Today, an estimated 2.2 billion people still have either limited or no access to the internet, largely because they live in remote places. But that number could drop this year, thanks to tests of stratospheric airships, uncrewed aircraft, and other high-altitude platforms for internet delivery. 

Even with nearly 10,000 active Starlink satellites in orbit and the OneWeb constellation of 650 satellites, solid internet coverage is not a given across vast swathes of the planet. 

One of the most prominent efforts to plug the connectivity gap was Google X’s Loon project. Launched in 2011, it aimed to deliver access using high-altitude balloons stationed above predetermined spots on Earth. But the project faced literal headwinds—the Loons kept drifting away and new ones had to be released constantly, making the venture economically unfeasible. 

Although Google shuttered the high-profile Loon in 2021, work on other kinds of high-altitude platform stations (HAPS) has continued behind the scenes. Now, several companies claim they have solved Loon’s problems with different designs—in particular, steerable airships and fixed-wing UAVs (unmanned aerial vehicles)—and are getting ready to prove the tech’s internet beaming potential starting this year, in tests above Japan and Indonesia.

Regulators, too, seem to be thinking seriously about HAPS. In mid-December, for example, the US Federal Aviation Administration released a 50-page document outlining how large numbers of HAPS could be integrated into American airspace. According to the US Census Bureau’s 2024 American Community Survey (ACS) data, some 8 million US households (4.5% of the population) still live completely offline, and HAPS proponents think the technology might get them connected more cheaply than alternatives.

Despite the optimism of the companies involved, though, some analysts remain cautious.

“The HAPS market has been really slow and challenging to develop,” says Dallas Kasaboski, a space industry analyst at the consultancy Analysis Mason. After all, Kasaboski says, the approach has struggled before: “A few companies were very interested in it, very ambitious about it, and then it just didn’t happen.”

Beaming down connections

Hovering in the thin air at altitudes above 12 miles, HAPS have a unique vantage point to beam down low-latency, high-speed connectivity directly to smartphone users in places too remote and too sparsely populated to justify the cost of laying fiber-optic cables or building ground-based cellular base stations.

“Mobile network operators have some commitment to provide coverage, but they frequently prefer to pay a fine than cover these remote areas,” says Pierre-Antoine Aubourg, chief technology officer of Aalto HAPS, a spinoff from the European aerospace manufacturer Airbus. “With HAPS, we make this remote connectivity case profitable.” 

Aalto HAPS has built a solar-powered UAV with a 25-meter wingspan that has conducted many long-duration test flights in recent years. In April 2025 the craft, called Zephyr, broke a HAPS record by staying afloat for 67 consecutive days. The first months of 2026 will be busy for the company, according to Aubourg; Zephyr will do a test run over southern Japan to trial connectivity delivery to residents of some of the country’s smallest and most poorly connected inhabited islands.

Because of its unique geography, Japan is a perfect test bed for HAPS. Many of the country’s roughly 430 inhabited islands are remote, mountainous, and sparsely populated, making them too costly to connect with terrestrial cell towers. Aalto HAPS is partnering with Japan’s largest mobile network operators, NTT DOCOMO and the telecom satellite operator Space Compass, which want to use Zephyr as part of next-generation telecommunication infrastructure.

“Non-terrestrial networks have the potential to transform Japan’s communications ecosystem, addressing access to connectivity in hard-to-reach areas while supporting our country’s response to emergencies,” Shigehiro Hori, co-CEO of Space Compass, said in a statement. 

Zephyr, Aubourg explains, will function like another cell tower in the NTT DOCOMO network, only it will be located well above the planet instead of on its surface. It will beam high-speed 5G connectivity to smartphone users without the need for the specialized terminals that are usually required to receive satellite internet. “For the user on the ground, there is no difference when they switch from the terrestrial network to the HAPS network,” Aubourg says. “It’s exactly the same frequency and the same network.”

New Mexico–based Sceye, which has developed a solar-powered helium-filled airship, is also eyeing Japan for pre-commercial trials of its stratospheric connectivity service this year. The firm, which extensively tested its slick 65-meter-long vehicle in 2025, is working with the Japanese telecommunications giant SoftBank. Just like NTT DOCOMO, Softbank is betting on HAPS to take its networks to another level. 

