The BlueWalker 3 satellite is officially one of the brightest objects in the sky

蓝行者3号卫星正式成为天空中最亮的物体之一

On Monday (Oct. 2), scientists with the International Astronomical Union announced that one of the brightest objects visible in the night sky is not a star or a planet, but rather the BlueWalker 3 prototype satellite.

周一（10月2日），国际天文学联合会的科学家宣布，夜空中可见的最亮物体之一不是恒星或行星，而是蓝行者3号原型卫星。

"It is unacceptably bright for many sky observers around the world," Meredith Rawls, co-author of a paper on the finding and member of the IAU Center for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (IAU CPS), told Space.com.

梅丽迪斯·罗尔斯是该论文的合著者，也是国际天文学联合会保护黑暗和安静天空免受卫星星座干扰中心（IAU CPS）的成员，她对Space.com说：“对于世界各地的许多天空观察者来说，蓝行者3号的亮度令人难以接受。”

Part of an ambitious 5G communications system developed by the company AST SpaceMobile, BlueWalker 3 appears so utterly luminous from our vantage point on Earth because, in addition to a Launch Vehicle Adapter (LVA), it possesses a massive structure known as a phased-array antenna. In fact, BlueWalker 3 is deemed the largest commercial antenna system ever deployed to low-Earth orbit; it was launched there in September of 2022.

蓝行者3号卫星是AST SpaceMobile公司开发的一个雄心勃勃的5G通信系统的一部分，它拥有一种被称为相控阵天线的巨大结构，并具有发射载荷适配器（LVA）。事实上，蓝行者3号被认为是迄今部署在低地球轨道上的最大商业天线系统，该卫星于2022年9月发射升空。正是由于这些因素，从地球上观察，它看起来异常亮眼。

That array takes up about 64 square meters (689 square feet) of space — and because those panels are reflective, it's almost like BlueWalker 3 is a giant mirror continuously bouncing sunlight toward our eyes.

那个相控阵天线占据了大约64平方米（689平方英尺）的空间，而且由于这些板面是有反射性的，所以蓝行者3号的状如一个巨大的镜子，不停地将阳光反射到我们的眼睛里。

Related: Astronomers denounce super-bright new BlueWalker 3 satellite

相关：天文学家谴责超级明亮的新蓝行者3号卫星

And that mirror could soon have company. AST says it envisions about 90 similar satellites roaming the skies in the near future to make what experts call a "satellite constellation," though an AST spokesperson told Space.com that, by contrast, other such constellations are expected to require thousands of satellites to achieve their coverage goals.

而且，这个巨大的镜子可能很快就会有陪伴。AST表示，他们设想在不久的将来会有大约90颗类似卫星在天空中漫游，形成专家所称的“卫星星座”，尽管AST的发言人告诉Space.com说，与此相比，其他类似的星座预计需要数千颗卫星才能实现其覆盖目标。

"We are building the first and only space-based cellular broadband network designed to seamlessly connect everyday smartphones," the AST spokesperson told Space.com. "By connecting people, we aim to alleviate poverty, spur economic development, foster a diverse digital society and save lives."

AST的发言人告诉Space.com：“我们正在建设首个也是唯一一个旨在无缝连接日常智能手机的太空移动宽带网络。通过连接人们，我们旨在减轻贫困、推动经济发展、培育多元化数字社会并挽救生命。”

Naturally, however, this ultrabright satellite prototype has opened the door to concerns about whether our night sky is on the road to being littered with far too many artificial stars — especially because it's not an isolated situation. SpaceX's Starlink satellites, for instance, have already spurred a similar discussion. Not only might such a future be an eerie one for stargazers to live in, but it also poses a threat to the work of astronomers.

然而，这颗超亮的卫星原型自然引发了人们对于我们的夜空是否将被过多的人造星体所遮挡的担忧，特别是因为这并非一种孤立的情况。例如，SpaceX的星链卫星已经引发了类似的讨论。这样的未来不仅对于观星者而言可能会带来一种怪异的感觉，而且还对天文学家的工作构成了威胁。

That's because excessive, human made brightness in the sky directly impacts astronomical observations, both radio and optical.

这是因为天空中过多的人造亮度直接影响了天文观测，包括无线电观测和光学观测。

"This satellite was launched without much consideration of its impact on astronomy," Siegfried Eggl, co-author of the study and member of the IAU CPS, told Space.com. "The IAU CPS seeks to change that and work on solutions together with the space industry."

