NASA Balloon Research Articles

SunbYte: an autonomous pointing framework for low-cost robotic solar telescopes on high altitude balloons

The design and usability of a fully autonomous robotic control system (SunbYte - Sheffield University Balloon “lYfted” TElescope) for solar tracking and observational applications onboard high-altitude balloons are addressed here. The design is based on a six-step development plan balancing scientific objectives and practical engineering requirements. The high-altitude solar observational system includes low-cost components such as a Cassegrain-type telescope, stepper motors, harmonic drives, USB cameras and microprocessors. OpenCV installed from ROS (Robotic Operating System), python and C facilitated the collection, compression, and processing of housekeeping and scientific data. This processed data was then transmitted to the ground station through the launch vehicle’s telecommunication link. The SunbYte system allows the brightest spot in the sky, the sun, to be identified, and a telescope pointed towards it with high enough accuracy that a scientific camera can capture images. This paper gathers and presents the results from primarily two missions with the High-Altitude Student Platform (HASP, NASA Balloon Program office and LaSpace). Additionally, a discussion will be made comparing these with an earlier iteration flown with the German-Swedish “REXUS/BEXUS” programme coordinated by the European Space Agency. By capturing and analysing a series of tracking images with the location of the Sun at the calibrated centre, the system demonstrated the tracking capabilities on an unstable balloon during ascent. Housekeeping sensor data was collected to further analyse the thermal and mechanical performance. The low temperature increased friction in the drive train and reduced the responsiveness of the harmonic drive actuation system. This caused some issues which require further work in future missions, for example, with SunbYte 4 and its work when flying with the HEMERA ZPB (Zero Pressure Balloon) program.

Celebrating 30 years of access to NASA Space Life Sciences data.

NASA's space life sciences research programs established a decades-long legacy of enhancing our ability to safely explore the cosmos. From Skylab and the Space Shuttle Program to the NASA Balloon Program and the International Space Station National Lab, these programs generated priceless data that continue to paint a vibrant picture of life in space. These data are available to the scientific community in various data repositories, including the NASA Ames Life Sciences Data Archive (ALSDA) and NASA GeneLab. Here we recognize the 30-year anniversary of data access through ALSDA and the 10-year anniversary of GeneLab.

Beam Waist Properties of Spiral Antenna Coupled HEB Mixers at Supra-THz Frequencies

We have simulated and measured the beam properties of lens-antenna coupled hot electron bolometer mixers at a few supra-terahertz frequencies between 1.4 and 5.3 THz. The quasi-optical structures consist of an elliptical lens and a logarithmic spiral antenna. The model used for our simulations consists of a finite-element analysis to simulate the far-field radiation pattern of the antenna, geometrical optics to map the antenna radiation to the lens surface, and physical optics to calculate an arbitrary far field. We perform a thorough study of the beam properties, such as beam waist radius, phase center location and axial ratio by varying the diameter and extension of the lens, and misalignments of the antenna relative to the lens, at different operating frequencies. The simulation results are applied to the design and optimization of three different lenses for mixers to be operated at 1.4, 1.9, and 4.7 THz, respectively, which will be used in the heterodyne array receivers on board of NASA's balloon borne GUSTO observatory. The beam properties were verified experimentally by measuring the beam patterns in amplitude at multiple planes using a heterodyne technique. We found that the experimental results show good agreement with those from the simulations. Our work has delivered the mixers with the required beam characteristics for GUSTO.

Analytical study on the inflated shape of a super pressure balloon covered with a diamond-shaped net

In the last two decades, extensive efforts have been made to develop a large super pressure balloon (SPB) capable of carrying heavy payloads for scientific observations of long durations. Due to recent achievements by the NASA Balloon Program Office, practical operations of large-scale lobed-pumpkin SPB will be realized in the near future. Meanwhile, the research team initiated the development of a lightweight SPB with an alternative design concept, in which the entire balloon is covered by a diamond-shaped net. In this work, the static structural response of the proposed SPB is analyzed by establishing a mathematical model to predict its inflated shape. This model is validated by comparing the generated results with those obtained from nonlinear finite element analysis. Excellent agreement between the analytical solutions and the corresponding finite element results was obtained. On the basis of the mathematical model, the inflated shape of the SPB is investigated and unique structural characteristics are deduced, i.e., the balloon inflates into a cylinder-like shape for a certain geometry of the cover net. This structural feature can be explained by considering the equilibrium of forces applied to the cover net.

