Project: Near-Space Balloon
NK Labs designed a custom payload and launched it on a weather balloon to capture this video.
Algorand came to NK Labs for assistance in creating a promotional video for the launch of their cryptocurrency. To invoke the borderless economy that Algorand envisions, they wanted NK to capture high-quality video of a high-altitude balloon flight displaying their logo.
High-altitude balloons are a group of passive flying devices which can reach near-space altitudes (approximately 11 - 23 miles above sea level). As they do not need a motor and are only powered by the potential energy stored in the balloon, they are extremely practical for many high-altitude applications. These balloons are typically used for conducting experiments and taking measurements for scientific purposes and are most commonly used as weather balloons. High-altitude balloons offer a lot of design flexibility since they can support a wide range of sensors and equipment.
Design and Construction
Every high-altitude balloon involves three core elements: the balloon, the parachute, and the payload. The regulation for the high-altitude balloons we worked with requires payloads to weigh less than four pounds. This gave us a strict maximum weight in which to fit all of the components listed above.
The design process began by identifying all of the critical components which needed to fit inside of the payload. This included:
Cameras to record video out the side and under the payload
Power bank to keep cameras charged
Flotation feature in case of a water landing
The electronic components had known weights, which, together, were well below the four-pound limit. Having established the internal components, the external structure of the housing could be designed. The payload housing was constructed of balsa wood and closed-cell foam to keep the payload light for flight as well as buoyant and well-cushioned for landing. To assist in recovery, the payload was also painted a high-visibility orange.
The GPS tracker needed to maintain an upward orientation so that it could transmit its position data. This created a challenge to control the orientation of the tracker in a small, light-weight, and strong package. We designed a custom gimbal system which we printed on our Form 2. We made the gimbal open-source, and the design files are available here.
A third camera was added to look out of the opposite side of the payload. At high altitude, if the camera had the Sun in view, that portion of video would not be usable, so having a secondary view removed that risk and added a backup in case there were any issues with the primary camera during the flight.
Internal view of the payload's structure and components: GPS on the custom gimbal on the left; 3 cameras on the right
After determining the expected weight of the payload, we moved forward with selecting the balloon and parachute. We calculated the necessary lift, ideal rate of ascent and descent, maximum altitude, and multiple other considerations to detail out this specific balloon's properties. We then selected an appropriate balloon and parachute to best match those estimations.
The launch site for a high-altitude balloon must be chosen with great care. Once a balloon is released, it is guided only by the wind, which is constantly changing. Without proper planning, payloads can easily end up in lakes, on top of buildings, or in other inaccessible/difficult areas. We used multiple balloon launch and trajectory simulators to estimate the flight path from a variety of locations. It is important to choose a launch site that is wide open and one which will likely allow the payload to land in a similar, minimally-inhabited, flat area. The northeastern United States is a challenging area for balloon launches because it is densely-populated, has tall trees, and many bodies of water. However, by choosing conservative locations, staying updated on weather patterns, and maintaining precise timing, balloon launches can be very successful.
On the day of launch, we set up our equipment in the middle of the field we had selected. We attached the payload to the parachute and the parachute to the balloon. Time was sensitive once the balloon was unpackaged, as the latex deteriorates in sunlight. The latex balloons are inherently delicate and can also be damaged by oils and sweat, so the team took care to wear gloves and avoid directly contacting the balloon. With some team members supporting the balloon off the ground, others filled it with helium. When the balloon was generating enough lift according to our force gauge, we tied it off using a specific technique outlined here. Then, the time came for the actual release of the balloon. The moment a balloon is launched is a uniquely exciting and significant moment because it is the point where all of the planning is realized; from this moment until the payload is recovered, it is traveling freely along the air currents.
GPS tracking of the balloon as it traveled east across Massachusetts
There was a high confidence that the payload would travel eastward from Great Barrington, MA, reach a maximum altitude near Springfield, MA, and land approximately 65 miles due east of the launch point. As the distance covered by the payload is so large, minute changes in wind patterns can have a substantial effect on the payload's trajectory, but the GPS tracker on the payload was routinely sending updates on its position throughout the flight. After about two hours, the payload's location settled on a constant position. The GPS tracker brought the recovery team to within 50 yards of the payload, which was found suspended in a tree.
The payload caught in the tree it landed in.
With the payload extracted from the tree, the team was able to review the hours of video that had been recorded. Even on the small camera screens, we could see we had captured the key visuals that were the goals of this project: watching the payload pull away from the ground, spanning landscape shots, and, best of all, the atmospheric shot to complete the launch video. We estimate that the balloon reached a maximum altitude of around 70,000 ft. We got back to the lab, reviewed the footage more thoroughly, transferred it to a USB flash drive, and delivered it to Algorand to assemble the final launch video shown at the top of the page.