Systems for long duration flights

This paper describes the systems for long duration flights developed in Japan for scientific observations. Much efforts have been expended to evolve systems for long duration flights in Japan, by controlling the balloon trajectories with a knowledge of wind pattern at high altitudes over Japan. These systems called “Cycling Balloon”, “Boomerang Balloon” and “New Boomerang Balloon” have been successfully used for the observations by keeping the balloons close to the balloon station.“Relay Balloon” is another system to extend the telemetry range by using an additional balloon as a relay station to link the telemetry from the main balloon.Some detailes of the exhaust valve, ascent meter and automatic level control devices used for the balloon control are also described in the paper.     

Worst Error Performance of Continuous Kalman Filters

The worst error performance of estimation filters is investigated for continuous systems in this paper. The pathological performance study, without assuming any dynamical model such as Markov processes for perturbations, except for its bounded amplitude, will give practical and dependable criteria in establishing the navigation and maneuver strategy in deep space missions.     

Polarization model for discrimination of broad and needle shaped leaves and estimation of LAI using polarization measurements

Method for estimation of Leaf Area Index (LAI) based on polarized radiance measurements is proposed. Leaf angle dependency on LAI estimation can be taken into account by considering polarization characteristics of leaves. Effectiveness of the proposed method is confirmed with the polarized radiance from tealeaves and the other needle leaf types of grasses. Convenient way to monitor quality and amount of leaves with network camera with polarization film is also proposed.     

Time variations of cosmic-ray helium isotopes with BESS-Polar I

The Balloon-borne Experiment with a Superconducting Spectrometer (BESS) is configured with a solenoidal superconducting magnet and a suite of precision particle detectors, including time-of-flight hodoscopes based on plastic scintillators, a silica-aerogel Cherenkov detector, and a high resolution tracking system with a central jet-type drift chamber. The charges of incident particles are determined from energy losses in the scintillators. Their magnetic rigidities (momentum/charge) are measured by reconstructing each particle trajectory in the magnetic field, and their velocities are obtained by using the time-of-flight system. Together, these measurements can accurately identify helium isotopes among the incoming cosmic-ray helium nuclei up to energies in the GeV per nucleon region. The BESS-Polar I instrument flew for 8.5 days over Antarctica from December 13th to December 21st, 2004. Its long-duration flight and large geometric acceptance allow the time variations of isotopic fluxes to be studied for the first time. The time variations of helium isotope fluxes are presented here for rigidities from 1.2 to 2.5 GV and results are compared to previously reported proton data and neutron monitor data.     

Balloon observation of the 1983 solar eclipse in Indonesia

A balloon observation of the total solar eclipse on 11 June 1983 was carried out as a cooperative work between Japanese and Indonesian teams. The observation was a photo-polarimetry of the F corona in both visual and near-infrared regions.The balloon of 15,000-m³ with a payload of 150-kg was launched at 7^h13^m on 11 June from Watukosek Balloon Base in East Java. Observation at an altitude of 30.5-km was successfully made during the totality (11^h28～32^m) at a position of ～40-km east-south-east from Jogjakarta.As a preliminary result, an excess in infrared brightness has been found near the position of 3.8R_⊙ west from the sun, which may be due to thermal emission from a high-temperature dust cloud located around the sun.     

Relay balloon

A relay balloon system for long-duration or large-area observations is described. The system consists of a balloon for scientific observations and a relay balloon for a data-relay terminal between a ground station and the balloon for observation. The system was successfully applied to the observation of electric-power fields (50 and 60 Hz) over the Pacific ocean. The maiximum distance between two balloons was about 1100 km and that between the Sanriku Balloon Center and the main balloon for the observation was about 1300 km.     

A new static-launch method for plastic balloons

A new static-launch method that we have developed as an improvement of our former method is described. The key procedure is to extend a whole balloon vertically upon the launcher before release, with squeezing the top bubble of the balloon by a soft collar. The new method improved the capability for heavier payload significantly. In 1981, 15 balloons, ranging from 5,000 m³ to 50,000 m³ in volume with a total lift from 150 kg to 650 kg, were launched by this new method successfully.     

Development of balloon-borne reel-down and -up winch system

Balloon-borne winches, which can reel down and up scientific instruments repeatedly, have been developed since 1981 in order to observe stratospheric vertical microstuctures. The instrument is suspended by a kevler wire through a traverse-cum ropeguide, and its depth is accurately measured by counting numbers of spool rotations and ropeguide turns. Battery consumption is minimized by utilizing an efficient deccelerator and a hysteresis brake. In 1983 we have successfully performed to reel up and down a 12 kg payload through 1 km for three cycles at 24 km altitude. We are improving the capability of the winch, and have succeeded (May 1984) to reel down a 22 kg payload up to 3 km from a balloon.