Mikkel Frandsen, Sceye’s founder and CEO, says that his firm succeeded where Loon failed by betting on the advantages offered by the more controllable airship shape, intelligent avionics, and innovative batteries that can power an electric fan to keep the aircraft in place.

“Google’s Loon was groundbreaking, but they used a balloon form factor, and despite advanced algorithms—and the ability to change altitude to find desired wind directions and wind speeds—Loon’s system relied on favorable winds to stay over a target area, resulting in unpredictable station-seeking performance,” Frandsen says. “This required a large amount of balloons in the air to have relative certainty that one would stay over the area of operation, which was financially unviable.”

He adds that Sceye’s airship can “point into the wind” and more effectively maintain its position. 

“We have significant surface area, providing enough physical space to lift 250-plus kilograms and host solar panels and batteries,” he says, “allowing Sceye to maintain power through day-night cycles, and therefore staying over an area of operation while maintaining altitude.” 

The persistent digital divide

Satellite internet currently comes at a price tag that can be too high for people in developing countries, says Kasaboski. For example, Starlink subscriptions start at $10 per month in Africa, but millions of people in these regions are surviving on a mere $2 a day.

Frandsen and Aubourg both claim that HAPS can connect the world’s unconnected more cheaply. Because satellites in low Earth orbit circle the planet at very high speeds, they quickly disappear from a ground terminal’s view, meaning large quantities of those satellites are needed to provide continuous coverage. HAPS can hover, affording a constant view of a region, and more HAPS can be launched to meet higher demand.

“If you want to deliver connectivity with a low-Earth-orbit constellation into one place, you still need a complete constellation,” says Aubourg. “We can deliver connectivity with one aircraft to one location. And then we can tailor much more the size of the fleet according to the market coverage that we need.”

Starlink gets a lot of attention, but satellite internet has some major drawbacks, says Frandsen. A big one is that its bandwidth gets diluted once the number of users in an area grows. 

In a recent interview, Starlink cofounder Elon Musk compared the Starlink beams to a flashlight. Given the distance at which those satellites orbit the planet, the cone is wide, covering a large area. That’s okay when users are few and far between, but it can become a problem with higher densities of users.

For example, Ukrainian defense technologists have said that Starlink bandwidth can drop on the front line to a mere 10 megabits per second, compared with the peak offering of 220 Mbps when drones and ground robots are in heavy use. Users in Indonesia, which like Japan is an island nation, also began reporting problems with Starlink shortly after the service was introduced in the country in 2024. Again, bandwidth declined as the number of subscribers grew.

In fact, Frandsen says, Starlink’s performance is less than optimal once the number of users exceeds one person per square kilometer. And that can happen almost anywhere—even relatively isolated island communities can have hundreds or thousands of residents in a small area. “There is a relationship between the altitude and the population you can serve,” Frandsen says. “You can’t bring space closer to the surface of the planet. So the telco companies want to use the stratosphere so that they can get out to more rural populations than they could otherwise serve.” Starlink did not respond to our queries about these challenges. 

Cheaper and faster

Sceye and Aalto HAPS see their stratospheric vehicles as part of integrated telecom networks that include both terrestrial cell towers and satellites. But they’re far from the only game in town. 

World Mobile, a telecommunications company headquartered in London, thinks its hydrogen-powered high-altitude UAV can compete directly with satellite mega-constellations. The company acquired the HAPS developer Stratospheric Platforms last year. This year, it plans to flight-test an innovative phased array antenna, which it claims will be able to deliver bandwidth of 200 megabits per second (enough to enable ultra-HD video streaming to 500,000 users at the same time over an area of 15,000 square kilometers—equivalent to the coverage of more than 500 terrestrial cell towers, the company says). 

Last year, World Mobile also signed a partnership with the Indonesian telecom operator Protelindo to build a prototype Stratomast aircraft, with tests scheduled to begin in late 2027.

Richard Deakin, CEO of World Mobile’s HAPS division World Mobile Stratospheric, says that just nine Stratomasts could supply Scotland’s 5.5 million residents with high-speed internet connectivity at a cost of £40 million ($54 million) per year. That’s equivalent to about 60 pence (80 cents) per person per month, he says. Starlink subscriptions in the UK, of which Scotland is a part, come at £75 ($100) per month.

