物理与天文2018agupubs.onlinelibrary.wiley.com
Formosat-5 发射触发的电离层圆形冲击声波
Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5
入门 · 约 45 分钟读完前置知识：电离层基础、声波与冲击波常识、GPS 定位原理
导读
这篇论文研究了 2017 年 8 月 24 日 SpaceX 猎鹰 9 号发射台湾 FORMOSAT-5 卫星时在电离层中引发的圆形冲击声波。由于该次发射载荷较轻，火箭以近乎垂直的高弹道直接将卫星送入 720 公里任务轨道，其尾羽与电离层等离子体快速化学反应形成等离子体空洞，并产生可被观测的圆形冲击波。
HN 关注点：火箭发射对电离层和 GPS 精度的潜在影响，以及这种罕见的高垂直弹道发射带来的独特观测现象。
HN 评论精选
这几条评论里：质疑 1 补充 3
补充改写并通俗解释论文摘要：垂直弹道发射引发电离层反应，可能影响 GPS 精度
我斗胆改写了论文的"通俗语言摘要"。火箭是近乎垂直地被"抛"上去的，而不是常规的更贴近地面、近乎水平的飞行路径，这产生了冲击波，随后火箭尾羽与电离层等离子体之间发生了一些有趣的反应，这些都需进一步研究，因为可能影响此类"空洞"附近区域 GPS 的精度。
eganist查看英文原文
I'm taking the liberty of reworking their "plain language summary." I aimed for maintaining accuracy with relaxed precision, but please correct me if I've lost too much of either in the process. I corrected a specific bit of imprecision in language in the source's plaintext summary not clearly distinguishing between vertical/y v. vertical/z, something the technical abstract clarified by stating "vertical altitude." --- In plainest language, the rocket was lobbed up, not hurled forward, and this resulted in a shock wave that was followed some interesting reactions in the ionosphere between the rocket exhaust plume and the plasma in the ionosphere, all of which need further study because of potential risks to things like how accurate your GPS might be in the area around the "hole" caused by these reactions. --- Plain(er) Language Summary On 24 August 2017, a SpaceX Falcon 9 rocket took off from Vandenberg Air Force Base in California, carrying Taiwan's FORMOSAT‐5 Earth observation satellite into orbit. The lightly weighted solo payload lets the rocket fly a path higher than the bare minimum to insert the payload directly where it needs to operate (the mission altitude), at 720 km. This unique nearly vertical path away from the ground is different from the usual satellite launches where rockets fly over horizontal paths more closely to the ground and insert satellites at 200 km above Earth and rely on orbit maneuvers to reach mission altitudes. Because of this lofty (more vertical) launch path, the rocket launch generated a gigantic circular shock wave in the ionosphere covering a wide area four times greater than California. It is followed by an ionospheric hole (plasma depletions) due to rapid chemical reactions of rocket exhaust plumes and ionospheric plasma. Large spatial gradients caused by these reactions and the resulting hole could lead to ~1 m range errors into GPS navigation and positioning system. Understanding how the rocket launches affect our upper atmosphere and space environment is important as these human-caused space weather events are expected to increase at an enormous rate in the near future.
质疑提问：电离层空洞除了 GPS 误差外是否还有其他危害
除了 GPS 误差，这还会造成其他问题吗？像"火箭尾羽与电离层等离子体快速化学反应导致电离层空洞（等离子体耗尽）"这样的句子听起来挺吓人的，但很可能只是因为我只懂一半的词，把它们串起来就更不懂了！
stanmancan查看英文原文
Can this cause any other issues other than GPS errors? Lines like It is followed by ionospheric hole (plasma depletions) due to rapid chemical reactions of rocket exhaust plumes and ionospheric plasma. sound concerning but that's most likely because I only understand half the words, and have even less of an understanding when they're strung together in that manner!
补充指出最严重事件也只造成约 1 米误差，且 GPS 通常有其他增强方案补偿
有记录以来最严重的一次此类事件造成了约 1 米的误差。反正民用 GPS 本来也没那么精确，这也是为什么各种方案要与 GPS 结合使用来提高精度？想必军用 GPS 也有类似的方案来应对这类事件？
jessaustin查看英文原文
The worst such event on record caused errors of ~1 meter. I didn't think civilian GPS was that precise anyway, and that's why various schemes are used in conjunction with GPS for greater accuracy? Presumably, military GPS has similar schemes to deal with this sort of event?
补充极简总结：火箭尾羽对大气的影响需要更多短期和长期研究
更通俗地说：火箭尾羽会对大气产生影响，无论短期还是长期效应，我们都需要更多研究。
m3kw9查看英文原文
Even plainer language: Rocket exhaust can have impact with atmosphere, we need to study it more on short and long term effects.
历次讨论
- 2018Hacker News 讨论帖313 分 · 83 评
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