Nobuyuki Yajima

Venus balloons at low altitudes

Abstract The Venus balloons are one of the most important vehicles to explore the dynamics and composition of Venusian atmosphere and several feasibility studies have been reported. /1/,/2/ We here propose the balloons at low altitude of 10 to 20 km floating below the cloud in the Venus atmosphere, which will make it possible to perform the study of the Venus atmosphere at low altitude together with a direct observation of the Venus surface. The atmospheric pressure is 20 to 40 atm. at this altitude, and the temperature is as high as 300°C to 400°C. The balloons proposed here are of the spherical shape of super pressure type filled by the Helium gas. The balloons are made of thin Ti alloy or reinforced by CFRP, and have capabilities to carry the payloads of weights of several kg. This type of the balloon has several merits on the weight considerations over the normal inflatable balloons with gas containers and its inlet systems.

Flight demonstration of a superpressure balloon by three-dimensional gore design

Abstract On May 15, 1999, a balloon with a volume of 3,100 cubic meters was successfully launched from Sanriku Balloon Center of Japan. It became a superpressure balloon at 19.2km in altitude with 20% pressure difference to the ambient atmosphere. This is the first superpressure balloon capable of suspending a heavy payload. It was designed by the new ‘three-dimensional gore design’ method and was based on a pumpkin shape balloon with bulges of small radii between adjacent load tapes without the help of film extensibility. The balloon climbed up to 21.6km in altitude by dropping the ballast and held out against a 64% pressure difference over the ambient atmosphere. This flight test proved the capability of large stratospheric superpressure balloons by this new design method.

Balloon operation for stratospheric air sampling at Antarctica

Abstract On January 3rd, 1998, a cryogenic air sampling experiment was carried out at Syowa Station (69S, 40E), which is the first successful trial in the world for collection of large amount of stratospheric air over the Antarctic. The samples are analyzed for CO 2 , CH 4 , CFCs, and C and O isotope ratios in CO 2 in the laboratories. As the meteorological conditions for launching and payload recovery are both critical, feasibility on wind conditions over Syowa Station was studied in detail. The balloon launching operations had to be performed without a specialist. Facilities for balloon launching, tracking, and other support systems were newly designed for ready-to- and easy-to-use. Realtime remote support from Japan for the balloon launching and flight control operations was applied using a computer network linked by INMARSAT.

The Future of Scientific Ballooning

This chapter describes future aspects of scientific ballooning including technological progress and future application trends. The applicability of balloon technology to other fields is also mentioned.

Engineering Fundamentals of Balloons

Balloons are giant membrane structures that float in the thin atmosphere. This chapter first presents the geometric design problems for the balloon body. Specifically, the shape of axisymmetric natural-shape balloons is discussed, and this design concept is then extended to superpressure balloons that are reinforced by load tapes. Throughout this discussion, current progress in research on design concepts that dramatically enhance balloon strength is explained in detail. The dynamics of a balloon flight are governed by a complex combination of fluid dynamics and thermodynamics. A mathematical model that describes the motion of a balloon is derived. This model includes the effects of the aerodynamical forces acting on the balloon, and of the gas temperature variation caused by thermal conduction and radiation between the balloon and surrounding atmosphere, the sun, the ground, and outer space. The ascent, descent, and the lateral motion of balloons are then explained in detail.