NASA’s Neil Gehrels Swift Observatory has ended its science mission now that the spacecraft is orbiting less than 171 miles (275 kilometers) above Earth’s surface. The greater atmospheric drag at this height prevents the satellite’s telescopes from steadily gazing at their astronomical targets.
美国宇航局尼尔·格尔尔斯·斯威夫特天文台现已结束其科学任务，该航天器的轨道距地球表面不到 171 英里（275 公里）。这个高度上更大的大气阻力使卫星望远镜无法稳定地凝视其天文目标。
Swift conducted its final observation on Oct. 20. It is expected to re-enter the atmosphere in the next few weeks.
斯威夫特于10月20日进行了最后一次观测。预计它将在未来几周内重新进入大气层。
“Swift delivered an incredible, lasting return on investment for the nation, designed for a two-year primary mission but productive for more than 10 times as long,” said Shawn Domagal-Goldman, director, Astrophysics Division at NASA Headquarters in Washington. “In that time, Swift played a major role in advancing our understanding of the changing universe and was part of a revolution in astrophysics that showed how critical rapid-response observations are to the entire community. To support rapid response to cosmic events in a post-Swift world, we’re exploring our ability to use and augment NASA’s fleet of existing space telescopes, from fast-to-orbit commercial capabilities to efficient, innovative new missions. And Swift leaves us with an extraordinary archive of multiwavelength observations that will fuel new discoveries for decades more.”
美国宇航局华盛顿总部天体物理部主任肖恩·多马加尔-戈德曼 (Shawn Domagal-Goldman) 表示：“Swift 为国家带来了令人难以置信、持久的投资回报，它是为两年的主要任务而设计的，但其生产力却是其 10 倍以上。” “当时，Swift 在增进我们对不断变化的宇宙的理解方面发挥了重要作用，并且是天体物理学革命的一部分，这场革命表明了快速响应观测对整个社区的重要性。为了支持对后 Swift 世界中的宇宙事件的快速响应，我们正在探索使用和增强 NASA 现有太空望远镜群的能力，从快速入轨商业能力到高效、创新的新任务。Swift 为我们留下了非凡的多波长观测档案，这些档案将推动新的研究几十年来的发现。”
In its storied career, Swift has observed more than 2,000 gamma-ray bursts , the most powerful explosions in the cosmos. It has studied more than 1,400 supernova explosions, witnessed stars shredded by black holes , monitored active galaxies , conducted an all-sky X-ray survey, studied asteroids and comets , and more. Swift data has contributed to about 7,000 published scientific papers.
在其传奇的职业生涯中，斯威夫特观测到了 2000 多次伽马射线暴，这是宇宙中最强大的爆炸。它研究了超过 1,400 次超新星爆炸，见证了被黑洞撕碎的恒星，监测了活跃星系，进行了全天 X 射线巡天，研究了小行星和彗星等等。 Swift 数据已为约 7,000 篇已发表的科学论文做出了贡献。
“Swift was designed as a satellite dedicated to studying gamma-ray bursts, outbursts that came and went so quickly that no one could target them with large telescopes to learn more,” said S. Bradley Cenko, the mission’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Swift needed to detect and locate gamma-ray bursts, communicate their position to other observatories, and then swing its telescopes around to image the burst locations before their afterglows faded out. This typically took Swift about a minute to do.”
“雨燕被设计为一颗专门研究伽马射线暴的卫星，这种爆发来得快，去得快，以至于没有人能够用大型望远镜瞄准它们来了解更多信息，”位于马里兰州格林贝尔特的美国宇航局戈达德太空飞行中心的该任务首席研究员 S. Bradley Cenko 说。 “斯威夫特需要探测和定位伽马射线爆发，将其位置传达给其他天文台，然后在余辉消失之前转动望远镜来拍摄爆发位置。这通常需要斯威夫特大约一分钟的时间才能完成。”
Led by its first principal investigator, Neil Gehrels, Swift was born as a multiwavelength observatory, with co-aligned Optical/Ultraviolet and X-ray telescopes that could quickly image and refine a burst’s position. The mission launched into orbit on Nov. 20, 2004, and went to work the following month. In 2018, NASA renamed the mission to honor Gehrels following his death.
