Earlier quoted context omitted.
This is ELI5 territory, which is cool because we probably need one of these as well.
The rocket made the air go funny which meant your phone got confused about where it was.
Spot on!
Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5
31–40 of 92 posts
Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5
#32The 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?
I don't have firsthand knowledge, but I'd be surprised if mission critical military gear uses GPS for more than a secondary / corrective role.
I can't imagine the signals play that well in a heavily-jammed environment.
High probability rough GPS fix + radar / optical terrain comparison & dead reckoning for terminal guidance seems more likely.
Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5
#33Earlier quoted context omitted.
It is followed by ionospheric hole (should be It was... holes ) A ~900km wide patch of the ion blanket around the earth became thinner. Probably in the density sense, not the size sense: there was less plasma there than normal. (The abstract measures this in terms of how many electrons they counted in that area.) due to rapid chemical reactions of rocket exhaust plumes and ionospheric plasma. They think the thin patc…
I'm curious about this too. The Falcon burns RP-1, essentially a very refined kerosene, with liquid oxygen. Exhaust should be water, carbon dioxide, and a bit of carbon monoxide. Not typically the most reactive things, but perhaps there are different interactions with plasma?
This other paper [0] seems to indicate that TEC (total electron count) fluctuations are caused by shock waves, not rapid chemical reactions, and can arise from ground explosions as well. IANA ionosphere scientist, so I don't know if the parent paper made a mistake.
Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5
#34Could major GPS issues become a nonstarter for the BFR intercontinental transport vision?
Maybe that's why the BFR interplanetary version is the focus. Screwing up GPS is less of a deal when you're leaving the planet for good... ;)
Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5
#35The 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?
Many commercial GPS systems can get to within 2cm (I don't know if the correction GPS will see the same error and thus give the correct correction factor or not.
Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5
#36Even plainer language: Rocket exhaust can have impact with atmosphere, we need to study it more on short and long term effects.
>Rocket exhaust can have impact with atmosphere, we need to study it more on short and long term effects.
Wasn't this already known? We have been sending rockets to space for a while now, right?
EDIT: Found something from 2014, https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2014...
Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5
#37I'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." -…
hmm, I put your "plainest" language answer into XKCD simple writer, and there was some complexity in there.
In most simple language, the space truck was thrown up, not tossed forward, and this caused a sound wave that was followed with some interesting events in one of the high bits of the sky, between the space truck refuse air and the hotter-than-air stuff in the high sky, all of which need further study because of possible bad things like how true your sky-computer computer-map might be in the area around the "hole" caused by these waves.
Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5
#38The 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?
US currently claims 4m RMS (7.8m 95% Confidence Interval) horizontal accuracy for civilian (SPS) GPS. Some devices/locations reliably (95% of the time or better) can get 3m accuracy.
Yes, my expectation is that standard consumer-grade devices with GPS capability (even using tiny chip antennas) can achieve ~2.5M horizontal on L1 when using WAAS/SBAS augmentation.
Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5
#39Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5
#40I'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." -…
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