Parabolic Flight Research Articles

Measurement model and accuracy analysis of parabolic ballistic projectile flight parameters based on random matrix

Measurement model and accuracy analysis of parabolic ballistic projectile flight parameters based on random matrix

Sensorimotor adaptation of locomotor synergies to gravitational constraint

This study investigates the impact of gravity on lower limb muscle coordination during pedaling. It explores how pedaling behaviors, kinematics, and muscle activation patterns dynamically adapts to changes in gravity and resistance levels. The experiment was conducted in parabolic flights, simulating microgravity, hypergravity (1.8 g), and normogravity conditions. Participants pedaled on an ergometer with varying resistances. The goal was to identify potential changes in muscle synergies and activation strategies under different gravitational contexts. Results indicate that pedaling cadence adjusted naturally in response to both gravity and resistance changes. Cadence increased with higher gravity and decreased with higher resistance levels. Muscular activities were characterized by two synergies representing pull and push phases of pedaling. The timing of synergy activation was influenced by gravity, with a delay in activation observed in microgravity compared to other conditions. Despite these changes, the velocity profile of pedaling remained stable across gravity conditions. The findings strongly suggest that the CNS dynamically manages the shift in body weight by finely tuning muscular coordination, thereby ensuring the maintenance of a stable motor output. Furthermore, electromyography analysis suggest that neuromuscular discharge frequencies were not affected by gravity changes. This implies that the types of muscle fibers recruited during exercise in modified gravity are similar to those used in normogravity. This research has contributed to a better understanding of how the human locomotor system responds to varying gravitational conditions, shedding light on the potential mechanisms underlying astronauts’ gait changes upon returning from space missions.

Viscosity of liquid Ni-based industrial alloys: experiments versus theory

The aim of this review is to succinctly review recent progress in experimental and theoretical investigation of the viscosity of binary and multicomponent Ni–Al-based industrial alloys, summarising the current state of knowledge of the topic. Viscosity data are important for simulation of microstructural evolution during solidification-related processes such as casting. Therefore, to obtain accurate predictions of defect-free microstructure, only reliable input data are required. Based on the synergy between experiment and theory, a review of the literature provides a critical evaluation of temperature- and composition-dependent viscosity data available from existing studies carried out over the last 60 years. The purpose of this review is threefold: to discuss container-based viscometer methods and alternative containerless processing via electromagnetic levitation during parabolic flights and on board the International Space Station; to analyse the viscosity models including their validation; and to refer to the first two points, to interpret the viscosity data.

The DEPLOY! Project: Development of a Deployable Pulsating Heat Pipe experiment on a parabolic flight

DEPLOY! Project aims at analysing the behaviour of Deployable Pulsating Heat Pipe (PHP) shaped as a helicoidal torsional spring in the adiabatic section on board a Parabolic Flight platform. A PHP is a passive thermal control device where the heat is efficiently transported by means of the self-sustained oscillatory fluid motion driven by the phase change phenomena. The microgravity environment allows to eliminate the buoyancy force contribution in the liquid phase momentum. Consequently, it is possible to isolate the contribution of the pressure drop caused by the 3D arrangement and infer on their effect on the PHP performance. As a result, a proper design based on the previous considerations would increase the flexibility of the PHP for use in space applications without significant reductions in efficiency. The goal of DEPLOY! is to demonstrate the functionality of a Deployable Pulsating Heat Pipe in various unfolding configurations by analysing its thermal-hydraulic response throughout a Parabolic Flight. The presented Deployable PHP is composed of an aluminium tube (inner/outer diameters 1.6mm/2.6 mm) and filled with HFE-7000. It is heated at the evaporator using a flat heater and cooled at the condenser with a water-cooled cold plate. T-type thermocouples are used to measure the wall temperature in several locations, while two pressure transducers (one located in the evaporator section and another in the condenser section of the same pipe) measure the local fluid pressure. Additionally, an IR Camera will be used to observe a section of the pipe for further analysis of the flow frequency. The device operation will be tested on ground and 0-g at different heat loads (24W, 34W), in multiple static positions corresponding to different opening angles (0°, 45°, 90°, 135°, 180°) and during its dynamic opening from 0° to 180°, thanks to a remotely controllable motion system.

