2026年4月9日 / 美国东部时间晚上7:41 / 哥伦比亚广播公司新闻
当阿尔忒弥斯二号猎户座载人舱完成环月飞行并于周五返回地球时，它将在太平洋上空约75英里处以每小时24000英里的惊人速度进入可辨识的大气层——这个速度足以在约6分钟内从洛杉矶飞到纽约。
短短数秒内，其16.5英尺宽的隔热盾整体温度将攀升至约5000华氏度——相当于太阳可见表面温度的一半。此时飞船在大气摩擦产生的带电火球中快速减速。
机上四名宇航员——指挥官里德·怀斯曼、维克多·格洛弗、克里斯蒂娜·科赫以及加拿大宇航员杰里米·汉森——全靠这层隔热盾保障安全，让他们身处舒适环境，顺利穿过峰值加热区，最终在加州附近太平洋海域借助降落伞溅落。
“我们对这套系统、隔热盾、降落伞以及我们研发的回收系统充满信心，”美国国家航空航天局（NASA）副局长阿米特·克沙特里亚周四表示，“工程数据支持这一点，阿尔忒弥斯一号的飞行数据支持这一点，所有地面测试支持这一点，我们的分析结果也支持这一点。明天，机组人员将用生命为这份信心背书。”
尽管2022年无人试飞的阿尔忒弥斯一号任务中，隔热盾出现过重大问题，但机组人员和任务管理层仍抱有信心。当时构成隔热盾的Avcoat材料出现了亚表面裂纹和气袋，导致防护层的外部“炭化”层整块脱落。
经过近两年的测试与分析，工程师意外发现，损坏很可能是因为Avcoat材料在特定再入阶段缺乏透气性：当时隔热盾外部温度较低，但内层仍处于极高温度，产生的气体无法逸出。
航天局管理层决定为后续阿尔忒弥斯任务更换全新的隔热盾设计。但阿尔忒弥斯二号使用的隔热盾与阿尔忒弥斯一号完全一致，此时已经完成安装。若更换全新设计，任务将推迟18个月甚至更久。
最终，NASA管理层选择基于测试数据和全面分析，按“现状”发射阿尔忒弥斯二号。分析表明，如果调整再入轨道，消除导致阿尔忒弥斯一号隔热盾受损的温度和压力波动，这套隔热盾就能正常工作。
“他们开展了大量研究，在一些此前从未使用过的设施中完成了突破性研究，并找到了根本原因，”怀斯曼说道。
“他们进行了风洞测试、激光测试和超高速测试，得出结论：如果我们采用这种高空抛射轨道……这层隔热盾将能保障我们安全飞行。”
“因此我认为所有证据都指向积极的结果，”他说，“我想，如果你作为一名即将登上这枚火箭的人，参加过我们参加的所有会议、听取过专家的意见、和他们一起梳理过数据，你也会同样安心。”
阿尔忒弥斯一号的隔热盾出了什么问题？
阿尔忒弥斯一号任务期间，无人舱遵循了规划的“跳跃”轨道，原理类似在静水面上打水漂。首次切入高层大气后，阿尔忒弥斯一号舱段再次跳出大气层，最终才完成最终下降并溅落。这种跳跃式再入有助于降低飞船速度，同时为NASA提供更多溅落区域选择，以防恶劣天气导致预定着陆点无法使用。
尽管飞行后隔热盾出现损坏，但阿尔忒弥斯一号的再入任务仍取得成功。舱段精准着陆，官员表示，即便当时有宇航员在舱内，也不会遇到任何问题。但这次损坏还是在NASA内部引发了警报。
“NASA发现，猎户座隔热盾的烧蚀热防护材料在进入地球大气层的过程中，有100多处区域的烧蚀情况与预期不符，”NASA监察长办公室写道。
“尽管在阿尔忒弥斯一号任务期间，隔热盾成功保护了乘员舱及其系统，但在回收猎户座后进行检查时，工程师注意到隔热盾Avcoat材料的外观出现了意外变化——这种烧蚀材料本应保护舱体免受再入高温的侵袭。”
“具体而言，部分炭化层的烧蚀情况与NASA工程师的预测不符，出现开裂并以碎片形式从航天器上脱落，留下了一道 debris 尾迹，而非按设计那样熔化消散，”该办公室表示，“Avcoat材料的异常行为带来了风险：在未来任务中，隔热盾可能无法充分保护舱体系统和乘员免受再入极端高温的伤害。”
