這項(xiàng)研究揭示了SpaceX的超級(jí)星座衛(wèi)星對(duì)天文學(xué)的影響

這項(xiàng)研究揭示了SpaceX的超級(jí)星座衛(wèi)星對(duì)天文學(xué)的影響

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月以來，埃隆·馬斯克的太空探索技術(shù)公司(SpaceX)每次發(fā)射60個(gè)名為“Starlink”的衛(wèi)星星座。自去年5月以來，天文學(xué)家一直在表達(dá)他們的擔(dān)憂，即這些明亮且數(shù)量眾多的天體將如何影響天文觀測(cè)。一項(xiàng)新的研究證實(shí)了他們的擔(dān)憂。

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.

據(jù)《天文學(xué)與天體物理學(xué)》報(bào)道，來自歐洲南方天文臺(tái)(ESO)的奧利維爾·海納特和安德魯·p·威廉姆斯對(duì)整個(gè)巨型星座(它們被稱為巨型星座)將如何影響天文學(xué)做出了保守估計(jì)。這些巨型星座來自SpaceX、亞馬遜(Amazon)、OneWeb等公司。當(dāng)所有的發(fā)射完成后，預(yù)計(jì)將有3萬到4萬顆新衛(wèi)星被安置在近地軌道上。

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擁有目前使用的超大望遠(yuǎn)鏡和即將使用的超大望遠(yuǎn)鏡，在黃昏時(shí)分，30分之一的長(zhǎng)時(shí)間曝光將受到衛(wèi)星軌跡的影響，而200分之一的短時(shí)間曝光將受到影響。

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.”

更令人關(guān)注的是大范圍調(diào)查的情況。它們可以同時(shí)掃描天空的大片區(qū)域，這對(duì)天文學(xué)的下一次突破至關(guān)重要。在美國(guó)的Vera C. Rubin天文臺(tái)，研究小組在論文中寫道:“高達(dá)30%的曝光量會(huì)在夜晚的頭幾個(gè)小時(shí)和最后幾個(gè)小時(shí)丟失，而將近50%的暮光照射量會(huì)被污染。”

These are conservative estimates.

這些都是保守估計(jì)。

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.

該小組提出了一些緩解措施。對(duì)太陽的相反方向的觀測(cè)(這樣衛(wèi)星就在地球的陰影下)將會(huì)有所幫助，避免衛(wèi)星將經(jīng)過的天空區(qū)域也會(huì)有所幫助。不過，這需要對(duì)這些巨型星座的軌道有詳細(xì)的了解，其中一些還可以自動(dòng)移動(dòng)。這些方法既費(fèi)力又昂貴，而且考慮到天文臺(tái)是由政府資助的，許多人提出的問題是，為什么要由他們來解決私人公司造成的問題。

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?

馬斯克曾表示，他們正在努力降低未來“星鏈”衛(wèi)星的反照率，這樣它們的反射率就會(huì)降低，必要時(shí)還會(huì)“在關(guān)鍵的天文實(shí)驗(yàn)中調(diào)整衛(wèi)星的方向，以減少太陽反射”，但這就足夠了嗎?

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.

還有一個(gè)關(guān)于這些新衛(wèi)星增加太空垃圾的討論。目前，大約有34000個(gè)大于10厘米(4英寸)大小的物體繞地球運(yùn)行。其中大部分是火箭和其他衛(wèi)星的碎片。只有5500個(gè)衛(wèi)星，其中只有2300個(gè)能用。衛(wèi)星星座將增加大量的新天體，最重要的是安全脫離軌道進(jìn)入大氣層，這是它們運(yùn)行壽命的一部分。

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.

這項(xiàng)研究主要集中在光學(xué)和紅外望遠(yuǎn)鏡上，但也涉及到無線電、毫米和亞毫米天文臺(tái)。這個(gè)私人衛(wèi)星的新時(shí)代對(duì)這些衛(wèi)星的影響將在進(jìn)一步的研究中揭示。