SoylentNews is people
SoylentNews
China balloon: US shoots down airship over Atlantic
The US has shot down a giant Chinese balloon that it says has been spying on key military sites across America.
The Department of Defense confirmed its fighter jets brought down the balloon over US territorial waters.
Three airports were shut and airspace was closed off the coast of North and South Carolina as the military carried out the operation on Saturday.
Footage on US TV networks showed the balloon falling to the sea after a small explosion.
An F-22 jet fighter engaged the high-altitude balloon with one missile - an AIM-9X Sidewinder - and it went down about six nautical miles off the US coast at 14:39 EST (19:39 GMT), a defence official told reporters.
US President Joe Biden had been under pressure to shoot the balloon down since defence officials first announced they were tracking it on Thursday.
Second balloon spotted over Latin America:
On Friday, the Pentagon said a second Chinese spy balloon had been spotted - this time over Latin America with reported sightings over Costa Rica and Venezuela.
See also:
US downs Chinese balloon, a flashpoint in US-China tensions
From China to Big Sky: The Balloon That Unnerved the White House
3 Navy Warships, FBI Now Hunting for Wreckage of Chinese Spy Balloon off South Carolina
Biden's 'Sputnik moment': Is China's spy balloon political warfare?
(Score: 3, Informative) by khallow on Sunday February 05 2023, @04:19AM (10 children)
So taking out a balloon with a Stinger missile is a statement of US military capabilities. And that might be a large part of the reason that they bothered to shoot down the balloon. I noticed they shot it down in early afternoon (it hit water at 2:39pm EST and fell near shore. That indicates that they didn't have to keep trying to shoot it down (as the Canadians did in the AC's linked story) and it went down quickly once they hit it. The time of day might be advantageous to the use of the Stinger since the balloon would still be near optimal solar heating and thus as bright as it'll get as a thermal target. So the shot might have been performed in a narrow window of opportunity.
As to what the balloon might be, I don't know. But if they can keep it in the air long enough (several weeks which isn't that hard), it will eventually return to the same side of the world as China and they would be able to do a controlled descent - also not hard.
For example, I used to work as a volunteer with an aerospace non-profit group, JP Aerospace [jpaerospace.com]. They routinely ran high altitude unmanned latex balloon flights to 80-110k feet (24 km to 34 km altitude) that lasted several hours. We actually had to precautions to prevent the balloon from staying in the air indefinitely - this consisted of two overlapping schemes. First, cutting the balloon loose from the cable and allowing the payload to fall back to Earth. The second is that the balloon was actually overinflated and would pop on its own when the latex stretched too much. The usual failure mode was premature popping of the balloon from latex with weak spots.
Under our approach, we could launch a balloon every half hour or so with a crew of maybe five or six people - just keep the helium, balloons, and payloads coming, though I think we only did that a couple of times for exotic mission schemes.
So it's easy to put a balloon up there that stays up for a while. But latex (which this Chinese balloon appears to be made of both from appearance and how it popped) leaks helium easily. So it drifts lower as time goes on. It'll keep floating, but eventually it'll be in air traffic lanes rather than kilometers above said traffic lanes. There are a couple of approaches to preventing that from happening. The first is to build the balloon of a less leaky latex. The second is putting a store of helium on board and slowly pumping it into the balloon to make up for leakage. Each adds weight to the balloon and takes away from the payload it can carry. Here, if the Chinese balloon really is carrying espionage/surveillance equipment, then it may already be carrying liquid helium for instruments. In that case, it'll have excess helium available without a lot of extra mass.
(Score: 1, Informative) by Anonymous Coward on Sunday February 05 2023, @05:40AM (1 child)
(Score: 1) by khallow on Sunday February 05 2023, @06:20AM
(Score: 2) by ElizabethGreene on Monday February 06 2023, @02:47AM (7 children)
A third method is to discard ballast, E.g. have a reservoir of a very low freezing point liquid (isopropyl alcohol) and a control for the ECU to dump it to maintain altitude. I built and tether-tested kit for this back when I played with the idea of attempting a transatlantic autonomous balloon flight. The guts of it are still sitting on a shelf in my closet. Iridium IOT comms modules are cheap now; I should pick that back up. Hmm.
