Alphabet’s Loon announced its high-altitude balloons, built to deliver internet connectivity, have clocked more than 1 million hours of flight in the Earth’s stratosphere.
In that time the balloons, which drift along wind currents between 50,000 and 70,000 feet, have traveled nearly 2.5 million miles, according to a blog post by Loon’s head of engineering Salvatore Candido.
This is the latest Loon milestone. In early July, the operations team said it had kept a balloon in the stratosphere for 223 days, breaking Loon’s previous flight record of 198 days.
Loon has a dedicated team of flight engineers, but a system built on automation software actually directs the vessels movements, making it possible to navigate the balloons around the world, or keep them above certain locations for extended periods, Candido explained. The software processes large amounts of real-time measurements from the fleet of balloons, and analyzes in-depth wind forecast data to help build maps.
“Over 1 million hours of flight, we’ve been surprised by some of the clever and complex navigational behaviors to emerge from this system,” wrote Candido. “These are not prescribed behaviors or ones directed by the engineers building it. Instead, they emerged as the system sought to maximize the navigational efficiency of the Loon fleet. “
For example, instead of taking a straight-line path from one place to another, the system sometimes had balloons fly in a zigzag pattern off of their directed course. In a surprise to the engineers, the system was executing a technique employed in sailing, by changing the balloons’ orientation in relation to the wind so it could still make progress on the route despite adverse wind conditions.
“We quickly realized we’d been outsmarted when the first balloon allowed to fully execute this technique set a flight time record from Puerto Rico to Peru,” Candido wrote.
When Loon’s balloons helped deliver emergency basic internet connectivity to Puerto Rico after Hurricane Maria in 2017, algorithms directed balloons to loiter in an area in anticipation of changing wind conditions, rather than take their usual loop after finishing a round of service. This resulted in a quicker return time to Puerto Rico. Candido said Loon has since “doubled-down” on this behavior via additional algorithms to bolster the consistency of Loon’s service.
When it comes to staying in one place, the automation software also unexpectedly executed a figure eight pattern, enabling balloons to remain in a desired location all day.
“Every previous LTE test was over in a few hours as the balloon drifted away,” wrote Candido. “But, this time our team testing the LTE connection below ran out of battery on their phones and laptops as the balloon stuck around overnight.”
Loon, a former project within Google, has been in development since 2013. In April, Softbank’s HAPSMobile announced it was investing $125 million in Loon’s business, as the two formed a long-term strategy partnership to advance high-altitude connectivity.