Giant Solar-Powered UAVs Are Atmospheric Satellites

Why go to orbit when you can spend five years in the upper atmosphere with a solar-powered UAV instead?

2 min read

Evan Ackerman is IEEE Spectrum’s robotics editor.

Giant Solar-Powered UAVs Are Atmospheric Satellites

The largest robot in the AUVSI expo hall last week belonged to Titan Aerospace. It was a model of their Solara 50 robotic atmospheric satellite, and they had to chop off the tail and most of the wings to get it to fit. The Solara is intended to lift a payload to 20,000 meters and then keep it there for five years, running entirely on solar power. It functions a bit like a satellite, except substantially cheaper and much more versatile. And, you can get it back when you're done.

It's a little bit hard to tell from the video, but these UAVs are big. The Solara 50 is 15 meters long with a wingspan of 50 meters, and there's an even larger one called the Solara 60, with a 60-meter wingspan. Despite its size, the Solara 50 only weighs 160 kilograms, and it can carry a 30 kg payload, which is fairly respectable.

What makes the Solara actually functional as an atmospheric satellite are two things. The first is the altitude that it's designed to fly at: at 20,000 meters, you're above pretty much everything. You're looking down on clouds and weather, and the winds and temperatures are generally very stable, or at least predictable. Being that high also gives you a field of view encompassing about 45,000 square kilometers. If you were to, say, mount a cellular base station on a Solara, it would take over for a hundred cell towers on the ground.

The second thing that makes Solara work is that it's solar powered. Every available surface on the wings and tail are covered in solar panels, and there are batteries inside the wings. During the day, Solara generates kilowatts of power, and there's enough left over in the batteries to provide hundreds of watts all night. Because the UAV never requires refueling, it can stay aloft for five years, either circling over one spot on the ground, or (if you want it to travel) it's got an effective range of something like 4.5 million kilometers, cruising at just under 60 knots. And that five year life is just based on components, so Solara may very well be able to stay up for longer.

And that leads to the final thing we like about Solara: you can always bring it back down if something goes wrong. Even if nothing goes wrong, you get your payload back at the end of five years, which is usually impossible with satellites. Solara is also much much cheaper than a satellite, although the company isn't quite ready to say how much. 

Smaller versions of Solara have already flown, and Titan Aerospace is planning to start selling operational systems in less than a year. This opens up some intriguing possibilities, including things like regional Internet or even a version of something like Google Maps that features real-time imagery. This certainly doesn't mean that the era of the satellite is over, but it means that we'll have a lot more options available than we ever did before.

[ Titan Aerospace ]

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