Cyclic pattern along the downward flame spread over cylindrical samples in partial gravity

Downward flame spread over thin electrical wires is investigated at reduced gravity. The wire is made of a Nickel/Chrome (NiCr) core coated with Low Density PolyEthylene (LDPE). The flame spreads in an opposed flow and the conditions of the free stream, i.e. oxygen content, pressure, and forced flow velocity, are varied. Parabolic flights allow experiments to be performed at various gravity levels to reproduce conditions met on Earth, Mars, the Moon, or in microgravity. Past studies showed that dripping of the molten coating occurs at Earth gravity but disappears in microgravity. A new process is here systematically observed at intermediate gravity levels: while the flame front spreads at a steady rate, a molten droplet of the LDPE coating exhibits a cyclic motion ahead of the flame front. This is driven by the balance among the gravitational, viscous, and adhesion forces. Gravity primarily powers the force driving the droplet away from the flame front, while the adhesion force ensures the droplet’s attachment to the wire. The viscous force critically influences the droplet’s velocity, which shows an inverse relationship with viscosity. This specific cycle can be decomposed into two stages where the aforementioned balance can be evaluated to clarify the conditions of the cycle’s existence. Experimental results show that increasing the oxygen content tends to shorten the cycle by increasing the velocity of the flame front, while increasing the pressure also shortens the cycle by increasing the cooling rate of the droplet. This cyclic behavior can trigger flame extinction at Martian gravity levels, even in scenarios where flames propagate under normal and microgravity conditions. These findings can significantly impact fire safety strategies in environments with intermediate gravity levels.

DMD analysis on sporadic flame behaviors in low-Lewis-number counterflow under microgravity

In order to deepen the understanding on the quasi-steady flame behaviors in counterflow field involving mixtures with low-Lewis number (Le) near lean limit, the experimental and numerical analyses for sporadic flames were carried out. The experiment was conducted with the mixture of Le 0.3 and 0.5 under microgravity environment using parabolic flights of an airplane to eliminate the effect of buoyancy for low-stretch conditions. Three-dimensional numerical simulation with simplified diffusive thermal model was carried out to investigate the three-dimensional structure of sporadic flames. The experimental observations showed the change in the conditions for sporadic flames with changes in Le. The sporadic flames of Le 0.3 could be observed under leaner conditions and endured higher stretch circumstances compared to those observed with Le 0.5. The numerical simulation also reproduced this trend and proved that Le has an important role in the conditions for sporadic flames. To understand the characteristic structure of sporadic flames, the analysis with dynamic mode decomposition (DMD) was conducted. Through this analysis, three characteristic structure modes—planar, radial, and circular—were identified. The decomposed modes showed that the domain of counterflow field could be divided into two; the area forming sporadic flames near the counterflow axis and the area splitting and transporting flame pieces at outer part of the counterflow field. The characteristic length scale was also analyzed using fast Fourier transform (FFT). FFT analysis quantified the characteristic length scale of the decomposed mode of radial and circular. It was also found that the characteristic length scale in radial and angular direction had the same value.

Behavior of glioblastoma brain tumor stem cells following a suborbital rocket flight: reaching the “edge” of outer space

The emerging arena of space exploration has created opportunities to study cancer cell biology in the environments of microgravity and hypergravity. Studying cellular behavior in altered gravity conditions has allowed researchers to make observations of cell function that would otherwise remain unnoticed. The patient-derived QNS108 brain tumor initiating cell line (BTIC), isolated from glioblastoma (GBM) tissue, was launched on a suborbital, parabolic rocket flight conducted by EXOS Aerospace Systems & Technologies. All biologicals and appropriate ground controls were secured post-launch and transported back to our research facility. Cells from the rocket-flight and ground-based controls were isolated from the culture containers and expanded on adherent flasks for two weeks. In vitro migration, proliferation, and stemness assays were performed. Following cell expansion, male nude mice were intracranially injected with either ground-control (GC) or rocket-flight (RF) exposed cells to assess tumorigenic capacity (n = 5 per group). Patient-derived QNS108 BTICs exposed to RF displayed more aggressive tumor growth than the GC cells in vitro and in vivo. RF cells showed significantly higher migration (p < 0.0000) and stemness profiles (p < 0.01) when compared to GC cells. Further, RF cells, when implanted in vivo in the brain of rodents had larger tumor-associated cystic growth areas (p = 0.00029) and decreased survival (p = 0.0172) as compared to those animals that had GC cells implanted.