该研究的共同作者、IAU CPS成员齐格弗里德·埃格尔（Siegfried Eggl）告诉Space.com：“发射这颗卫星时没有太多考虑它对天文学的影响。”“IAU CPS寻求改变这种状况，并与航天工业一起研究解决方案。”

In particular, astronomers are concerned about how BlueWalker 3 will affect studies conducted during twilight hours.

天文学家们特别担心蓝行者3号卫星对于在黄昏时段进行的研究会产生怎样的影响。

"These observations look towards the inner solar system and so need the sun just below the horizon," Jeremy Tregloan-Reed, co-author of the study and member of IAU CPS, told Space.com. "One such type of observation looks for near-Earth objects and provides an early warning to potential asteroids on a collision course with Earth. Hence, these satellites could hinder any attempt of an early warning and so, prevent us from protecting ourselves from an extinction level impact."

这项研究的共同作者、IAU CPS成员杰里米·特雷格隆-里德告诉Space.com：“这些观测朝向内太阳系，因此需要太阳在地平线下方。其中一种类型的观测是寻找近地天体，并提供对可能与地球相撞的潜在小行星的早期警报。因此，这些卫星可能妨碍我们对灭绝级撞击的早期警报和自我保护的努力。”

Though all satellites reflect sunlight and have the potential to be disruptive, including the thousands of Starlink internet connection satellites currently shining in Earth's lower orbit (with plenty more to come) as well as the OneWeb endeavor, which has over 600 in the region, "BlueWalker 3 is the brightest of them all," Rawls said, "by a significant amount."

虽然所有的卫星都会反射阳光，并有可能对天文观测产生干扰，包括目前在地球低轨道上大量运行的星链互联网卫星（数量还将继续增加），以及OneWeb项目在该区域拥有600多颗卫星，但是"蓝行者3号是其中最亮的一颗"，Rawls表示，"亮度显著超过其他卫星。"

"The good news is," she continued, "astronomers have established dialogs with each of these companies, significant progress has been made toward darkening mitigations and there are new coordination agreements with the National Science Foundation."

她继续说道：“好消息是，天文学家已与这些公司建立了对话，已经在减少亮度方面取得了重要进展，并且与美国国家科学基金会签订了新的协调协议。”

But much more work is needed throughout the industry, astronomers argue. "In the case of SpaceX and the Starlink constellation, everyone was taken by surprise by how bright they were," Tregloan-Reed said. "Three years later and after many media reports on the the brightness of such LEO constellations and their impact to the night sky, we are seeing companies like Amazon Kuiper who are developing mitigation designs and working with astronomers prior to launch, while other companies like AST SpaceMobile appear to consider the brightness issue as an afterthought."

但是天文学家们认为整个行业还需要更多的工作。“在SpaceX和Starlink的情况下，人们都对它们的亮度感到意外，” Tregloan-Reed说。 “三年过去了，在许多媒体报道了低地球轨道星座的亮度及其对夜空的影响之后，我们看到像亚马逊·柯伊伯这样的公司正在开发减轻影响的设计，并在发射之前与天文学家合作，而其他公司如AST SpaceMobile则似乎将亮度问题视为事后的考虑。”

AST's spokesperson did note that the company is aware of BlueWalker 3's brightness concerns and is working to address them by employing a list of strategies including collaborating with NASA and other astronomy groups, positioning gateway antennas at a considerable distance from radio-quiet zones vital to astronomy and using roll-tilting flight maneuvers that reduce apparent magnitude.

AST的发言人确实提到，该公司意识到了蓝行者3号的亮度问题，并正在采取一系列策略来解决这个问题，包括与NASA和其他天文学组织合作，将网关天线放置在对天文学至关重要的无电波干扰区域相当远的地方，并采用滚转倾斜的飞行机动来减小视星等。

Per the spokesperson, AST also intends to equip its next-generation satellites with anti-reflective materials and share detailed location data to help astronomers plan their observations. However, Rawls suggests more clear-cut regulations should be put into place because coordination with the NSF, for instance, only applies to U.S.-based launches.

据发言人称，AST还计划在其下一代卫星上装备防反射材料，并共享详细的位置数据，以帮助天文学家规划观测。然而，Rawls认为应该制定更明确的规定，因为与美国国家科学基金会的协调仅适用于美国的发射活动。

There is also effectively no limit, she said, on how many satellites any one company may launch or operate.