Any soylentils interested in helping me navigate the EU's airspace regulations for a project like this? Launching from Tennessee the highest probability is it'll crash before it even reaches the Atlantic, but prudence dictates I have to plan for the unlikely chance of success.
(Score: 1) by khallow on Monday February 06 2023, @05:42AM (6 children)
This sounds like an interesting project idea. Can't say that I can assist directly on site with launches, but I'm game for offering free planning and remote assistance on the above issues should you need it.
(Score: 2) by ElizabethGreene on Monday February 06 2023, @03:55PM (5 children)
Q: Do you have any ideas on how to force the balloon envelope to fail? I fit it with an overpressure relief to maximize range, but that means I can't trust it to pop from overexpansion at the end of the flight. I'm able to cut away the flight package, but that still leaves the balloon floating about for however long it takes the helium to diffuse. That's not ideal.
I tried a nichrome wire loop, but the package spins on the tether and rips it off.
(Score: 1) by khallow on Monday February 06 2023, @06:57PM (4 children)
Depends on the balloon type. With latex you can just cut the connection between balloon and payload. The balloon will rise up to the point where it pops and then come down as a loose blob of biodegradable latex. As long as there isn't a lot of weight still attached to the balloon at this point, I think it will fall softly.
With a Mylar or polyethylene zero pressure balloon (basically a bag of helium with an opening on the bottom to keep the bag at the same pressure as the outside, hence "zero pressure") you will need something that ruptures the balloon envelope over a long slice like a long strip of pyrotechnics or heat wire. I don't have experience with that, but there are a few problems: it can trigger prematurely either in storage, on the ground, early on in flight, or even after the balloon part lands again; it needs to work in vacuum (at 80-100k feet it's technically a near vacuum, but you don't have enough air to act as an oxidizer) and with significant temperature extremes (I don't recall the temperature ranges, but you pass through a very cold section around 60k feet and at 100k feet, sunlight portions get pretty hot); and these plastics normally are transparent tot both light and radio waves - if your balloon ever drifts into air traffic altitudes you'll want some way for planes and radar to see it.
Going with latex balloons, the type I'm much more familiar with, you have two conflicting parts to your mission profile. You want to get up to 80-100k feet. But you want to stop at that point. Both latex and zero pressure have the characteristic that they keep rising at the same rate until you get near their limits (latex can't stretch more and zero pressure leaks helium out the bottom). As I understand it, a lot of duration flights rely on this limiting behavior as the brake to keep the balloon in place, but it requires careful calculation and reliable bags (often with very particular and costly characteristics like very inelastic near limit). Alternately, they vent helium as they get near the desired altitude. Zero pressure is trickier here because it has to vent helium from the top. Latex balloons can vent from the balloon mouth though it is slow.
I'll note here that there's good reason to have a fast rise at the start. You need to punch through a cold layer at about 30-70k feet. Latex can freeze and shatter in this zone (though I think it depends on whether the balloon changes shape in this zone) so when you're rising with latex you want to spend as little time in this zone as possible. Similarly, 0-40k? is air traffic zone. Again as little time as you can in this zone. In other words, you want to pop up to 70k feet or higher as soon as you reasonably can. The people I worked with aimed for about 1000 feet per minute rise (that worked most of the time though we did get the occasional shatter at higher altitudes - possibly a balloon quality issue). They didn't worry about the balloon staying up, missions rarely were longer than two hours.
Also, this is why I don't worry in this scenario about latex balloons sticking around once they're cut loose. They weren't rising slowly with the mass of a payload connected to them, and when that's cut loose, they rise quickly to a pop altitude and cease to be a problem. If you go with a venting system, you might be able to put the balloon in a mode where it's barely buoyant and result in an indefinite balloon flight.
