Parabolic Flight Research Articles

Shared Metabolic Remodeling Processes Characterize the Transcriptome of Arabidopsis thaliana within Various Suborbital Flight Environments

Abstract The increasing availability of flights on suborbital rockets creates new avenues for the study of spaceflight effects on biological systems, particularly of the transitions between hypergravity and microgravity. This paper presents an initial comparison of the responses of Arabidopsis thaliana to suborbital and atmospheric parabolic flights as an important step toward characterizing these emerging suborbital platforms and their effects on biology. Transcriptomic profiling of the response of the Arabidopsis ecotype Wassilewskija (WS) to the aggregate suborbital spaceflight experiences in Blue Origin New Shepard and Virgin Galactic SpaceShipTwo revealed that the transcriptomic load induced by flight differed between the two flights, yet was biologically related to traditional parabolic flight responses. The sku5 skewing mutant and 14-3-3κ:GFP regulatory protein overexpression lines, flown in the Blue Origin and parabolic flights, respectively, each showed altered intra-platform responses compared to WS. An additional parabolic flight using the F-104 Starfighter showed that the response of 14-3-3κ:GFP to flight was modulated in a similar manner to the WS line. Despite the differing genotypes, experimental workflows, flight profiles, and platforms, differential gene expression linked to remodeling of central metabolic processes was commonly observed in the flight responses. However, the timing and directionality of differentially expressed genes involved in the conserved processes differed among the platforms. The processes included carbon and nitrogen metabolism, branched-chain amino acid degradation, and hypoxic responses. The data presented herein highlight the potential for various suborbital platforms to contribute insights into biological responses to spaceflight, and further suggest that in-flight fixation during suborbital experiments will enhance insights into responses during each phase of flight.

Autonomous navigation system for free floating experiments in parabolic flights

Abstract This paper presents the development of an Extended Kalman Filter for the navigation system of a spacecraft in a parabolic flight. The algorithm blends the measurements coming from two Inertia Measurement Units, one mounted on the spacecraft and one on the baseplate of the aircraft; and a camera system connected to the baseplate as well. During the zero-g phases the attitude and position of the spacecraft in the experimental area are recovered thanks to a series of Alvar markers attached on the spacecraft casing and detected by the camera system. Results from parabolic test campaign of October 2019 are finally presented.

Dynamics of single hydrogen bubbles at Pt microelectrodes in microgravity.

The dynamics of single hydrogen bubbles electrogenerated in acidic electrolytes at a Pt microelectrode under potentiostatic conditions is investigated in microgravity during parabolic flights. Three bubble evolution scenarios have been identified depending on the electric potential applied and the acid concentration. The dominant scenario, characterized by lateral detachment of the grown bubble, is studied in detail. For that purpose, the evolution of the bubble radius, electric current and bubble trajectories, as well as the bubble lifetime are comprehensively addressed for different potentials and electrolyte concentrations. We focus particularly on analyzing bubble-bubble coalescence events which are responsible for reversals of the direction of bubble motion. Finally, as parabolic flights also permit hypergravity conditions, a detailed comparison of the characteristic bubble phenomena at various levels of gravity is drawn.

Urologic Innovation in the Spaceflight Environment: Challenges, Opportunities, and Future Directions

The coming decades are poised to usher in an era of commercial spaceflight and extended duration missions beyond low-earth orbit. Urologic challenges and conditions have been central to the history of human spaceflight, and their effective management will continue to play a key role in future endeavors. Voiding equipment, such as the Universal Waste Management System aboard the International Space Station, is emblematic of the significant technical strides that have been made to improve the usability and functionality of non-terrestrial waste elimination and containment devices. Detailed investigations over the past few decades have demonstrated that crew members are at an increased risk of developing nephrolithiasis due, in large part, to the effects of microgravity. Renal calculi and their potentially debilitating effects represent one of the most significant urologic complications that could impact the success of future long duration missions. Other urologic conditions, such as urinary tract infections, urinary retention, and urinary incontinence have been well documented during flight and pose their own challenges. While preventive measures remain central to all mitigation strategies, imaging and treatment modalities such as a S-Mode ultrasound, burst wave lithotripsy, and ultrasonic propulsion are being developed and evaluated as in-flight countermeasures for urologic pathology. Parabolic flights have been conducted to develop and evaluate the feasibility of using surgical and endoscopic techniques to treat urologic conditions in microgravity. Although less often discussed, occupation-related delayed conception and the risk of radiation-induced gamete damage suggests that there may be a need for NASA to adopt a policy for Assisted Reproductive Technology for both male and female astronauts. The last 60 years of human spaceflight have provided a unique opportunity for discovery and medical technology innovation. This paper serves to highlight the advancements that will help pave the way for the next 60 years of human spaceflight.

