'Eternal planes' to watch over us ?
Unmanned Aerial Vehicles (UAVs) patrol innocuous-looking skies and silently report back streams of strategically important data, video, and images from locations around the world.
They are the ultimate Earth watchers.
It is believed that up to 800 remotely piloted aircraft are in operation in Iraq and Afghanistan.
But observing Earth from afar is not just about battlefields and spy missions, the type usually done by expensive and heavy craft like the US's Predator drone. UAVs are increasingly being recruited to carry out more humanitarian missions, from the stratosphere."