这项研究揭示了SpaceX的超级星座卫星对天文学的影响

Since last May, Elon Musk’s SpaceX has been launching satellite constellations called Starlink in batches of 60 per launch, and since last May astronomers have been voicing their concerns about how these bright and numerous objects will affect astronomical observations. A new study out confirms their worries.

自去年5月以来，埃隆·马斯克的太空探索技术公司(SpaceX)每次发射60个名为“Starlink”的卫星星座。自去年5月以来，天文学家一直在表达他们的担忧，即这些明亮且数量众多的天体将如何影响天文观测。一项新的研究证实了他们的担忧。

As reported in Astronomy & Astrophysics, Olivier Hainaut and Andrew P. Williams from the European Southern Observatory (ESO) produced a conservative estimate for how the complete mega-constellations, as they're being called, from SpaceX, Amazon, OneWeb, and others will affect astronomy. When all the launches are complete, somewhere between 30,000 and 40,000 new satellites are expected to be located in low-Earth orbit.

据《天文学与天体物理学》报道，来自欧洲南方天文台(ESO)的奥利维尔·海纳特和安德鲁·p·威廉姆斯对整个巨型星座(它们被称为巨型星座)将如何影响天文学做出了保守估计。这些巨型星座来自SpaceX、亚马逊(Amazon)、OneWeb等公司。当所有的发射完成后，预计将有3万到4万颗新卫星被安置在近地轨道上。

Alfredo Carpineti

For the ESO facility, which houses the current Very Large Telescope and upcoming Extremely Large Telescope, one-in-30 long exposures will be affected by the satellite trails during twilight hours, and one-in-200 will be affected for shorter exposures.

ESO拥有目前使用的超大望远镜和即将使用的超大望远镜，在黄昏时分，30分之一的长时间曝光将受到卫星轨迹的影响，而200分之一的短时间曝光将受到影响。

More concerning is the situation for Wide-Field surveys. These can scan large areas of the sky at once and are crucial for the next breakthrough in astronomy. Looking at the Vera C. Rubin Observatory in the US, the team writes in the paper that up to “up to 30% of the exposures would be lost during the first and last hours of the night, and almost 50% of the twilight exposures would be contaminated.”

更令人关注的是大范围调查的情况。它们可以同时扫描天空的大片区域，这对天文学的下一次突破至关重要。在美国的Vera C. Rubin天文台，研究小组在论文中写道:“高达30%的曝光量会在夜晚的头几个小时和最后几个小时丢失，而将近50%的暮光照射量会被污染。”

These are conservative estimates.

这些都是保守估计。

The team suggests some mitigation solutions. Observing towards the opposite direction of the Sun (so that the satellites are in the shadow of Earth) will help, as will avoiding areas of the sky where the satellites will pass through. These will require detailed knowledge of the orbits of these mega-constellations though, and some of them can automatically move. These approaches are also both laborious and costly, and given that the observatories are publicly funded, the question that many are asking is why is it up to them to fix a problem created by private companies.

该小组提出了一些缓解措施。对太阳的相反方向的观测(这样卫星就在地球的阴影下)将会有所帮助，避免卫星将经过的天空区域也会有所帮助。不过，这需要对这些巨型星座的轨道有详细的了解，其中一些还可以自动移动。这些方法既费力又昂贵，而且考虑到天文台是由政府资助的，许多人提出的问题是，为什么要由他们来解决私人公司造成的问题。

Musk has said that they are working on lowering the albedo of future Starlink satellites, so they will have lower reflectivity, and that they will "tweak satellite orientation to minimize solar reflection during critical astronomical experiments" when needed, but is it enough?

马斯克曾表示，他们正在努力降低未来“星链”卫星的反照率，这样它们的反射率就会降低，必要时还会“在关键的天文实验中调整卫星的方向，以减少太阳反射”，但这就足够了吗?

There is also a discussion over the increase in space junk due to these new satellites. Currently, about 34 000 objects greater than 10 centimeters (4 inches) in size are orbiting Earth. Most of them are fragments of rockets and other satellites. Only 5,500 are satellites and of those, only 2,300 work. The satellite constellations will add a huge number of new objects and it is paramount that safely deorbiting into the atmosphere is part of their operational life.

还有一个关于这些新卫星增加太空垃圾的讨论。目前，大约有34000个大于10厘米(4英寸)大小的物体绕地球运行。其中大部分是火箭和其他卫星的碎片。只有5500个卫星，其中只有2300个能用。卫星星座将增加大量的新天体，最重要的是安全脱离轨道进入大气层，这是它们运行寿命的一部分。

This study focused specifically on optical and infrared telescopes but there are also concerns regarding radio, millimeter, and submillimeter observatories, too. The impact of this new era of private satellites on those will be revealed in further studies.

这项研究主要集中在光学和红外望远镜上，但也涉及到无线电、毫米和亚毫米天文台。这个私人卫星的新时代对这些卫星的影响将在进一步的研究中揭示。