Balloons are interesting problems for military detection systems as the thinness and non-conductivity of the lifting body is completely transparent to radar. Thin solar panels are likely also difficult to pick up as they are flat and angled. Then, in the case of the china balloon, there is some goofy aluminum structure which will reflect radar, but if you recall, they used to describe stealth bombers in terms of their size – the radar signature of a bird or something. If the actual size of the structure you are trying to detect is small, then it is naturally stealthy.
The other bit which makes them difficult to detect is the speed. A lot of radar installations rely partially on a heavy Doppler shift to note incoming objects. We think of Doppler shift as light related, but you can hear the effect when a car or train passes. The sound pitch changes from high to low as it goes by.
An aircraft, even a stealthy one, with a minimal signal but solid doppler shift will light up nice and bright on detection radars. A weak signal with small movement might just be a flock of seagulls. A weak signal with movement correlated to the speed of surrounding weather could easily just be weather. A balloon is naturally stealthy to these systems.
the Air Vent 
It is nice that they have set the precedent to shoot these things down. I was not surprised that the sidewinder locked on the hardware rather than the balloon envelope but it would have been much smarter to hit the balloon as it would have brought the assembly down relatively intact. This is something I was thinking about quite a bit before it happened. Poke a small hole, retrieve intelligence gathering garbage. It looked to me like the sidewinder didn’t even go bang as it passed through the light weight mess.
Hopefully, they are in development of a balloon hole poker missile (maybe visible spectrum) as bullets won’t have enough altitude.
Not sure why we didn’t put the effort into capture to balloon whole.
I have an idea why we didn’t, but the screeches of CONSPIRACY would be intolerable.
Interesting thoughts about balloon stealthiness. It makes me wonder if this might have been a trial run by China to see it is possible to do and what the United States’ response would be. Maybe next time it’ll be swarm of balloons, each carrying a low-yield nuclear device to create EMP effects over large parts of the continental U.S.
…see *if* it is possible…
Lol. Gotta love this blog!
If you have ever seen ground clutter on a radar return, you know that modern systems work very hard to remove that clutter. The same is true for weather. All kinds of weather create return signals and they are sometimes filtered by doppler shift.
Any method to reduce noise is used. If I were in the field, I would likely be telling you about FFT based filtering methods that used signal persistence to highlight objects. I’m not though.
Is the goal to impress with your technical knowledge?
Regardless, it’s a wonder some people ever venture out of their bunkers.
Although I suppose some may not.
Hell dude, what should I do with what I know?
It’s not meant to be that big of a deal because I don’t even need to look this stuff up. There was a time where most of the readers here would just nod their heads and say yup. Others would say things like interesting and still others would point out some technical mistake I made.
I was today years old when I learned this song even had English lyrics. It was insanely popular in German, (In the FRG, and DDR and Austria and even Switzerland…) when I was on assignment in that region. [phonetically:] “Noyne and noinsig looft bowllooons. Hohst doo etvass Zeyte foyer mish? Dann singe ish ein Leeed foyer dish!” …
https://en.wikipedia.org/wiki/99_Luftballons
Largely unappreciated during the cold war were the asymmetries between US and USSR requirements to “win.” I’d discuss that background danger in depth, but I’m trying to break the habit of hijacking the Air Vent site comment fields as if I were top posting to my own blog. Let it be summarized that the US had little reason to launch a massive “counter-attack” upon signals of a few missiles, or birds or balloons. Because, the Soviets had little reason to start with just a few missiles. On the other hand, the USSR was — properly and reasonably — ape-manure-paranoid that the US could and might and rationally would open hostilities with just a few ICBMs, carefully targeted. So we got this very “near miss” scenario.
https://en.wikipedia.org/wiki/1983_Soviet_nuclear_false_alarm_incident
( I was in the vicinity at the time. I take absolutely NO CREDIT AT ALL for the March, 1983 release of the original German pop song which filtered into East Germany, and thence to young rock-n-roll fans serving in the Russian Army, in time to raise doubts six months later that small ambiguous radar signals might be missiles. Not me. Not my assignment. I categorically deny it all. )
(ALSO, I had nothing to do with this demonstration to show the futility of anti-missile systems installed to protect Moscow and the Kremlin : https://en.wikipedia.org/wiki/Mathias_Rust )
(I can’t imagine how such rumors and accusations get started… But it’s why I insist on pseudonyms on line. )
Too fun. Hijack away IMHO.
Comments like that make blogging fun.