High Accuracy Pointing for Quasi-Optical THz Mixer Arrays

We report a high accuracy pointing technique for quasi-optical hot electron bolometer (HEB) mixers in focal-plane arrays designed to operate at 1.4, 1.9, and 4.7 THz. The high accuracy pointing is achieved by prealignment of a HEB chip to a lens, measuring the angular error of each mixer in an array assembly, and then realignment of the chip to the same lens to correct the error. The realigned mixers, using 5 mm diameter Si elliptical lenses designed for operation at 4.7 THz, show a final pointing error distribution with an average (μ) = 0.13° and standard deviation ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">σ</i> ) = 0.06°, with respect to the normal direction of the respective array plane. Those using 10 mm diameter lenses designed for operation either at 1.4 or 1.9 THz, show μ = 0.08° and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">σ</i> = 0.03°. We demonstrated our pointing technique in five 4×2 HEB focal plane arrays developed for NASA's balloon borne GUSTO THz observatory. Our results corroborate the simulated beam steering factors used to calculate the realignment corrections. With the unprecedented pointing accuracy at the high frequencies, our technique can significantly facilitate the use of lens-antenna, quasi-optical mixers for future focal-plane arrays, which is able to compete with traditional feedhorn-waveguide mixer arrays, operated typically below 1 THz, for astronomical instrumentation.

Mini-EUSO data acquisition and control software

We present the data acquisition and control software for the operation of the Mini-Extreme Universe Space Observatory (EUSO), a space-based fluorescence telescope for the observation of extensive air showers and atmospheric phenomena. This framework has been extensively tested alongside the development of Mini-EUSO and was finalized ahead of the successful launch of the instrument to the ISS on August 22, 2019. The data acquisition, housekeeping, and subsystem control are achieved using custom-designed front-end electronics based on a Xilinx Zynq XC7Z030 chip interfaced with a PCIe/104 CPU module via the integrated Zynq processing system. The instrument control interface is handled using an object-oriented C++ design, which can be run both autonomously and interactively as required. Although developed for Mini-EUSO, the modular design of both the software and hardware can easily be scaled up to larger instrument designs and adapted to different subsystem and communication requirements. As such, this framework will also be used in the upgrade of the EUSO-TA instrument and potentially for the next EUSO-SPB2 NASA Balloon flight. The software and firmware presented are open source and released with detailed and integrated documentation.

Boundary layer pollution profiles from a rural site in South Korea

During the NASA 2016 KORUS-AQ campaign, the ground based NASA GSFC ozone lidar and balloon borne instrumentation were deployed to the remote Taehwa Forest site (37.3 N, 127.3 E, 151 m AGL) to characterize the transport of pollution downwind of the Seoul metropolitan region. On most days from 02 May to 10 June 2016, continuous hours of lidar profiles of ozone were measured. Select days are shown to represent key ozone events that occurred at the rural site.

Stratosphere Conditions Inactivate Bacterial Endospores from a Mars Spacecraft Assembly Facility.

