Technology development for a long duration,mid-cloud level Venus balloon

This paper describes the results of ongoing technology development activities for a Venus spherical superpressure balloon capable of flying for long durations (30 days) in the middle cloud layer at an altitude of 55.5 km. Data is presented from a successful aerial deployment and inflation flight experiment on a 5.5 m diameter prototype balloon conducted at a 2.5 km altitude above the Earth. Although the balloon in that test was not released for free flight, all other steps in the deployment and inflation process were successfully executed. Experimental and computational results are also presented from an investigation of the stress concentration phenomenon at the junction of the metal end fitting and fabric end cap of the prototype Venus balloon. Good agreement was found between the simulation and experimental results and a stress concentration factor of 1.55 determined for this end cap design compared to the expectations of thin membrane theory. Finally, results are presented for a new, second-generation Venus balloon material utilizing Aclar™ film instead of Teflon. Optical property and sulfuric acid tolerance data are presented for this material based on laboratory testing of samples.     

Second generation prototype design and testing for a high altitude Venus balloon

This paper describes the development of a second generation prototype balloon intended for flight in the upper atmosphere of Venus. The design of this new prototype incorporates lessons learned from the construction and testing of the first generation prototype, including finite element analyses of the balloon stresses and deformations, measured leak performance after handling and packaging, permeability and optical property measurements on material samples, and sulfuric acid testing. An improved design for the second generation prototype was formulated based on these results, although the spherical shape and 5.5 m diameter size were retained. The resulting balloon has a volume of 87 m³ and is capable of carrying a 45 kg payload at a 55 km altitude at Venus. The design and fabrication of the new prototype is described, along with test data for inflation and leakage performance.     

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.     

A neutral gas mass spectrometer to measure the chemical composition of the stratosphere

The Polar Balloon Atmospheric Composition Experiment (P-BACE) is a new generation of neutral gas mass spectrometer based on the time-of-flight principle. P-BACE is the scientific experiment on the Mars Environment Analog Platform (MEAP) flown successfully on a balloon mission in summer 2008. The MEAP mission was flown with a 334,000 m³ helium balloon in the stratosphere on a semicircular trajectory from northern Sweden around the North Pole to Canada using the summer northern hemispheric wind current. The atmospheric conditions at an atmospheric altitude of 35–40 km are remarkably similar to those on the surface of Mars and thus the balloon mission was an ideal testbed for our mass spectrometer P-BACE. Originally this instrument was designed for in situ measurements of the chemical composition of the Martian atmosphere.P-BACE has a unique mass range from 0 to 1000 amu/q with a mass resolution m/Δm (FWHM) > 1000, and the dynamic range is at least six orders of magnitude. During this experiment, the acquisition of one mass spectrum is a sum of 65,535 single spectra, recorded in a time frame of 66 s.The balloon mission lasted 5 days and had successfully demonstrated the functionality of the P-BACE instrument during flight conditions. We had recorded more than 4500 mass spectra. With little modifications, P-BACE can be used on a planetary mission for Mars, but for example also for Venus or Mercury, if placed on a satellite.     

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.     

Venus atmospheric platform options revisited

Various balloon systems intended as scientific platforms to float in the atmosphere of Venus at altitudes between about 35 and 65 km are briefly reviewed. Previous predictions of the altitude oscillations of balloons filled with helium gas and water vapor are largely confirmed through numerical simulation and analysis. The need for refined thermal modelling is emphasised. Several novel technical concepts are introduced. It is concluded that phase change balloons would be more suitable than non-condensing super pressure gas balloons when repeated altitude excursions are a mission requirement.     

A challenge to the highest balloon altitude

Development of a balloon to fly at higher altitudes is one of the most attractive challenges for scientific balloon technologies. After reaching the highest balloon altitude of 53.0 km using the 3.4 μm film in 2002, a thinner balloon film with a thickness of 2.8 μm was developed. A 5000 m³ balloon made with this film was launched successfully in 2004. However, three 60,000 m³ balloons with the same film launched in 2005, 2006, and 2007, failed during ascent. The mechanical properties of the 2.8 μm film were investigated intensively to look for degradation of the ultimate strength and its elongation as compared to the other thicker balloon films. The requirement of the balloon film was also studied using an empirical and a physical model assuming an axis-symmetrical balloon shape and the static pressure. It was found that the film was strong enough. A stress due to the dynamic pressure by the wind shear is considered as the possible reason for the unsuccessful flights. A 80,000 m³ balloon with cap films covering 9 m from the balloon top will be launch in 2011 to test the appropriateness of this reinforcement.     

