It looks like a cross between a toy airplane and a drone, but this British solar-powered aircraft could be the future of aerial surveillance.
PHASA-35, built by British company BAE Systems, is a 150kg solar-electric aircraft that can quietly cruise through the stratosphere for months at a time.
Named after its 35-metre wingspan, the unmanned aerial vehicle (UAV) travels at a maximum height of 70,000 feet, at a leisurely speed of 55mph.
Designed as a cheaper and lighter alternative to satellites, it can be used for Earth observation and surveillance, border control, communications and disaster relief.
Now, BAE Systems reveals that PHASA-35 has just completed a second round of test flights into the stratosphere – the second layer of Earth’s atmosphere.
Launching from Spaceport America in New Mexico, it flew for 24 hours, climbing to more than 66,000 feet before completing a smooth landing.
PHASA-35 will be able to fly non-stop in the stratosphere for up to 20 months by 2026, offering a ‘persistent and affordable alternative’ to satellites.
It harnesses power from the sun to stay airborne, charging a bank of small batteries during the day to keep it flying overnight.
BAE Systems said PHASA-35 completed two stratospheric test flights from Spaceport America in October, the first since its maiden flight in June 2023.
Both times it made a successful landing back down at Spaceport America in a serviceable condition, meaning it was ready to fly again just two days later.
This is a key advantage over satellites – that it can be brought back down to Earth again and the payload switched or added to and sent back up again quickly.
‘These latest flight trials are a significant step forward in proving PHASA-35’s capability for operations and a real moment of pride for our entire team,’ said Bob Davidson, CEO of BAE Systems’ Prismatic subsidiary.
‘We’re committed to continuing to develop PHASA-35 at pace to make it available for operational activity as soon as 2026.’
What’s more, PHASA-35 has flown this time around with an operational payload for the first time – a software defined radio developed by BAE Systems.
‘This is basically a really powerful sensor that allows for Earth observation and can be modified remotely using software,’ a company spokesperson told MailOnline.
It weighed 10kg – a payload twice as heavy as its first stratospheric test flight in 2023 – but PHASA-35 can carry a payload up to 15kg if required.
These recent flights are part of a series of trials intended to confirm the performance of the aircraft before it can be bought by defence and commercial customers.
The firm wouldn’t comment on who exactly these are, but it’s in discussions with ‘a number of customers’ about further funding additional flight trials.
BAE Systems has invested tens of millions of pounds in PHASA-35, which builds speed on a runway just like conventional aircraft but detaches its wheels shortly after takeoff.
It glides to a soft landing on its belly and any damaged propellers or components are replaced.
Because it glides gently more akin to a paper plane, the risk of a hard landing causing any substantial damage is low.
Because it operates in the stratosphere, above any issues with weather like wind and rain, it can provide stable observations of a specific area for long periods.
According to Prismatic – the Hampshire-based BAE Systems subsidiary that has designed and manufactured the aircraft – PHASA-35 can deliver services at a ‘fraction of the cost of satellites’ and is capable of deployment anywhere.
Prismatic says: ‘Further key benefits include the simplicity of construction and ease of transportation, due to the relative low number of structures forming the overall assembly of the aircraft.’
PHASA-35’s maximum payload of 15kg could comprise cameras, sensors and communications equipment to allow troops to talk to each other or provide internet access to rural locations during a natural disaster or emergency.
Engineers see a number of core applications for the drone in areas usually covered by satellites in low Earth orbit, like environmental surveillance, disaster relief, border protection, maritime and military surveillance and mobile internet communications.
An example is the ability to include a sensor, fly over a vulnerable forest for months at a time and constantly monitor moisture levels in the trees – predicting with weeks notice when a fire is likely to break out.
It also has the potential to be used in the delivery of communications networks including 4G and 5G, such as for regions that currently have poor coverage.
Construction of the UAV began in 2018 along with the release of concept images, following the successful launch of a quarter-scale model called PHASE-8 back in 2017.
The full-sized version of PHASA-35 got its maiden flight in February 2020, when it flew from the Woomera Test Range in South Australia, followed by the first full-sized stratospheric test in June 2023.
