How hard is it to build orbital data centers, actually?

建造轨道数据中心到底有多难？

Editor’s note: This is the second of three feature articles Ars is publishing to explore the financial, technical, and competitive dimensions of orbital data centers. Although the idea of putting data centers into space has long been discussed on a theoretical basis, the technology has rapidly become a red-hot topic. This series attempts to ground-truth some of the rhetoric flying around. In this article, we discuss the technical challenges of building an orbital data center constellation: launching all of it, dissipating heat in space, dealing with radiation, and addressing latency issues in orbit. Read part one here.

编者注：这是 Ars 发布的系列专题文章中的第二篇，旨在探讨轨道数据中心的财务、技术和竞争维度。尽管将数据中心部署到太空的想法在理论层面已讨论多年，但该技术近期已迅速成为热门话题。本系列文章试图对当前流传的各种言论进行实证分析。在本文中，我们将讨论构建轨道数据中心星座所面临的技术挑战：发射任务、太空散热、辐射防护以及轨道延迟问题。点击此处阅读第一部分。

SpaceX has pinned the bulk of its future value on orbital data centers. Not rockets. Not spacecraft. Instead, it envisions launching and maintaining a constellation of 1 million satellites capable of generating 120 GW to power tens of millions—and potentially up to 100 million—frontier-class GPUs for data center services. The company’s founder, Elon Musk, revealed plans for this massive constellation months ago, but until recently, the scope of the individual satellites was largely unknown. That changed in June, when Musk and Ian Dahl, director of satellite engineering for SpaceX, spoke in a promotional video about the company’s plans to develop the first iteration of an orbital data center, called an AI1 satellite. The video finally provided the company’s numbers about the satellite’s size and power capabilities.

SpaceX 已将其未来价值的大部分押注在轨道数据中心上。不是火箭，也不是航天器。相反，它设想发射并维护一个由 100 万颗卫星组成的星座，能够产生 120 GW 的电力，为数千万（甚至可能高达 1 亿）台前沿级 GPU 提供数据中心服务。该公司创始人埃隆·马斯克（Elon Musk）几个月前就披露了这一庞大星座的计划，但直到最近，单颗卫星的规模仍不为人知。这种情况在 6 月发生了变化，当时马斯克与 SpaceX 卫星工程总监 Ian Dahl 在一段宣传视频中谈到了公司开发第一代轨道数据中心（称为 AI1 卫星）的计划。该视频终于提供了有关卫星尺寸和功率能力的具体数据。

“There’s not some magic that’s necessary that doesn’t exist,” Musk said during the video, reflecting on the challenge of building AI1 satellites. “A lot of this is technology we’ve already made for Starlink V3 satellites. Basically, we don’t think this is a super hard problem.” As Ars wrote in part 1 of this series, the physics of orbital data centers are indeed non-magical. But the economics are, to put it mildly, challenging. This subject has sparked a broad debate about the near-term viability of this technology, both in terms of feasibility and whether it’s all hype now that SpaceX is a publicly traded company.

“并不需要什么不存在的魔法，”马斯克在视频中谈到建造 AI1 卫星的挑战时说道。“其中很多技术是我们已经为星链（Starlink）V3 卫星制造过的。基本上，我们认为这不是一个超级难题。”正如 Ars 在本系列第一部分中所写，轨道数据中心的物理原理确实没有魔法可言。但往轻了说，其经济性极具挑战性。这一话题引发了关于该技术近期可行性的广泛争论，包括其技术可行性，以及在 SpaceX 成为上市公司后，这是否仅仅是一场炒作。

Iridium Communications chief executive Matt Desch, a long-time, level-headed satellite industry executive, was asked during an earnings call earlier this year what he thought about the concept. “It’s a hot, hot area right now of discussion, mainly because of Starlink’s announcement and some others,” Desch replied. “It looks like a problem that can be solved in space… (But) there’s massive technical challenges to overcome.” Desch speculated that the recent enthusiasm for orbital data centers is not driven by a profound need to put them into space but by pecuniary reasons. “It’s a really, really long-term opportunity at best, and I wonder if all the discussion isn’t for other reasons than maybe just solving an immediate problem,” he said.

铱星通讯（Iridium Communications）首席执行官马特·德施（Matt Desch）是一位资深且冷静的卫星行业高管，他在今年早些时候的一次财报电话会议上被问及对这一概念的看法。“这目前是一个非常、非常热门的讨论领域，主要是因为星链和其他公司的公告，”德施回答道。“这看起来是一个可以在太空中解决的问题……（但）仍有巨大的技术挑战需要克服。”德施推测，近期对轨道数据中心的热情并非源于将其送入太空的迫切需求，而是出于金钱利益。“往好了说，这确实是一个非常、非常长期的机会，我怀疑所有的讨论是否还有其他原因，而不仅仅是为了解决眼下的问题，”他说。

So who is right? With part 2 of this series, we want to see if we can put some rough numbers on the true viability of orbital data centers in general and SpaceX’s concept in particular. The short answer is that a lot has to go right. The optimistic, neutral, and pessimistic cases. A chief reason to put orbital data centers in space is the free, limitless power from the Sun. Based on the schematic SpaceX released, each of its AI1 satellites would have solar panels encompassing about 600 square meters, or about 1.5 times the size of a basketball court. These solar panels would generate 150 kW of peak power and 120 kW of average power for computing.

