Rebecca Heilweil指出，国际空间站最严重的威胁是轨道碎片穿刺。太空中有数百万个物体——废旧火箭级、碎片、流星体——以约17,000 mph（27,360 km/h）速度运行。穿刺可能导致快速去增压：0.6 cm 孔洞约有14小时可反应，而20 cm 孔洞不足一分钟。NASA在预测碰撞概率至少为1/100,000时启动规避，依赖追踪约45,000个目标的Space Surveillance Network。防护并不均衡：Whipple护盾大致对应1 cm³冲击，而有效追踪仅对10 cm³及以上碎片可靠，存在明显缺口。

若压力下降，机组可隔离或封堵，但压力降至约490 mmHg（65.3 kPa）时，NASA称关键系统可能失效并可能因低氧而迫使撤离。一个去增压的国际空间站随后变成退轨处置问题，牵涉到多个伙伴：欧洲航天局23个成员国再加上日本和加拿大，而俄罗斯的支持仅正式延续到2028年。优选方案是美国Dragon去轨飞行器；备选方案是俄Progress。可控再入需要供电、通信、航电、热控、冷却和推进系统在真空环境下仍能运行。失效会导致姿态丢失、太阳翼偏离日照、碎片后果范围扩大，尤其在较浅的俄方辅助再入路径中。

概率估计仍然较低但不确定：NASA在2017年给出的最坏情况去增压概率为1/121；到2025年底，六个月风险为1/36到1/170。即使再入受控，碎片仍可能构成风险。专家比较失控解体碎片可能达到汽车到火车尺寸；历史上尚无人因空间站碎片死亡。2024年有一枚再入碎片击中佛罗里达一户住宅，Skylab残骸也曾落在澳大利亚偏远西部。若将国际空间站抬高640 km可延寿100年，至少需18.9公吨推进剂（约2,000个登机箱），若目标1000年则需36吨，均超出当前可运能力。

Rebecca Heilweil argues the ISS’s worst threat is orbital debris puncture. Millions of objects—spent stages, fragments, micrometeoroids—are moving around 17,000 mph (27,360 km/h). A puncture can cause rapid depressurization: a 0.6 cm hole leaves about 14 hours to respond, while a 20 cm hole leaves less than one minute. NASA triggers avoidance when collision probability is at least 1 in 100,000, using the Space Surveillance Network that tracks about 45,000 objects. Protection is uneven: the Whipple Shield is rated for roughly 1 cm³ impacts, while tracking is reliably effective mainly for pieces 10 cm³ or larger, leaving a gap.

If pressure drops, crews can isolate or seal, but at around 490 mmHg (65.3 kPa), NASA says critical systems may fail and hypoxia may force evacuation. A depressurized ISS then becomes a deorbit-problem governance issue: the ESA partnership includes 23 member states plus Japan and Canada, while Russian support is formally guaranteed only through 2028. The preferred option is the US Dragon deorbit vehicle; fallback is Russian Progress. Controlled reentry still requires power, communications, avionics, thermal control, coolant, and propellant systems to operate in vacuum conditions. Failure can cause attitude loss, solar-array misalignment, and broader debris fallout, especially on shallower Russian-assisted reentry trajectories.

Probability estimates remain low but uncertain: NASA cited a worst-case depressurization probability of 1 in 121 in 2017, and by late 2025 a six-month risk range of 1 in 36 to 1 in 170. Even when reentry is controlled, fragments still pose risk. Experts compare potential uncontrolled break-up pieces to sizes from cars to trains; historically no one has died from station debris. In 2024, one reentry fragment hit a home in Florida, and Skylab debris once landed in remote Western Australia. Raising the ISS by more than 640 km could extend life by 100 years but needs at least 18.9 metric tons of propellant (about 2,000 airline carry-ons), and 1000 years would need 36 t—beyond current delivery capability.