她还表示，实际上没有限制任何一家公司可以发射或运营的卫星数量。

To reach their conclusions on BlueWalker 3's impact on astronomy and the visibility of the night sky, the researchers ran an international campaign to collect sky observation data from both amateur and professional stargazers across the world. This included statistics from the United States, Morocco, Chile, Aotearoa New Zealand, Mexico and the Netherlands. According to the study, visual observations made before BlueWalker 3 launched indeed indicated the satellite would be "particularly bright," but it wasn't until post-deployment that scientists could really see the impact.

为了得出蓝行者3号对天文学和夜空能见度的影响的结论，研究人员发起了一项国际性的活动，收集了来自世界各地的业余和专业观星者的天空观测数据。这包括来自美国、摩洛哥、智利、新西兰、墨西哥和荷兰的统计数据。根据该研究，蓝行者3号发射之前进行的视觉观察确实表明该卫星将是“特别亮”的，但直到部署后科学家才能真正看到其影响。

Once BlueWalker 3's antenna array was totally unfolded in space, its brightness reached a peak magnitude of about 0.4. In this centuries-old magnitude system, smaller numbers are brighter than larger numbers — a magnitude 0 object is 100 times brighter than a magnitude 5 object. Super bright objects can even go into the negatives (a full moon has a magnitude of around -12.6, while the sun shines around magnitude -27).

一旦蓝行者3号的天线阵列在太空中完全展开，其亮度达到了约0.4等星等的峰值。在这个几个世纪以来使用的星等系统中，较小的数字代表更亮的物体，而较大的数字代表较暗的物体——0等星物体比5等星物体要亮100倍。超亮的物体甚至可以进入负数（满月的星等约为-12.6，而太阳的星等约为-27）。

For context, most satellite constellations we can see in space have magnitudes between 4 and 6, the study states, likening BlueWalker 3's magnitude of 0.4 to the stars Procyon and Achernar. These stellar bodies appear to us on Earth as the brightest stars in the constellations Canis Minor and Eridanus, respectively.

研究指出，为了提供背景信息，我们在太空中看到的大多数卫星星等在4至6之间，将蓝行者3号的星等0.4比作南河座和阿奇纳，这些恒星在地球上分别是小犬座和波江座中最亮的星。

Giant antenna array aside, even the satellite's Launch Vehicle Adapter itself appeared to reach a brightness of about magnitude 5.5, which the team says is four times brighter than the current International Astronomical Union recommendation of magnitude 7. In part, this recommendation is based on a brightness level that's expected to be particularly challenging for observations with the Vera C. Rubin Observatory’s LSSTCamera when it begins its decade-long survey of the southern sky next year, among other things.

除了巨大的天线阵列之外，就连卫星的运载火箭适配器本身的亮度似乎也达到了约5.5星等，研究团队称这比国际天文学联合会目前推荐的7等星等亮度要明亮四倍。这项推荐部分基于一个被预计将对Vera C. Rubin Observatory的LSST相机观测造成特别挑战的亮度水平，该相机将在明年开始对南方天空进行为期十年的调查，而该推荐还考虑了其他因素。

"Fainter than this limit would allow either the use of software such as AI to remove the satellite from an image whilst recovering the astronomical data underneath, or at least to mask the affected pixels," Tregloan-Reed said. "Above this limit means that the satellite will most likely saturate the pixels, making it impossible to recover the data underneath the satellite."

“低于这个限制将允许使用诸如人工智能等软件来从图像中去除卫星，同时恢复卫星下方的天文数据，或者至少对受影响的像素进行掩盖。”特雷格隆-里德表示。“超过这个限制意味着卫星很可能会使像素饱和，从而无法恢复卫星下方的数据。”

BlueWalker 3 is over 400 times brighter than that target.

蓝行者3号的亮度是目标亮度的400多倍。

"At the moment, essentially all constellation satellites are brighter than the 7th magnitude recommendation set by the IAU," Eggl said. "So, in some sense, they are all troubling. Their aggregate effect on sky brightness is yet another issue."

“目前，基本上所有星座卫星的亮度都比国际天文学联合会所设定的第7等星等的推荐值要高，”埃格尔表示。“因此，在某种程度上，它们都令人担忧。它们对天空亮度的集成效应是另一个问题。”

Starlink satellites, for instance, are individually only about 0.7% as bright as BlueWalker 3 (yes, they're still visible to the unaided eye in the night sky) yet SpaceX wishes to create a constellation of about 40,000 of them, Tregloan-Reed said: "The overall impact, particularly to the sky glow, is worrisome."