那么谁是对的呢？在本系列的第二部分中，我们希望看看能否为轨道数据中心（总体而言）以及 SpaceX 的概念（特别是）的真实可行性提供一些粗略的数据。简短的回答是：必须一切顺利才行。乐观、中立和悲观的情况。将轨道数据中心置于太空的一个主要原因是来自太阳的免费、无限的能源。根据 SpaceX 发布的示意图，其每颗 AI1 卫星将拥有约 600 平方米的太阳能电池板，大约是篮球场面积的 1.5 倍。这些太阳能电池板将产生 150 kW 的峰值功率和 120 kW 的平均计算功率。

The weight of these solar panels adds up quickly—we’re looking at probably 1 to 2 metric tons. Satellite industry consultant Stuart Taylor told Ars that SpaceX might consider using a newer material called perovskite (there are some Internet rumors about this) instead of silicon, which could enable much lighter solar panels. But questions remain about the long-term stability of perovskites, so we’ll base our analysis on standard silicon solar cells. The satellites’ on-board computing power will generate significant heat, requiring a large radiator (more on this below). Estimates from various sources put this at around another 1 to 2 metric tons at a minimum. Adding everything else in, such as a bus (backbone), GPUs, and other components, the satellites will likely weigh between 3.5 and 7.5 metric tons.

这些太阳能电池板的重量增加得很快——我们估计大约在 1 到 2 公吨之间。卫星行业顾问斯图尔特·泰勒（Stuart Taylor）告诉 Ars，SpaceX 可能会考虑使用一种名为钙钛矿（perovskite）的新型材料（互联网上有一些相关传言）来代替硅，这可以使太阳能电池板轻得多。但关于钙钛矿的长期稳定性仍存在疑问，因此我们的分析将基于标准的硅太阳能电池。卫星的机载计算能力会产生巨大的热量，需要大型散热器（下文详述）。各种来源的估计显示，这至少还需要 1 到 2 公吨的重量。加上其他所有部件，如总线（骨干网）、GPU 和其他组件，卫星的重量可能在 3.5 到 7.5 公吨之间。

To get all of this mass into orbit, you need a super heavy lift rocket. SpaceX’s Starship V3 rocket is estimated to have a payload capacity of 100 metric tons to low-Earth orbit, but the company’s engineers are already planning a V4 with a significantly higher capacity: 200 metric tons. A final variable to consider is launch costs. The platonic ideal for Starship is full reusability, with both the first and second stages returning to the launch site and being re-stacked for launch within hours. The only costs would be propellant (perhaps $1.5 million per launch for liquid oxygen, methane, and other consumables) and personnel to manufacture and maintain the rockets and ground support equipment.

要将所有这些质量送入轨道，你需要一枚超重型运载火箭。SpaceX 的星舰（Starship）V3 火箭估计拥有 100 公吨的近地轨道载荷能力，但该公司的工程师已经在规划 V4 版本，其载荷能力将显著提高：达到 200 公吨。最后一个需要考虑的变量是发射成本。星舰的理想状态是完全可重复使用，第一级和第二级都能返回发射场，并在数小时内重新组装以备发射。唯一的成本将是推进剂（每次发射可能需要 150 万美元用于液氧、甲烷和其他消耗品）以及制造和维护火箭及地面支持设备的人员成本。

For the sake of argument, let’s assume an idealized Starship launch cost of $20 million, which would translate to a truly remarkable $100 per kg to low-Earth orbit. That’s not unattainable if things go well for Starship, but it would take time. So those are the basic numbers. For the purposes of this analysis, we will consider three cases: optimistic, neutral, and pessimistic. Optimistic: Starship payload capacity of 200 metric tons; AI1 satellite mass of 3.5 tons; Starship launch cost of $…

为了讨论方便，我们假设星舰的理想发射成本为 2000 万美元，这意味着每公斤送入近地轨道的成本仅为 100 美元，这确实非常惊人。如果星舰进展顺利，这并非遥不可及，但需要时间。以上就是基本数据。为了进行本次分析，我们将考虑三种情况：乐观、中立和悲观。乐观情况：星舰载荷能力 200 公吨；AI1 卫星质量 3.5 公吨；星舰发射成本为 $…