Purpose of the flight and payload description
The flight was devoted to test a tandem combination of a zero pressure balloon and a super-pressure balloon, to achieve the longest flight possible. In this configurations the superpressure balloon (SPB - closed) hangs below the zero pressure balloon (ZPB - open) acting as a virtual ballast/anchor system not allowing the ZPB to ascend when overheated by the sun. By this, the balloon is not forced to vent helium to achieve balance, and a longer flight can be possible without carrying huge amounts of ballast.
Details of the balloon flight
Balloon launched on: 6/9/2012 at 3:35 jst
Launch site: Multipurpose Aviation Research Field, Taiki-Cho, Hokkaido, Japan
Balloon launched by: Institute of Space and Astronautical Science (ISAS) / Japan Aerospace Exploration Agency (JAXA)
Balloon manufacturer/size/composition: Balloon Tandem BSO 15.000 m3 + BSP 3.000 m3
Flight identification number: B12-02
End of flight (L for landing time, W for last contact, otherwise termination time): 6/9/2012 at 7:15 jst
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 3 h 40 m
Landing site: In the Pacific Ocean, 30 km E of Taiki, Japan
The balloons measured 15.000 m3 and 3.000 m3 of volume for the ZPB and SPB respectively and were launched at 3:35 japan standard time from the Taiki Aerospace Research Field in Hokkaido. The SPB began to pressurize while ascending and reached a differential pressure of 600 Pa at 26.5 km. After that, it was ejected some ballast to simulate the sunset time, thus achieving an altitude of 30.4 km.
Once all tests were completed the balloon was terminated at 7:15 jst being recovered from the Ocean's surface in a point located 30 km east of Taiki, by a fishing vessel.