Experts warn current Starship heat shield tech is a “dead end” for rapid reuse

专家警告：目前的星舰隔热罩技术是实现“快速复用”的死胡同

SpaceX successfully launched its Starship vehicle on Friday and appeared to demonstrate important and credible steps toward fulfilling the massive rocket’s immense promise. As soon as the vehicle’s next flight, Starship could go orbital, begin delivering satellites into space, and potentially return to the launch site to be ‘caught’ by the tower. All of this is impressive engineering on a gigantic scale.

SpaceX 周五成功发射了星舰（Starship），并展示了向实现这一巨型火箭宏伟愿景迈出的重要且可靠的步伐。最早在下一次飞行中，星舰就可能进入轨道，开始向太空运送卫星，并有可能返回发射场被发射塔“捕获”。所有这些都是宏大规模下令人印象深刻的工程成就。

But despite the marked progress with the 13th test flight of Starship, one key issue—probably the key issue when it comes to Starship’s future—remains unresolved. This concerns Starship’s heat shield, the roughly 18,000 ceramic tiles that protect the vehicle’s underbelly during its fiery return through Earth’s atmosphere. And some experts say SpaceX’s current approach may not get Starship to its ultimate goal of flying frequently, at low cost.

尽管星舰第 13 次试飞取得了显著进展，但一个关键问题——或许是关乎星舰未来的核心问题——仍未解决。这涉及到星舰的隔热罩，即在大气层重返过程中保护飞行器腹部的约 18,000 块陶瓷瓦。一些专家认为，SpaceX 目前的方法可能无法让星舰实现其频繁、低成本飞行的最终目标。

A dead end? “Starship’s current thermal protection system is a dead-end for all missions that require full and rapid reusability,” Dan Rasky, a former NASA engineer who studied heat shield materials for nearly four decades at NASA Ames Research Center, told Ars. Rasky is credible: He co-invented PICA, the material used for Crew Dragon’s heat shield.

这是死胡同吗？曾在 NASA 艾姆斯研究中心研究隔热材料近四十年的前 NASA 工程师丹·拉斯基（Dan Rasky）告诉 Ars：“对于所有需要完全且快速复用的任务而言，星舰目前的隔热系统是一条死胡同。”拉斯基的观点具有权威性：他是载人龙飞船（Crew Dragon）隔热罩所用材料 PICA 的共同发明人。

NASA confronted this same issue half a century ago during development of the Space Shuttle, which used thousands of lightweight ceramic tiles to insulate the vehicle’s aluminum structure. Although the tiles worked fairly well, the US space agency was never able to crack the code on “rapid” reuse. Each tile required post-flight inspections, so reuse of Space Shuttle orbiters remained expensive and time-consuming.

半个世纪前，NASA 在开发航天飞机时也面临同样的问题，当时航天飞机使用了数千块轻质陶瓷瓦来隔绝铝制结构。尽管这些瓦片效果尚可，但美国航天局始终未能破解“快速”复用的密码。每一块瓦片都需要在飞行后进行检查，因此航天飞机的复用成本高昂且耗时。

SpaceX has some advantages over the shuttle. Starship’s steel structure is far more tolerant of heating, capable of withstanding temperatures up to 800° Celsius where there are tile failures. So some burn-through is probably acceptable. However, according to a new analysis by Rasky and two other space industry officials, former NASA astronaut Charles Camarda and the head of the NASA transition team for the Trump-Vance White House, Charles Miller, significant challenges remain for rapidly reusing Starship.

SpaceX 比航天飞机有一些优势。星舰的钢结构对热量的耐受力要强得多，在瓦片失效的情况下，能够承受高达 800 摄氏度的高温。因此，一定程度的烧蚀或许是可以接受的。然而，根据拉斯基与另外两位航天业人士——前 NASA 宇航员查尔斯·卡马达（Charles Camarda）和特朗普-万斯白宫 NASA 过渡团队负责人查尔斯·米勒（Charles Miller）——的一项新分析，快速复用星舰仍面临重大挑战。

A need for rapid reuse: Following Flight 13 last week, the experts noted that only a few of Starship’s ceramic tiles were lost during the flight, obviously a good thing. And the heat shield protected Starship during the reentry process such that it made a controlled descent and landing. However in SpaceX’s drone footage of the landed Starship in the Indian Ocean, there were notable white streaks across the heat shield. All of these appeared to originate at boundaries between tiles, suggesting hot gas may have penetrated these boundaries. There were also indications of cracked tiles and broken edges.