A troubled past 

Companies working on HAPS also extol the convenience of prompt deployments in areas struck by war or natural disasters like Hurricane Maria in Puerto Rico, after which Loon played an important role. And they say that HAPS could make it possible for smaller nations to obtain complete control over their celestial internet-beaming infrastructure rather than relying on mega-constellations controlled by larger nations, a major boon at a time of rising geopolitical tensions and crumbling political alliances. 

Analysts, however, remain cautious, projecting a HAPS market totaling a modest $1.9 billion by 2033. The satellite internet industry, on the other hand, is expected to be worth $33.44 billion by 2030, according to some estimates. 

The use of HAPS for internet delivery to remote locations has been explored since the 1990s, about as long as the concept of low-Earth-orbit mega-constellations. The seemingly more cost-effective stratospheric technology, however, lost to the space fleets thanks to the falling cost of space launches and ambitious investment by Musk’s SpaceX. 

Google wasn’t the only tech giant to explore the HAPS idea. Facebook also had a project, called Aquila, that was discontinued after it too faced technical difficulties. Although the current cohort of HAPS makers claim they have solved the challenges that killed their predecessors, Kasaboski warns that they’re playing a different game: catching up with now-established internet-beaming mega constellations. By the end of this year, it’ll be much clearer whether they stand a good chance of doing so.

MIT Technology Review Explains: Let our writers untangle the complex, messy world of technology to help you understand what’s coming next. You can read more from the series here.

In mid-October, a mysterious object cracked the windshield of a packed Boeing 737 cruising at 36,000 feet above Utah, forcing the pilots into an emergency landing. The internet was suddenly buzzing with the prospect that the plane had been hit by a piece of space debris. We still don’t know exactly what hit the plane—likely a remnant of a weather balloon—but it turns out the speculation online wasn’t that far-fetched.

That’s because while the risk of flights being hit by space junk is still small, it is, in fact, growing. 

About three pieces of old space equipment—used rockets and defunct satellites—fall into Earth’s atmosphere every day, according to estimates by the European Space Agency. By the mid-2030s, there may be dozens. The increase is linked to the growth in the number of satellites in orbit. Currently, around 12,900 active satellites circle the planet. In a decade, there may be 100,000 of them, according to analyst estimates.

To minimize the risk of orbital collisions, operators guide old satellites to burn up in Earth’s atmosphere. But the physics of that reentry process are not well understood, and we don’t know how much material burns up and how much reaches the ground.

“The number of such landfall events is increasing,” says Richard Ocaya, a professor of physics at the University of Free State in South Africa and a coauthor of a recent paper on space debris risk. “We expect it may be increasing exponentially in the next few years.”

So far, space debris hasn’t injured anybody—in the air or on the ground. But multiple close calls have been reported in recent years. In March last year, an 0.7-kilogram chunk of metal pierced the roof of a house in Florida. The object was later confirmed to be a remnant of a battery pallet tossed out from the International Space Station. When the strike occurred, the homeowner’s 19-year-old son was resting in a next-door room.

And in February this year, a 1.5-meter-long fragment of SpaceX’s Falcon 9 rocket crashed down near a warehouse outside Poland’s fifth-largest city, Poznan. Another piece was found in a nearby forest. A month later, a 2.5-kilogram piece of a Starlink satellite dropped on a farm in the Canadian province of Saskatchewan. Other incidents have been reported in Australia and Africa. And many more may be going completely unnoticed. 

“If you were to find a bunch of burnt electronics in a forest somewhere, your first thought is not that it came from a spaceship,” says James Beck, the director of the UK-based space engineering research firm Belstead Research. He warns that we don’t fully understand the risk of space debris strikes and that it might be much higher than satellite operators want us to believe. 

For example, SpaceX, the owner of the currently largest mega-constellation, Starlink, claims that its satellites are “designed for demise” and completely burn up when they spiral from orbit and fall through the atmosphere.