Conception of a compact flow boiling loop for the International Space Station- First results in parabolic flights

The design of a pipe flow boiling experiment for the International Space Station is proposed, taking into account typical weight, power consumption and size constraints. The effect of singularities such as elbows upstream the test section is investigated. Velocity profiles downstream two elbows, measured by Particle Image Velocimetry are in good agreement with numerical simulation and allow to determine a specific distance (decay length) downstream the elbows for which the velocity profile recover its axisymmetry. From these results a breadboard is designed and tested in parabolic flights. Care has been taken to generate boiling downstream the decay length. Two-phase bubbly flow is observed with 2 perpendicular high-speed cameras in the test section and a symmetry of the bubble distribution in the pipe is verified for different gravity conditions when the bubbles are created after the decay length.

Thermoelectric convection in a planar capacitor: theoretical studies and experiments in parabolic flights

Thermoelectric convection in a plane capacitor is investigated in a microgravity environment and in the case of the thermal stable and unstable stratification in terrestrial conditions. Energetic analysis shows that in the thermal stable stratification, the thermoelectric convection is delayed while in the thermal unstable stratification, it is enhanced by the Archimedean buoyancy before the latter takes over the dielectrophoretic buoyancy and drives natural thermal convection. An experiment in parabolic flights shows the formation of thermoelectric convection at the end of the microgravity phase.

A new experimental set-up for aerosol stability investigations in microgravity conditions

The temporal and spatial evolution of dispersed media is a fundamental problem in a wide range of physicochemical systems, such as emulsions, suspensions and aerosols. These systems are multiphasic and involve compounds of different densities. They are therefore subject to the influence of gravity which determines the sedimentation rate of their dispersed phase. This effect can be dominant and prevent a detailed study of the phenomena occurring between the constituents themselves, such as the coalescence of drops in emulsions, the evaporation of droplets or the flocculation in suspensions. In this context, the Centre National d’Etudes Spatiales (CNES) has recently supported the development of a new instrument to produce populations of droplets, a few micrometers in radius, under controlled conditions with the objective of allowing a detailed study of their properties in microgravity conditions. The principle of this instrument is to generate, by a fast compression/expansion of air, populations of water droplets and to track their evolution by optical scanning tomography in transmission mode within a volume of approximately 2 mm 3 . Parabolic flight experiments have shown the possibility to generate and accurately follow the evolution of populations of several hundred droplets for more than 20 s. The first experimental results show that it is possible to study their evaporation kinetics or their motion when imposing von Karman swirling flows. This work is part of the AEROSOL project of DECLIC-EVO supported by CNES and aims to help the understanding of cloud microphysics which remains a critical open problem in the context of global warming.

30 years of CNES parabolic flights for the benefit of the scientific community

30 years of CNES parabolic flights for the benefit of the scientific community

An engineering model for creeping flame spread over idealized electrical wires in microgravity

