# When CleanTech Gets Used For Bad: How Much Power Did The Spy Balloon Have?

When social media, regular media, and trash media were all discussing the Chinese spy balloon (NO, it wasn’t a wayward weather balloon) that passed over the United States last week, the first thing I thought of was those solar panels. It probably didn’t contain any missiles, a nuclear bomb for an EMP attack, or anything truly frightening. Given that China already has other ways to get imagery (mostly satellites, but there’s also TikTok and other means), the only logical solution left was probably signals intelligence gathering (SIGINT).

### Does The Amount of Solar Power Support Radio Spying?

But, I wanted to see if I could figure out what kind of power those panels were making. Not only would it be interesting because I write about clean technologies, but it would also make for better educated guessing about what the balloon was doing. I tried first to see if anybody else knew, but the guesses were all pretty wild, with this being a good example:

Both the size of the balloon and the 20-40 kW of power was a very unlikely answer, so I had to do more digging and waiting. The final answer (that I know of right now) was that the balloon was somewhere around 30-40 meters in diameter (around 120 feet, or as the Pentagon said: “three buses”). So, this meant that the array of equipment hanging below the balloon was probably less than half of that, with my best guess at 40-60 feet long. With the big gap in the middle and spaces between solar panels, the size of each of the 16 panels was probably about the same as a normal commercial solar panel that goes on roofs.

Assuming 320 watts, that puts the minimum power for the balloon at about 5 kilowatts. While that sounds like a lot of power, the off-grid nature of the balloon means the daylight hours have to provide enough battery power to run equipment 24/7. Being up in the sky that high probably means there’s about an extra hour of sunlight per day, for a grand total of about 11.5 hours. That means the maximum potential of the system is to produce about 55 kWh of power daily. But, conditions aren’t always ideal, so it’s a good idea to cut that estimate in half, meaning the equipment needs to run on 27.5 kWh per day at most.

That comes out to about 1.2 kWh per hour, which means you can drop the hour and make the max continuous load about 1.2 kW. This pretty much rules out having enough power for propulsion except for very minor steering power, but that doesn’t mean Chinese state media is correct when they assert that the balloon can’t steer itself at all. Balloons have been steering themselves by moving up and down to get to favorable wind currents since World War II, and their ability to navigate with onboard computers has only improved since that time. 1,000 watts is definitely enough to run a flight navigation computer, and perhaps leave enough power to run small propellers for some additional steering (something that’s been seen in the wreckage) in conjunction with choosing the right altitude.

After control systems, there’s really only enough room left over for radios in that power estimate. This matches up with what US officials have been saying as they’ve analyzed wreckage, saying that the balloon was meant to spy on radio signals in places it flies over and may have been able to steer with small propellers.

Keep in mind that this is a minimum estimate. The balloon could have had 2-3x more power, giving greater steering capability.

### Why Use A Balloon To Spy On Radio Signals?

While there are radio signals that can travel around the planet, most uses of radio technology don’t rely on it. HF, or “shortwave” signals, tend to be pretty unreliable and there’s not enough spectrum to support much data throughput. They’re great for things like broadcasting, low-speed data, and voice communications when conditions are right, though. Much of the fun of amateur radio is in this frequency range.

But, things like cell phones, public safety radio (police/fire/EMS), wifi, military communications, and satellite communications all happens in the VHF, UHF, or higher frequencies. While there’s more room for high-speed data and reliability is higher, these signals can’t “skip” off the ionosphere the way HF signals can, so they’re limited to just past what you can see. With lower power levels, many of these signals fade in the atmosphere, and would be pretty weak and unreadable by the time they get up as high as a spy satellite flies.

Putting a balloon at 60,000 feet means that your ability to pick up signals from pretty much everything we use radio waves for would greatly increase. At 60,000 feet, the balloon could probably pick up everything within about 350 miles of its flight path. Statista already made a map showing the flight path and approximate range.

### Why I Wouldn’t Worry Too Much About Future Balloons

While there was probably opportunity to “splash” the balloon in Alaska without risking harm to people on the ground, this was the first time one of these balloons caught public attention. Prior balloons were noticed by the military, but there was no outcry or public fear and the balloons were largely ignored. There’s lots of finger-pointing by people trying to score political points, but the fact is that it’s not terribly easy to down a stratospheric balloon. Most aircraft don’t even fly that high, and the few that do aren’t armed.

But, I can tell you that I saw some very interesting testing at a military facility in New Mexico recently. When waiting for a road closure at White Sands Missile Range on Wednesday, I watched a test missile fire almost straight up, which is unusual (most missiles are designed to go downrange toward a target). So, it’s pretty likely that any future balloons will be brought down much more quickly with modified surface to air missiles (SAMs) before they have any chance to overfly the US or its allies.

Featured image by Statista (CC-BY-SA License).

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