A plan to turn the atmosphere into an enormous sensor | Hacker News Reader

A plan to turn the atmosphere into an enormous sensor

economist.com

30 pointsnoir-york11 comments

From the article:

The first 27 months of the programme will be dedicated to understanding the science behind ripples in both the ionosphere and the electrically neutral atmosphere below it, and then building computer simulations of what is going on. These will be tested to see if they can replicate accurately effects seen in the past.

Once the team have a better understanding of the basic science, they will proceed to the second stage: field trials. This will involve three tests at three-month intervals in which researchers attempt to locate pertinent events, such as storm cells, mining operations and earthquakes. If that works, the project will then move on to matters of military interest by spying on missile launches, tracking aircraft and even watching underground bunkers being dug. The result, if all goes well, may be the world’s first true panopticon.

Hopefully they spend more time on the atmospheric stuff than the military stuff. Exciting news, if the former.

Any sufficiently advanced technology will be purposed for military use. This will be purposed for Intelligence and Reconnaissance use if it fills a niche they need filled.

Having worked in remote sensing[1] in the distant past, every now and then I still glance at the Wassenaar Agreement[2] to find out what today's fun stuff may be.

[1] interplanetary on my part, but I have no illusions that our funders didn't have further intraplanetary applications in mind. I was young and needed the money.

[2] https://www.wassenaar.org/app/uploads/2019/12/WA-DOC-19-PUB-...

(as far as watching bunkers being dug, I'm pretty sure LIDAR already gives a much cleaner signal)

Hey, that’s perfectly reasonable. No, the problem we have as a society is we live in this kind of reality which is governed by this thing called physics, and as our understanding of physics progresses, our ability to abuse the shit out of it also progresses. Some things aren’t a matter of if, but when.

That PDF is a gold mine by the way.

> as far as watching bunkers being dug, I'm pretty sure LIDAR already gives a much cleaner signal

The proposed applications are probably nothing more than something to get the ball rolling but can already be done very effectively today. I hesitate to be overly skeptical because an atmospheric panopticon would probably have more applications than they would imagine or dare to propose themselves.

something something Unrestricted Warfare

The atmosphere is also used as a detection medium for Imaging Atmospheric Cherenkov Telescopes (IACTs) [1]. Very high energy (>tens GeV) photons, electrons or nuclons hit atoms in the atmosphere and produce a cascade of secondary particles, which move faster than the speed of light in the air emitting Cherenkov light [2]. Flashes of this light are lasting for few nanoseconds, so the cameras have nanosecond sampling time and are based on photo multipliers.

There are many such telescopes around the world: MAGIC (2 telescopes), FACT (1), HESS (5), Veritas (4). The biggest assembly of such telescopes is currently under construction - Cherenkov Telescole Array [3] with hundred of telescopes in Paranal, Chile and 20 in La Palma, Canary Islands. One large telescope with a mirror of 23m diameter is already operating [4].

[1] https://en.m.wikipedia.org/wiki/IACT

[2] https://en.m.wikipedia.org/wiki/Air_shower_(physics)

[3] https://m.youtube.com/watch?v=5gRHFQP_SjU

[4] https://www.cta-observatory.org/lst-1_inauguration/

This is fascinating, but:

> which move faster than the speed of light

Citation needed. I was of the understanding that this is impossible, and your first two links provide no evidence to the contrary.

Crucial detail:

> which move faster than the speed of light in the air

The speed of light in air is slightly less than the speed of light in a vacuum (c)

Nothing is going faster than c

> which move faster than the speed of light in the air emitting Cherenkov light

Key words "in the air". As they can't go faster than C in this medium[0], they are forced to slow down, and emit this lost kinetic energy as radiation - my understanding.

Something a bit better, from https://en.wikipedia.org/wiki/Cherenkov_radiation

Cherenkov radiation is electromagnetic radiation emitted when a charged particle passes through a dielectric medium at a speed greater than the phase velocity of light in that medium. A classic example of Cherenkov radiation is the characteristic blue glow of an underwater nuclear reactor.

[0] I realise this seems contradictory - they can't but for a short time they are - I don't understand that either.

Exactly, speed of light in the vacuum (c) is the hard limit, only mass-less objects can move that fast (e.g. photons). The refraction index (n) tells you how fast light moves in a medium. It is defined as n=c/v, where v is the speed of light in the medium. That's why (and also because of internal reflections) the speed of light in the fiber optics is not quite reaching c [0], and with inter-satellite communication Starlink may provide lower latency than the one using landline fiber optics channels. For air refraction index is very close to 1 [1], but not quite, at 10km altitude n=1.0001, which is 99.99% of c. For example a proton with an energy of 1TeV (Tera electron-volt, 1x10^12 eV) is moving 99.999956% speed of light in vacuum [2], and we see protons up to 5x10^19 eV reaching 99.99999999999999999998% of c [3]. Even "low" energy protons (tens of GeV) hitting molecules of air can kick out electrons, which, due to being lighter, can move faster than the initial protons and emit Cherenkov radiation.

[0] https://www.quora.com/What-is-precisely-the-speed-of-light-i...

[1] https://www.researchgate.net/profile/Dmytro_Vasylyev/publica...

[2] https://uspas.fnal.gov/materials/10MIT/Review_of_Relativity....

[3] https://en.wikipedia.org/wiki/Greisen–Zatsepin–Kuzmin_limit

http://archive.is/IJD98

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