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著者人数: 20名, Accepted: 2011-05-04, 資料番号: SA1003239000

著者人数：19名, Accepted: 2009-10-07, 資料番号: SA1000727000

The Scientific Balloon Center of ISAS/JAXA has managed balloon-borne experiments in Japan. Since 1971 domestic balloon campaigns have been carried out at Sanriku Balloon Center. In 2007 ten scientific experiments were conducted by seven balloon flights at Sanriku. We have also developed next generation super-pressure balloons and ultra-thin balloons. In order to meet recent user requirements, i.e., stable flights of heavier payloads at the highest possible altitude, Japanese scientific balloons will be operated at Taiki, Hokkaido from 2008. This new balloon facility was constructed to launch the first balloon in May 2008. Standardization of balloons and the balloon system is also in progress, in order to maximize the reliability for our operation of larger balloons with heavier payloads. In this paper, we introduce the new balloon facility in Taiki and discuss the strategy of the Japanese scientific balloon activities. The status of the development of new balloon technologies and international collaborati...

著者人数: 18名, 資料番号: SA1000073000

We have observed cosmic-ray electrons from 10 to 1000 GeV by a long duration balloon flight using Polar Patrol Balloon (PPB) in Antarctica. The observation was carried out for 13 days at an altitude of 35 km in January 2004. The detector is an imaging calorimeter composed of scintillating-fiber belts and plastic scintillators inserted between lead plates. The geometrical factor of detector is about 600 cm 2 sr and the total thickness of lead absorber is 9 radiation lengths. The performance of the detector has been confirmed by the CERN-SPS beam test and also investigated by Monte-Carlo simulations. New telemetry system using a commercial satellite of iridium, power supply by solar batteries, and automatic level control using CPU have successfully been developed and operated during the flight. We have collected 5.7 × 10 3 events over 100 GeV including nearly 100 candidates of primary electrons.

A balloon-borne superconducting submillimeter-wave limb-emission sounder (BSMILES) was developed to observe thermal emission lines from stratospheric minor constituents. BSMILES carries a 300-mm-diameter offset parabolic antenna, a 624-639-GHz superconductor-insulator-superconductor (SIS) receiver, a three-axis fiber-optical gyroscope, and an acousto-optical spectrometer. BSMILES was launched from the Pacific Coast of Japan. All systems operated properly and emission line spectra of stratospheric gases, such as O/sub 3/, HCl, HO/sub 2/, and O/sub 3/ isotopes were measured. The system noise temperature in double sideband (DSB) during the flight was less than 460 K over the observing bandwidth with a best value of 330 K that is 11 times as large as the quantum limit (11h/spl nu//k/sub B/). After the observation, the gondola splashed down in the Pacific Ocean and was retrieved. Almost all instruments were waterproofed, and it has been proved that they are reusable.

Development of a balloon to fly at higher altitudes is one of the most attractive challenges in scientific balloon technologies. After reaching the highest record setting balloon altitude of 53.0 km using the 3.4 μm film in 2002, we tried to make a thinner balloon film. In 2003, we developed a forming die and an air-ring and succeeded in forming a film with a thickness of 3.0 μm and a width of 220 cm. Using this film, we manufactured a balloon with a volume of 5000 m3 and succeeded in flying the balloon up to an altitude of 46.0 km. We then searched for a good combination of resins to make a thinner and wider film and obtained films with widths of 280 cm, and a thickness of 3.0 μm at first, and then 2.8 μm. In 2004, we performed balloon experiments making a 30,000 m3 balloon with the 3.0 μm film and a 5000 m3 balloon with the 2.8 μm film. Both balloons were well manufactured and reached the highest altitudes of 50.7 and 42.6 km, respectively.

Launching a large balloon in a limited launching field is a long standing problem in Japan. The largest balloon ever launched successfully was 200,000 m3 in volume. It was launched in 1973. A larger balloon with a volume of 500,000 m3 was tried later, but it burst during the ascending phase. For launching balloons with a large lift exceeding 500 kg, the conventional static launching method had the most serious problem with possible damage to the polyethylene film of the balloon caused by the holding mechanism. After that, we had developed a new static launching method to launch balloons with a total lift of 1.0 ton. For launching a large balloon with a total lift above 1.5 ton, the new static launching method had a weak point in that if there was an air bubble in the folded part of the balloon, it may puncture the balloon as it is pushed by a spool. To avoid this problem, we developed a semi-dynamic launching method in 1999 using a launcher fixed to the ground leaving a freedom of rotation around the vertical axis. We have launched some balloons using the method and have gradually enriched our experience in using this system. In 2003, we successfully launched a balloon with a volume of 500,000 m3 by using the method. This balloon was made of polyethylene films with a thickness of 20 μm and it is the largest balloon ever launched in Japan.