Cluster dynamics in dense granular gases of rod-like particles

Granular gases are interesting multiparticle systems which, irrespective of the apparent simplicity of particle interactions, exhibit a rich scenario of so far only little understood features. We have numerically investigated a dense granular gas composed of frictional spherocylinders which are excited mechanically by lateral vibrating container walls. This study was stimulated by experiments in microgravity on parabolic flights. The formation of spatial inhomogeneities (clusters) was observed in a region near the corners of the container, about halfway from the excitation plates. The particles in the clusters show a tendency to align parallel to the container walls, seemingly increasing the stabilizing effect of friction. The simulation results provide hints that the phase difference of the vibrations of the two excitation walls might affect the cluster dynamics.

Probing regolith-covered surfaces in low gravity

The surfaces of many planetary bodies, including asteroids, moons, and planets, are composed of rubble-like grains held together by varying levels of gravitational attraction and cohesive forces. Future instrumentation for operation on, and interacting with, such surfaces will require efficient and effective design principles and methods of testing. Here we present results from the EMPANADA experiment (Ejecta-Minimizing Protocols for Applications Needing Anchoring or Digging on Asteroids) which flew on several reduced gravity parabolic flights. EMPANADA studies the effects of the insertion of a flexible probe into a granular medium as a function of ambient gravity. This is done for an idealized 2D system as well as a more realistic 3D sample. To quantify the dynamics inside the 2D granular material we employ photoelasticity to identify the grain-scale forces throughout the system, while in 3D experiments we use simulated regolith. Experiments were conducted at three different levels of gravity: martian, lunar, and microgravity. In this work, we demonstrate that the photoelastic technique provides results that complement traditional load cell measurements in the 2D sample, and show that the idealized system exhibits similar behaviour to the more realistic 3D sample. We note that the presence of discrete, stick-slip failure events depends on the gravitational acceleration.

Contactless measurement of temperaturedependent viscosity and surface tension of liquid Al69.1Cu12.8Ag18.1 eutectic alloy under microgravity conditions using the oscillating-drop-method

Thermophysical properties of the Al69.1Cu12.8Ag18.1 eutectic liquid alloy are of particular interest for support of self-and inter-diffusion studies. In the presented work, Al69.1Cu12.8Ag18.1-samples were processed contactlessly by electromagnetic levitation under microgravity conditions using the TEMPUS facility. The measurements were performed onboard the Airbus A310 Zero-G in parabolic flight campaigns. The oscillating-drop-method (ODM) was used for measurements of the viscosity via oscillations damping and surface tension via oscillations frequency. These were determined for temperatures in the range of 900–1500 K by analysis of the oscillation spectrum obtained from the electrical impedance. The latter was measured using the Sample Coupling Electronics. An Arrhenius-law η(T) ∝η∞ exp(Eη /RT) was used to fit the temperature-dependent viscosity data. The resulting fit parameters were η∞ = (0.632±0.160) mPas and activation energy of viscous flow Eη = (2.344±0.233) · 104 J/mol. A linear law γ(T) = γl + γT (T - Tm) was fit to the surface tension data yielding γl = (0.9013±0.02625) Nm−1 and γT = −(0.7462±0.2675)·10−4 Nm−1 K−1. The Kozlov-model was applied to determine the enthalphy of mixing as ΔHmix = -(18.576±0.018)kJ/mol.

