ON AUGUST 6th a flimsy-looking pilotless aircraft, the Zephyr S, came slowly in to land at an undisclosed location in Arizona, and was caught by a group of people jogging along beside it. The reception committee was needed because the craft, which weighs less than 75kg, lacks an undercarriage—or, indeed, anything else that would add unnecessary weight. The touchdown meant the Zephyr S had set a new flight-endurance record for a drone, of 25 days, 23 hours and 57 minutes. The point of doing so was to show that solar-powered aircraft of this sort can compete with satellites in the markets for Earth observation and telecommunications. This has led some people to dub them “pseudo-satellites”. The idea is that eventually they will stay aloft for months.

The previous endurance record for drones, of just over 14 days, was set in 2010 by the Zephyr 7, an earlier version of this aircraft. The Zephyr 7 was developed by QinetiQ, a British defence company. In 2013 QinetiQ sold the Zephyr programme to Airbus, a European aerospace firm. Airbus has now built, at Farnborough, in Britain, a factory to make them. The model S, with a wingspan of 25 metres, will soon be joined by a bigger, more advanced version, the model T.

Zephyrs fly in the stratosphere. During daylight hours they cruise at an altitude of about 21km. At night, when solar energy is unavailable and they must rely solely on their batteries, they make a slow but powered and controlled descent to 16.7km. That, though, is still well above troublesome weather, and also clear of commercial aircraft.

They are powered by a pair of propellers driven by electric motors. Airbus says the craft are fitted with batteries which use an “advanced chemistry” and are recharged by “novel” solar cells that cover their wings. But it will provide no other details for fear of tipping off rivals, of whom there are several. (Though one potential competitor, Facebook, closed its own high-altitude-solar-powered-drone operation earlier this year with a view to using drones built by others to provide internet access in remote regions.) At the opening of the Farnborough factory, in July, the wings of the three Zephyrs then on the production line were carefully covered, in order to avoid prying eyes.

Rather than selling the craft outright, Airbus plans to use them to conduct particular jobs for particular customers, says Nigel Chandler, head of sales for the operation. A craft thus leased out might engage in Earth-observation tasks such as maritime surveillance or detecting forest fires—or it might, by travelling in small circles, act as an internet node or as a platform for mobile telephony. Moreover it could, if required, be moved around in mid mission, for example to act as an observation platform for a disaster area. That would both be much simpler than repositioning a satellite and cheaper to operate.

Airbus will run its Zephyr service from a base at Wyndham, Western Australia, that will open later this year. This is surrounded by a large area of unrestricted airspace and has reliable weather for landings and take-offs (like landings, these also involve people giving the craft a helping hand). Depending on conditions, a Zephyr on the move can travel between 1,000km and 2,000km a day, so in principle only this one base is needed to serve the world. Airbus will, though, offer a portable ground-station and launching services in other parts of the world, for those customers who do not wish to wait for a craft to arrive under its own (or, rather, the sun’s) power from Australia.