To what extent is modern "maneuverable spy balloonery" really a thing?

Question

There's a high altitude balloon in the news recently. It seems to have come from the Pacific, passed over Canada and is now over the US. I don't have any official tracking data but notional trajectories are shown in screenshots below. The CNN graphic is labeled conservatively:

Potential trajectory: suspected spy balloon

Question: Balloons certainly have a place in the history of warfare and intelligence gathering, but these days are there really noted, plausible modern instances of spy balloonery? And are investigative balloons (spy or otherwise) of this size really maneuverable?

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screenshots from CNN's February 4, 2023 See path the suspected spy balloon may have taken showing a "potential trajectory" of a "suspected spy balloon" and some high resolution photos showing the balloon and an array of panels that seem likely to be for solar power.

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A different hypothetical map from Sky News's February 4, 2023 Spy balloon: China wanted 'to be noticed' says Professor Michael Clarke showing a trajectory for an object at 40,000 feet ending up in Montana

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Screenshot from the April 30, 2020 NASA Wallops video B-Line to Space: The Scientific Balloon Story showing the payload and its solar panels. I don't know which balloon mission this is, but we can see images of another similar one in Space SE's What cosmic ray sensor is attached to this Balloon?

From the video:

NASA’s Wallops Flight Facility in Virginia manages the agency’s Scientific Balloon Program with 10 to 15 flights each year from launch sites worldwide. Northrop Grumman, which operates NASA’s Columbia Scientific Balloon Facility (CSBF) in Texas, provides mission planning, engineering services and field operations for the program. The CSBF team has launched more than 1,700 scientific balloons in the over 35 years of operation.

Answer 1

To what extent is modern "maneuverable spy balloonery" really a thing?

To the extent that it helps to sell news and stoke irrational fear of secret Chinese technology.

Much of what a "spy balloon" can accomplish can be done better with a satellite. But there is maybe one thing for which a balloon is the better option: Signal intelligence, meaning the listening in on radio signals. This could be anything from intercepting radio communications to provoking air defenses in order to learn what frequencies and tactics are used.

The "navigating" part is rather limited. Other than changing altitude in order to catch a different wind direction there is nothing a balloon can do for flying into a certain direction. Altitude changes happen automatically with the heating of the balloon from solar radiation and cooling again during the night. In order to deliberately change altitude, ballast must be carried along in order to be dropped when the balloon should climb.

To me it looks as if the balloon flew into US airspace by chance and not by active control.

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EDIT (Feb. 18, 2023): Aviation Week cites an ex-Google Loon engineer with the information that in the most recent balloons altitude is controlled by a ballonet, an internal gas bag that can be in- or deflated to change the pressure (and thus the buoyancy) of the balloon:

The most advanced ultra-long-endurance, high-altitude balloons seldom use propellers for directional control. Instead, such aircraft pump regular air into an internal ballonet envelope to descend or release the air to climb, Bowen says. Altitude adjustments are made to find wind currents moving in other directions. The system provides a limited capability for directional control.

Answer 2

to what extent is modern maneuverable spy balloonery really a thing?

While it is certainly debatable whether or not recent balloons in the news were maneuverable or not, technology does exist to attempt it.

Goal: drift over Montana from around 10,000 km away

Montana is around 1000 km × 400 km. Prevailing winds would favor a broad side approach.

Error margin: +/- 500 km. $arc$ $sine$ (500/10000) = +/- 3 degrees.

check the weather before you go flying

Weather forecasting has grown in leaps and bounds in recent years, and world wide wind field maps are available.

moving with the air mass.

An all-time Aviation Stack Exchange favorite. Use buoyancy for lift, ride the wind. This is exactly what this airship did during its 1929 round the world flight along a similar trans-Pacific route. Knowing the weather helps.

maneuverability?

A 10,000 km trip at 100 km/hr will take 100 hours. Gently moving in the airmass at 5 km/hour perpendicular to the ground speed would allow 500 km in either direction of manuverability. Montana or bust!

is it really a thing?

It is technologically possible, but one can only ask that the science of this site not be dragged down into the political folly of the day. Returning to 1929 may not be the best course, returning to 1914, worse still.

Answer 3

For intelligence gathering a balloon would have a couple of advantages and several disadvantages. The disadvantages first. Limited maneuverability, most balloons can only float on the wind. You could add the ability to change altitude hoping to find winds blowing the direction you want to go. This leads to the second issue weight. To keep the size reasonable the mass of the payload must be limited. limited mass means things like large high resolution cameras are not feasible. this would include large motor for propulsion and equipment to change altitudes. Now for the advantages. They are much cheaper than satellites, high performance spy planes, or even drones. They are harder to detect. Ours defensive radar networks were simply not looking for them. Our radars were optimized to look for aircraft and missiles, not balloons. I assume that is being changed. Finally because we did not initially detect them we did not take any measures to "hide" ay activities. When I was in the USAF we knew when Soviet satellites were passing over head and made sure no aircraft were transmitting radar, radio, or ECM, and that all exterior panels were closed. We would sometimes even suspend work during the time they were overhead.