Onera

JUST below a half-opened garage door a tiny device can be seen at the feet of someone lurking in the shadows. It looks like a blue dragonfly. Then its miniature wings begin to flap as it slips under the door and darts along the street. After rising through the air it stops to hover outside the window of a building several storeys high. There is an opening on the roof, and it slips inside. As it flits from room to room its video-camera “eye” transmits pictures to a screen on a remote-control unit strapped to the wrist of its clandestine operator.

This is not a scene from a James Bond film, in which 007 tests a new device from “Q”, but an animated video produced by Onera, France's national aerospace centre, to explain REMANTA, a project to develop the technologies needed for miniature robotic aircraft. More bug-like flying devices are being developed in other research laboratories around the world. A few are already small enough to be carried in a briefcase; others are the size of a jet fighter and need a runway for take-off.

Having evolved from military use, drones, or unmanned aerial vehicles (UAVs), are taking to the air in increasing numbers for public-service and civilian roles. They are being operated by groups as diverse as police, surveyors and archaeologists. A UAV helped firemen track the blaze that recently ravaged southern California. The most immediate advantage of a UAV is cost: operating even a small helicopter can cost $1,000 an hour or more, but the bill for a drone is a fraction of that. However, the growing use of UAVs is causing a number of concerns.

The first is safety. Last month America's National Transportation Safety Board (NTSB) completed its first-ever investigation into an unmanned-aircraft accident. Pilot error was blamed for the crash in Arizona in April 2006 of a 4,500kg (10,000lb) Predator B, a type of UAV used by American forces in Iraq and Afghanistan. It was being operated by Customs and Border Protection when its engine was accidentally turned off by the team piloting it from a control room at an army base. No one was hurt, but the NTSB issued 22 recommendations to address what Mark Rosenker, its chairman, described as “a wide range of safety issues involving the civilian use of unmanned aircraft.”

The second concern is privacy. UAVs can peek much more easily and cheaply than satellites and fixed cameras can. Although it is possible to peer into someone's back garden with Google Earth, the images are not “live”—some are years old. Live satellite images can be impaired by clouds and darkness. A UAV, however, is more flexible. It can get closer to its target, move to new locations faster and hover almost silently above a property or outside a window. And the tiny ones that are coming will be able to fly inside buildings. Before long paparazzi will put cameras in them to snatch pictures of celebrities.

Unmanned aircraft have been around almost as long as powered flight. In the first world war they were used as flying bombs and by the second as radio-controlled targets and for reconnaissance missions. In Afghanistan and Iraq they have also been fitted with missiles.

In more recent years the development of unmanned aircraft has become a process of technological democratisation. Lightweight construction materials, engines, microelectronics, signal-processing equipment and navigation by global-positioning satellites (GPS), are all getting more sophisticated, smaller and cheaper. As a result, so have UAVs.

Flown from afar

A Predator, including ground equipment, costs around $8m. It is capable of operating in harsh conditions for more than a day. Even though a Predator may be flying over a remote part of Iraq, it is more than likely being controlled by pilots working in shifts and sitting in front of a video screen thousands of miles away at an air force base in America. Smaller, lighter and simpler UAV reconnaissance systems are being developed for troops in the field. These can be hand-launched, which reduces the need for remote-control piloting skills. Landings can be as simple as cutting the engine once the UAV has returned from its pre-programmed mission, at which point it flutters down to earth on a parachute.

Some hovering types can land automatically. One such device is made by Microdrones, a German company. Their flying machine looks like a small flying saucer with four rotor blades on stubby arms. It is not much bigger than the laptop computer used to program its flight and monitor what it is looking at. It can stooge around for about 20 minutes carrying video and infra-red cameras. Some police forces have started to try it out. Earlier this year British bobbies used one to keep an eye on a music festival, busting people for drug offences and catching others breaking into cars.

The Los Angeles County Sheriff's Department, which operates more than a dozen helicopters, has experimented with a foldaway UAV. It has wings and an electric engine, and can be assembled in minutes for hand-launching. It has a flight time of around 70 minutes. At around $30,000 all in, it is a lot cheaper than another new helicopter at around $3m.

Scientists are using UAVs to help with experiments. The Scripps Institute of Oceanography in San Diego flew a fleet of them in stacked formation over the Maldives in the Indian Ocean last year. They were collecting air samples simultaneously from different altitudes for research into the effects of global warming.

In time, UAVs are likely to be employed for all sorts of jobs for which the use of an aircraft big enough to carry a pilot would be too dangerous, impractical or too expensive. Surveyors, for instance, could use a hovering UAV to inspect the walls of a tall building in a crowded city. A television station could use one to show traffic conditions. And as with all new technologies, unmanned vehicles will have uses that have not yet been imagined.