Spaceflight not an eye-popping experience for astronauts.

Spaceflight not an eye-popping experience for astronauts.

How to Test a Medical Technology for Space: Trauma Sonography in Microgravity

Preventable trauma deaths in remote environments often result from inadequate diagnosis of thoracic and abdominal injuries. Full-time habitation of the International Space Station increases the risk of traumatic injury requiring intervention. This publication describes the evaluation of trauma sonography (TS) as a noninvasive, fast and effective space-based imaging tool for diagnosing intracavity hemorrhage or visceral leakage. The NASA Space Medicine Clinical Care Capability Development Project is using a four-phase approach: 1) identify terrestrial techniques for human diagnosis through literature or ground studies; 2) develop and test a model at 1-g if microgravity evaluations are required; 3) evaluate the model in microgravity (parabolic or shuttle flight); 4) implement the technology or technique for clinical use aboard the shuttle or space station. The Phase I literature review confirmed TS as the screening tool of choice for blunt trauma in most North American hospitals. In Phase II, an animal model was developed and tested for 1-g ground studies in which either fluid or air was injected into specific anatomical sites. Trained sonographers, using standard ultrasound techniques, successfully detected the fluid and air. The animal model was then prepared for the NASA KC-135 Microgravity Laboratory (Phase III). Injection and examination procedures were synchronized to the pull-in, 0-g and pull-out segments of the parabolic flight manoeuvres. Preliminary results indicate that trauma sonography is a clinically useful tool in microgravity. Phase IV efforts will address training, procedures, hardware, and data transfer requirements necessary to implement this technique for space.

Phase Separation in Porous Media Integrated Capillary Channels

Phase separation in space is critical for gas-free propellant supply, life support systems, refueling of spacecraft in low earth orbit (LEO), and for deep space exploration missions. In the absence of gravity, the stability of the liquid-gas interface depends on capillary forces. High liquid flow rates, sudden accelerations, and vibrational disturbances can cause the free surface of the liquid to collapse, which results in the ingestion of gas. Propellant tanks may have screen channel liquid acquisition devices (SCLADs) to position and maintain a gas-free propellant supply to the outlet. A saturated porous screen permits liquid to pass through but acts as a barrier to the gas. We investigated phase separation in porous media integrated capillary channels during parabolic flights (33rd DLR parabolic flight campaign in March 2019). An open side of a rectangular channel was covered with a dutch twill weave 200×1400. The liquid was ingested into the channel from its surroundings by establishing a differential pressure across the screen section. The gas-phase was blocked during the liquid withdrawal. We could show that the gas breakthrough occurs when the pressure difference across the screen exceeds the bubble point pressure. The experimental results showed good agreement with correlations from literature.

Next-generation sequencing analysis of circulating micro-RNA expression in response to parabolic flight as a spaceflight analogue

Understanding physiologic reactions to weightlessness is an indispensable requirement for safe human space missions. This study aims to analyse changes in the expression of circulating miRNAs following exposure to gravitational changes. Eight healthy volunteers (age: 24.5 years, male: 4, female: 4) were included. Each subject underwent 31 short-term phases of weightlessness and hypergravity induced by parabolic flight as a spaceflight analogue. At baseline, 1 and 24 h after parabolic flight, venous blood was withdrawn. Analysis of circulating miRNAs in serum was conducted by means of next generation sequencing. In total, 213 miRNAs were robustly detected (TPM > 5) by small RNA sequencing in all 24 samples. Four miRNAs evidenced a significant change in expression after adjusting for multiple testing. Only miR-223-3p showed a consistent significant decrease 24 h after parabolic flight compared to baseline values and values at 1 h after parabolic flight. miR-941 and miR-24-3p showed a significant decrease 24 h after parabolic flight compared to 1 h after parabolic flight but not to baseline values. miR-486-5p showed a significant increase 24 h after parabolic flight compared to 1 h after parabolic flight but not to baseline values. A target network analysis identified genes of the p53 signaling pathway and the cell cycle highly enriched among the targets of the four microRNAs. Our findings suggest cellular adaption to gravitational changes at the post-transcriptional level. Based on our results, we suggest a change in cell cycle regulation as potential explanation for adaptational changes observed in space missions.