例如，星链卫星的亮度只有蓝行者3号的0.7%（是的，它们在夜空中仍然可以用肉眼看到），然而SpaceX希望创建一个约有40,000颗卫星的星座，特雷格隆-里德表示：“总体影响，特别是对天空亮度的影响，令人担忧。”

Ultimately, the goal of the team's work is to bring attention to this issue in an effort to encourage both scientists and satellite engineers to think about how to protect our dark skies.

团队的工作最终目标是引起对这个问题的关注，以鼓励科学家和卫星工程师思考如何保护我们的夜空。

Satellite manufacturers should find ways to mitigate the brightness these modules emit in low-Earth orbit, the team says, but telescope facilities ought also to consider ways of working around the brightness issue. "On the one hand, astronomers are pretty experienced at dealing with 'noise' in our data," Rawls said, thinking about unwanted signals from moonlight, camera electronics, clouds and terrestrial light pollution, for instance.

该团队表示，卫星制造商应该寻找方法来减轻这些模块在低地球轨道发射的亮度，但望远镜设施也应考虑解决亮度问题的方法。“一方面，天文学家在处理数据中的‘噪声’方面非常有经验，”罗尔斯考虑到例如月光、相机电子、云和地球光污染等无用信号。

So, BlueWalker 3 is just one more source of noise to contend with.

因此，蓝行者3号只是要处理的噪声来源之一。

Rawls also mentioned that scientists are already developing various tools to combat the issue such as what are known as image analysis pipelines, streak identification programs and telescope scheduling algorithms.

罗尔斯还提到，科学家们已经在开发各种工具来应对这个问题，例如被称为图像分析管道、流痕识别程序和望远镜调度算法的工具。

"On the other hand," she added, "building all of these tools requires real resources and would not be necessary if the sky were not filling with bright satellites at an astonishing rate."

“另一方面，”她补充道，“构建所有这些工具需要实际资源，如果天空没有以惊人的速度填满明亮的卫星，这些工具也是不必要的。”

Tregloan-Reed also suggested a few solutions for satellite engineers to consider, one of which is quite interesting. The concept basically requests mirroring the satellite market with the energy market, where consumers can select what energy supplier they wish to use based on the suppliers' green credentials.

特雷格隆-里德还提出了一些卫星工程师应该考虑的解决方案，其中一个非常有趣。这个概念基本上要求将卫星市场与能源市场相匹配，即消费者可以根据供应商的绿色认证选择他们希望使用的能源供应商。

For instance, satellite operators can advertise that their satellite constellation has the lowest impact to the night sky, which would hopefully help consumers make more informed choices about which of these constellations' services, if any, they want to use. Another idea would be to target geostationary orbit rather than low-Earth orbit for satellite constellations.

例如，卫星运营商可以宣传他们的卫星星座对夜空的影响最小，这有助于消费者更明智地选择他们想要使用的星座服务（如果有的话）。另一个想法是针对地球静止轨道而不是低地球轨道进行卫星星座布局。

"If BlueWalker 3 was placed in GEO at an altitude of 35,000 kilometers instead of its current 500 kilometers, it would instantly become 0.02% of its current brightness, an order of magnitude fainter than the 7th magnitude limit set by the IAU," he said.

他说：“如果蓝行者3号被放置在地球静止轨道的高度35,000公里处，而不是目前的500公里，它将立即变成目前亮度的0.02％，比国际天文学联合会设置的第7星等限制要暗一个数量级。”

To start aiding astronomers in avoiding noise in their data, the team also made sure to look into how brightness levels of BlueWalker 3's array changed depending on the satellite's location. Potentially, this could help observatories plan for how to conduct astronomical research in a future in which the night sky is overwhelmed with an abundance of artificial light.

为了帮助天文学家避免数据中的噪声，团队还确保研究了蓝行者3号阵列的亮度水平如何随卫星位置的变化而改变。潜在地，这可以帮助天文观测站规划如何在未来夜空被大量人造光线淹没的情况下进行天文研究。

"Most surfaces are naturally reflective to some degree, and the type of reflection and how bright it appears at various locations on Earth is tricky to accurately predict ahead of time," Rawls said. "It is not necessarily something you would think of when you sit down to design a satellite."

“大多数表面在某种程度上自然反射，并且在地球上的各个位置上，反射类型及其亮度如何准确预测是很棘手的问题，”罗尔斯说。“当你坐下来设计卫星时，这不一定是你会考虑的事情。”

"Preserving dark skies has to be a priority for darkening mitigations to be developed, tested, and deployed."

“保护黑暗的天空必须成为开发、测试和部署变暗措施的首要任务。”

The paper was published on Oct. 2 in the journal Nature.

这篇论文发表在10月2日的《自然》杂志上。