A plan C that might work better with limited resources is to use two equal sized balloons so that you have the fast rise time at the beginning (the time we did this, the balloons rose separately from each other so there was no damaging bumping). Then release one balloon (which will quickly pop) so that you're floating or a touch heavy with the second. My feel is that you'll probably rise faster in the beginning than the above 1000 feet per minute target due to all that balloon, but not much faster. That quickly gets you to the desired altitude while spending as little time as you can in the problem zones. If your remaining balloon doesn't pop at the stop altitude (for example, because it continues to rise), then you'll probably be good for a while until you run out of ballast.
I haven't found the launch in question I refer to above, but here's a similar one [jpaerospace.com] (Tandem High Altitude Airship) that launched in 2011. I assisted with balloon fill on this launch which required two teams working in tandem and used a similar layout.
As to the cutting mechanism, we used both pyrotechnics and nichrome. The latter was wrapped around the cord tightly about a dozen times and very reliable (for example, used in the 2011 Tandem launch above to cut both balloons). We stopped using pyros a few years after I started volunteering.
(Score: 2) by ElizabethGreene on Monday February 06 2023, @08:56PM (3 children)
The tandem airship looks super cool. I wonder how fast they have to spin the props to get a bite of anything up that high.
Your suggestion of pyrotechnics got me thinking and I may have a solution. With a small redesign I should be able to incorporate a mechanical pyrotechnic self-destruct in the overpressure vent when the payload cuts away. I'd previously only considered electrical solutions. Gracias.
Do you know of any 101 primer on balloon launch safety? I made assumptions and don't know what I don't know in this space. The obvious concerns I see are entanglement, losing the envelope on ground contact, premature release before complete filling, and the normal hazards of transporting and using compressed gas cylinders. Are there other big gotchas? For scale, my payload fits within the FAA regulation for a weather balloon (12 pounds max, 6 pounds per package, 3oz/in^2 surface loading). It's a lot smaller than the tandems.
(Score: 1) by khallow on Tuesday February 07 2023, @03:02AM
That's pretty comprehensive though I saw a few missing spots. For the edification of people reading this thread, I'll explain why these things are problems.
The gas cylinders are the most dangerous thing on the field. They're heavy (~80 pounds or 35 kg) and can cause physical injury from rolling/falling or poor lifting technique. Unlike almost everything else, they can cause problems during transport too, including rolling around during transport - imagine a few cylinders rolling through the side of your vehicle onto the road or you losing control of the vehicle due to all this sliding weight in the rear. Knocking the end off one turns it into an impromptu, lethal rocket capable of easily punching through vehicles and buildings and traveling hundreds of yards/meters. The extremely high pressure can damage equipment hooked up to it (pressure regulators required) and cause frostbite (I always wore insulated gloves while handling gas cylinders and the hoses during fill and sometimes we would freeze metering equipment if we ran the gas too fast).
If you ever inflate a balloon in an enclosed area, you need both ventilation and an observer with better air supply to make sure the balloon filler doesn't lose consciousness. Helium has killed people before. It's generally safer to handle than say, pure nitrogen or carbon dioxide, because it rises so aggressively - just stay low to the ground. This is why it took three people to fill a balloon with our setup. One person outside managed the tanks and the gas meter (we had a natural gas meter that didn't have actual numbers, we used a click counter every time the meter's needle did a full revolution). The second person was the balloon whisperer who filled the balloon and also positioned the balloon inside a tent we had set up. And the third person held open the tent opening for ventilation and observed the balloon whisperer.
Nothing else will cause this variety of hazards during so many stages of the mission.
Your isopropyl alcohol storage would be a safety risk specific to your project, especially since it's intended to be released under certain circumstances, and could create fire, explosive, and ventilation hazards if it leaks while in an enclosed space (though it's relatively safe as far as such substances go and easy to control).
So is pyrotechnics. It's a significant fire hazard. We would store such in its own, clearly marked tool box.
The "losing the envelope on ground contact" is actually part of a huge problem. No matter what bag choice you use for the balloon, it is flimsy and you can puncture/cut the bag/envelope on contact with anything that is hard, pointed, or even sticky. In my group, we called these things "sharps". In a strict safety sense, sharps are any object that can cause cuts or punctures on the human body like blades, needles, glass shards, even the edge of paper under certain circumstances. But as you can imagine, a balloon is vastly easier to cut and puncture than the human body.