Stabilisation of condensate flow from curvilinear surfaces by means of porous media for space applications

A new concept of vapour condenser is proposed to solve the drainage problem and to provide an effective condensate flow under weightlessness conditions. The concept combines the capability of a curvilinear surface to drive liquid, and a combination of a porous media and a pump, as an active condensate retraction system. The porous media collects and stores the condensed fluid and acts as a barrier for the vapour phase. Hydrodynamic validation of the liquid flow was done against retraction overflow under terrestrial conditions. It was figured out that the time available for adjusting the retraction system to avoid film disturbances decreased non-linearly with an increase in retraction overflow. The behaviour of the proposed condenser with the retraction system was tested under weightlessness condition during the ESA parabolic flights campaign as a part of concept validation. Three porous media with different values of the pore size and material were tested. It was found that the combination of the pump and porous media helped to improve the condensate flow. It was observed that the stabilisation effect was influencing the condensate flow not only during weightlessness condition but also under acceleration disturbances during the campaign.

Acoustic Manipulation of Dense Nanorods in Microgravity

Because the absence of sedimentation in zero-gravity makes the culture and the manipulation of cells or particles challenging, an attractive alternative is to use the Acoustic Radiation Force (ARF) as an artificial “acoustic gravity.” To evaluate the potential of this approach we studied the behavior of dense gold nanorods under ARF during a parabolic flight campaign. Using dense objects enhances the effect of gravity on the axial position of the so-called “levitation plane,” which is the equilibrium position at which ARF balances gravity in the laboratory. Further, using elongated objects, instead of spherical particles provides information about their spatial orientations in addition to their propulsion observed in standard gravity conditions. Our experiments clearly show a different collective organization and individual behavior of the rods in micro-gravity conditions. First, the axial location of the levitation plane is different in microgravity than in hypergravity: it matches the nodal pressure plane in microgravity while it is much lower than the nodal plane in hypergravity. Our experiments also show a sharp transition from horizontal to axial orientation of the rods axis. The propulsion of the rods also stops when transitioning to micro-gravity. A possible explanation for the sudden change of orientation and stopping of propulsion is the modification of the equilibrium between the axial and transverse components of the ARF. While these experiments show that some phenomena, like the propulsion of nanorods by ARF, may not be applicable in microgravity, they do confirm that acoustic manipulation of particles or cells in microgravity is possible, which paves for the development of many useful techniques for particles or cells manipulation, like cell cultures, during long-term space travel.

Experimental Characterization of Weightlessness During Glider Parabolic Flights

Access to earthbound weightlessness is critical to many branches of applied sciences. Besides, several space systems require microgravity testing before their launch. Existing solutions (drop towers, parabolic flights, sounding rockets) offer variable durations and qualities of microgravity environment, but their cost and lead times make them unpractical for small actors such as universities or start-up companies. This leads to a growing interest for alternative microgravity platforms. Here, we study the use of gliders to perform parabolic flights at a lower cost, and we propose a systematic quantification of glider’s 0-g flight capabilities. Results of our flight test campaign show that gliders offer up to 5.5s of weightlessness, with excursions below 0.1g, and a satisfactory level of repeatability. Besides, the recordings do not suffer from the increased level of vibrations generated by piston engines, typical of light-aircraft-based alternatives. Operational considerations associated with glider parabolic flights are also discussed. Finally, we conclude that a microgravity platform based on gliders would be suitable especially for compact experiments and equipment in order to support accelerated design and development, or to produce preliminary experimental results.

