Nobutaka Bando

The pGAPS experiment: an engineering balloon flight of prototype GAPS

The General Anti-Particle Spectrometer (GAPS) project is being carried out to search for primary cosmic-ray antiparticles especially for antideuterons produced by cold dark matter. GAPS plans to realize the science observation by Antarctic long duration balloon flights in the late 2010s. In preparation for the Antarctic science flights, an engineering balloon flight using a prototype of the GAPS instrument, “pGAPS”, was successfully carried out in June 2012 in Japan to verify the basic performance of each GAPS subsystem. The outline of the pGAPS flight campaign is briefly reported.

The flight of the GAPS prototype experiment

Abstract The General AntiParticle Spectrometer experiment (GAPS) is foreseen to carry out a dark matter search using low-energy cosmic ray antideuterons at stratospheric altitudes with a novel detection approach. A prototype flight from Taiki, Japan was carried out in June 2012 to prove the performance of the GAPS instrument subsystems (Lithium-drifted Silicon tracker and time-of-flight) and the thermal cooling concept as well as to measure background levels. The flight was a success and the stable flight operation of the GAPS detector concept was proven. During the flight about 10 6 charged particle triggers were recorded, extensive X-ray calibrations of the individual tracker modules were performed by using an onboard X-ray tube, and the background level of atmospheric and cosmic X-rays was measured. The behavior of the tracker performance as a function of temperature was investigated. The tracks of charged particle events were reconstructed and used to study the tracking resolution, the detection efficiency of the tracker, and coherent X-ray backgrounds. A timing calibration of the time-of-flight subsystem was performed to measure the particle velocity. The flux as a function of flight altitude and as a function of velocity was extracted taking into account systematic instrumental effects. The developed analysis techniques will form the basis for future flights.

Touchdown Dynamics for Sampling in Hayabusa Mission

Hayabusa spacecraft performed the final descents and touchdowns twice in November 2005. In final descent phase, terrain alignment maneuvers were accomplished to control both altitude and attitude with respect to the surface by using four beams Laser Range Finder onboard. Then Hayabusa spacecraft made dynamic touchdowns the surface of the asteroid by the sampler system to collect samples automatically. This paper presents the terrain alignment maneuver and touchdown scheme. This paper also describes the novel sample horn system and touchdown dynamics. Touchdown tests on the ground are presented. Then the flight results on touchdown dynamics are shown and discussed.

Control system of new micro-gravity experimental system “BOV“ from high altitude balloon

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 40 km 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. The inner shell can fall freely since the outer shell is controlled not to collide with the inner shell. To realize this non-contact control, BOVs body is controlled by translationa] control and attitude control. For translational control, there are four laser displacement sensors in the middle of BOV to measure clearance between the inner shell and the outer shell. The center position of the inner shell is estimated by the Newton-Raphson method with four laser displacement sensors. Using this estimation, force commands are calculated with PD controller. Attitude control is also necessary to maintain stable micro gravity experiments. BOV has three fiber optical gyros to measure the body rates. Torque commands are also calculated with PD controller. The rolling angle is controlled by only D controller since the initial error angle is possible to exert a bad influence for that the balloon is rotated in the upper air. BOV is separated from the high altitude balloon after the balloon arrives at 40 km altitude. For 35 seconds the micro gravity experiment is carried out. After the experiment, the pilot-chute is opened for speed reduction. In addition, main- chute is opened at 7.5 km altitude for safety descent. In this paper, control system for the new micro gravity experimental system is proposed. This system has double shell structure and the inner shell can fall freely. In the experiment. we realize good-quality micro gravity and realize to continue moderate micro gravity duration. This system is now improving and near future we can utilize BOVs system for moderate micro gravity duration with low-cost easily.

A Balloon-Borne Very Long Baseline Interferometry Experiment in the Stratosphere: Systems Design and Developments

Abstract The balloon-borne very long baseline interferometry (VLBI) experiment is a technical feasibility study for performing radio interferometry in the stratosphere. The flight model has been developed. A balloon-borne VLBI station will be launched to establish interferometric fringes with ground-based VLBI stations distributed over the Japanese islands at an observing frequency of approximately 20 GHz as the first step. This paper describes the system design and development of a series of observing instruments and bus systems. In addition to the advantages of avoiding the atmospheric effects of absorption and fluctuation in high frequency radio observation, the mobility of a station can improve the sampling coverage (“uv-coverage”) by increasing the number of baselines by the number of ground-based counterparts for each observation day. This benefit cannot be obtained with conventional arrays that solely comprise ground-based stations. The balloon-borne VLBI can contribute to a future progress of research fields such as black holes by direct imaging.

Droplet Array Combustion Experiment under Microgravity by Using the Balloon Operated Vehicle

For demonstration of the upgraded microgravity experimental system by the balloon operated vehicle, combustion experiment of fuel droplet array has been prepared. Development of the experimental apparatus is completed and preparation toward execution of the flight experiment in 2013 is proceeding. In this paper, overview of the experiment and the latest status will be explained with emphasis on scientific aspects of combustion research.

Vibration suppression effect of translational motion control for asymmetric flexible satellite

As a case of asymmetric satellite with flexible appendages, it is known that there exists coupled vibration between rotational motion and translational motion via flexible appendages which make satellite asymmetric. Hereby, when an asymmetric satellite rotates, elastic vibration excited by control input of rotational motion may, more or less, be transmitted to translational motion. Therefore, suppression of such an excited vibration of translational motion can, in turn, suppress the elastic vibration, and herewith attitude maneuver with little excitation of elastic modes can be expected. From the reason mentioned above, in this paper, we propose translational motion control system using proof-mass actuators and co-located accelerometers for asymmetric satellite. Then, translational motion control law with consideration of actuator saturation was studied. The proposed translational motion control system was verified through numerical simulations. Finally, feasibility of the proposed method was discussed.