Development overview of the revised NASA Ultra Long Duration Balloon

The desire for longer duration stratospheric flights at constant float altitudes for heavy payloads has been the focus of the development of the National Aeronautics and Space Administration’s (NASA) Ultra Long Duration Balloon (ULDB) effort. Recent efforts have focused on ground testing and analysis to understand the previously observed issue of balloon deployment. A revised approach to the pumpkin balloon design has been tested through ground testing of model balloons and through two test flights. The design approach does not require foreshortening, and will significantly reduce the balloon handling during manufacture reducing the chances of inducing damage to the envelope. Successful ground testing of model balloons lead to the fabrication and test flight of a ∼176,000 m³ (∼6.2 MCF – Million Cubic Foot) balloon. Pre-flight analytical predictions predicted that the proposed flight balloon design to be stable and should fully deploy. This paper provides an overview of this first test flight of the revised Ultra Long Duration Balloon design which was a short domestic test flight from Ft. Sumner, NM, USA. This balloon fully deployed, but developed a leak under pressurization. After an extensive investigation to the cause of the leak, a second test flight balloon was fabricated. This ∼176,000 m³ (∼6.2 MCF) balloon was flown from Kiruna, Sweden in June of 2006. Flight results for both test flights, including flight performance are presented.     

Development of a super-pressure balloon with a diamond-shaped net

The essential reason of the lobed-pumpkin shaped super-pressure balloon to withstand against the high pressure is that the local curvature of the balloon film is kept small. Recently, it has been found that the small local curvature can also be obtained if the balloon is covered by a diamond-shaped net with a vertically elongated shape. The development of the super-pressure balloon using this method was started from a 3-m balloon with a polyethylene film covered by a net using Kevlar ropes. The ground inflation test showed the expected high burst pressure. Then, a 6-m and a 12-m balloon using a polyethylene film and a net using the Vectran were developed and stable deployment was checked through the ground inflation tests. The flight test of a 3000 m³ balloon was performed in 2013 and shown to resist a pressure of at least 400 Pa. In the future, after testing a new design to relax a possible stress concentration around the polar area, test flights of scaled balloons will be performed gradually enlarging their size. The goal is to launch a 300,000 m³ super-pressure balloon.     

Study of >100 GeV electrons with BETS detector using a long duration balloon flight in Antarctica

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 cm²sr 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 × 10³ events over 100 GeV including nearly 100 candidates of primary electrons.     

Cosmic-ray electron spectrum above 100 GeV from PPB-BETS experiment in Antarctica

Cosmic-ray electrons have been observed in the energy region from 10 GeV to 1 TeV with the PPB-BETS by a long duration balloon flight using a Polar Patrol Balloon (PPB) in Antarctica. The observation was carried out for 13 days at an average altitude of 35 km in January 2004. The PPB-BETS detector is an imaging calorimeter composed of scintillating-fiber belts and plastic scintillators inserted between lead plates. In the study of cosmic-ray electrons, there have been some suggestions that high-energy electrons above 100 GeV are a powerful probe to identify nearby cosmic-ray sources and search for particle dark matter. In this paper, we present the energy spectrum of cosmic-ray electrons in the energy range from 100 GeV to 1 TeV at the top of atmosphere, and compare our spectrum with the results from other experiments.     