Flame spread over an insulated electrical wire is a major source of fire scenario in a space vehicle. In this work, an engineering model that predicts the creeping flame spread over cylindrical wires in microgravity is developed. The model is applied to interpret experimental data obtained in parabolic flights for wires composed by a 0.25 mm radius nickel-chromium (NiCr) metallic core coated by low-density polyethylene (LDPE) of different thicknesses ranging from 0.15 mm to 0.4 mm. The model relies on the assumption that, in the pyrolysis region, the NiCr and the LDPE are in thermal equilibrium. This assumption is supported by more detailed numerical simulations and the model reduces then to solving the heat transfer equations for both NiCr and LDPE in the pyrolysis region and in the region ahead of the flame front along with a simple degradation model for LDPE, an Oseen approximation of opposed oxidizer flow and an infinitely fast gas-phase chemistry. The flame spread rate (FSR) is controlled by two model parameters, which are measurable from intrinsic material and ambient gas properties: the convective flame heat flux transferred to the solid ahead from the flame front and the gaseous thermal heat length near the flame front. These parameters are then calibrated from experimental data for a given wire geometry and the calibrated model is validated against experimental data for other wire geometries and ambient conditions. The heat transfer mechanisms ahead of the pyrolysis front are investigated with a special emphasis on the LDPE thickness and the conductivity of the metallic core. In addition to NiCr, metallic cores of lower and higher conductivities are considered. The polymer is shown to be thermally thick for all tested wire geometries and core conductivities. The flame heat flux is found to dominate the heat transfer in the preheat zone where it applies. The core has nevertheless a significant impact in the heating of the LDPE with its contribution increasing with the core conductivity and when decreasing the LDPE thickness.

Simulative validation of a novel experiment carrier for the Einstein-Elevator

In order to develop hardware that can be used in space, tests under those space conditions are often important to ensure the functionality in advance. Facilities that are used to recreate gravity conditions of space include space stations, satellites, parabolic flights and earthbound facilities. Drop towers are earthbound facilities, that can replicate the gravitational conditions of free falling in space by dropping objects. Those objects would not experience any measurable force due to gravity according to Einstein’s famous thought experiment. The Einstein-Elevator is one of the first active driven drop towers with an experiment carrier falling inside a gondola. A major indicator for the quality of the facility is the residual acceleration of the payload. With the Einstein-Elevators current setup vibrations of the experiment carrier cause measurable residual accelerations of higher than 10^{-3}g. To achieve the targeted 0-g-quality with a residual acceleration of less than 1 mu g (microgravity) in the Einstein-Elevator, a new experiment carrier is required that minimizes the residual acceleration for a payload. This paper describes a design of the experiment carrier for the Einstein-Elevator that is able to reach microgravity and analyzes its functionality using FEM-simulations.

CFD Modeling of Bidirectional PMDs Inside Cryogenic Propellant Tanks Onboard Parabolic Flights

Future cryogenic propulsion systems will require efficient methods for transferring cryogenic propellants from a depot storage tank to a customer receiver tank to minimize costs and maximize reusability. The Reduced Gravity Cryogenic Transfer Project is currently developing advanced cryogenic fluid management technology and developing and validating new numerical models for three phases of transfer: line chill down, tank chill down, and tank fill. Additionally, multiple liquid nitrogen (LN2) parabolic flight transfer rigs are being designed by universities and NASA to investigate the gravitational sensitivities that exist in these three technologies. To maximize the collection of low-g data during flights, it is required to extract as much LN2 as possible from the supply tank, despite variable gravity levels. The purpose of this study is to present computational fluid dynamics volume of fluid simulations of LN2 behavior in the supply tank onboard parabolic flights to validate the optimal design of a bidirectional propellant management device (PMD) using the commercial software FLOW-3D. A parametric study was conducted on the effects of gravity level, fill level, pore size, open area, thickness, and type of baffle on PMD performance. Based on the results, the designed PMD exceeded the targeted expulsion efficiency.

Simplified equations for object trajectories in rotating space habitats and space juggling

Rotating space habitats provide artificial gravity as a physiological countermeasure for long-term space habitation, though the lived experience of a person in these habitats requires further investigation. Movement planning will require adaptation to the Coriolis and centrifugal forces. The multicultural arts of juggling may offer potential psycho-physiological countermeasures for some individuals and provide interesting insights into movement planning and arts in both microgravity and rotating habitats. Previously developed equations of motion for thrown objects in rotating habitats have not been centered within the lived rotating environment. Here, I show a set of simplified equations for object trajectories in rotating environments and their underlying mathematical framework. The full set of possible trajectories for objects thrown in rotating environments is provided and a simplified approach to the Coriolis and centrifugal force differential equation using complex algebra is demonstrated. Experimentation reported in this article was conducted on parabolic flights and an analog weightlessness and rotating apparatus. Near the surface of the Earth, thrown objects travel along parabolas. In rotating space environments, thrown objects will travel along a set of mathematical curves known as roulettes, created by a fixed circle and rolling line with generator point connected to the line. These roulette trajectories will be the everyday experience of every person living in a rotating space habitat, always.

