a stage in the project where all of DESI’s complex components are functioning together.
密歇根大学（University of Michigan）物理学教授格Gregory Tarle领导的学生团队为DESI和相关组件组装了机器人定位器。
UM delivered a total of 7,300 robotic positioners, including spares. During the production peak, the teams were churning out about 50 positioners a day.
UM总共交付了7300个机器人定位器，包括备件。在生产高峰期，这些团队每天要生产大约50个定位器。
“It was quite a process,” Tarlé said. “We were at the limits of precision for these production parts.”
“这是一个相当复杂的过程，”Tarlé说。“这些生产部件的精度已经到了极限。”
The positioners were installed in the focal plane petals at Berkeley Lab, and after assembly and testing the completed petals were shipped to Kitt Peak and installed one at a time on the Mayall Telescope.
定位器被安装在伯克利实验室的焦平面花瓣上，在组装和测试完成后，花瓣被运送到凯特峰，并安装在 Mayall 望远镜上。
Now that the hard work of building DESI is largely done, Tarlé said he looks forward to DESI discoveries.
既然建造DESI的艰苦工作已经基本完成，Tarlé说他期待着DESI的发现。
“I want to find out what the nature of dark energy is,” he said. “We finally have a shot at really trying to understand the nature of this stuff that dominates the universe.”
“我想找出暗能量的本质，”他说。“我们终于有机会真正去理解这种主宰宇宙的物质的本质了。”
