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NASA NTRS2016

Microspine Gripping Mechanism for Asteroid Capture

This paper details the development and early testing of a compliant suspension for a microspine gripper device for asteroid capture or micro-gravity percussive drilling. The microspine gripper architecture is reviewed, and a proposed microspine suspension design is presented and discussed. Prototyping methods are discussed, as well as testing methods and results. A path forward is identified from the results of the testing completed thus far. Key findings include: the microspine concept has been established as a valid architecture and the compliant suspension exhibits the desired stiffness characteristics for good gripping behavior. These developments will aid in developing the capability to grasp irregularly shaped boulders in micro-gravity.

Merriam, Ezekiel G.↗

NASA NTRS2017

Blockage Testing in the NASA Glenn 225 Square Centimeter Supersonic Wind Tunnel

A feasibility study is in progress at NASA Glenn Research Center to implement a magnetic suspension and balance system in the 225 sq cm Supersonic Wind Tunnel for the purpose of testing the dynamic stability of blunt bodies. An important area of investigation in this study was determining the optimum size of the model and the iron spherical core inside of it. In order to minimize the required magnetic field and thus the size of the magnetic suspension system, it was determined that the test model should be as large as possible. Blockage tests were conducted to determine the largest possible model that would allow for tunnel start at Mach 2, 2.5, and 3. Three different forebody model geometries were tested at different Mach numbers, axial locations in the tunnel, and in both a square and axisymmetric test section. Experimental results showed that different model geometries produced more varied results at higher Mach Numbers. It was also shown that testing closer to the nozzle allowed larger models to start compared with testing near the end of the test section. Finally, allowable model blockage was larger in the axisymmetric test section compared with the square test section at the same Mach number. This testing answered key questions posed by the feasibility study and will be used in the future to dictate model size and performance required from the magnetic suspension system.

entry vehicles↗

NASA NTRS2017

Drag-Free Control and Drag Force Recovery of Small Satellites

Drag-free satellites provide autonomous precision orbit determination, accurately map the static and time varying components of Earth's mass distribution, aid in our understanding of the fundamental force of gravity, and will ultimately open up a new window to our universe through the detection and observation of gravitational waves. At the heart of this technology is a gravitational reference sensor, which (a) contains and shields a free-floating proof mass from all non-gravitational forces, and (b) precisely measures the position of the test mass inside the sensor. Thus, both test mass and spacecraft follow a pure geodesic in spacetime. By tracking the position of a low Earth orbiting drag-free satellite we can directly determine the detailed shape of geodesics and through analysis, the higher order harmonics of the Earths geopotential. This paper explores two different drag-free control systems on small satellites. The first drag-free control system is a continuously compensated single thruster 3-unit CubeSat with a suspension-free spherical proof-mass. A feedback control system commands the thruster and Attitude and Determination Control System to fly the tender spacecraft with respect to the test mass. The spheres position is sensed with a LED-based differential optical shadow sensor, its electric charge controlled by photoemission using UV LEDs, and the spacecraft position is maintained with respect to the sphere using an ion electrospray propulsion system. This configuration is the most fuel-efficient drag-free system possible today. The second drag-free control system is an electro-statically suspended cubical proof-mass that is operated with a low duty cycle, limiting suspension force noise over brief, known time intervals on a small GRACE-II -like satellite. The readout is performed using a laser interferometer, which is immune to the dynamic range limitations of voltage references. This system eliminates the need for a thruster, enabling drag-free control systems for passive satellites. In both cases, the test mass position, GPS tracking data, and commanded actuation, either thrust or suspension system, can be analyzed to estimate the 3-axis drag forces acting on the satellite. The data produces the most precise maps of upper atmospheric drag forces and with additional information, detailed models that describe the dynamics of the upper atmosphere and its impact on all satellites that orbit the Earth. This paper highlights the history, applications, design, laboratory technology development and highly detailed simulation results of each control system.