测试显示，损坏与隔热盾的透气性有关，更确切地说，是透气性不足。首次相对深入地进入大气层后，构成隔热盾的Avcoat材料无法在再次跳出大气层的过程中，有效散发其内层残留的热量。
再入加热会使Avcoat的外部炭化层变得足够透气，允许气体逸出。阿尔忒弥斯一号的隔热盾在初始下降阶段工作正常。但当它再次跳出大气层时，再入加热减弱，外部炭化层的透气性大幅下降。
内层材料仍处于极高温度，正在经历一种被称为热解的过程——无氧燃烧——并产生无法逸出的气体。这些气体积聚最终导致隔热盾外层大块脱落。
“首次再入后，它们仍处于高温状态，仍在释放气体，”一位熟悉调查情况的工程师说道，“材料本身透气性不足，导致气体压力迅速积聚，因为它们仍然很热，但炭化层已经停止透气。”
“外部炭化层是阿尔忒弥斯一号和二号隔热盾唯一能够‘呼吸’或释放气体的部分，”他说，“一旦炭化层停止透气，隔热盾深层就不再有任何机制可以让气体逸出。”
“因此压力不断积聚，当舱体再次下降并重新被加热时，压力已经存在。
“所有那些裂纹、气袋都已经形成。而现在，砰、砰、砰——嘭。在第二次再入过程中，Avcoat材料开始大片脱落。”这位工程师说道。
调整后的再入轨道将解决问题
工程师在实验室测试中证实，调整后的跳跃式再入轨道——即首次切入高层大气后，以更短的时间再次跳出——将让Avcoat材料全程保持“呼吸”状态，防止裂纹和被困气体的形成。一个独立审查小组也认同这一结论。
有趣的是，阿波罗计划的工程师早就意识到了Avcoat透气性问题，并据此设计了该项目的隔热盾。阿波罗舱段同样采用跳跃式再入轨道，未出现任何问题。但阿尔忒弥斯隔热盾使用的Avcoat材料经过了小幅重新配方，最终影响了其透气性。
无论如何，阿尔忒弥斯二号调整后的再入轨道存在一个缺点：猎户座舱段为避开预定溅落区的恶劣天气，可机动的距离将缩短。同时，下降过程中持续的加热强度会更高，但工程师表示，这正是维持外部炭化层透气性、确保隔热盾性能良好所必需的。
前宇航员查尔斯·卡马尔达对此强烈反对，严厉批评了“按现状发射”的决定。他认为，工程师并未完全弄清阿尔忒弥斯一号隔热盾损坏的根本原因，无法准确预测阿尔忒弥斯二号隔热盾的性能，也无法确定修订后的进入轨道是否会带来意外后果。
在致NASA局长的一封信中，卡马尔达写道：“历史表明，当组织自以为完全理解了其实并未掌握的问题时，事故就会发生。”
与怀斯曼一样，格洛弗表示他相信对阿尔忒弥斯一号问题的分析，并称批评者“从未从第一天起就参与这些会议，从未见过团队成员，从未与他们对视握手，结束这些研讨”。
尽管如此，他补充道：“我不会轻视他们所说的一切。每当谈及火焰、再入和隔热盾，或是降落伞，这些都是高风险事物……没有内置的容错机制。它们必须一次成功。”
“因此，我感谢他们带来的所有质疑和审视，”格洛弗说，“这促使我们更加严谨，在流程中投入更多的尽职调查和警惕。但我认为我们已经做到了。正因这支团队，我认为机组人员都感到安心。”
As Artemis II heads back to Earth, crew is staking their lives on the heat shield
April 9, 2026 / 7:41 PM EDT / CBS News
When the Artemis II Orion crew capsule returns to Earth on Friday after flying around the moon, it will hit the discernible atmosphere some 75 miles above the Pacific Ocean at a blistering 24,000 mph — fast enough to fly from Los Angeles to New York in about 6 minutes.
