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.     

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.     

VLBI Space Observatory Programme (VSOP) satellite

The Institute of Space and Astronautical Science (ISAS), Japan, is developing a satellite, named MUSES-B, for VLBI (very long baseline interferometry) observations from space. The science observation program using MUSES-B is called the VLBI Space Observatory Programme (VSOP). The satellite is formed as an orbiting radiotelescope with a parabolic antenna of 8 meters diameter. Fine-resolution and high-quality imaging of active galactic nuclei and quasars, and observations of maser sources, are the main science objectives. The satellite will be launched in summer 1996. The satellite operation and science observations will be performed in collaboration with NASA and ground radio observatories around the world     

Automatic control of balloon altitude

An ascentmeter with a sensitivity of 1 cm/s was applied to the automatic control of balloon altitudes. In the flight tests made in 1980 and 1981, the automatic control system was successfully operated to keep a balloon altitude constant during sunset or to descend a balloon with a constant speed.     

Microgravity experiment system utilizing a balloon

A system for microgravity experiments by using a stratospheric balloon has been planned and developed in ISAS since 1978. A rocket-shaped chamber mounting the experiment apparatus is released from the balloon around 30 km altitude. The microgravity duration is from the release to opening of parachute, controlled by an on-board sequential timer. Test flights were performed in 1980 and in 1981. In September 1983 the first scientific experiment, observing behaviors and brain activities of fishes in the microgravity circumstance, have been successfully carried out. The chamber is specially equipped with movie cameras and subtransmitters, and its release altitude is about 32 km. The microgravity observed inside the chamber is less than 2.9 × 10^?3 G during 10 sec. Engineering aspects of the system used in the 1983 experiment are presented.     

Dual Speed PN Ranging System for Tracking of Deep Space Probes

A new pseudonoise (PN) ranging system is proposed for trackingof deep space probes, named the dual speed PN ranging system,that transmits two different PN sequences simultaneously through a PSK/PSK (phase-shift keying) dual speed communication channel.The dual speed PN ranging system improves the maximummeasurable range significantly, with no degradation of theacquisition time, when compared with usual PN ranging systems.According to the analysis, the tracking error of this system becomesas small as those of usual PN ranging systems when the inputsignal-to-noise ratio (SNR) is large enough.