Airships have spent the better part of a century as a punchline. We picture the Hindenburg, or a Goodyear blimp wallowing over a stadium at halftime, and quietly file the whole lighter-than-air idea under “nice try, wrong decade.” So it would be easy to scroll past the news that a company in New Mexico just kept one in the sky for 12 straight days. You probably shouldn’t.<\/p>\n
Between March 25 and April 6, a solar-powered airship called SE2, built by a startup named Sceye (it rhymes with “sky”), flew about 6,400 miles from New Mexico to the coast of Brazil and spent the entire trip cruising above 52,000 feet, close to 10 miles up and well past where airliners fly and where weather happens. Sceye isn’t selling it as a stunt. It’s selling it as a cheaper stand-in for a satellite, the kind you can steer, land in the ocean on purpose, and fly again.<\/p>\n
The technical label for what Sceye flew is a high-altitude platform system, or HAPS, and the shorthand the industry likes is “pseudo-satellite.” The idea is to park an aircraft in the stratosphere, well above the jet stream and every airliner, where it’s close enough to the ground to do a satellite’s job without ever going to orbit. From up there a HAPS can relay phone signals or stare down at the planet with sensors, the same work a satellite does, except it sits a few dozen kilometers up instead of hundreds or thousands, costs a fraction as much to put up, and comes home when you want it back. For the cell-tower role, Sceye’s craft is built to work at around 20 kilometers up, roughly 65,000 feet.<\/p>\n
The “solar airship” framing also hides a useful distinction. Helium does the lifting here, the same inert gas in a party balloon, just a great deal more of it inside a hull that runs about 270 feet long, which makes it longer than a Boeing 747. The sun does the powering. Those are two separate jobs, and Sceye’s craft splits them cleanly: buoyancy from gas, electricity from light.<\/p>\n
A craft that’s supposed to stay up for weeks has one obvious problem: the sun sets. Sceye’s answer is a skin of solar cells across the top of the hull that powers the airship and its electric, tail-mounted propeller by day, then charges a battery pack that takes over at night. Get that handoff right, every day and every night, and the aircraft never has to come down to refuel. Sceye calls this “closing the power loop,” and says its 2024 program was the first time an airship pulled it off in the stratosphere while also holding position over a fixed spot.<\/p>\n
The batteries are the interesting part. Sceye uses lithium-sulfur cells rated at 425 watt-hours per kilogram, a figure reported by Interesting Engineering<\/a> and worth pausing on. It’s the same number electric-aviation and EV engineers chase constantly, because every watt-hour you can pack into a kilogram is range you aren’t hauling around as dead weight. Most of the lithium-ion cells in today’s EVs sit somewhere near 250 to 300 Wh\/kg. Lithium-sulfur promises more and has spent years being maddeningly hard to make last; Sceye says it now has a version flying. The company also claims its hull skin is five times stronger than the materials normally used for airships, and its solar cells 53% lighter than conventional ones, per trade outlet The Chemical Engineer<\/a>.<\/p>\n That sunlight-plus-battery approach is also how you dodge the wall that has boxed in small electric flight for a decade. Battery-powered drones tend to drop out of the sky after about half an hour<\/a>, and no amount of clever software has moved that ceiling much. Sceye’s bet is that charging through every daylight cycle turns “half an hour” into “until something actually breaks.”<\/p>\n Here’s the honest caveat. Twelve days is a milestone for Sceye and its longest flight yet, but it is not the longest anyone has kept a solar aircraft in the stratosphere. That title belongs to Airbus-backed Aalto and its fixed-wing Zephyr, which has logged a 67-day flight, according to SpaceNews<\/a>. So why does Sceye’s shorter run matter more than that gap makes it look?<\/p>\n Payload. Zephyr and the solar planes like it are gossamer fixed-wing aircraft that carry very little. Sceye’s airship is a lighter-than-air vehicle built to haul a real load, the kind of weight a working cell tower or a serious sensor package actually adds up to. Getting an airship to behave in the stratosphere is the harder trick, because it’s big and buoyant and the stratosphere still has fierce winds even above the weather, as IEEE Spectrum<\/a> has noted.