Small Satellites↗

NASA NTRS2015

Development of the Resource Prospector Planetary Rover

The Resource Prospector (RP) is an In-‐Situ Resource Utilization (ISRU) lunar rover mission under study by NASA. RP is planned to launch in 2020 to prospect for subsurface volatiles and to extract oxygen from lunar regolith. The mission will address several of NASA's "Strategic Knowledge Gaps" for lunar exploration. The mission will also address the Global Exploration Roadmap's strategic goal of using local resources for human exploration. The distribution of lunar subsurface volatiles drives the mission requirement for mobility. The spatial distribution is hypothesized to be governed by impact cratering with the top 0.5 m being patchy at scales of 100 m. The mixing time scale increases with depth (less frequent larger impacts). Consequently, increased mobility reduces the depth requirement for sampling. The target RP traverse will extend 1 km radially from the landing site to sample craters of varying sizes. Sampling craters with different ages will reveal possible volatile emplacement history. In 1 Ga, approximately 60-70 craters of 10 m diameter form per km2. Thus, the rover will need to sample at least ten of these craters, which may require a total traverse path length of 2-‐3 km. During 2014-2015, we developed an initial prototype rover for RP. The current design is a solar powered, four-wheeled vehicle, with hub motor drive, offset four wheel steering, and active suspension. Active suspension provides capabilities including changing vehicle ride height, traversing comparatively large obstacles, and controlling load on the wheels. All-wheel steering enables the vehicle to point arbitrarily while roving, e.g., to keep the solar array pointed at the sun while in motion. The offset steering combined with active suspension improves driving in soft soil. The rover's on-board software utilizes NASA's Core Flight Software, which is a reusable flight software environment. During 2015, we completed the initial rover software build, which provides low-level hardware interfaces, basic mobility control, waypoint driving, odometry, basic error checking, and camera services. Development of the prototype rover has enabled maturation of many of the subsystems to TRL 5. During the next year, we will conduct integrated testing of concepts of operation, navigation, and remote driving tools. In addition, we will perform environmental tests including radiation (avionics), thermal and thermal/vacuum (mechanisms), and gravity offload (mobility).

robotics↗

NASA NTRS2016

Microspine Gripping Mechanism for Asteroid Capture

This paper details the development and early testing of a compliant suspension for a microspine gripper device for asteroid capture or zero-gravity percussive drilling. The microspine gripper architecture is reviewed, and a proposed microspine suspension design is presented and discussed. Prototyping methods are discussed, as well as testing methods and results. A path forward is identified from the results of the testing completed thus far. Key findings include: the microspine concept has been established as a valid architecture and the compliant suspension exhibits the desired stiffness characteristics for good gripping behavior. These developments will aid in developing the capability to grasp irregularly shaped boulders in microgravity.

Merriam, Ezekiel G.↗

NASA NTRSDate not supplied

Correlation of Canopy Distortion with Asymmetric Loading in Large Diameter Ringsail Parachutes

The second generation of the main parachutes for the Orion Capsule Parachute Assembly System (CPAS) were subjected to multiple flight tests. Three of the tests included were instrumented with the Tension Measuring System (TMS) to record main dispersion bridle loads. While these units were not able to resolve the individual suspension line loads, they were able to record a course representation of the asymmetric loading of the main parachutes during inflation. These tests were also equipped with upward looking cameras mounted on the test vehicles to collect detailed imagery of main deployment and inflation. When analyzed independently, both data sources exhibit similar features. These similarities provide evidence that the suspension line loads and the distortions in the canopy geometry are not independent. This paper will examine both data sources simultaneously to establish a correlation between asymmetric loading at the canopy skirt and the deformations of the canopy. This correlation will be used to build a model which can estimate individual suspension line loads from a measured riser load and detailed imagery.

Parachutes↗

NASA NTRSDate not supplied

Optimizing Single Nuclei Sequencing of Brain Samples From Space Flown Mice Across Age and Strain

The NASA GeneLab Sample Processing Laboratory offers high-throughput sequencing services to NASA-funded space biology researchers. Space biology studies have specific challenges such as low sample numbers, introducing susceptibility to batch effects from sample handling. These issues are compounded by complex protocols such as single-nuclei isolation and sequencing, which has recently become an attractive methodology for assessing the cellular diversity within spaceflight samples. High quality single-nuclei sequencing requires reproducible protocols to dissociate tissue and generate clean suspension of intact single nuclei. Producing single-nuclei suspension from brain tissue is particularly challenging due to cell type heterogeneity and the myelin sheath that carries over into the nuclei suspension as debris. Current procedures tend to be time consuming and sometimes include steps that can alter gene expression and create cell-type bias. Commercially available nuclei isolation kits, such as the 10X Genomics nuclei isolation kit, offers a streamlined way to process samples for nuclei isolation, thereby minimizing batch effects and enabling reproducibility. In this study, we report on the performance of the 10X Genomics nuclei isolation kit and Chromium Next GEM Single Cell Multiome ATAC + Gene Expression kit to generate sequencing libraries from space-flown mouse brain samples. Single nuclei sequencing was performed on frozen mouse brain tissue from two spaceflight missions, Rodent Research-10 (RR-10) and RR Reference Mission-2 (RRRM-2). RR-10 mice were female B6129SF2/J, euthanized at 18-19 weeks whereas RRRM-2 mice were female C57BL/6NTac, euthanized at 20 or 37 weeks. Sequencing data was processed using standard GeneLab data processing pipelines. We report evaluation of the performance of the 10X Genomics nuclei isolation kit for spaceflight samples from mouse brain, and evaluation of reproducibility across different mouse strains and age groups. We also report preliminary scientific results including cell type inference, cell clustering, and differentially expressed genes and pathways between spaceflight and ground control samples.

