A new unmanned solar-powered aircraft is being developed by BAE Systems and could potentially revolutionise military surveillance.
'Phasa-35', which is known as a 'pseudo satellite', is designed to fly in a deserted part of the earth’s atmosphere – high above jets but far below satellites.
The aim is for it to gather data like other platforms, but the way it operates could be a gamechanger.
BAE Systems Aviation Adviser, Drew Steel, told Forces News: "It's a very lightweight, huge and very long-endurance, unmanned aircraft system. I say very lightweight, it weighs about 150 kilogrammes, which is probably about the same as you and I.
"It's called Phasa-35 – the 35 refers to its wingspan. It's 35 metres and that’s the same size as an airliner. It's huge but it only weighs 150 kilos.
"That means it's able to go up to heights way above normal air traffic, up in 60/65,000 feet where it can operate in constant sunlight, obviously during the day, and at night time, it operates off batteries that are charged during the day.
"The solar power enables it to have this persistence, where it can stay airborne for up to a year.
"It stays up for a long while and it can look a long way – those are two of the real key attributes for any sort of surveillance platform."
Following success in a maiden flight early last year, two of the aircraft have now been shipped to the United States to see if they can reach the stratosphere.
How is surveillance currently carried out?
Satellites are constantly watching but are expensive to put up and cannot be moved or brought down.
Manned aircraft can have hi-tech kit on board, but only offer surveillance for a few hours at a time, and need to take off from somewhere nearby, plus huge teams and levels of resources are needed.
And humans can man observation posts on the ground but of course, have a limited field of view and need breaks.
The intention is for Phasa-35 aircraft to complement, not replace, current systems and create a 'car park' of solar planes permanently in the sky and awaiting deployment.
Bethany Lowe, Chief Engineer of Phasa-35, said: "It also adds the opportunity to start to connect up to other air vehicles or other ground stations and start to transfer data in real-time in some instances, or also maybe set up a network across a large area which will enhance communications for military users."
Mr Steel suggested it could be operationally available within a year of completing flight trials which he said is, in aviation asset terms, "the blink of an eye".