观测美国太空探索技术公司发射下一批巨大的星链卫星
Watch SpaceX Launch Its Next Huge Batch of Starlink Satellites
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2020-01-11 12:47
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火星译客

If you haven't heard, there's a new space race underway. The goal is to bring the “other 3 billion” people who lack internet access online using massive constellations of broadband satellites that number in the thousands. Leading the pack are SpaceX's Starlink and OneWeb, former collaborators whose bid to bring the net to orbit has turned into a rivalry that plays out in FCC petitions and spicy Twitter exchanges. The tension is understandable given the stakes. For OneWeb, the global adoption of space-based internet is critical to the company's existence; for SpaceX, it is key to funding Elon Musk's Mars ambitions.

如果你还没有听过,有一场新的太空竞赛正在进行。其目标是运用成千上万个宽频带卫星群,使得另外30亿未能使用互联网的人群可以上网。美国太空探索技术公司的“星链”和“一网”在这场竞争中居于领先地位,这两家公司曾是合作伙伴,它们将网络引入轨道的努力已经变成了一场竞争,这场竞争在美国联邦通信委员会的申请书和推特上激烈的交涉中结束。鉴于其中的利害关系,这种紧张是可以理解的。对于“一网”来说,全球采用天基网络对公司的生存至关重要;对于“星链”而言,这是为埃隆.马斯克(Elon Musk)的火星雄心提供资金的关键。

Both companies put their first satellites into orbit last year, but 2020 is when things will get serious. In February, OneWeb will launch a batch of 34 internet satellites to bring its total to 40, and more launches are expected later in the year. SpaceX already has 122 Starlink satellites in orbit and plans to do as many as 24 Starlink launches this year with 60 satellites per batch—starting today. SpaceX says it is aiming to launch a Falcon 9 rocket today at 9:19 pm ET, and the video below will go live 15 minutes beforehand.

去年,两家公司发射了第一批卫星进入轨道,但于2020年事态将变得严峻。今年2月“一网”将发射34颗互联网卫星,使其总数达到40颗,预计今年晚些时候还将发射更多卫星。美国太空探索技术公司已经在轨运行了122颗星链卫星,并计划从今天开始,每批发射60颗星,今年最多发射24颗星链卫星。美国太空探索技术公司公司表示,他们的目标是在今天美国东部时间晚上9点19分发射猎鹰9号火箭,下面的视频将提前15分钟直播。

So far both SpaceX and OneWeb have used their internet satellites only for testing (or tweeting, in Musk's case), but SpaceX says it will have enough birds in the air to start providing internet service by the summer. OneWeb says its constellation will offer limited service by the end of the year.

到目前为止,“星链”和“一网”都只将它们的互联网卫星用于测试(或者在推特中,马斯克的例子一样),但“星链”表示,到今年夏天,它将有足够多的卫星在空中飞行,开始提供互联网服务。“一网”表示,到今年年底constellation将提供有限的服务。

Space-based internet is nothing new, of course. Companies like Viasat, HughesNet, and Iridium have been raining bits and bytes on Earth for decades. But the next generation of internet satellites promises to be far faster than its predecessors and to make memes accessible anywhere on the planet by rethinking extraterrestrial networking.

当然,基于太空的互联网并不新鲜。几十年来,像Viasat、HughesNet和Iridium这样的公司近十年来一直在向地球上传送比特和字节。但新一代的互联网卫星有望比前一代快得多,并通过重新思考地外网络,使迷因在地球上任何地方都能被访问。

No matter who you're getting satellite internet from, the basics of the system are the same. A user sends packets of data from an antenna at their home toward a satellite, which relays these packets to a ground station back on Earth. At this point, the spacefaring data travels along the global internet's fiber optic cables just like any other data. Once it reaches its destination, say a Google cloud server, a new packet of data is sent back to the ground station, beamed up to the satellite, and then beamed back to the user's home.