The Sanriku Balloon Center (SBC), which belongs to the Institute of Space and Astronautical Science, was built in 1971. The launching field of SBC was 140 m in length and 20 m in width. In Japan, the balloon launching method that we have been using since 1971 is a kind of static launching method. In 1998, we extended the launching field 20 m in length and created a new launcher at this point. We have recently developed a “semi-dynamic” launching method. This newly developed launcher is different from the launcher used in the dynamic launching method, it is fixed to the ground creating freedom of rotation around the vertical axis. It is also possible for the launcher to lift up a payload to a height of 5 m from the ground. We succeeded in launching the first test balloon by using this new launching method on September 6, 1999. Utilizing the new launching machine, it became possible to launch a balloon with a volume of 1,000,000 m 3 and a total lift of 2 tons, even in Japan.

The balloon group at the Institute of Space and Astronautical Science (ISAS) has studied to develop high altitude balloons that could reach an altitude of more than 40 km with a light payload in order to meet the requirements of observations at extremely high altitudes. In 1999, we developed a ultra thin balloon film with a thickness of 3.4 μm. It is synthesized with a new catalyst, metallocene, and has a ultimate strength of ∼650 kg/cm 2 at −80°C. Using the film, we made the first balloon with 1,000 m 3 in volume and 2.6 kg in weight. We launched the balloon from Sanriku Balloon Center on September 1, 1999 and it successfully reached an altitude of 37.1 km. In 2000, we prepared the second balloon with 5,000 m 3 in volume with 6.8 kg in weight. It was launched on June 7, 2000 and it successfully reached an altitude of 43.0 km. Such light weight balloons are planned to be used for scientific studies in near future.

Balloons made of thin films have been frequently used to observe high altitude winds. Such a balloon is also useful to perform some scientific observations now performed by sounding rockets. Since this balloon is lighter than a normal balloon, it can easily reach an altitude more than 40km with a payload less than 10 kg. A ceiling altitude of 48.7 km was achieved by the new balloon with a volume of 30,000m 3 in a test flight in 1995. We need to reduce mechanical stress by attaching an exhaust duct especially for a thin polyethylene balloon. Three types of exhaust ducts were tested in flights in 1995. We have confirmed good performance of the thin polyethylene balloon. The launching device for the high altitude balloon is also described.

We have improved the static launch method in the Sanriku Balloon Center (SBC). The motivation of the improvement is to reduce the shock for the scientific instruments during launching and to increase the ability of launching heavier payloads. In the new launch method, the entire balloon train is extended vertically before launch. We have found that the launch condition in the new system is satisfactory, for both lowering shock while launching and maintaining stability of the payload, when the balloon lift is equally divided to the launch rope and the payload suspension rope. Under the new launch method, a payload of more than 1000 kgs has been successfully launched with the launching shock of about 0.3G.

A balloon observation of auroral X-rays has been carried out by using two types of X-ray imagers. The first is a new type of imager consisting of a two-dimensional 5×5 matrix array of Si(Li) semiconductor detectors whereas the other is a one-dimensional array of 8 NaI(Tl) scintillation detectors. Both are pinhole camera type imagers. The balloon carrying these imagers was launched from Abelver, Norway, on July 5, 1985, and flew westward over Iceland. Near the location of L=5.2 at the geomagnetic midnight during a geomagnetic substorm, temporal variations of auroral X-ray images were observed with 3-s time intervals by the Si(Li) imager. These images were confirmed simultaneously by the NaI(Tl) imager. A time sequence of the auroral X-ray images did not show a stable arc structure, but rather a localized small-scale structure with rapid time variation. The present observation suggests that localized intermittent precipitations of energetic electrons with energies of several tens keV occurred in the post-break-up phase of an auroral substorm. It is fully possible that localized energetic electron precipitations are due to the localized field-aligned electric field.

著者人数: 19名, 資料番号: SA1002820000

著者人数：21名, 資料番号: SA1000962000

著者人数：19名, 資料番号: SA1000927000

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 m 3 to 50,000 m 3 in volume with a total lift from 150 kg to 650 kg, were launched by this new method successfully.