Space Invaders: How Pseudo Satellites Will Soon Conquer the Stratosphere
WHY YOU SHOULD CARE
These almost-satellites might soon connect your phone when you need it most.
By Tom Cassauwers
The Zephyr looks like a detached airliner wing with propellers soldered on top. The unmanned Airbus-designed vehicle with a wingspan of 82 feet can fly for almost a month and is so light that two people can lift it. But that’s not the most unusual thing about it. The Zephyr is not actually an airplane.
It flies higher than any plane, deep in the stratosphere. Yet it stays below the Kármán line — a height of 62 miles — that marks the start of outer space, so it isn’t a satellite. The Zephyr is one of a growing number of high-altitude pseudo satellites (HAPS) that are being designed to watch over Earth like satellites, but with the flexibility of drones, using the unique advantages of a strip of the atmosphere below outer space.
It’s an idea that’s exciting researchers, space agencies, defense firms, technology giants and airplane manufacturers alike. The Royal Belgian Institute for Space Aeronomy is working on a proposal for the European Space Agency to build a HAPS. French firm Thales is designing what it’s calling the Stratobus — an unmanned, solar-powered stratospheric airship that it hopes to unveil by late 2020. The U.K.’s Ordnance Survey — the country’s mapping agency — is also designing a solar-powered HAPS that it plans to test at high altitudes later this year.
You can fly almost forever.
Jesús Gonzalo, University of León
Russian aerospace firms RosAeroSystems and Lavochkin are both designing pseudo satellites. China’s Aviation Industry Corp. tested a HAPS in the lower stratosphere last September. Alphabet, Google’s parent company, plans to deploy its Loon telecommunication balloons, which use technology similar to that of the HAPS, in Kenya by June, to see whether it can deliver the internet to remote parts of the world. And in the summer of 2018, the Zephyr flew continuously for 25 days — the longest HAPS flight to date.
“It’s a new domain and a new tool,” says Alain Dupiech, communications manager at Airbus, where he works on the Zephyr project.
Once the technology gets off the ground, pseudo satellites could fly for very long times. That’s because of the unique space in the stratosphere they plan to occupy. They’re high enough to serve many key functions of the 4,900 satellites orbiting the Earth. They tap solar energy — which airplanes don’t — and at the same time don’t need the massive boosters that satellites require to propel them beyond the stratosphere.
“If you minimize consumption of energy and use solar panels to harvest electricity from the sun while you are flying, it’s possible to have an energy balance,” says Jesús Gonzalo, a professor at Spain’s University of León who studies HAPS. “You can fly almost forever.”
The idea of HAPS has long been little more than a pipe dream. Flying at such high altitudes is hard on engineering. Temperatures can reach minus 184 degrees Fahrenheit in the stratosphere. And the higher it goes, the less lift a vehicle has, which comes with real dangers: In 2011, a stratospheric airship by Lockheed Martin crashed and burned during a test flight.
But what were earlier isolated — often literally pie-in-the-sky — projects are now being replaced by a crush of initiatives across Europe, the U.S., Russia and Asia, as companies look to grab a slice of a HAPS market that’s expected to touch $22 billion by 2022. This growth is in part because of advances in technology that allow both the pseudo satellites and their batteries to be built much lighter than was possible when Lockheed Martin first tested its HAPS. “We can do this today, and not 10 years ago,” says Gonzalo. “Materials like the batteries had to be light, and only now the ratio between power capacity and weight is enabling these types of systems.”
This isn’t just an engineering gimmick. HAPS could provide a new, missing layer for a range of applications currently not being adequately filled by satellites or airplanes, like monitoring forest fires, observing battlefields or providing connectivity to remote areas and disaster zones. A Zephyr-like craft might in the future give you a cell signal when you need it most.
One specific use could be the monitoring of air pollution, says Frederik Tack, an atmospheric scientist at the Royal Belgian Institute for Space Aeronomy. Using current tools, Tack can reconstruct pollution levels from satellite images. But satellites pass over an area only once a day, and the images are too coarse to make detailed maps. “A middle-size Belgian city might only be composed of one pixel,” he says. On the other hand, airplane flights over cities work well but are expensive and hard to arrange. And ground stations are expensive to build, so making a full map of a large area is difficult.
That’s where HAPS come in. “This is the missing layer,” says Tack. “HAPS can obtain a high resolution, and we can get it to fly for days or even months over one city and monitor gradients in pollution.”
This pseudo-satellite revolution will need to address a few obstacles first, though. First among them is regulation — or the absence of it, for the area above commercial airspace where HAPS would operate. Since countries exert sovereignty over the region as they do with commercial airspace, that could reduce the effectiveness of pseudo satellites in comparison with traditional satellites. “Regulations are the biggest barrier,” says Juan Lizarraga Cubillos, a communications systems engineer at the European Space Agency. “The technology might be ready very soon,” adds Gonzalo. “But regulations might delay rollout another few years.”
Within the HAPS industry, two major designs are competing — each with its advantages and limitations. There are pseudo satellites modeled on the airplane, like the Zephyr. These, says Tack, are “more flexible — you can simply steer them along a course.” But available designs usually can’t carry more than 45 to 66 pounds, which limits the instruments they can carry. Airships like Thales’ Stratobus can carry hundreds of pounds but have proved harder to design. “It’s also difficult to make them economical because you will need hangars to support airships that are 150 to 200 meters long,” says Tack.
But whichever design wins out, the HAPS appear set to fly high. Gonzalo is optimistic. “In the next few years, we will progressively be conquering the stratosphere,” he says.
- Tom Cassauwers, OZY Author Contact Tom Cassauwers