旅行者航天器每年是否拍至少一次全景照片?Should Voyager take a panoramic set of images at least once a year?

【翻译自quora,作者 Jeffrey Naujok 】

Even assuming that Voyager still had the power to do this, that the cameras hadn’t been switched off leaving the entire instrument boom at the temperature of liquid helium, and that even the software for sending images hadn’t been removed from the flight computers (and the ground computers and software retired and scrapped)… why, exactly, would you want to do this?

就算假设旅行者还有足够的能源去做这件事,也没有关闭相机而使整个仪表杆处于液氦温度下,甚至没有从飞行计算机上删除了用于发送图像的软件 (以及淘汰和报废的地球地面的计算机和软件)…但是,您为什么要这样做?

Do you think that, looking back towards the sun, Voyager would see something like this?

你是不是认为,当它转身朝着太阳的时候,旅行者会看到下面这张图的景象?

Well, I hate to break it to you, but that’s not how the solar system actually works.

我本来不想告诉你的,但这不是太阳系运转的方式。

Space, as I’ve mentioned before on Quora, is big. Really big. And more importantly, it’s empty. Really empty.

太空,就像我之前在Quora上说的那样,很大。真的很大。更重要的是,很空,真的很空。

Voyager did turn around and take a “Family Portrait” of the solar system. It looks like this:

旅行者转向并拍摄太阳系的“全家福”的时候,它其实像是这样的:

Over on the left in the middle of the “arc” of pictures, is a bright star. That’s the Sun. In the image to the left of that is the Earth, and Venus. Mercury and Mars were lost in the glare of the sun. The entire inner Solar System — Mercury, Venus, Earth, Mars and the Sun — are contained in those two 800×800 pixel squares.

图片“弧”中间的左上方有一颗明亮的星星。 那是太阳。 在左边的图像中是地球和金星。 水星和火星在阳光的照耀下没法看到。 整个内太阳系-水星,金星,地球,火星和太阳-只包含在这两个800×800像素的正方形中。

To put that in perspective, were the sun the size of a basketball, that area would be the size of a football field, with Mars skirting the end zones. (Or the end lines on a soccer field, for those who prefer European football.) And even at that scale, Earth would be just about a millimeter across. Imagine standing a mile away from the football field and trying to find a single BB lit only by the light blasting from a carbon arc-lamp in the middle of the field. Like I said, Space is Big.

准确来说,如果太阳大小等于篮球大小,那么内太阳系就是足球场的大小,而火星会绕过边界区域。 (或者,对于喜欢欧洲足球的人来说,是足球场上的终点线。)即使在这样的规模下,地球也只有约一毫米宽。 想象一下,站在距离棒球场一英里远的地方,您要找到一个这个棒球场上的一个棒球(指地球和火星这类行星),而这个棒球场仅由场中央的碳弧光灯照亮(指太阳)。 就像我说的,空间很大。

Yet when they turned the Narrow Angle Camera (think “Zoom lens”) on where the Earth should be, they managed to catch a photo of it, despite the glare of the Sun.

当他们将窄角相机(想像为“变焦镜头”)转向地球应该位于的位置时,尽管有太阳的眩光,他们还是设法拍摄了一张照片。

To Paraphrase Carl Sagan, the Earth, the planet where every scrap of history you’ve ever heard of, every man, woman, and child you’ve ever met, every war, every accomplishment, every disaster, every triumph, every living thing… is a single, pale blue dot, caught in a ray of sunshine.

如Carl Sagan所说的那样,地球,这星球上的每一个历史遗迹,您遇到的每个男人,女人和孩子,每一次战争,每一次成就,每一次灾难,每一次胜利,每一个生物 ……是一个浅蓝色的单点,成为一束阳光的一部分。

【译注,Carl Sagan,美国著名宇航员,科幻作家。上面这段话出自他的科幻小说《暗淡蓝点》】

(NASA – The Pale Blue Dot photograph)

See it? On the right? In the orange-ish beam of sunlight?

看待了吗?在右边,一束橘黄色的太阳光?

One Pixel. (Technically, Earth was only 0.12 pixels wide at that distance.)

一个像素。(计算后可以发现,这种比例尺下,地球只有0.12像素)。

That’s you. That’s me. That’s the whole Earth. Lost in vast sea of darkness, balanced on a sunbeam.

这就是你,这就是我,在一片黑暗中迷失,却在一束阳光中重获新生。

Jupiter, the King of the Planets, is four pixels across.

木星,行星之王,也才4像素大。

Saturn with it’s vast rings, is six pixels wide, and is halfway across the panorama, though even with how brightly Saturn reflects the Sun’s light, it cannot be seen on the Wide Angle panorama.

土星和它巨大的土星环,有6像素大,在这张全景图的正中间,尽管它由于发射太阳的光线而非常明亮,但在这个光脚全景图中仍然看不到。

Uranus, still closer to voyager, is a blue streak (the camera couldn’t be held steady for the 15 second exposure it took to get a picture) that covers about 12 pixels.

天王星,与旅行者更近,一个蓝色条纹,大约有12像素。旅行者号的相机不能稳定地保持15秒,所以没法让海王星在图片上曝光。

And Neptune, at the far right edge, and closest to Voyager when the picture was taken, is lost in a field of stars, a mere four pixels wide, and that mostly from motion smearing as well.

