We examined the effects of temperature, mixing ratio of a titania precursor (titanium oxysulfate acid hydrate; TiOSAH)/cationic surfactant (cetyltrimethylammonium bromide; CTAB) and gravity on the framework formation (hexagonal structure, pore size and wall thickness) and crystal growth of hexagonal-structured self-assemblies of nanocrystalline (anatase) titania templated by CTAB (Hex-ncTiO2/CTAB Nanoskeleton). In order to examine the effect of gravity on the framework formation and crystal growth of the Hex-ncTiO2/CTAB Nanoskeleton, the Hex-ncTiO2/CTAB Nanoskeleton was prepared under increased-gravity environments (generated with centrifuge). We found that growth of nanocrystalline titania in and/or on the Hex-ncTiO2/CTAB Nanoskeleton was enhanced with higher temperature, lower TiOSAH content and higher gravity. On the other hand, temperature, the TiOSAH/CTAB mixing ratio and gravity did not affect significantly the hexagonal-structure formation and pore size of the Hex-ncTiO2/CATB Nanoskeleton.
To realize micro-gravity environment of long duration and good quality with moderate cost, an experimental system which is released from a high altitude balloon has developed. The system has a double-shell drag-free structure and the outer shell, namely flight capsule, is controlled not to collide with the inner shell to realize micro-gravity environment of good quality. This paper shows the design philosophy and the configuration of the system. The system was successfully tested twice, in May, 2006 and in May, 2007. Outline of the test results and future development plan are also described. Key Words: High-altitude balloon, Micro gravity, Drag-free, Supersonic.
The scientific balloons have been used for varios space missions including the micro gravity experiments. To ensure the long experiment time, we developed the high altitude balloon using thin main shell covered by additional caps.This technique is to evaluate the possible maximum strain on the balloon film at various flight altitude assuming the axis symmetrical shape conserving the surface density and support the weak points by adding more films as caps. In this paper,after reviewing the balloon experiment and basic equations to determine the balloon shape,the capping technique will be introduced and its applications to the micro gravity experiment will be described.
A novel way to conduct microgravity experiments using high altitude balloon is now under development at ISAS/JAXA. By dropping the rocket shaped vehicle from the high altitude balloon, high quality microgravity environment can be served during its free fall of 30 to 60 sec. This paper summarizes the outline of free fall vehicle, which is called as BOV (Balloon based Operation Vehicle). The preliminary results of its second flight test are also presented to show its feasibility.
This paper proposes control system for a new micro gravity experimental system called BOV (Balloon-based Operation Vehicle). BOV uses a free-fall capsule with double-shell structure to prevent influence of aerodynamic disturbance. Additionally, BOV is raised to 40km by a high altitude balloon to extend micro gravity duration to 30 (or possibly 60) seconds. Thus we realize a medium duration micro gravity experimental system with good micro gravity environment. In this system, the most characteristic point is double-shell structure to realize drag-free system. The inner shell can fall freely since the outer shell is controlled not to collide with the inner shell. In the experiments, we realize good-quality micro gravity and realize to continue moderate micro gravity duration. This system is now improving and near future we can practically utilize BOV's system for moderate micro gravity duration with low-cost easily.
We developed ultra-small Gravitational-Wave detector called SWIMμν. It is attached on SDS-1, which is a JAXA’s small satellite for technology demonstration. SDS-1 is to be launched in January 2009. SWIMμν aims at : (i) observing gravitational waves from orbit for the first time, (ii) being a precursor for future space gravitational wave detector missions, (iii) detecting vibrational motion of the satellite which is not well-studied noise source of a space gravitational-wave detector. We also successfully demonstrated its function in microgravity using parabolic flight operated by Diamond Air Service, Inc.
The Balloon-based Operation Vehicle (BOV) originally developed for the micro-gravity experiments is modified as a supersonic flight demonstrator of a sub-scale precooled turbojet engine developed in Japan Aerospace Exploration Agency. In the supersonic flight demonstration, the vehicle is raised by a high-altitude balloon up to a 40 km altitude and is dropped to accelerate to a supersonic velocity. To extend the flight time for an engine combustion test in the supersonic environments, the vehicle is redesigned in a wing- body configuration with a main delta wing and movable vertical and horizontal tail wings so that it can be pulled up above an altitude of 5 km. In this paper, the supersonic flight test plan is introduced, and an overview of the flight demonstrator and the tested supersonic air breathing engine is summarized.