无论你从谁那里得到卫星网络,这个系统的基础都是一样的。用户从家中的天线向卫星发送数据包,卫星再将这些数据包转发给地球上的地面站。在这一点上,太空飞行数据就像其他数据一样通过全球互联网的光纤传输。一旦到达目的地,比如一台谷歌云服务器,一个新的数据包被发送回地面站,发送到卫星,然后再发送回用户的家中。

The two largest satellite internet providers in the US, HughesNet and Viasat, both use satellites the size of a car to deliver their service. They sit in geostationary orbit, which means they always stay in the same position relative to the surface of the Earth and have hundreds of gigabits per second of network capacity. The advantage of this approach is that a single satellite can provide internet services for an entire continent. The downside is that it takes a signal almost half a second to travel the 22,000 miles from Earth. This might not sound like a lot, but it's about 10 times the latency of someone using fiber-based internet. It's fast enough to stream Netflix, but not fast enough to have fun gaming.

美国最大的两家卫星互联网服务提供商——休斯网络(HughesNet)和Viasat——都使用汽车大小的卫星来提供服务。它们位于地球静止轨道,这意味着它们总是保持在相对于地球表面的相同位置,并且拥有每秒数百千兆的网络容量。这种方法的优点是一颗卫星可以为整个大陆提供互联网服务。不利的一面是,从地球到22000英里的地方需要几乎半秒的信号。这听起来可能不是很多,但它是使用基于光纤的internet的人的10倍的延迟。它的速度快到可以流媒体观看Netflix,但还不够快到可以玩有趣的游戏。

The alternative approach taken by SpaceX and OneWeb is a constellation, which packs hundreds or thousands of satellites into orbits just a few hundred miles above the Earth. To get total coverage, satellites are sprinkled between a few dozen rings around the Earth. Of the first 1,500 Starlink satellites, for instance, batches of 22 satellites each will occupy 72 different orbits at an altitude of 340 miles; OneWeb's satellites will occupy 12 rings, with 49 satellites per ring at 745 miles up.

“星链”和“一网”采取的另一种方法是一个星座,将数百或数千颗卫星送入距地球仅几百英里的轨道。为了获得全面覆盖,卫星散布在地球周围的几十个环中。例如,在首批1500颗“星链”卫星中,每批22颗卫星将在340英里的高空占据72条不同的轨道;“一网”的卫星将占据12个环,每个环有49颗卫星,位于745英里的高空。

“The new space companies aren't built on some incredible new technology,” says Iridium CEO Matt Desch. “They're really just taking geostationary satellites with hundreds of beams and disaggregating that into hundreds of satellites in low earth orbit.”

“新的太空公司不是建立在一些令人难以置信的新技术上,”铱星公司首席执行官马特·德施说。“他们只是把数百束光束的地球同步卫星分解成数百颗近地轨道卫星。”

That approach has its problems. First, the sheer number of satellites is staggering. SpaceX's Starlink will have nearly 12,000 satellites, and OneWeb's initial constellation will have 648; for the sake of comparison, there are only about 2,000 functioning satellites in orbit right now. With today's Starlink launch, SpaceX will surpass the imaging company Planet as the operator of the world's largest satellite fleet. It didn't take astronomers long to realize that SpaceX's satellites reflect a lot of light and could ruin the night sky for observations. (SpaceX says its working to fix the issue, and the latest batch of Starlink satellites will test an antireflective coating.)

这种方法有它的问题。首先,卫星的数量是惊人的。“星链”的Starlink将拥有近1.2万颗卫星,“一网”最初的星座将拥有648颗;为了便于比较,目前在轨运行的卫星只有2000颗左右。通过今天的Starlink发射,“星链”将超越成像公司Planet,成为全球最大卫星舰队的运营商。天文学家们很快就意识到,“星链”的卫星反射了大量的光,可能会破坏夜空的观测。(SpaceX表示正在努力解决这个问题,最新一批的Starlink卫星将测试一种抗反射涂层。)

Photograph: Paul Hennessy/Getty Images

照片:保罗·亨尼斯/盖蒂图片社

Another issue is that an individual satellite can “see” a much smaller portion of Earth's surface compared to a geostationary satellite, which means the system relies on far more ground stations to connect the satellites to the global internet. Indeed, the next generation of Viasat satellites will need “hundreds” of ground stations to achieve global broadband coverage, but SpaceX recently submitted an FCC application for up to 1 million ground stations.

