Purpose of the flight and payload description
This balloon mission was part of the developmental effort for IKAROS a Japanese spacecraft launched in May 2010, that was the first to successfully use a SOLAR SAIL at some distance from Earth.
Solar sails use large membrane mirrors instead of rocket engines for propulsion. The kinetic force is obtained from light particles (photons) emitted by the Sun. When photons reflects off the surface of the solar sail, their energy and momentum are transferred to the sail. This gives the sail a "push" that accelerates it through space. Although radiation pressure is small and decreases by the square of the distance from the sun, the great advantage of this kind of vehicles is that they require no fuel. While the science of solar sails is well-proven, the technology to manage large solar sails is not, especially regarding the unfolding in space of these thin and delicate structures.
The Kawaguchi Laboratory drove during the 2000's decade a research effort to develop such a vehicle specially focusing in craft's membrane unfolding and steering mechanisms both dynamic and cuasi-static.
As part of the studies of the deployment of the sail in space, it was planned to carry out a series of tests using balloons in the stratosphere to simulate as accurately as possible the conditions of deployment with a very low drag coefficient due to the thin air.
During this flight -the first in the series- the objectives of the experiment were to drop a scaled down model of the Solar Sail . The folded membrane was made of polymer film, almost round shape measuring 4 meters in diameter at deployment. It was released from the balloon gondola at a spin rate of 60 revolutions per minute to simulate and measure the dynamic characteristics of deployment movement under conditions very similar to zero gravity. A second goal was to establish a method to simulate the numerically dynamic behavior of the thin film, which was not equipped with analysis tools, and served as the preliminary test for a future deployment in orbit using a sounding rocket.
The two onboard video cameras operated normally and succeeded in recording detailed images of the deployment sequence to compare them with the numerical simulation results.
Details of the balloon flight
Balloon launched on: 8/23/2003 at 6:27 jst
Launch site: Sanriku Balloon Center, Iwate, Japan
Balloon launched by: Institute of Space and Astronautical Science (ISAS)
Balloon manufacturer/size/composition: Zero Pressure Balloon model B30 30.000 m3
Flight identification number: B30-71
End of flight (L for landing time, W for last contact, otherwise termination time): 8/23/2003 at 9:23 jst
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 3 h 38 m
Landing site: On the sea 20 km E of Touni Bay, Japan
After vertical launch, the balloon ascended normally at a mean velocity of 270m/min and, 2 hours and 15 minutes after takeoff, it began level floating 40km east of SBC at an altitude of 35.8km.
At 8:56 a.m., the balloon released the solar sail experimental payload, and the deployment measuring experiment was successfully conducted.
After that, the balloon moved west, and the observation instruments were released from the balloon 7km east-northeast of Touni Bay by the command signal sent at 9:23 a.m.
The observation instruments descended slowly using the parachute and landed on the sea about 20km east of Touni Bay (Long.: 142° 10' E, Lat.: 39° 14' N).
The helicopter and recovery ship successfully recovered the balloon and instruments.