Crystal Growth of [Ca3Al(OH)6·12H2O]2·(SO4)3·2H2O (Ettringite) Studied Under Microgravity Conditions

On parabolic flights, the growth of ettringite, [Ca3Al(OH)6·12H2O]2·(SO4)3·2H2O, a major reaction product of cement with water which forms instantaneously, was crystallized under microgravity conditions and studied. In the experiments, Ca(OH)2/Al2(SO4)3 solutions were combined and reacted for 10 s, followed by immediate filtration of the suspension and subsequent quenching with acetone. For the ettringite crystals, the size, aspect ratios, quantity and morphology were determined and the results were compared with those from identical experiments performed under terrestric gravity. Under microgravity, generally smaller crystals (l–2.9 µm) precipitated in larger amount than under normal gravity (1–3.5 µm). The aspect ratios of the crystals grown under terrestric or microgravity condition were comparable at about 5.6. It is assumed that the reason for the smaller ettringite crystals is the absence of convection leading to more initial nuclei, but slower crystal growth which is diffusion limited. Apparently, no preference relative to the ion transport to the different faces of the crystals exists. The results contribute to the understanding of the mineralization of inorganic salts under microgravity conditions for which hitherto only a handful of examples were reported.

Dressing the weightless body: Subjective verticality and the disoriented experience of dress in microgravity

Design practice has historically been constrained by the assumption that designed objects, including clothing, will be made and worn in Earth gravity. The notion that designed objects have an upright state has influenced common approaches to design, including the tendency towards depiction and presentation of designed objects in elevation view, which, for fashion, is frequently understood in terms of silhouette. However, those who have experienced weightlessness, either in space travel or on board reduced-gravity aircraft, describe a post-gravity experience that prompts them to revisit these assumptions and consider the extent to which future commercial space travel will liberate creative practitioners to operate at all angles and orientations. As we enter the commercial space age, fashion will be increasingly worn in a variety of gravitational conditions, and the dressed body will therefore be encountered at a variety of orientations, showcasing views of garments that are not often encountered on Earth, and that are therefore often overlooked by fashion designers. This article responds to descriptions of the post-gravity experience by identifying the need to consider alternative views of the clothed body, and consequently to define garments without reference to the silhouette in fashion design for the new commercial space age.

The effect of hypergravity on upright balance and voluntary sway.

We compared voluntary oscillatory sway for eight subjects tested in 1.8-g and 1-g gravito-inertial force (GIF) levels of parabolic flight. Subjects performed voluntary forward-backward (FB) and lateral left-right (LR) swaying as the forces and moments under the soles of each foot were measured. We calculated the experimental values of three parameters: two ankle stiffness parameters KSAP and KSML acting in orthogonal FB and LR directions and one parameter KED related to leg pivot shifting. Simulations of the engaged leg model (Bakshi A, DiZio P, Lackner JR. J Neurophysiol 121: 2042-2060, 2019; Bakshi A, DiZio P, Lackner JR. J Neurophysiol 121: 2028-2041, 2019) correctly predicted the experimentally determined stability bounds of upright balance and also the scaling of the postural parameters as a function of GIF magnitude. The effective stiffness, KSAP, at the ankles played the primary role to prevent falling in FB swaying and both model predictions, and experimental data showed KSAP to scale up in proportion to GIF magnitude. For LR swaying, the model predicted a 3:4 scaling of anterior-posterior stiffness to change in GIF magnitude, which was borne out by the experimental data. Simulations predict stability (nonfalling) not to depend on lateral stiffness, KSML, which was experimentally found not to depend on the GIF magnitude. Both model and experiment showed that the geometry-dependent pivot shift parameter KED was invariant to a change in GIF magnitude. Thus the ELM explains voluntary sway and balance in altered GIF magnitude conditions, rotating environments with Coriolis perturbations of sway, as well as normal terrestrial conditions.NEW & NOTEWORTHY A nonparallel leg model of balance, the engaged leg model (ELM), was previously developed to characterize adaptive balance control in a rotating environment. Here we show the ELM also explains sway in hypergravity. It predicts the changes in balance control parameters with changes in gravity. ELM is currently the only balance model applicable to artificial and hypergravity conditions. ELM can also be applied to terrestrial clinical situations for pathologies that generate postural asymmetries.