Balloon support systems performance for the cosmic rays energetics and mass mission

The Ballooncraft Support Systems were developed by NASA Wallops Flight Facility for use on ULDB class balloon missions. The support systems have now flown two missions supporting the Cosmic Rays Energetics and Mass (CREAM) experiment. The first, CREAM I, flown in December 2004, was for a record breaking 41 days, 21 h, and the second flight flown in December 2005, was for 28 days, 9 h. These support systems provide CREAM with power, telecommunications, command, and data handling including flight computers, mechanical structures, thermal management, and attitude control to help ensure a successful scientific mission. This paper addresses the performance and success of these support systems over the two missions.     

EUV observation from the Earth-orbiting satellite,EXCEED

An Earth-orbiting small satellite “EXtreme ultraviolet spectrosCope for ExosphEric Dynamics” (EXCEED) which will be launched in 2012 is under development. The mission will carry out spectroscopic and imaging observation of EUV (Extreme Ultraviolet: 60–145 nm) emissions from tenuous plasmas around the planets (Venus, Mars, Mercury, and Jupiter). It is essential for EUV observation to put on an observing site outside the Earth’s atmosphere to avoid the absorption. It is also essential that the detection efficiency must be very high in order to catch the faint signals from those targets. In this mission, we employ cesium iodide coated microchannel plate as a 2 dimensional photon counting devise which shows 1.5–50 times higher quantum detection efficiency comparing with the bared one. We coat the surface of the grating and entrance mirror with silicon carbides by the chemical vapor deposition method in order to archive the high diffraction efficiency and reflectivity. The whole spectrometer is shielded by the 2 mm thick stainless steel to prevent the contamination caused by the high energy electrons from the inner radiation belt. In this paper, we will introduce the mission overview, its instrument, and their performance.     

A gas management system for an ultra long duration Titan blimp

This paper presents analyses, designs and experimental results for the gas management system of a hydrogen-filled blimp capable of flying in the lower atmosphere of Titan for a period of 1 year or more. The engineering strategy has two basic elements: first, to minimize leakage rates from the blimp envelope and ballonets; and second, to provide auxiliary subsystems to mitigate the life-limiting effects resulting from those leaks. Leak minimization is achieved through use of cryogenically compatible balloon materials and adhesives, and selection of ballonet geometries that minimize pinhole generation via folding and material fatigue. Hydrogen loss to the environment through leaks in the blimp envelope is compensated by producing new hydrogen through chemical processing of atmospheric methane. Nitrogen leaked into the blimp from the ballonets is removed by a carbon absorption system and periodically vented to the atmosphere. Data is presented on the measured leak rate from a full scale (13 m long) prototype blimp envelope and on the performance of a low mass, low power prototype device that generates hydrogen from methane. These results are factored in to an overall system design that quantifies the mass and power requirements for a minimum 1 year operational lifetime.     

Scientific ballooning in India – Recent developments

Established in 1971, the National Balloon Facility operated by TIFR in Hyderabad, India, is a unique facility in the country, which provides a complete solution in scientific ballooning. It is also one of its kind in the world since it combines both, the in-house balloon production and a complete flight support for scientific ballooning. With a large team working through out the year to design, fabricate and launch scientific balloons, the Hyderabad Facility is a unique centre of expertise where the balloon design, research and development, the production and launch facilities are located under one roof. Our balloons are manufactured from 100% indigenous components. The mission specific balloon design, high reliability control and support instrumentation, in-house competence in tracking, telemetry, telecommand, data processing, system design and mechanics is its hallmark. In the past few years, we have executed a major programme of upgradation of different components of balloon production, telemetry and telecommand hardware and various support facilities. This paper focuses on our increased capability of balloon production of large sizes up to 780,000 m³ using Antrix film, development of high strength balloon load tapes with the breaking strength of 182 kg, and the recent introduction of S-band telemetry and a commandable timer cut-off unit in the flight hardware. A summary of the various flights conducted in recent years will be presented along with the plans for new facilities.     