Rehydration outcomes for freeze-dried red blood cells in reduced gravity

Medical planning for space exploration is based on the “floating” blood bank model to store life-saving red blood cells (RBCs) for emergencies. The “floating” blood bank approach is not sufficient in cases where multiple crewmembers are affected by space anemia. In these situations, long-term preserved RBCs will be vital to guarantee the health and safety of crew members. Transfusable RBC units can only be refrigerated for 42 days or frozen at −80 °C. However, storing frozen RBCs at −80 °C is challenging during the confined condition of long-duration space flight. Freeze-dried, viable RBCs would be an appropriate alternative because they can be stored without cooling, are predicted to have a shelf-life of years, and could be transfused immediately after rehydration. This study explores if freeze-dried RBCs can be rehydrated and transfused in reduced gravity with similar outcomes in recovery as observed at Earth gravity. Experiments analyzing freeze-dried RBC recoveries, rehydration fluid dynamics, and transfusion flow rates were analyzed utilizing an experimental glovebox in simulated 0 g during parabolic flights. RBC recoveries and rehydration fluid dynamics for volumes of 5 mL and 10 mL were the same in simulated 0 g compared to results obtained at 1 g. A clinically acceptable range of flow rates for slow intravenous infusion and rapid fluid resuscitation was possible with the simple augmentation of a hand-pumped clinical pressure bag around a unit of rehydrated RBCs. The results demonstrate the potential feasibility of using freeze-dried cells for healthcare during deep-space exploration.

Cryogenic flow boiling in microgravity: Effects of reduced gravity on two-phase fluid physics and heat transfer

With the growing interest in space exploration, cryogenic technologies involving two-phase flow and heat transfer are in high demand to successfully procure advanced space applications such as fuel depots and nuclear thermal propulsion (NTP) systems for deep space missions. However, the unique and extreme thermal properties of cryogenic fluids introduce distinct flow boiling fluid physics and energy transport phenomena, which differ significantly from those observed with conventional fluids. Understanding the unique two-phase physics in cryogenic flow boiling remains an ongoing challenge. Furthermore, the lack of readily available microgravity cryogenic steady-state heat transfer data hinders the assessment of gravitational effects on cryogenic flow boiling. This study aims to elucidate the gravitational effects on two-phase fluid physics and heat transfer by conducting the first-ever experimental measurement of cryogenic flow boiling performance using a steady-state heated method in a reduced gravity environment. Parabolic flight experiments were performed to acquire both heat transfer measurements and high-speed video of interfacial behaviors, under varying gravity levels (microgravity, hypergravity, Lunar gravity, and Martian gravity). The experiments involved flow boiling of liquid nitrogen (LN2) with a near-saturated inlet along a circular heated tube of dimensions 8.5-mm inner diameter and 680-mm heated length. The operating parameters varied are mass velocity of 398.3 – 1342.8 kg/m2s, inlet quality of -0.08 to -0.01, and inlet pressure of 413.68 – 689.48 kPa. Captured microgravity flow patterns range from bubbly to annular, all having vapor structures that are larger than those under higher gravity levels. Under microgravity, absence of buoyancy yields symmetrical vapor structures without flow stratification, laying a physical foundation for the distinct two-phase heat transfer trends during LN2 flow boiling in microgravity. Transient data collected during the flight parabolas exhibited decreasing heated wall temperature as the aircraft transitioned from hypergravity to microgravity phases. The temperature variation indicated an enhancement in flow boiling heat transfer with decreasing gravity levels and a reduction with increasing gravity levels. The effect of reduced gravity on cryogenic flow boiling heat transfer coefficient (HTC) is discussed based on steady state heat transfer analysis. Seminal HTC correlations are evaluated against the measured microgravity HTC data, of which one is identified for superior accuracy in predicting microgravity data. Finally, a new HTC correlation is proposed to improve accuracy of microgravity predictions, yet there still exists room for further improvement with future terrestrial flow boiling experiments at different flow orientations relative to Earth gravity.