Within seconds, temperatures across its 16.5-foot-wide heat shield will climb to some 5,000 degrees — half as hot as the visible surface of the sun — as the ship rapidly slows in an electrically charged fireball of atmospheric friction.
The four astronauts on board — commander Reid Wiseman, Victor Glover, Christina Koch and Canadian astronaut Jeremy Hansen — are counting on the heat shield to keep them safe, in a comfortable environment, all the way through the peak heating zone to a parachute-assisted splashdown in the Pacific off the coast of California.
“We have high confidence in the system, in the heat shield and the parachutes and the recovery systems we put together,” Amit Kshatriya, NASA’s associate administrator, said Thursday. “The engineering supports it, the Artemis I flight data supports it. All of our ground tests support it, our analysis supports it, and tomorrow the crew is going to put their lives behind that confidence.”
The Artemis II heat shield during its assembly. The 16.5-foot-wide heat shield is required to protect the Orion capsule and its crew from the 5,000-degree heat of the ship’s high-speed plunge back into the atmosphere. NASA
The crew and mission managers are confident, they say, despite major problems with the heat shield that was used during the unpiloted Artemis I test flight in 2022, when the Avcoat material making up the shield developed sub-surface cracks and gas pockets that blew away chunks of the protective barrier’s outer “char” layer.
Based on nearly two years of tests and analysis, engineers were surprised to discover the damage was most likely caused by the Avcoat material’s lack of permeability during a specific phase of the reentry when the shield was experiencing lower external temperatures while internal layers were still extremely high, generating gas that could not escape.
Agency managers decided to order a different heat shield design for downstream Artemis missions. But the heat shield for the Artemis II flight, identical to the one used with Artemis I, was already installed. Replacing it with a new design would have delayed the mission by 18 months or more.
The 16.5-foot-wide heat shield protecting the Orion capsule during an unpiloted test flight in 2022 was seriously damaged during reentry. NASA
Instead, NASA managers opted to launch Artemis II “as is” based on test data and an exhaustive analysis that indicated the shield would work properly if the reentry trajectory was modified to eliminate the temperature and pressure swings that contributed to the damage seen after the Artemis I flight.
“They did a tremendous amount of research, a lot of groundbreaking research in some facilities that we had not used before, and they discovered the root cause,” Wiseman said.
“They did wind tunnel testing and laser testing and hyper-velocity testing, and they determined that if we come in with this lofted profile … that this heat shield will be safe for us to go fly.
“So I think all that points in the direction of goodness,” he said. “And I think if you, as a human being who was about to board this rocket, had sat in the meetings that we sat in and listened to the experts and gone through the data with them, you would have the same comfort.”
What went wrong with Artemis I?
During the Artemis I mission, the unpiloted capsule followed a planned “skip” trajectory, similar in concept to skipping a flat stone across still water. After an initial dip into the upper atmosphere, the Artemis I capsule skipped back out again before making its final descent to splashdown. The skip reentry helps reduce the spacecraft’s velocity while offering NASA a wider range of splashdown options in case bad weather makes a targeted landing site problematic.
The Artemis I heat shield after its return to Earth in 2022. Regions of the shield suffered unexpected damage that did not match computer modeling, kicking off months of detailed tests and analysis. NASA
Despite the heat shield damage seen after the flight, the Artemis I reentry was successful. The capsule landed on target, and officials said that had any astronauts been aboard, they would have had no problems. But the damage triggered alarm at NASA.
“NASA identified more than 100 locations where ablative thermal protective material from Orion’s heat shield wore away differently than expected during reentry into Earth’s atmosphere,” NASA’s Office of Inspector General wrote.
“While the heat shield successfully protected the Crew Module and its systems during the Artemis I mission, upon inspection after Orion’s recovery, engineers noted unexpected variations in the appearance of the heat shield Avcoat — the ablative material that helps protect the capsule from the heat of reentry.
