Sails are useless in a balloon. The only way to steer a balloon without a propeller is to raise and lower its altitude seeking a wind blowing in the right direction.
Add a fin to a baloon and you can steer it.
And once the baloon can hold direction in the wind with the help of the fin, you can add sail to actually get some propulsion in direction other than wind.
There is no keel on a balloon. Without a keel, one is only going downwind.
Mind == blown*
*Sincere, but pun intended
Is that true? Just from quickly poking around, LEO satellites seem to orbit at about triple the height, moving far faster than a balloon lazily floating along the jetstream. Probably can use a larger variety of instruments as well.
Hundred times the height, to be exact.
Or perhaps both at once. I really hope the details of this craft are published, the machine nerd in me needs to know.
It is a lot easier to take pictures and collect data at 60,000 ft (balloon) than from a satellite in low earth orbit, which is closer to 6,000,000 ft.
https://geo-matching.com/content/new-approach-to-use-ground-...
Outside the atmosphere you would not be able to do it
Yes, SAR [1].
[1] https://www.earthdata.nasa.gov/learn/backgrounders/what-is-s...
The Space Shuttle flew missions with an imaging radar that discovered ancient riverbeds beneath deep sand in the Sahara. At the time, some thought it would have worked equally well to disclose buried military infrastructure.
https://www.jpl.nasa.gov/missions/shuttle-imaging-radar-a-si...
Now compare that challenge to simply setting up a shell company and purchasing 15-30cm commercial satellite imagery in their choice of bands.
Commercial satellites can generate 15-30cm images good enough to tell what make and model a car is in a parking lot. https://blog.maxar.com/earth-intelligence/2020/introducing-1...
Camera gimbals provide image stability regardless of motion in 3D space. Digital post processing is used to clean up images from planes and other moving sources.
> with the weight restrictions of a high altitude balloon.
People seem to really underestimate the size of these balloons. They are hundreds of feet across and capable of lifting massive loads. Using Google's Loon as an example it had a balloon that weighed almost 200 pounds and carried an additional 175 pounds of solar panels before you even added the mission payload.
> compare that challenge to simply setting up a shell company and purchasing 15-30cm commercial satellite imagery
Satellites have predictable passes and military installations schedule sensitive outdoor activities around them. The problem for defenders with balloons is that they can loiter on station for months at a time making scheduling around them impractical.
The U-2 spy plane did just that, as did Project Genetrix (Unmanned surveillance balloons), and then later, the SR-71 Blackbird, and as much as the Soviets complained, complaining and shooting at them was pretty much all they could do.
They shot down/recovered so many Project Genetrix balloons, in fact, that their left-over radiation-hardened film was re-used by the Soviet space program in their Luna 3 Moon probe.
Because they’re denying it. Presumably, they’d want their denial to be plausible.
If something flies over your country, you get to loudly complain about it and shoot at it.
If you are able to hit it too, good for you.
This overflight was termed by the Soviets as an "Act of aggression". This Chinese incident is no less an act of aggression, and merely continues the precedent.
If the Chinese really wanted it considered otherwise because they had actually lost control of the device, they could have easily warned us of the problem and requested coordinated assistance in recovering their device (which would of course allow us to examine it). The PRC govt did no such thing.
And the critics complaining about not shooting it down sooner are ignoring two key things. First, the payload was 2-4 school-busses in length, and dropping such a thing from 12+ miles up in a random location even in sparsely populated areas is a ridiculous hazard. Second, we can be quite confident that the US military could neutralize any data collection or transmission during the transit, and the shoot-down over our waters eliminated the possibility of PRC recovering any stored data.
[0] https://en.m.wikipedia.org/wiki/Hurting_the_feelings_of_the_...
https://www.beale.af.mil/Library/Fact-Sheets/Display/Article...
The comment you replied to says "no commercial aircraft flies at that altitude" and the concorde hasn't flown in decades.
Edit: By the way, that comment said, and I quote, "Name one plane that flies at more than 60,000 feet, I'll wait."
No word "commercial" there. So, aside from the Concorde, there were/are several others, some already mentioned.
In contrast, every orbital launch has to deal with 10s of thousands of pieces of space debris.
https://www.beale.af.mil/Library/Fact-Sheets/Display/Article...
SR-71: "QQ requesting clearance to flight level 600"
ATC: "QQ, climb and maintain flight level 600... if you can get there."
SR-71: "Roger, descending to flight level 600"
especially in view of the fact that the upper limit of sovereign airspace is not defined by international law. In fact there are proposals to treat the 18-160km zone as a transitional region of reduced sovereignty akin to EEZs.
https://iaass.space-safety.org/wp-content/uploads/sites/24/2...
> Legally however, it is an indistinct region where it is not clear whether the operations that take place are covered by aviation or space conventions and treaties, in particular with reference to the freedom of overflight that applies to space orbital operations
Also:
> Although outer space is free, if states are allowed to claim vertical sovereignty up to the point where orbital dynamics are possible, other states will be precluded from having free access to space
> John A. Johnson, General Counsel of [NASA] and [of USAF], said in 1964 "there should therefore be no legal basis for protesting, merely on grounds of unpermitted presence, the overflight of national territory by ascending and descending spacecraft, regardless of altitude."
https://scholar.smu.edu/cgi/viewcontent.cgi?article=1126&con...
Also see:
https://aviation.stackexchange.com/questions/43439/is-there-...
For instance, the Pentagon has just reported that several Chinese balloons have been crossing US airspace in the recent years [1], also during Trump presidency. These were not shut down, they were not even reported at the time AFAIK.
[1] https://www.businessinsider.com/conservatives-blame-biden-ch...
And if they could, other countries would love to shoot them out of the air and it would be fair. You don't put planes like the U2 in operation without being aware of the risks.
I don't understand what you're trying to achieve by pointing that out.
There's a tradeoff between the weight of the solar panels vs simply using batteries (though batteries don't like the cold, and solar panels do), so I think maybe they were hoping the thing would stay aloft for a long time?
My guess is that the actual package of equipment - batteries and sensors - is quite small. Maybe a telescope and gyro stabilizer or gimbal was part of the setup. Insulation probably bulked it up quite a bit; it's very, very cold at that altitude.
I'd be curious what sort of uplink they were using, assuming the thing was actually fully functional as a spying device. I'd say there is a decent chance it was largely a dummy, designed to see what our reaction would be.
I don't particularly like the precedent we just set. There's no evidence it was a weapon, its flight path was easily tracked and slow so our military could hardly argue it was a surveillance threat especially compared to satellites, it's well outside commercial aviation flight ranges.
If they want to send balloons over us at 80,000 feet...let them? Who cares? They can task commercial satellites and get as good or better imagery.
We can hardly point fingers. The U2 flew at similar altitudes, we still use them to this day, and they almost certainly contain far more powerful spying equipment.