61–70 of 92 posts
I'd be curious to know roughly how long the disturbance lasted. Did it dissipate/recover in minutes, or did it stick around for the better part of a day (or two, or three)?
"In the case of this Falcon 9 launch, it induced a plasma hole that lasted for two to three hours, which a magnitude comparable to a magnetic storm"
https://arstechnica.com/science/2018/03/spacex-launch-last-y...
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.
Even plainer language: Rocket exhaust can have impact with atmosphere, we need to study it more on short and long term effects.
Earlier quoted context omitted.
The ionosphere is not the same thing as the atmosphere. The ionosphere is a shell of super hot gas outside of the atmosphere.
The ionosphere is not outside the atmosphere, it's part of the atmosphere. The atmosphere consists of many layers. From the ground up, these are the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. You may be thinking of the thermosphere, which is indeed very hot (thus the name), albeit with such low density that it wouldn't transfer much heat to your spacesuit or spacecraft. But the thermosphere i…
Earlier quoted context omitted.
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.
By "another GPS" do you mean a different satellite in the same network, or a different GNSS?
Atmospheric conditions cause errors that are in some cases hard to predict.
If you have a GPS receiver at a known nearby location, you can subtract the difference from what you receive and what you would expect to receive at your actual location, and then add that in to your GPS receiver at the unknown location.
It needs to be nearby because you want the atmospheric conditions between your fixed receiver and your moving receiver to be as similar as possible.
See https://en.wikipedia.org/wiki/Differential_GPS for more information
Also https://en.wikipedia.org/wiki/Real_Time_Kinematic is what's used to get ~1cm accuracy, but RTK would not be useful because while RTK increases precision of the measurements it does not (by itself) eliminate errors introduced by the atmosphere, which are already larger than what can be obtained without taking carrier phase into account.
Earlier quoted context omitted.
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.
You mean, like HAARP? Not saying it is a weapon. But it certainly has the pedigree to perceived that way, from a program & pop-culture standpoint: https://www.popsci.com/military-aviation-space/article/2008-... * Note: University of Alaska fairbanks appears to have taken over HAARP and converted it to a "Fee based" research center -- much like a radiotelescope at other academic institutions I assume?
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." -…
Is '~1 m' meters or miles?