另一个问题是,与地球同步卫星相比,单个卫星能“看到”的地球表面面积要小得多,这意味着该系统要依靠多得多的地面站将卫星与全球互联网连接起来。事实上,下一代Viasat卫星将需要“数百个”地面站才能实现全球宽带覆盖,但“星链”最近提交了一份FCC申请,要求建立多达100万个地面站。

The upshot is reduced latency, because signals between a customer's terminal and a satellite have to travel only a few hundred miles rather than several thousand. Coupled with improvements in download speeds—both OneWeb and SpaceX are expected to provide around 50 megabits per second, comparable to the average internet speed in the US—the promise is that you'll finally be able to play Fortnite from space.

这样做的结果是减少了延迟,因为客户终端和卫星之间的信号只需传输几百英里,而不是几千英里。再加上下载速度的提高——“一网”和“星链”都有望提供每秒50兆左右的网速,与美国的平均网速相当——这意味着你终于能够在太空中玩Fortnite了。

What remains to be seen is how SpaceX and OneWeb handle the terminals, which are the physical interface between a customer and the satellites in orbit. Both companies are planning to use phased array antennas in their terminals, which create steerable radio beams without requiring the antennas themselves to move. This allows a terminal to track satellites as they fly overhead and smoothly pass signals between them.

目前尚不清楚“一网”和“星链”如何处理这些终端,它们是客户与在轨卫星之间的物理接口。两家公司都计划在他们的终端上使用相控阵天线,这样就可以在不需要天线移动的情况下产生可控的无线电波束。这使得终端能够在卫星飞过头顶时跟踪它们,并顺利地在它们之间传递信号。

Neither SpaceX nor OneWeb would comment on their terminals, but these pizza-box-sized antennas will be critical to the success of their satellite internet businesses. According to Iridium's Desch, it was the overpriced, bulky terminals that ultimately led to the downfall of Globalstar, a pioneer of telecom satellite constellations in the '90s. A similar fate could await SpaceX or OneWeb if their terminals are too expensive or complicated for customers to set up.

“星链”和“一网”都不愿对它们的终端发表评论,但这些披萨盒大小的天线将对它们的卫星互联网业务的成功至关重要。根据铱星公司的设计,Globalstar作为90年代通信卫星星座的先驱,正是过高的价格和庞大的终端最终导致了其公司的垮台。如果“星链”或“一网”的终端过于昂贵或复杂,客户无法安装,它们也可能面临类似的命运。

“We still have a lot to do to get that right,” SpaceX president Gwynne Shotwell told reporters in October about the Starlink terminals. “The more engineering we do on the user terminal, the less service people we will have to hire. Knowing Elon, he wants everything to be beautiful, so the user terminal will be beautiful.”

“要做到这一点,我们还有很多工作要做,”SpaceX总裁格温于10月就星链的终端这一话题对记者说道,“我们在用户终端上做的工程越多,我们需要雇佣的服务人员就越少。了解伊隆,他希望一切都是美好的,这样用户终端才会是美好的。”

But even if the companies manage to iron out all the technical and aesthetic hurdles, it's still unclear whether the market is large enough to support these constellations. “They're competing with the wired world, with Verizon, Comcast, and AT&T,” Desch says. This means they're going to have to drastically reduce the price of satellite internet, which has historically been an expensive product. At the same time, a number of other companies, like Amazon and Telesat, are also working on broadband satellite constellations.

但即使这些公司设法消除了所有技术和审美上的障碍,市场是否足够大,足以支撑这些星座,仍然不清楚。“他们正在与有线世界竞争,与Verizon、Comcast和AT&T竞争,”Desch说。这意味着他们将不得不大幅降低卫星互联网的价格,而卫星互联网在历史上一直是一种昂贵的产品。与此同时,其他一些公司,如亚马逊和Telesat,也在开发宽带卫星星座。

There's never been more competition in the satellite internet game, which is good news for rural populations looking to get online. But unless someone figures out how to make it profitable, we might never get to ask for the Wi-Fi password on Mars.

卫星网络游戏的竞争从未如此激烈,这对希望上网的农村人口来说是个好消息。但除非有人想出赚钱的办法,否则我们可能永远都不会在火星上索要Wi-Fi密码。

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