So the variety of things that can be considered sharps are much, much broader. For example, when we filled up a balloon, we would stick it in the above-mentioned specialized tent which happened to have a top strip held on with velcro. There were so many sharps in this environment: the velcro has to be covered up especially the edge of the velcro and the stiffer side of the velcro. Also for weighing down the edges of the tent, we used zip lock bags filled with beans - seriously, because there were no sharp edges or dense objects in beans. Merely handling the balloon surface with work gloves counts. When they wanted to move the balloon around in the bag, they would move a blanket positioned under and touching the balloon rather than touch the bag directly. The sticky side of tape is a sharp as are the untrimmed ends of cut zip-ties. Zippers on a jacket are sharps. Eyeglass frames are sharps. Long nails are sharps. And of course, the ground is an entire surface of sharps.
If you're holding a large, inflated balloon in wind, it will go all over the place and is very difficult to control. It needs to be held clear of everything while being inflated. This is first half of the reason high wind is a no go for balloon use. The above tent system allowed us to launch in higher wind, but we still had significant problems.
One of the procedures you would see during the above launches is that there is a team assigned to hold the payload under the balloon after balloon release. This can involve running, if there's the above stiff wind. They only let go when the balloon has gained enough altitude that it's lifting the payload out of their hands (they supported not held the payload). A large part of that was so that the balloon doesn't get pulled down by the payload and hit the ground (another is the payload doesn't drag on the ground). This movement creates a new safety issue since one has to clear the launch area of tripping hazards and refuse to launch in high winds.
Premature release is a big issue aside from losing a pricey balloon and whatever is attached to it. FCC requirements are that balloons don't launch unless you confirm high sky visibility and no air traffic in the way. Accidentally letting go of a balloon means you don't have this. And if it's slightly buoyant rather than the 1000 ft/minute rise (5 m/s) above, then you might have it drag whatever it's carrying through air traffic lanes and power lines.
Entanglement can happen under a variety of situations. At launch, your launch crew can get entangled in cables and rope hanging off the balloon or payload. If the balloon pops prematurely, it can easily entangle your parachute or other devices for descent control. So can cables that connect the balloon to the payload. The usual approach is to make the payload fluffy enough that even if it's wrapped up in a popped balloon, it'll come down softly enough.
Objects falling off the payload is another problem. Our safety procedures included examining the entire payload for loose items like loose screws, forgotten tools, or improperly fastened components. That way we don't have objects falling off the vehicle in flight. A metal wrench falling 10 km straight down could really hurt.
And as I mentioned, when the payload falls, you need to design for it to be falling without parachute properly deployed. That's where the "3oz/in^2 surface loading" you mentioned above comes into play. Even if everything fails, it'll be fluffy enough to fall slowly.
You have the usual environment safety risks: sunburn, heat and cold exposure injuries, insect bites, lightning, dangerous weather, etc.
If you're doing last minute electronics, then you have the various risks from that such as power cables in the outdoors/puddles or soldering iron safety.
If you're recovering the gear, which you might often want to do, there's a variety of safety issues. Bad roads are your greatest enemy. JP Aerospace routinely had customers who thought they could rent some SUVs from Reno and drive them crazily on Nevada backroads. One particularly bad year saw 15 lost tires and two rear axles. Another time, I broke my arm in two places when I was driving too fast on a dirt road (driving an unfamiliar rear wheel pick up truck while following someone in a four wheel drive SUV). Communicate with private property owners before you enter their property so you don't get shot and/or arrested. And bring food, water, and warm clothing as well as basic hiking gear, detailed maps of a couple hundred miles around your expected landing spot, GPS, etc.
(Score: 1) by khallow on Wednesday February 08 2023, @07:09PM (1 child)
Welp, JP doesn't know of one either though he says he has some video on YouTube for how to do balloon rigging and how to do a balloon check list which might help put together a safety checklist. I'll see if I can find these videos.
(Score: 2) by ElizabethGreene on Thursday February 09 2023, @12:46AM
Don't burn a lot of time on it. I very much appreciate the help you've already shared. Thank you for that.