When it comes to taking high-res aerial photographs, we generally look to satellites, drones or full-size aircraft. Colorado-based Urban Sky's new Microballoon system, however, is claimed to deliver higher-resolution images at a much lower cost.
Each Microballoon unit consists of a small reusable stratospheric balloon, underneath which is slung a payload module that includes a downward-facing high-res optical camera – other imaging sensors, such as infrared or hyperspectral cameras, can also be used.
While still on the ground, the 2.5-meter-diameter (8.2-ft) balloon is partially filled with helium gas, which expands in volume as the balloon rises from its mobile launching point. Once it reaches the desired altitude – typically somewhere over 60,000 ft (18,288 m) – the helium has expanded to the extent that it fills the now 5.5-m (18-ft) balloon. From that point onwards, any excess gas simply escapes out of strategically placed vents in the bottom of the balloon. In this fashion, the gas volume is maintained, so the balloon remains at the desired altitude.
The Microballoon's camera then sets about taking pictures, utilizing a custom-designed lens which is designed to withstand the harsh conditions in the stratosphere. As the balloon drifts horizontally through the air, the camera rotates to capture as large an area of the ground as possible – the speed at which it rotates is determined by the speed at which the balloon is moving.
The resulting images are digitally stitched together, resulting in one gap-free composite photo of the entire area in question. Urban Sky Co-founder/CEO Andrew Antonio tells us that utilizing this setup, it's possible to image approximately 1,000 square kilometers (386 sq mi) per hour.
Once the photo-snapping process is complete, a ground-based crew remotely activates the payload module to release itself from the bottom of the balloon. That said, one line still runs from the module, up one side of the Microballoon, to a cap located at the top of the balloon.
Therefore, as the module free-falls, it pulls the ballon around so that it goes upside-down, allowing all of the helium to escape out of what was previously its bottom. A parachute is deployed at a lower altitude, slowing the descent of the payload module and the attached balloon. Both are retrieved for reuse, once they've landed on the ground.
Antonio says that the Microballoon system is already being used by a handful of paying clients, and that it should enter regular use over Colorado and the Rocky Mountain region beginning next spring (Northern Hemisphere). Urban Sky also recently won a contract from the US Air Force to develop a version of the system for the real-time monitoring of forest fires, plus the company won a development grant from the National Science Foundation.
"They’re really interested in the flight modeling and balloon reusability aspect of our system," he tells us. "No one (governments included) has ever successfully flown a reusable stratospheric balloon envelope, and we’re now consistently reusing the same balloon envelopes, so that’s pretty awesome."
Source: Urban Sky
