The Spirit of Knoxville:

autonomous trans-atlantic balloon project
Spirit of Knoxville IV Marks Proof that Crossing is Possible

The Spirit of Knoxville IV Flight was successful in crossing 90% the Atlantic Ocean and setting two world records. It took off from Knoxville, TN on March 10 2008 at 02:45 UTC, flew for 40 hours, and landed on March 11 2008 at 19:10 UTC. It was the first amateur zero-pressure balloon to stay in the air long enough to see two sunrises and sunsets. The flight demonstrated that it is possible to complete an amateur Trans-Atlantic crossing as it splashed down in the North Atlantic Ocean, just 300 miles from Ireland, at a great circle distance of 3360 miles from launch.

This effort was only possible due to the amazing commitment of the amateur scientists and radio operators involved. This challenge was undertaken to expand the boundaries of citizen science, and in that spirit, we release our research and would like to work with others in the effort to make it all the way across the ocean soon.