Thermo-electric convection in a cylindrical annulus during a sounding rocket flight

An experiment on convective flows induced by the dielectrophoretic force was performed under the microgravity condition provided during a sounding rocket flight. The dielectrophoretic force possesses a non-conservative term that can be seen as resulting from an electric gravity. That gravity can be responsible for an electric Rayleigh–Bénard convection between a hot inner cylinder and a cold outer cylinder when an electric field is applied in the radial direction. Four cells with independent temperature and electric field controls allowed the investigation of eight different values of the electric Rayleigh number relatively close to the onset of the thermo-electric instability. A linear stability analysis is performed to predict the stability threshold and the evolution of the growth rate of the instability. The three-dimensional structure of the flow is captured by simultaneous particle image velocimetry and by shadowgraphy. The amplitude of the instability modes and the time evolution of the flow is analysed, and various methods are proposed to extrapolate the experimental critical value of the electric Rayleigh number for the onset of convection. The measured critical electric Rayleigh number is in agreement with the prediction of the linear stability theory. The comparison of the new experimental results with previous ones from parabolic flight campaigns highlights the importance of long-term microgravity for the achievement of thermal convection at low values of the control parameters.

X-Ray Imaging in the Simulated Microgravity Environment of Parabolic Flight.

INTRODUCTION: The advancement of human spaceflight has made urgent the need to develop medical imaging technology to ensure a high level of in-flight care. To date, only ultrasound has been used in spaceflight. Radiography has multiple advantages over ultrasound, including lower operator dependence, more rapid acquisition, typically higher spatial resolution, and characterization of tissue with acoustic impedance precluding ultrasound. This proof-of-concept work demonstrates for the first time the feasibility of performing human radiographs in microgravity.METHODS: Radiographs of a phantom and human subject's hand, knee, chest, cervical spine, and pelvis were obtained aboard a parabolic flight in microgravity and simulated lunar gravity with various subject and operator positions. Control radiographs were acquired with the same system on the ground. These radiographs were performed with a Food and Drug Administration-approved ultra-portable, wireless, battery-powered, digital x-ray system.RESULTS: The radiographs of the phantom acquired in reduced gravity were qualitatively and quantitatively compared to the ground controls and found to exhibit similar diagnostic adequacy. There was no statistically significant difference in contrast resolution or spatial resolution with a spatial resolution across all imaging environments up to the Nyquist frequency of 3.6 line-pairs/mm and an average contrast-to-noise ratio of 2.44.DISCUSSION: As mass, power, and volume limitations lessen over the coming decades and the miniaturization of imaging equipment continues, in-flight implementation of nonsonographic modalities will become practical. Given the demonstrated ease of use and satisfactory image quality, portable radiography is ready to be the new frontier of space medical imaging.Lerner D, Pohlen M, Wang A, Walter J, Cairnie M, Gifford S. X-ray imaging in the simulated microgravity environment of parabolic flight. Aerosp Med Hum Perform. 2023; 94(10):786-791.

Swiss Parabolic Flights: Development of a Non-Governmental Parabolic Flight Program in Switzerland Based on the Airbus A310 ZERO-G

Parabolic flights are one of the most important pillars for research, development, and applications in space. Accordingly, we developed the world’s first non-governmental parabolic flight program using Novespace’s Airbus A310 ZERO-G. Through the flexible combination of academic research with industrial experiments, as well as with the support of private persons and low administrative efforts, we achieved a highly cost-efficient small-scale campaign concept, which is located at the Air Base Dübendorf in Switzerland. The program was very successful, and it resulted in 31 experiments and tests conducted by Universities and organizations in the industry in microgravity, culminating in many scientific publications and in larger subsequent projects for all users. We describe here how we designed, developed, tested, and built up this program. We also discuss the difficulties, problems, and success factors of a project that—for the first time—was successfully built from the “bottom-up”, and which was a large-scale flight research platform by scientists for scientists on a voluntary, non-governmental, and non-commercial basis.