This years was repeated experiment with sending balloon with some device to the stratosphere. As last year, balloon carries module called Dropion, which contains camera and some caches, which will be released at altitudes near 30 km. When they land back to the ground, people will search them and get some prize when they're successful.
As like last time there were some technical difficulties. Camera transmitter had interference with GPS modules in caches, so finally flight was launched without live stream from the Dropion. Recording of the flight will therefore be released later. However last year's problems were solved - frost this time didn't damaged any cache despite temperature of -60 centigrade!
Some data: balloon was released on 11:43 and 11:56 reached altitude of 5 km. Five minutes later it reached 8 km and 12:15 it was 12 km above sea level. Temperature outside was -60 centigrades, inside of technical equipment -13 centigrades.
Ascent speed at this moment was 6 meters per second.
12:30 - altitude 19 km, temperature -60/-24 centigrades
12:54 - altitude 28,5 km. Caches were released a few minutes later.
~ 13:30 caches start to inform about its positions as they reach GSM signal.
Two hours after start Dropion module safely landed near Lipany just a few kilometers from Prague together with most of caches. Except one all were found.
Video from the start (Czech)
Some English info