Optical performance of PHEBUS/EUV detector onboard BepiColombo

BepiColombo, a mission of ESA (European Space Agency) in cooperation with JAXA (Japan Aerospace Exploration Agency), will explore Mercury, the planet closest to the Sun. BepiColombo will launch in 2014 on a journey lasting up to six and a half years; the data gathering phase should occupy a one year nominal mission, with a possible extension of another year. The data which will be brought back from the orbiters will tell us about the Hermean surface, atmospheric composition, and magnetospheric dynamics; it will also contribute to understanding the history and formation of terrestrial planets. The PHEBUS (Probing of Hermean Exosphere by Ultraviolet Spectroscopy) instrument will be flown on MPO: Mercury Planetary Orbiter, one of the two BepiColombo orbiters. The main purpose of the instrument is to reveal the composition and the distribution of the exosphere of Mercury through EUV (Extreme Ultraviolet: 55–155 nm) and FUV (Far Ultraviolet: 145–315 nm) measurements. A consortium composed of four main countries has been formed to build it. Japan provides the two detectors (EUV and FUV), Russia implements the scanning system, and France and Italy take charge of the overall design, assembly, test, integration, and also provide two small NUV (Near Ultraviolet) detectors (for the light from calcium and potassium molecules). An optical prototype of the EUV detector which is identical to the flight configuration has been manufactured and evaluated. In this paper, we show the first spectra results observed by the EUV channel optical prototype. We also describe the design of PHEBUS and discuss the possibility of detecting noble gases in Mercury’s exosphere taking the experimental results so far into account.     

Resolving electrons from protons in ATIC

The Advanced Thin Ionization Calorimeter (ATIC) experiment is designed for high energy cosmic ray ion detection. The possibility to identify high energy primary cosmic ray electrons in the presence of the ‘background’ of cosmic ray protons has been studied by simulating nuclear-electromagnetic cascade showers using the FLUKA Monte Carlo simulation code. The ATIC design, consisting of a graphite target and an energy detection device, a totally active calorimeter built up of 2.5 cm × 2.5 cm × 25.0 cm BGO scintillator bars, gives sufficient information to distinguish electrons from protons. While identifying about 80% of electrons as such, only about 2 in 10,000 protons (@ 150 GeV) will mimic electrons. In September of 1999 ATIC was exposed to high-energy electron and proton beams at the CERN H2 beam line, and this data confirmed the electron detection capabilities of ATIC. From 2000-12-28 to 2001-01-13 ATIC was flown as a long duration balloon test flight from McMurdo, Antarctica, recording over 360 h of data and allowing electron separation to be confirmed in the flight data. In addition, ATIC electron detection capabilities can be checked by atmospheric gamma-ray observations.     

Results of the VEGA 1 balloon nephelometer experiment

Backscatter nephelometer measurements obtained during the VEGA 1 balloon flight are reported. During periods of minor convective activity and initial balloon ascent, the data generally agree with those obtained from other Venus mission descent probes. However, during the period of greatest convective activity experienced by the VEGA 1 balloon, the signals were about a factor of two greater than any previously obtained. Although the clouds appear to be unbroken, deviations in the behavior of the detailed backscatter signals with time from those of the ambient pressure or temperature signals, especially during periods of minor convective activity, indicate much small-scale variability in cloud structure.     

Development of the High Altitude Student Platform

The High Altitude Student Platform (HASP) was originally conceived to provide student groups with access to the near-space environment for flight durations and experiment capabilities intermediate between what is possible with small sounding balloons and low Earth orbit rocket launches. HASP is designed to carry up to twelve student payloads to an altitude of about 36 km with flight durations of 15–20 h using a small zero-pressure polyethylene film balloon. This provides a flight capability that can be used to flight-test compact satellites, prototypes and other small payloads designed and built by students. HASP includes a standard mechanical, power and communication interface for the student payload to simplify integration and allows the payloads to be fully exercised. Over the last two years a partnership between the NASA Balloon Program Office (BPO), Columbia Scientific Balloon Facility (CSBF), Louisiana State University (LSU), the Louisiana Board of Regents (BoR), and the Louisiana Space Consortium (LaSPACE) has led to the development, construction and, finally, the first flight of HASP with a complement of eight student payloads on September 4, 2006. Here we discuss the primary as-built HASP systems and features, the student payload interface, HASP performance during the first flight and plans for continuing HASP flights. The HASP project maintains a website at http://laspace.lsu.edu/hasp/ where flight application, interface documentation and status information can be obtained.     

