Inspired by the incredible achievements of the Spirit of Knoxville flights in 2008, Atlantic Halo is a project to develop and launch a zero pressure balloon and payload from Canada which will 'ride' the jetstream across the Atlantic to Europe or North Africa.
The balloon - a lightweight transparent plastic envelope with an open end is filled with helium and launched at dawn. As the balloon rises the helium expands until some 'vents' out of the bottom of the balloon. Less helium means that there is less lift and so will slow the ascent of the balloon, this process repeats until an floating equilibrium is reached and the lift matches the weight of the balloon and payload. By carefully calculating the weight of the payload and the amount of helium we can get the balloon to float within the jetstream which will speed it towards Europe. However during the day the helium is also heated by the sun increasing its lift and causing further expansion, the balloon rises and more helium is vented. Unfortunately at night the balloon cools and with less helium due to the venting during the day has less lift, the equilibrium is upset and the balloon and payload descend. To reduce the descent at night the payload contains a ballast tank which will drop ballast, reducing the weight of the payload and therefore maintaining the floating equilibrium. By carefully releasing ballast liquid it should be possible to reduce the descent at night sufficiently so that the balloon is still in the air when the sun rises causing it to be heated again and rise. This technique should allow the payload to remain flying over a couple of days, the longer the payload and balloon survive the further it can travel.
The balloon and payload once launched will be controlled by the onboard flight computer and will relay its location coordinates by HF radio and also via a SPOT satellite transmitter. Receiving the radio transmissions will require a network of people with radio receivers and so if you would like to get involved and help out relaying the transmissions please sign up to the mailing list.