Already, the technology is so easily available that you can build a basic UAV for around $1,000 from model-aircraft parts, the innards of a GPS unit and a Lego Mindstorms robotics kit—just as Chris Anderson has done. Mr Anderson, the editor of WIRED magazine, has set up a website for other DIY-makers of low-cost UAVs.

Not surprisingly aviation officials are watching things closely. “We have just entered a new era, and we have got to be concerned about protecting persons and property,” says Nicholas Sabatini, who is in charge of aviation safety at America's Federal Aviation Administration (FAA).

As the difference between sophisticated model aircraft equipped with auto-pilot systems and cameras and commercial UAVs blurs, the FAA is reconsidering its guidelines for model-flyers. At the moment these basically amount to keeping unmanned planes in sight at all times and away from people, buildings and other aircraft. Britain's Civil Aviation Authority is working with various industry groups to see what new rules may be needed. As a spokesman points out, UAVs will range from large jet-powered machines capable of flying across the Atlantic to tiny devices, so regulations will vary too depending on their size, weight and speed. Below a certain size, unmanned aircraft could be impossible to regulate. Nor would regulation do much to remove a chilling worry: that a UAV could be used as a weapon, to carry explosives or a biological agent.

Blown away

The smallest UAVS are the most intriguing because they will be able to fly in places where it was never thought aircraft could venture. Just how small might these machines be? The REMANTA bug has a total wingspan of less than 15cm (six inches). It flies by flapping its wings a bit like an insect. This means it needs less power than helicopter-type rotors and should be better able to withstand being blown off-course by wind, says Agnès Luc-Bouhali, a member of the project team.

Such a device can fly and be controlled remotely, but it could not yet conduct a mission like that portrayed in Onera's video. “Today, that is a dream,” admits Ms Luc-Bouhali. But the team is working on it. Miniaturising power sources and sensors, and fitting REMANTA with systems to operate semi-autonomously in order to avoid obstacles such as walls are the main areas of future research and development.

Such concerns also occupy researchers at Harvard University. They are working on a fly-like robot which weighs only 60 milligrams (0.002 ounces) and has a wingspan of just three centimetres—about the size of a real fly and so most unlikely to be noticed. This means going beyond scaling down existing components, like electric motors, and trying entirely new manufacturing processes. The Harvard “fly-bot” has flown, but so far only on a tether from which it gets external power.

A different approach is being tried by a team at Britain's Portsmouth University working with a company called ANT Scientific. Next summer the group will enter a robotics competition to be held at a British army urban-warfare training centre. The Portsmouth team is working on a UAV small enough to fit on a hand. Charlie Barker-Wyatt, a member of the university group, says all he can reveal about the device is that it contains sensors, can remain airborne for about 15 minutes, has a range of 500 metres and flies like a “hovering and spinning frisbee”.

Such tiny devices are of less concern to safety officials than bigger UAVs that would cause damage if they hit an aeroplane or crashed to the ground. Until now UAVs have mostly been confined to conflict zones, no-go military areas or remote places. Some operate under the same guidelines as for model aircraft. But they are not welcome in “controlled” airspace, where manned aircraft fly under air-traffic control. The FAA's Mr Sabatini says his agency does not want to stifle their development, but insists it must at the same time maintain safety standards. This means larger UAVs could be considered “experimental” aircraft and allowed to operate in closely controlled circumstances. But until they have some ability reliably to detect and avoid other aircraft they will have to keep clear of controlled airspace.

Some bigger systems operate like manned aircraft even in remote areas. The “pilots” of the Predator that crashed in Arizona were in contact with air-traffic controllers. But NTSB officials were still concerned about UAVs being flown too much like a computer game rather than as they would be if their pilots were on board.

Strict operating conditions for bigger UAVs might suit aviation firms, which are used to regulation and face competition from unmanned aircraft. Evergreen, a big aerospace group based in Oregon, has set up a UAV operation within its helicopter division. It offers relatively large and sophisticated systems for use in long-range operations, like checking on oil rigs, search and rescue, and wildlife monitoring.

Medium-sized systems might also have to be regulated, especially if used commercially. In the case of the smallest UAVs, the genie is already out of the bottle. When such devices are so small they might not even be noticed it would prove extremely difficult to regulate their use.

Unmanned aircraft will become more common, but how they swarm will depend on how safely they are used and how people react to the invasion of privacy. Some UAV missions may not be very welcome at all. “It smacks of Big Brother if every time you look up there's a bug looking at you,” reckons the FAA's Mr Sabatini. Time to buy a good fly swat, perhaps.