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Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5

agupubs.onlinelibrary.wiley.com

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Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5

#41

Post by marcosdumay »

wlesieutre wrote: post #25
lainga wrote: post #14

Earlier 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?

Anything is reactive when interacting with plasma.

There should be little of those gases naturally up there (mostly so for water), and even throwing a large mass of gases up there may be enough to disturb everything.

Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5

#43

Post by drag0nballz »

ethbro wrote: post #32
jessaustin wrote: post #12

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?

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.

I'm not sure if you consider this "mission critical" but US military drones use GPS for navigation. There have been several cases of them being captured via GPS jamming.

Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5

#44

Post by tener »

eganist wrote: post #7

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." -…

We sure need to study the ability to affect the ionosphere. And then people will build weapons capable of doing it in suitable ways. Unless they already have those.

Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5

#45

Post by zaroth »

I thought orbiting was all about horizontal velocity, otherwise what comes up must come down!

Did the rocket just turn sideways to accumulate the necessary horizontal velocity to actually maintain an orbit at a much later phase in its flight?

Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5

#46

Post by [deleted] »

eganist wrote: post #7

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." -…

[deleted]

Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5

#47

Post by teh_klev »

taneq wrote: post #20
eganist wrote: post #10

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.

The really fast up goer made the air go funny which meant your phone got confused about where it was.

https://xkcd.com/1133/

Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5

#48

Post by cbhl »

bdamm wrote: post #42

Did anyone try downloading the actual paper? My browser opened and then closed a tab. Kind of odd.

The paper is behind a paywall. It probably went back to the abstract page because the login / buy panel is on the right side of that page.

Maybe see if your local library or university has an institutional subscription you can use to access the paper?

Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5

#49

Post by Tuna-Fish »

zaroth wrote: post #45

I thought orbiting was all about horizontal velocity, otherwise what comes up must come down! Did the rocket just turn sideways to accumulate the necessary horizontal velocity to actually maintain an orbit at a much later phase in its flight?

Yes, absolutely. The total sideways velocity required is fixed, going on a steeper trajectory requires more fuel for the same target orbit.

The reason Falcon 9 still does that sometimes is that a more vertical trajectory makes the return flight back to the launchpad easier. So if the payload is light enough that there is enough free delta-v, they want to do that. If there isn't, they land on the barge or fly expendable.

Re: Circular Shock Acoustic Waves in Ionosphere Triggered by Launch of Formosat‐5

#50

Post by InclinedPlane »

zaroth wrote: post #45

I thought orbiting was all about horizontal velocity, otherwise what comes up must come down! Did the rocket just turn sideways to accumulate the necessary horizontal velocity to actually maintain an orbit at a much later phase in its flight?

It is almost, but not quite, entirely about horizontal velocity. You also need sufficient altitude to be outside the atmosphere, as orbits with altitudes of under 100km are very short lived.

Additionally, it's generally not great to try to spend a lot of time accelerating through the atmosphere. For this reason rockets tend to fly upwards and then once they are out of the bulk of the atmosphere they fly mostly sideways.

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