Every spacecraft sent to Mars is allowed to land viable microbial bioburden, including hardy endospore-forming bacteria resistant to environmental extremes. Earth's stratosphere is severely cold, dry, irradiated, and oligotrophic; it can be used as a stand-in location for predicting how stowaway microbes might respond to the martian surface. We launched E-MIST, a high-altitude NASA balloon payload on 10 October 2015 carrying known quantities of viable Bacillus pumilus SAFR-032 (4.07 × 107 spores per sample), a radiation-tolerant strain collected from a spacecraft assembly facility. The payload spent 8 h at ∼31 km above sea level, exposing bacterial spores to the stratosphere. We found that within 120 and 240 min, spore viability was significantly reduced by 2 and 4 orders of magnitude, respectively. By 480 min, <0.001% of spores carried to the stratosphere remained viable. Our balloon flight results predict that most terrestrial bacteria would be inactivated within the first sol on Mars if contaminated spacecraft surfaces receive direct sunlight. Unfortunately, an instrument malfunction prevented the acquisition of UV light measurements during our balloon mission. To make up for the absence of radiometer data, we calculated a stratosphere UV model and conducted ground tests with a 271.1 nm UVC light source (0.5 W/m2), observing a similarly rapid inactivation rate when using a lower number of contaminants (640 spores per sample). The starting concentration of spores and microconfiguration on hardware surfaces appeared to influence survivability outcomes in both experiments. With the relatively few spores that survived the stratosphere, we performed a resequencing analysis and identified three single nucleotide polymorphisms compared to unexposed controls. It is therefore plausible that bacteria enduring radiation-rich environments (e.g., Earth's upper atmosphere, interplanetary space, or the surface of Mars) may be pushed in evolutionarily consequential directions. Key Words: Planetary protection—Stratosphere—Balloon—Mars analog environment—E-MIST payload—Bacillus pumilus SAFR-032. Astrobiology 17, 337–350.

Design and validation of the mounting structure for BETTII balloon-based telescope with thin-walled optics

The NASA Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) system is designed to study the infrared emissions from star formation and active galactic nuclei through a double-Fourier Michelson interferometer located on a balloon at an altitude of 37 km. The BETTII external optics include a pair of identical beam-reducing, four-mirror telescopes, each with a 522-mm aperture, nonrotationally symmetric primary mirror. These telescopes were designed and assembled at the North Carolina State University Precision Engineering Consortium and are composed entirely of thin-walled aluminum components. The mounting structure is designed to be light weight and stiff to reduce thermal equilibration time in the rarified air at the edge of space and to maintain robust alignment of the optical elements. The mounts also prevent deformation of the large optical elements via custom-built kinematic Kelvin couplings and fixed-load clamps; the maximum form error of the optical surfaces are 300 nm RMS. This work details the design of the thin mirrors and mounting structure as well as validation of the mount assembly process, mount stiffness, and the kinematic couplings.

BFORE: The B-mode Foreground Experiment

The B-mode Foreground Experiment (BFORE) is a proposed NASA balloon project designed to make optimal use of the sub-orbital platform by concentrating on three dust foreground bands (270, 350, and 600 GHz) that complement ground-based cosmic microwave background (CMB) programs. BFORE will survey ~1/4 of the sky with 1.7 - 3.7 arcminute resolution, enabling precise characterization of the Galactic dust that now limits constraints on inflation from CMB B-mode polarization measurements. In addition, BFORE's combination of frequency coverage, large survey area, and angular resolution enables science far beyond the critical goal of measuring foregrounds. BFORE will constrain the velocities of thousands of galaxy clusters, provide a new window on the cosmic infrared background, and probe magnetic fields in the interstellar medium. We review the BFORE science case, timeline, and instrument design, which is based on a compact off-axis telescope coupled to >10,000 superconducting detectors.

Particle Astrophysics in NASAʼs Long Duration Balloon Program

A century after Viktor Hessʼ discovery of cosmic rays, balloon flights still play a central role in the investigation of cosmic rays over nearly their entire spectrum. We report on the current status of NASA balloon program for particle astrophysics, with particular emphasis on the very successful Antarctic long-duration balloon program, and new developments in the progress toward ultra-long duration balloons.