对快速复用的需求：在上周第 13 次飞行后，专家们指出，飞行过程中仅有少量陶瓷瓦脱落，这显然是件好事。隔热罩在重返大气层过程中保护了星舰，使其能够受控下降并着陆。然而，在 SpaceX 拍摄的星舰降落在印度洋的无人机画面中，隔热罩上出现了明显的白色条纹。这些条纹似乎都源于瓦片之间的缝隙，表明高温气体可能已经穿透了这些边界。此外，还有迹象显示存在瓦片开裂和边缘破损的情况。

Clearly, Starship’s heat shield was good enough for this vehicle to reenter Earth’s atmosphere. The problem is that, with the signs of damage, such a heat shield would appear to require a fair amount of inspection and refurbishment before another launch. In other words, SpaceX has a ways to go to reach “full and rapid” reuse of Starship. “Full” means reusing both the booster and the Starship upper stage, and “rapid” reuse means turning each Starship around in days or weeks, instead of months, at considerable expense.

显然，星舰的隔热罩足以让飞行器重返大气层。问题在于，鉴于这些损坏迹象，这种隔热罩在下次发射前似乎需要大量的检查和翻新。换句话说，SpaceX 要实现星舰的“完全且快速”复用还有很长的路要走。“完全”意味着助推器和星舰上面级都要复用，“快速”复用则意味着在几天或几周内（而非几个月）完成星舰的周转，且成本要低得多。

SpaceX is aware of the challenges: We should stop here to point out that SpaceX is not oblivious to the magnitude of this heat shield challenge, nor blithely whistling past the graveyard. On various podcasts and X social media postings, SpaceX founder Elon Musk has repeatedly stated that solving the reusable heat shield problem is one of the toughest problems the company faces. Back in February on a podcast with Dwarkesh Patel, Musk expounded on this, saying a reusable heat shield is “the biggest problem that remains” for Starship. “If you want to be able to land it, refill propellant, and fly again, you can’t do this laborious inspection of 40,000 tiles type of thing,” he said.

SpaceX 意识到了这些挑战：我们在此需要指出，SpaceX 并非不知道隔热罩挑战的严峻性，也不是在盲目乐观。在各种播客和 X 社交媒体帖子中，SpaceX 创始人埃隆·马斯克多次表示，解决可复用隔热罩问题是公司面临的最棘手问题之一。早在二月份与 Dwarkesh Patel 的播客中，马斯克就详细阐述了这一点，称可复用隔热罩是星舰“目前遗留的最大问题”。他说：“如果你想实现着陆、加注燃料并再次飞行，你就不能进行那种对 4 万块瓦片进行繁琐检查的工作。”

To address this challenge, the company has made substantial investments in new formulations for tile materials, standardizing shapes, and more. And it has been rigorously testing various approaches during Starship’s experimental flight campaign. The independent industry experts said they believe that SpaceX’s approach to a modern thermal protection systems represents a good “incremental” step forward from the space shuttle’s tiles but relies on the same fundamental solution. As such, SpaceX’s heat shield will likely be good enough to deploy a next-generation Starlink constellation. But the experts are concerned that it will be unable to hit the high flight rate needed—several hundred to thousands of low-cost launches annually—for large settlements on the Moon and Mars, orbital data centers, or large-scale space-based solar power.

为了应对这一挑战，该公司在瓦片材料的新配方、形状标准化等方面进行了大量投资。在星舰的实验飞行活动中，它一直在严格测试各种方案。独立行业专家表示，他们认为 SpaceX 对现代热防护系统的处理方式代表了航天飞机瓦片技术的良好“渐进式”进步，但其依赖的仍是相同的基本解决方案。因此，SpaceX 的隔热罩很可能足以部署下一代星链卫星群。但专家们担心，它将无法达到实现月球和火星大型定居点、轨道数据中心或大规模天基太阳能发电所需的极高飞行频率——即每年数百到数千次的低成本发射。

No help from NASA, at least not yet: This is an area where NASA could probably help. The experts noted that NASA has not made substantial investments in thermal protection research for vehicles entering from low-Earth orbit (speeds of Mach 25) for three decades. The underlying technologies on Starship, they note, are all based on work done for the space shuttle, National Aerospace Plane, or X-33 programs. No one today, they said, is seriously investing in new, advanced thermal materials for orbital reentry. Miller, who interviewed a number of senior NASA officials as part of the transition team work in late 2024, said he was told nothing was in the basic research development pipeline. However, he said current and former NASA researchers in this area felt like there were some promising solutions to pursue.

NASA 尚未提供帮助（至少目前如此）：这是 NASA 可能提供帮助的领域。专家们指出，三十年来，NASA 一直没有对从近地轨道进入（速度为 25 马赫）的飞行器的热防护研究进行实质性投资。他们指出，星舰的基础技术都基于航天飞机、国家航空航天飞机（NASP）或 X-33 项目的研究成果。他们表示，如今没有人真正在投资用于轨道重返的新型先进热防护材料。米勒在 2024 年底作为过渡团队成员采访了多位 NASA 高级官员，他被告知基础研究开发渠道中没有任何相关项目。不过，他说该领域的现任和前任 NASA 研究人员认为，确实有一些有前景的解决方案值得探索。