But Beck, who has performed multiple wind tunnel tests using satellite mock-ups to mimic atmospheric forces, says the results of such experiments raise doubts. Some satellite components are made of durable materials such as titanium and special alloy composites that don’t melt even at the extremely high temperatures that arise during a hypersonic atmospheric descent. 

“We have done some work for some small-satellite manufacturers and basically, their major problem is that the tanks get down,” Beck says. “For larger satellites, around 800 kilos, we would expect maybe two or three objects to land.” 

It can be challenging to quantify how much of a danger space debris poses. The International Civil Aviation Organization (ICAO) told MIT Technology Review that “the rapid growth in satellite deployments presents a novel challenge” for aviation safety, one that “cannot be quantified with the same precision as more established hazards.” 

But the Federal Aviation Administration has calculated some preliminary numbers on the risk to flights: In a 2023 analysis, the agency estimated that by 2035, the risk that one plane per year will experience a disastrous space debris strike will be around 7 in 10,000. Such a collision would either destroy the aircraft immediately or lead to a rapid loss of air pressure, threatening the lives of all on board.

The casualty risk to humans on the ground will be much higher. Aaron Boley, an associate professor in astronomy and a space debris researcher at the University of British Columbia, Canada, says that if megaconstellation satellites “don’t demise entirely,” the risk of a single human death or injury caused by a space debris strike on the ground could reach around 10% per year by 2035. That would mean a better than even chance that someone on Earth would be hit by space junk about every decade. In its report, the FAA put the chances even higher with similar assumptions, estimating that “one person on the planet would be expected to be injured or killed every two years.”

Experts are starting to think about how they might incorporate space debris into their air safety processes. The German space situational awareness company Okapi Orbits, for example, in cooperation with the German Aerospace Center and the European Organization for the Safety of Air Navigation (Eurocontrol), is exploring ways to adapt air traffic control systems so that pilots and air traffic controllers can receive timely and accurate alerts about space debris threats.

But predicting the path of space debris is challenging too. In recent years, advances in AI have helped improve predictions of space objects’ trajectories in the vacuum of space, potentially reducing the risk of orbital collisions. But so far, these algorithms can’t properly account for the effects of the gradually thickening atmosphere that space junk encounters during reentry. Radar and telescope observations can help, but the exact location of the impact becomes clear with only very short notice.

“Even with high-fidelity models, there’s so many variables at play that having a very accurate reentry location is difficult,” says Njord Eggen, a data analyst at Okapi Orbits. Space debris goes around the planet every hour and a half when in low Earth orbit, he notes, “so even if you have uncertainties on the order of 10 minutes, that’s going to have drastic consequences when it comes to the location where it could impact.”

For aviation companies, the problem is not just a potential strike, as catastrophic as that would be. To avoid accidents, authorities are likely to temporarily close the airspace in at-risk regions, which creates delays and costs money. Boley and his colleagues published a paper earlier this year estimating that busy aerospace regions such as northern Europe or the northeastern United States already have about a 26% yearly chance of experiencing at least one disruption due to the reentry of a major space debris item. By the time all planned constellations are fully deployed, aerospace closures due to space debris hazards may become nearly as common as those due to bad weather.

Because current reentry predictions are unreliable, many of these closures may end up being unnecessary.

For example, when a 21-metric-ton Chinese Long March mega-rocket was falling to Earth in 2022, predictions suggested its debris could scatter across Spain and parts of France. In the end, the rocket crashed into the Pacific Ocean. But the 30-minute closure of south European airspace delayed and diverted hundreds of flights. 

In the meantime, international regulators are urging satellite operators and launch providers to deorbit large satellites and rocket bodies in a controlled way, when possible, by carefully guiding them into remote parts of the ocean using residual fuel. 

The European Space Agency estimates that only about half the rocket bodies reentering the atmosphere do so in a controlled way. 

Moreover, around 2,300 old and no-longer-controllable rocket bodies still linger in orbit, slowly spiraling toward Earth with no mechanisms for operators to safely guide them into the ocean.

“There’s enough material up there that even if we change our practices, we will still have all those rocket bodies eventually reenter,” Boley says. “Although the probability of space debris hitting an aircraft is small, the probability that the debris will spread and fall over busy airspace is not small. That’s actually quite likely.”