<\/p>\n On this flight, according to Sceye’s announcement of the flight<\/a>, SE2 held station for more than 88 hours across selected spots, at one point staying inside a radius as tight as 1 kilometer, and ran clean through repeated day-night cycles. It also closed what the company calls its “pressure loop” and flew its first fully in-house-built hull. Mikkel Vestergaard Frandsen, Sceye’s founder and CEO, called it the “defining step toward unlocking the stratosphere as a new layer of infrastructure,” which is exactly the sort of thing a founder says after a big test. The difference here is the flight data sitting under the slogan.<\/p>\n The pitch for all this lands in three buckets. The first is connectivity: a HAPS carries the same kind of base station that sits on a ground tower, so it can beam phone and broadband coverage down over places ground towers and fiber never reach, from open ocean to mountains to remote islands. Sceye recently showed off an antenna it calls SceyeCELL, basically a cell tower designed to work from the edge of space.<\/p>\n The second is disaster response, and it’s the one Sceye leans on hardest. When an earthquake or a wildfire takes out the towers on the ground, a craft already loitering overhead can keep emergency communications alive while crews rebuild. It runs on the same logic now pulling clean-powered aircraft into defense and emergency work, where militaries are buying hydrogen drones that can watch a coastline for most of a day<\/a>: put a long-endurance eye or radio where you need it, and leave it there.<\/p>\n The third is watching the planet. Sceye says it pulled off the world’s first real-time methane detection from the stratosphere, in a project with the U.S. EPA and the state of New Mexico, spotting not just that gas was leaking but which site was leaking how much, as it happened. For a greenhouse gas as potent and as invisible as methane, that’s the kind of data that’s genuinely hard to get any other way.<\/p>\n The next test is already booked, and it comes with a real customer. Japanese telecom giant SoftBank signed an exclusive deal with Sceye in June 2025 for the rights to run stratospheric airship services over Japan, took an equity stake as part of Sceye’s Series C round, and effectively bought a pre-commercial flight. Sceye says that flight is set to launch this summer, lifting off from New Mexico with the goal of plugging into SoftBank’s core network as a high-altitude relay and running disaster-response demos.<\/p>\n SoftBank, whose president Junichi Miyakawa has been pushing HAPS since 2017, is eyeing a single aircraft staying aloft for a full year at a time.<\/p>\n The money behind it isn’t small. Sceye raised around $580 million in 2025, per The Chemical Engineer, and has separately taken NASA funding for climate work. It also isn’t alone up there. Aalto plans its own Japan demonstration in 2026 with SoftBank’s rival NTT Docomo, and the wider race to make clean-powered flight pay is getting crowded with companies and governments, from solar-and-battery mega-projects to rival hydrogen aircraft programs<\/a>. The stratosphere, long an empty band between the airliners and orbit, is starting to look like contested real estate.<\/p>\n So the thing Sceye actually proved is the small, stubborn one: can a solar airship climb to the edge of space, hold its spot, and survive the night over and over without coming down? For 12 days, yes. The bigger question, the one a telecom operator or a disaster agency will pay for, is whether 12 days becomes 12 months, and whether the math still works once you’re paying for helium, hull and a ground crew instead of a rocket. Sceye says it now has the data to chase months, then years. Until one of these things stays up long enough to send an invoice, that’s a promise rather than a product. It’s a far more credible promise than it was a couple of months ago, which for a technology most people had written off next to the Hindenburg is no small thing.<\/p>\n","protected":false},"excerpt":{"rendered":" Airships have spent the better part of a century as a punchline. We picture the Hindenburg, or a Goodyear blimp … <\/p>\nTwelve days isn’t the endurance record, and that’s not the point<\/h2>\n
What you’d actually point a floating cell tower at<\/h2>\n
SoftBank wants one floating over Japan this summer<\/h2>\n
The hard question Sceye still has to answer<\/h2>\n