Pressure effects on the soot production and radiative heat transfer of non-buoyant laminar diffusion flames spreading in opposed flow over insulated wires

Abstract This paper investigates experimentally and numerically pressure effects on soot production and radiative heat transfer in non-buoyant opposed-flow flames spreading over wires coated by Low Density PolyEthylene (LDPE). Experiments, conducted in parabolic flights, consider pressure levels ranging from 50.7 kPa to 121.6 kPa and an oxidizer flowing parallel to the wire's axis at a velocity of 150 mm/s and composed of 20% O2/80% N2 in volume. The numerical model includes a detailed chemistry, a two-equation smoke-point based soot production model, a radiation model coupling the Full-Spectrum correlated-k method with the finite volume method and a simple degradation model for LDPE. An analysis of the experimental data shows that the spread rate, the pyrolysis mass flow rate, and the residence time for soot formation are independent of pressure whereas the soot formation rate is third-order in pressure. The model reproduces quantitatively the effects of pressure on soot production and captures the transition from non-smoking to smoking flames. The radiant fraction increases with pressure because of an enhancement in soot radiation whereas the contribution of radiating gases remains approximately constant over the range of pressures considered. In addition, gas radiation dominates at pressure lower than 75 kPa whereas soot radiation prevails at higher-pressure levels. Consistently with the data obtained at normal gravity, the smoke-point transition is found to occur for a radiant fraction of about 0.3 and the soot oxidation freezing temperature is estimated in the range 1350–1450 K. Eventually, whatever the pressure considered, the surface re-radiation from the wire is higher than the incident radiative flux from the flame to the surface along the entire wire. This shows that radiative heat transfer contributes negatively to the heating of the unburnt LDPE and to the heat balance along the pyrolysing surface.

Brain stimulation in zero gravity: transcranial magnetic stimulation (TMS) motor threshold decreases during zero gravity induced by parabolic flight

We are just beginning to understand how spaceflight may impact brain function. As NASA proceeds with plans to send astronauts to the Moon and commercial space travel interest increases, it is critical to understand how the human brain and peripheral nervous system respond to zero gravity. Here, we developed and refined head-worn transcranial magnetic stimulation (TMS) systems capable of reliably and quickly determining the amount of electromagnetism each individual needs to detect electromyographic (EMG) threshold levels in the thumb (called the resting motor threshold (rMT)). We then collected rMTs in 10 healthy adult participants in the laboratory at baseline, and subsequently at three time points onboard an airplane: (T1) pre-flight at Earth gravity, (T2) during zero gravity periods induced by parabolic flight and (T3) post-flight at Earth gravity. Overall, the subjects required 12.6% less electromagnetism applied to the brain to cause thumb muscle activation during weightlessness compared to Earth gravity, suggesting neurophysiological changes occur during brief periods of zero gravity. We discuss several candidate explanations for this finding, including upward shift of the brain within the skull, acute increases in cortical excitability, changes in intracranial pressure, and diffuse spinal or neuromuscular system effects. All of these possible explanations warrant further study. In summary, we documented neurophysiological changes during brief episodes of zero gravity and thus highlighting the need for further studies of human brain function in altered gravity conditions to optimally prepare for prolonged microgravity exposure during spaceflight.

Computational investigation of annular flow condensation in microgravity with two-phase inlet conditions

Condensation heat exchangers contribute significantly to the size of the thermal management system, and their implementation in future spacecraft will require a better understanding of the underlying heat transfer phenomena. In this study, we computationally investigate flow condensation in microgravity with two-phase inlet conditions utilizing the VOF multi-phase model and a 2-dimensional axisymmetric domain. The model is validated utilizing experiments from prior microgravity flow condensation tests conducted onboard a parabolic flight. A control-volume-based theoretical model is utilized to estimate the inlet vapor fraction and inlet phase velocity boundary conditions. The computational model predicts complex flow behavior occurring at the two-phase interface during condensation, but the model suffers from some liquid accumulation in the vapor region. Local condensation heat transfer is under-estimated in the inlet section, and over-estimated in the exit section, compared with the experimental measurements. Mean condensation heat transfer coefficients compare well to experiments. Results show a need for full 3D simulations of flow condensation to improve predictions of liquid entrainment and liquid deposition phenomena that significantly influence local heat transfer coefficients predictions