在第一位首席研究员 Neil Gehrels 的领导下，雨燕天文台诞生了，它是一个多波长天文台，配备并列的光学/紫外线和 X 射线望远镜，可以快速成像并精确确定爆发的位置。该任务于2004年11月20日发射进入轨道，并于次月开始工作。 2018 年，美国国家航空航天局 (NASA) 在盖勒尔去世后重新命名了该任务，以纪念他。
Speed was especially important for an elusive population called short gamma-ray bursts, which reach peak brightness in less than two seconds. Until Swift, it had been impossible to locate these bursts rapidly and precisely enough to observe their afterglows. In May 2005, Swift achieved this milestone with GRB 050509B , which lasted just 0.03 seconds. Swift turned to the burst fast enough to detect 11 X-ray photons, making this the first short burst with a detected afterglow. These observations validated long-standing theoretical models, showing that short gamma-ray bursts likely come from mergers of two neutron stars — objects with the mass of the Sun that have been crushed to the size of a city.
速度对于一种被称为短伽马射线爆发的难以捉摸的群体尤其重要，这种爆发在不到两秒的时间内达到峰值亮度。在斯威夫特之前，人们不可能快速而精确地定位这些爆发，以观察它们的余辉。 2005 年 5 月，Swift 通过 GRB 050509B 实现了这一里程碑，仅持续了 0.03 秒。斯威夫特以足够快的速度转向爆发，检测到 11 个 X 射线光子，这使得这是第一个检测到余辉的短爆发。这些观测结果验证了长期存在的理论模型，表明短伽马射线爆发可能来自两颗中子星的合并，中子星是质量与太阳相当的物体，被压碎到了城市大小。
Another factor led to Swift’s success as a kind of astronomical multitool. Its flexible planning system enabled astronomers to request “target-of-opportunity” observations that could be commanded from the ground in as little as a few minutes, or to set up monitoring programs for observing specific sources lasting from as little as a few minutes to months. The system could schedule up to 75 independent targets a day.
另一个因素导致 Swift 作为一种天文数字多功能工具取得成功。其灵活的规划系统使天文学家能够请求“机会目标”观测，这些观测可以在短短几分钟内从地面发出指令，或者建立监测计划来观测特定的源，持续时间从几分钟到几个月不等。该系统每天最多可以安排 75 个独立目标。
“The unique speed of response of the Swift hardware, the extraordinary success of the rapid mission operations, and the closely knit teamwork of the Swift Flight and Science Operations teams placed Swift at the crossroads of burgeoning areas of research,” said John Nousek, the mission’s operations director and professor of astronomy and astrophysics in the Eberly College of Science at Penn State in University Park, Pennsylvania.
“Swift 硬件独特的响应速度、快速任务操作的非凡成功，以及 Swift 飞行和科学操作团队紧密的团队合作，使 Swift 处于新兴研究领域的十字路口，”任务操作主任、宾夕法尼亚州立大学帕克分校埃伯利科学学院天文学和天体物理学教授约翰·努塞克 (John Nousek) 说。
The Swift archive contains nearly 22 years of brightness measurements of all kinds of cosmic outbursts, multiwavelength spectra, more than 1.5 million images from its Ultraviolet/Optical Telescope, and much more. The full dataset, publicly available as part of NASA’s commitment to open, gold standard science, spans approximately 12 terabytes, the storage equivalent of about 600 high-definition movies.
Swift 档案包含近 22 年各种宇宙爆发的亮度测量、多波长光谱、来自紫外/光学望远镜的超过 150 万张图像等等。完整的数据集是 NASA 致力于开放、黄金标准科学的一部分，公开提供，其大小约为 12 TB，相当于约 600 部高清电影的存储空间。
As part of the agency’s previous planning for Swift’s end of mission, NASA will continue to prioritize finding new options to react rapidly to cosmic events, using current missions to help fill the gap in the meantime.
作为该机构之前针对雨燕号任务结束计划的一部分，美国宇航局将继续优先寻找新的选择来对宇宙事件做出快速反应，同时利用当前的任务来帮助填补空白。
To learn more about the Swift mission, visit:
要了解有关 Swift 任务的更多信息，请访问：