海王星,在远处的右边缘,是这张照片被拍下时里旅行者最近的行星。在群星中找不到了。大概有4像素,这4像素主要由运动拖尾构成。

(By NASA – Public Domain, File:Voyager Portrait Family diagram.jpg)

It took nearly two hours to take this panorama of 60 photos. It took another 10 hours to transmit them from the edge of the Solar System back to Earth. Most of the frames (39) were taken with the Wide Angle Camera, but each planet was imaged with the Narrow Angle Camera, three times each, with different filters over the black and white camera to produce a color image (21 frames).

拍这60张全景照花了大概2小时,然后又花了10小时把它们从太阳系边缘送回地球。大部分帧(39张)是用广角摄像机拍的,但每个行星都用窄角摄像机拍摄过,拍三次,在黑白相机上使用不同的滤镜可产生彩色图像。(21张)

The image of the sun was taken with the darkest filter (Methane absorption band) and only for 1/125th of a second. The Wide Angle Camera panorama was taken with one second exposures. The Narrow Angle Camera images were taken with up to 15 second exposures just to get the planets to show up.

太阳图像是使用最暗的滤镜(甲烷吸收带)拍摄的,仅拍摄了1/125秒。广角全景相机是用一秒钟的曝光拍摄的。 窄角相机图像的曝光时间长达15秒,目的是使行星曝光出来。

Voyager 1 was 6 billion kilometers (4 billion miles) from Earth when it took this picture on Valentine’s Day of 1990.

当旅行者1990年的情人节拍下这张照片时,旅行者1号距离地球60亿公里(40亿英里)。

The entire panorama is only about 4000 pixels wide.

整个全景图只有大约4000像素宽。

Every year, Voyager 1 travels another 3.6(ish) AUs further away. That’s about another half a billion kilometers. In the 27 years since Voyager took this photo, it has gotten to three times the distance – 141 AUs, 21 billion kilometers, or 13 Billion miles. That means the entire picture would be 9 times smaller now (inverse square law). Meaning the whole Solar System (not counting the Kuiper Belt and the Oort Cloud) would now take up about 440 pixels of one picture.

每年,旅行者1号又要行驶3.6(ish)个AU(astronomy unit,天文单位)。 大约又是十亿公里。 自Voyager拍摄这张照片以来的27年中,它的距离已达到之前距离的三倍-141个AU,210亿公里或130亿英里。 这意味着整个图片现在将缩小9倍(平方反比)。 这意味着整个太阳系(不包括柯伊伯带和奥尔特云)现在将占据一张图片的约440像素。

Which means, your panorama of the Solar System, which would be totally swamped by the light of the sun (still several orders of magnitude brighter than anything else in the sky) would look like this:

这意味着,太阳系全景将完全被太阳的光淹没(太阳仍然比天空中的任何其他物体还要亮几个数量级),如下所示:

Or, to put it in perspective, here’s the same 800×800 Voyager-sized image with the original “Family Portrait” overlaid to scale. Even Jupiter and Saturn are lost in the glare of the Sun, and Uranus and Neptune (despite them being slightly brighter pixels here) would be far too small and dim to see.

或者,换句话说,如果根据原来的“太阳系全家福”按比例计算的话,那么将在这张旅行者号所拍下的4000×4000像素的图中占800×800像素。 这张图甚至木星和土星也都在太阳的眩光中迷失了,天王星和海王星(尽管它们在这里的像素稍亮)太小了所以很昏暗。

The real fact is, the “Family Portrait” taken by Voyager 1 was really right at the limit of the instruments, and any further pictures would just have been of the sun getting dimmer and dimmer. So there’s really no point in spending what’s left of Voyager’s extremely limited power budget on taking pictures out where it’s dark, and there’s nothing to see anyway.

但事实是,旅行者1号拍的这张全家福,已经用到它设备的极限了,如果在更远处拍摄,太阳将会变得越来越暗。因此花费旅行者号极其有限的电力拍黑暗处的照片是在不合算,并且那儿也没什么可看的。

Which is, of course, why the “Family Portrait” was the last set of images taken by either of the Voyager spacecraft before the cameras and their heaters were switched off to preserve power for the other instruments that were still doing real science.

这张“全家福”就是旅行者号航天器拍摄的最后一组照片。之后它的相机及其加热器将被关闭,以让电力能够被送到其他仍在实验的科学设备上。

So, the reason there were no more panoramas taken was that there was no reason to take any more of them. Carl Sagan convinced them to take the Family Portrait, and it is still a great object lesson in both how small we are as a people, and how vast space is. We are a curious species, and this should just whet our appetite to venture further and explore more.

因此,不再拍摄全景图的原因是没有必要了。 卡尔·萨根(Carl Sagan)说服他们拍摄了全家福,这仍然是能让我们认识到人类有多渺小,太空有多宽广的一节好课。我们只是好奇的物种,为了满足我们永远满足不了的好奇心,我们将继续探索更深更远。

The surface of the Earth is the shore of the cosmic ocean. On this shore, we’ve learned most of what we know. Recently, we’ve waded a little way out, maybe ankle-deep, and the water seems inviting.” — Carl Sagan, Cosmos.

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