The effects of simulated microgravity on the seminiferous tubules of rats

Space flight has been shown to have many adverse effects on various systems throughout the body. Because the opportunity to place research animals on board a Space Shuttle or the International Space Station is infrequent, various techniques have been designed to simulate the effects of microgravity in Earth based laboratories. A commonly used technique is known as antiorthostatic suspension, also often referred to as hind limb suspension. In this technique the hind portion of the animal is raised so that its hind limbs are non-weight bearing. This places the animal in roughly a 30° head down tilt position. This results in cephalic fluid shifts similar to those seen in actual space flight. This technique has also been shown to mimic other physiological parameters that are affected during space flight. This study examined testicular tissue from rats subjected to a 7 day antiorthostatic suspension. This tissue was acquired through a tissue sharing program and some of the experimental animals were injected with Interleukin 1 receptor antagonist (IL-1ra) which was hoped to ameliorate some of the effects of antiorthostatic suspension. The injection of IL-1ra was not expected to have any effect on testicular tissue, however this tissue was included in the morphological and statistical analysis to conduct a more complete study. All tissues were embedded in paraffin, sectioned, and stained using standard H&E staining. The tissue was then qualitatively ranked according to the “health” of the seminiferous tubules. Our findings indicate that 7 days of antiorthostatic suspension had adverse effects on the tissue that comprises the walls of the seminiferous tubules. It has long been known that antiorthostatic suspension has deleterious effects on testicular tissue, however this research indicates that these effects occur much faster than indicated by previous researchers. This is a significant finding because it indicates that meaningful earth based studies in this area can be carried out in a shorter time span. This could result in more studies per year as well as saving money by avoiding longer than necessary animal suspensions. This is especially important as we enter an era when, without Space Shuttle, flight opportunities will become scarce. These antiorthostatic suspension studies indicate that space flight, even short duration spaceflight, may have harmful effects on the seminiferous tubules and blood-testis barrier of astronauts.     

The high altitude student platform (HASP) for student-built payloads

An outstanding issue with aerospace workforce development is what should be done at the university level to attract and prepare undergraduates for an aerospace career. One approach adopted by many institutions is to lead students through the design and development of small payloads (less than about 500 grams) that can be carried up to high altitude (around 30 km) by a latex sounding balloon. This approach has been very successful in helping students to integrate their content knowledge with practical skills and to understand the end-to-end process of aerospace project development. Sounding balloons, however, are usually constrained in flight duration (∼30 min above 24 km) and payload weight, limiting the kinds investigations that are possible. Student built picosatellites, such as CubeSats, can be placed in low Earth orbit removing the flight duration constraint, but the delays between satellite development and launch can be years. Here, we present the inexpensive high altitude student platform (HASP) that is designed to carry at least eight student payloads at a time to an altitude of about 36 km with flight durations of 15–20 h using a small zero-pressure polyethylene film balloon. This platform provides a flight capability greater than sounding balloons and can be used to flight-test compact satellites, prototypes and other small payloads designed and built by students. The HASP includes a standard mechanical, power and communication interface for the student payload to simplify integration and allows the payloads to be fully exercised. HASP is lightweight, has simple mission requirements providing flexibility in the launch schedule, will provide a flight test opportunity at the end of each academic year.     

栅格翼展开等效试验方法研究

为了在运载器真实飞行前对栅格翼展开过程和系统力学性能进行考核，针对现有模拟试验方法不能有效模拟飞行工况栅格翼在气动力作用下展开过程及该过程对壳体和栅格翼的冲击的问题提出了一种等效试验方法，试验结果表明具有很好的可行性和有效性，为后续类似试验提供了有益的参考。     

Measurements of water vapour in the mesosphere with the spectral absorption line imager (SALI)

Water vapour concentration is one of the most important, yet one of the least known quantities of the mesosphere. Knowledge of water vapour concentration is the key to understanding many mesospheric processes, including the one that is primary focus of our investigation, Polar Mesospheric Clouds (PMC). The processes of formation and occurrence parameters of PMC constitute an interesting problem in their own right, but recent evidence had been provided which suggests that PMC are a critical indicator of climate change. In this context the feasibility of a low cost method of water vapour measurements using an instrument carried aloft by a sounding rocket has been examined and some of the results discussed. It is proposed to measure the strength of the 936nm water absorption line in a solar occultation configuration employing a CCD detector. This leads to the design of a small, low cost and low-mass instrument, which can be flown on a small rocket, of the type of the Orbital Sciences Corporation Viper 5. Alternatively the instrument can be flown as a “passenger” on larger rocket carrying other experiments. In either case flight costs are relatively low. Some performance simulations are presented showing that the instrument we have designed will be sufficiently sensitive to measure water vapor in concentrations that are expected at the summer mesopause, about 85 km height. Sufficient payload design work was carried out showing that the structural, thermal and electrical requirements for a flight on the Viper 5 rocket can be met and thus making the experiment feasible for a flight.