“Specifically, portions of the char layer wore away differently than NASA engineers predicted, cracking and breaking off the spacecraft in fragments that created a trail of debris rather than melting away as designed,” the office said. “The unexpected behavior of the Avcoat creates a risk that the heat shield may not sufficiently protect the capsule’s systems and crew from the extreme heat of reentry on future missions.”
Another look at the Artemis I heat shield showing areas where major damage was observed. NASA
Testing revealed the damage was related to the heat shield’s permeability, or rather, its lack thereof. After the initial, relatively deep dive into the atmosphere, the Avcoat material making up the shield was unable to properly dissipate the heat that remained in its lower layers during the skip back out of the atmosphere.
Entry heating is what makes the Avcoat’s outer char layer permeable enough to allow gas to escape. The Artemis I heat shield worked normally during its initial descent into the atmosphere. But when it climbed back out, reentry heating eased and the outer char layer became much less permeable.
The underlying material was still extremely hot, undergoing a process known as pyrolysis — combustion without oxygen — and generating gas that had no way to escape. Those buildups eventually blew chunks of the heat shield’s outer layers away.
“They go back up from that first entry, they’re still hot, they’re still off-gassing,” said an engineer familiar with the investigation. “The fact that the material itself isn’t permeable enough is causing that gas pressure to build up now, very rapidly, because they’re still hot. But the char layer has paused.”
A closeup of the Artemis I heat shield shows an area where a chunk of the outer layer was blown off during entry in 2022. NASA
The outer char layer is “the only part of the Artemis I and Artemis II heat shield that actually allows it to breathe, or allows it to off-gas. So once it stops, now there’s no mechanism in the deeper parts of the heat shield for that gas to escape,” he said.
“So the pressure built up, and as the capsule came back down and started reheating, the pressure was already there.
“All those cracks, the pockets had already formed. And now, bang, bang, bang, pop. Avcoat started sloughing off during that second entry,” the engineer said.
A modified reentry trajectory should solve the problem
Engineers verified in lab tests that a modified skip-entry trajectory — one with an initial dip into the upper atmosphere followed by a shorter-duration climb back out — would allow the Avcoat to “breathe” throughout, preventing the formation of cracks and trapped gas. An independent review team agreed with those conclusions.
The unpiloted Artemis I flight used a “skip” reentry trajectory in which the Orion crew capsule dipped into the atmosphere, skipped back up, and then made its final descent. NASA
Interestingly, Apollo engineers were aware of the Avcoat permeability issue and designed that program’s heat shields accordingly. Apollo capsules also used skip reentry trajectories and had no problems. But the Avcoat used in the Artemis heat shields was reformulated slightly, and that ended up affecting its permeability.
In any case, the downside to the modified reentry trajectory for Artemis II will reduce the distance the Orion capsule can fly to avoid bad weather in the planned splashdown zone. It will also result in higher sustained heating during the descent, but engineers say that is exactly what is needed to maintain permeability in the outer char layer and ensure good performance.
Former astronaut Charles Camarda disagreed, strongly criticizing the “fly as is” decision. He argues that engineers do not fully understand the root cause of the Artemis I heat shield damage and cannot accurately predict how the Artemis II heat shield will perform or whether the revised entry trajectory might have unintended consequences.
In a letter to the NASA administrator, Camarda wrote that “history shows accidents occur when organizations convince themselves they understand problems they do not.”
Like Wiseman, Glover says he trusts the analysis of the Artemis I problem, saying critics “haven’t been in these meetings from day one and met the team and looked them in the eye and shook their hands at the ends of these meetings.”
That said, he added, “I don’t want to discount the things that they’ve said. Any time you talk about fire, any time you talk about entry and heat shields, talk about parachutes, these are high-risk things that … don’t have fault tolerance built in. They have to work.”
“And so I appreciate all of that nudging and poking and prodding that they’ve caused,” Glover said. “They have made us sharpen our pencils and put more due diligence, more vigilance into that process. But I think we’ve done that. And so I think the crew is comfortable because of that team.”