Exploring the Stability Landscape of Constant-Stress Pumpkin Balloon Designs

Pumpkin balloon designs such as the constant-bulge-angle design, the constant-bulge-radius design, and hybrids of the constant-bulge-angle and constant-bulge-radius schemes have been used in an attempt to achieve a cyclically symmetric pumpkinlike shape when fully inflated. A number of flight balloons that were built based on the constant-bulge-angle, constant-bulge-radius, and hybrid design strategies encountered deployment problems. In June 2006, Flight 555-NT (a hybrid design) formed an S-cleft and did not deploy. Currently, NASA's approach to superpressure balloon design uses a constant-stress model developed at NASA Goddard Space Flight Center. To fully understand the mechanism behind cleft formation in pumpkin balloons and to explore the constant-stress design space, NASA's Balloon Program Office carried out a series of inflation tests in 2007 involving four 27-meter-diameter 200-gore pumpkin balloons. One of the test vehicles was a one-third-scale mockup of the Flight 555-NT balloon. Using an inflation procedure intended to mimic ascent, the one-third-scale mockup developed an S-cleft feature that was strikingly similar to the one observed in Flight 555-NT. The remaining three 27-meter balloons tested were constant-stress designs and deployed properly. In an effort to gauge constant-stress design susceptibility to deployment problems, we carry out a number of parametric studies and assess the stability landscape of the constant-stress design space. In our studies, we examine two types of top end-fitting boundary conditions, one restrictive and one less restrictive, that help to define a cleft-free design envelope. We correlate our analytical predictions with outcomes of inflation tests involving 27-meter-diameter test vehicles and outcomes from flight 586-NT and flight 591-NT, which involved larger constant-stress designs. To study scaling effects, we consider a 14-million-cubic-foot design. Our analysis suggests that as one scales up the balloon, the size of the cleft-free envelope shrinks.

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.

On the Design and Analysis of Inflated Membranes: Natural and Pumpkin Shaped Balloons

Large scientific balloons are used by NASA and the space agencies of many countries to carry out research in the upper stratosphere. Such a balloon typically consists of a thin plastic shell with several external caps. Load tendons run the length of the balloon from top fitting to bottom fitting, dividing the balloon into identical regions called gores. The gores are made from flat panels of 20--30 $\mu$m polyethylene film that are sealed edge-to-edge to form the complete shape. A typical fully inflated shape can be over 120 meters in diameter and over 1 million cubic meters in volume. To date, the workhorse of NASA's balloon program has been the zero-pressure natural shape balloon, an axisymmetric onion-like design that dates back to the 1950s. The equilibrium equations at float for a natural shape balloon lead to a nonlinear boundary value problem that can be solved to determine the design shape. In recent years, demand for long duration midlatitude balloon flights has led to a design concept known as the pumpkin balloon. A number of ad hoc approaches based on crude approximations of equilibrium have been put forth that lead to pumpkin-like balloon shapes. In this paper, we derive equilibrium equations for a pumpkin balloon. We also present a brief review of balloon models that follow from the axisymmetric membrane theory. Numerical solutions are included.

Overview of the ultra long duration balloon project

The NASA balloon program research and development (R&D) efforts have focused on the development of technologies to support increased capability balloon missions. Advances made in analytical structural/performance modeling and light-weight composite materials offered the promise of superpressure balloons capable of extended flight duration. Experience with the NASA long duration balloon (LDB) systems have demonstrated the ability to send and receive scientific data and control missions on a global basis for up to approximately 20 days. It appeared that scientific ballooning was ready for the next step in capability. In 1997 a project was approved to develop and demonstrate those technologies required to support balloon missions lasting up to 100 days above 33.5 kms. The development project, called the ultra long duration balloon project (ULDB), will conclude with a demonstration flight in the year 2000. The ULDB project consists of four major systems: vehicle and recovery, ballooncraft, mission and operations, and science instrument. Technical challenges include the balloon materials, fabrication, power, thermal control, attitude control, telecommunications, data storage and international overflight. An overview of the ULDB project will be presented which addresses requirements, technical challenges, development activities, results and status of the ULDB project.

The Ultra Long Duration Balloon Project

Abstract The USA NASA Balloon Program research and development (R&D) efforts have focused on the development of technologies to support increased capability balloon missions. Advances made in analytical structural/performance modeling and lightweight composite materials offered the promise of superpressure balloons capable of extended flight duration. In 1997 a project was approved to develop and demonstrate a new capability to support balloon missions lasting up to 100 days above 33.5 kms. The development project, called the Ultra Long Duration Balloon Project (ULDB), will conclude with a demonstration flight in the year 2000. The ULDB Project consists of four major systems: Vehicle and Recovery, Ballooncraft, Mission and Operations, and the Science Instrument. Major challenges include the balloon material, balloon fabrication, power, cryogenic refrigeration, thermal control, attitude control, telecommunications and data storage, and international overflight. An overview of ULDB Project (Smith, et al, 1998) will be presented.