The dynamics and control of the CubeSail mission: A solar sailing demonstration

The CubeSail mission is a low-cost demonstration of the UltraSail solar sailing concept (, ,  and ), using two near-identical CubeSat satellites to deploy a 260 m-long, 20 m² reflecting film. The two satellites are launched as a unit, detumbled, and separated, with the film unwinding symmetrically from motorized reels. The conformity to the CubeSat specification allows for reduction in launch costs as a secondary payload and utilization of the University of Illinois-developed spacecraft bus. The CubeSail demonstration is the first in a series of increasingly-complex missions aimed at validating several spacecraft subsystems, including attitude determination and control, the separation release unit, reel-based film deployment, as well as the dynamical behavior of the sail and on-orbit solar propulsion. The presented work describes dynamical behavior and control methods used during three main phases of the mission. The three phases include initial detumbling and stabilization using magnetic torque actuators, gravity-gradient-based deployment of the film, and steady-state film deformations in low Earth orbit in the presence of external forces of solar radiation pressure, aerodynamic drag, and gravity-gradient.     

Power supplies for long duration balloon flights

Long duration balloon flights require more electrical power than can be carried in primary batteries. This paper provides design information for selecting rechargeable batteries and charging systems. Solar panels for recharging batteries are discussed, with particular emphasis on cells mounting suitable for balloon flights and panel orientation for maximum power collection. Since efficient utilization of power is so important, modern DC to DC power conversion techniques are presented.On short flights of 1 day or less, system designers have not been greatly concerned with battery weight. But, with the advent of long duration balloon flights using superpressure balloons, anchor balloon systems, and RACOON balloon techniques, power supplies and their weight become of prime importance. The criteria for evaluating power systems for long duration balloon flights is performance per unit weight. Instrumented balloon systems have flown 44 days. For these very long duration flights, batteries recharged from solar cells are the only solution. For intermediate flight duration, say less than 10 days, the system designer should seriously consider using primary cells.     

R3D-B2 – Measurement of ionizing and solar radiation in open space in the BIOPAN 5 facility outside the FOTON M2 satellite

Solar and space radiation have been monitored using the R3D-B2 radiation risks radiometer-dosimeter on board a recent space flight on the Russian satellite Foton M2 within the ESA Biopan 5 facility mounted on the outside of the satellite exposed to space conditions. The solar radiation has been assayed in four wavelength bands (UV-C, 170–280 nm, UV-B, 280–315 nm), UV-A (315–400 nm) and PAR (photosynthetic active radiation, 400–700 nm). The data show an increasing tumbling rotation of the satellite during the mission. The photodiodes do not show a cosine response to the incident light which has been corrected. After calibration of the signals using the extraterrestrial spectrum, doses have been calculated for each orbit, for each day and for the total mission as basic data for the biological material which has been exposed in parallel in the Biopan facility. Cosmic ionizing radiation has been monitored and separated in 256 deposited energy spectra, which were further used for determination of the absorbed dose rate and flux. Basic data tables were prepared to be used by other Biopan 5 experiments. The paper summarizes the results for the Earth radiation environment at the altitude (262–304 km) of the Foton M2 spacecraft. Comparisons with the predictions of NASA Earth radiation environment experimental models AE-8 and AP-8, and the PSB97 model are also presented, which calculate the fluxes of ionizing radiation from a simulation. AP-8 is a model for trapped radiation.     

An in situ laser induced breakdown spectroscope (LIBS) for Chandrayaan-2 rover: Ablation kinetics and emissivity estimations

A miniaturized in situ laser induced breakdown spectroscope-LIBS is one of the two lunar rover payloads to be flown in India’s next lunar mission Chandrayaan-2, with an objective to carry-out a precise qualitative and quantitative elemental analyses of lunar regolith at the proximity of the landing region. As per the imposed mission constraints and the executed design optimization studies, a compact and light-weight LIBS prototype model is developed at our premises. This paper mainly concerns with the estimation of theoretical aspects; especially on evaluation of elemental ablation parameters and signal-to-noise ratio (SNR) calculations for the designed instrument. Theoretical estimations and simulations yielded an incident laser power density of the order of 5 × 10¹⁰ W/cm² on the target surface at a defined lens-to-surface distance (LTSD) of 200 mm and revealed an SNR > 100 for most of the elements under consideration. This paper also addresses the impact of LTSD variation on detection capability. The estimation of plasma-temperatures was carried out utilizing the emission spectra obtained under high vacuum environments employing the LIBS laboratory model. Experimental investigations and the performed theoretical estimations asserted the successful operation of the configured LIBS instrument for in situ elemental analyses on lunar surface.