Scientific balloon effective radiative properties

Prediction of the flight performance of a scientific balloon is dependent on the radiative properties of the balloon. To determine its optical properties for use in performance calculations, the balloon must be viewed as a composite structure. Determination of the balloon's effective radiative properties takes into account the shape, the orientation to radiative sources, and the construction of the balloon including film properties, layers of film, and load tapes. A method for determining the effective radiative properties of a scientific balloon, that is independent of the specific constituent materials attributes, has been developed and has been applied to the standard natural shaped balloons utilized in the U.S. NASA Balloon Program. It can be applied to balloons of any size and construction for both terrestrial and planetary balloons. A commercial computer code is used to compute the total thermal radiation environment. The calculation of the effective absorptivity and effective emissivity of the balloon can now be based on the actual measured absorptivity and measured emissivity of the film and the load tapes. This new method accurately accounts for the physics and the non-uniformities of the balloon surface, and dispenses with the need for adjustments that previously required data from numerous flights. A description of the analysis approach, developed method, and results will be presented.

The challenge to balloon science

A thorough review of the NASA balloon program in 1995 confirmed both the inherent importance of balloon science investigations and their value for developing technology for future space missions. A follow-on study in 1996 looked into restructuring the entire suborbital program, in order to find more efficient and effective ways of doing business. These studies were mandated by the adverse impact of NASA's declining budgets and work force constraints on all aspects of space research. The challenge is to accomplish more with less. The balloon program began stepping up to this challenge several years ago with the advent of 10 – 20 day long-duration flights in Antarctica. We must now push ahead with enhanced flight capabilities and with new science instrument technologies, as we forge alliances with other modes of low-cost access to space. Specifically, the development of sealed superpressure balloons could extend flight duration by another order of magnitude, to about 100 days, making ballooning even more competitive with space missions.

Liquid crystalline polymer (LCP) reinforced polyethylene blend blown film: Effects of counter‐rotating die on fiber orientation and film properties

AbstractPolyethylene blends (LLDPE:HDPE ≈ 2:1 by wt) used in NASA's balloon film applications can be effectively reinforced by addition of a small amount of liquid crystalline polymer (LCP). Cast and blown PE films containing ≈ 10% LCP show an appreciable enhancement in tensile modulus ≈400% over that of the neat PE matrix. Anisotropy in these in‐situ composites was reduced by controlling LCP molecular orientation via a counter‐rotating (C/R) annular die. LCP/PE blend blown films with nearly isotropic properties are obtained. Based on microscopy studies, LCP domains were generally present as fibrils with diameters of ≈ 1 to 3 µM and lengths of ≈ 100 to 300 µM. Films, produced using a C/R die, had fibrillated LCP phases and variable orientation through the film thickness. This paper describes the influence of some key process variables including temperature profile, number of extrusion cycles, degree of mixing, adapter geometry, and die counter‐rotation on LCP/PE blend film morphology and mechanical properties. The structure of LCP/PE blend blown films was also evaluated using scanning electron microscope (SEM) and wide angle X‐ray scattering (WAXS) techniques.

Advancements in NASA balloon research and development

A comprehensive balloon research and development (R&D) plan was developed by NASA in 1986 and implemented in 1987. The objectives are to develop the understanding of balloon system performance, limitations, and failure mechanisms. The program consists of five major technical areas: structures, performance and analysis, materials, chemistry and processing, and quality control. Research activities are being conducted at NASA/Goddard Space Flight Center (GSFC)/Wallops Flight Facility (WFF), other NASA centers and government facilities, universities, and the private sector. Significant technical advances have been made in the structural design and analysis of balloons, vertical flight performance modeling, materials characterization, materials development and processing, and the development of automated flight control hardware and software. This has resulted in new balloon designs with increased capabilities with improved flight control. The recent findings, new capabilities, and plans for the NASA Balloon R&D Program will be presented.