RR-10↗

NASA NTRS2001

The Spacelab 3 simulation: basis for a model of growth plate response in microgravity in the rat

Data from Spacelab 3 (SL3) suggested that spaceflight significantly reduces the activity of the rat tibial growth plate. Animal processing after SL3 began twelve hours post-landing, so data reflect post-flight re-adaptation in addition to spaceflight effects. To determine if a twelve-hour period of weight bearing after seven days of unloading could affect the physes of spaceflown rats, the present study assessed the growth plate response to unloading with or without a reloading period. Rats were subjected to hind-limb suspension for seven days and then euthanized, with or without twelve hours of reloading. Activity of the growth plate was assessed by morphometric analysis. Rats suspended without reloading had reserve zone (RZ) height greater than controls, and shorter hypertrophy/calcification zone (HCZ) with fewer cells. The greater RZ was associated with a larger cell area, indicating a possible mitotic delay or secretion defect. Twelve hours of reloading decreased RZ height and cell number, and restored the number of cells in HCZ to control values, but the number of cells in the proliferative zone and height in HCZ were reduced. These results suggest the rebound response to preserve/restore skeletal function after a period of unloading involves an acceleration of growth associated with a decreased cell cycle time in PZ. Changes during the reloading period in this simulation support our hypothesis that the effects of spaceflight on SL3 growth plates were altered by changes that occurred post-landing. The similarities in response to unloading by suspension or during spaceflight are used to propose a model of growth plate response during spaceflight.

manned↗

NASA NTRS1997

Growth hormone, IGF-I, and exercise effects on non-weight-bearing fast muscles of hypophysectomized rats

The effects of growth hormone (GH) or insulin-like growth factor I (IGF-I) with or without exercise (ladder climbing) in countering the effects of unweighting on fast muscles of hypophysectomized rats during 10 days of hindlimb suspension were determined. Compared with untreated suspended rats, muscle weights were 16-29% larger in GH-treated and 5-15% larger in IGF-I-treated suspended rats. Exercise alone had no effect on muscle weights. Compared with ambulatory control, the medial gastrocnemius weight in suspended, exercised rats was larger after GH treatment and maintained with IGF-I treatment. The combination of GH or IGF-I plus exercise in suspended rats resulted in an increase in size of each predominant fiber type, i.e., types I, I + IIa and IIa + IIx, in the medial gastrocnemius compared with untreated suspended rats. Normal ambulation or exercise during suspension increased the proportion of fibers expressing embryonic myosin heavy chain in hypophysectomized rats. The phenotype of the medial gastrocnemius was minimally affected by GH, IGF-I, and/or exercise. These results show that there is an IGF-I, as well as a GH, and exercise interactive effect in maintaining medial gastrocnemius fiber size in suspended hypophysectomized rats.

NASA Center ARC↗

NASA NTRS2004

Load-dependent regulation of neuromuscular system

Roles of gravitational loading, sarcomere length, and/or tension development on the electromyogram (EMG) of soleus and afferent neurogram recorded at the L5 segmental level of spinal cord were investigated during parabolic flight of a jet airplane or hindlimb suspension in conscious rats. Both EMG and neurogram levels were increased when the gravity levels were elevated from 1-G to 2-G during the parabolic flight. They were decreased when the hindlimbs were unloaded by exposure to actual microgravity or by suspension. These phenomena were related to passive shortening of muscle fibers and/or sarcomeres. Unloading-related decrease in sarcomere length was greater at the central rather than the proximal and distal regions of fibers. These activities and tension development were not detected when the mean sarcomere length was less than 2.03 micrometers. It is suggested that load-dependent regulation of neuromuscular system is related to the tension development which is influenced by sarcomere length.

short duration↗

NASA NTRS1961

Photosynthetic Gas Exchange in the Closed Ecosystem for Space. Phase II, Part II. Studies on the Growth of Thermophilic Chlorella 71105

Bench-scale studies with Chlorella pyrenoidosa 71105 were conducted in four- and eight-liter culture vessels, with and without recycling. It was established that the algal strain could be maintained for periods up to 72 days with supplemented re-cycled medium. In a factorial series of experiments, the highest yields were obtained with a 2.0% concentration of carbon dioxide, a 0.07 dilution factor (nutrient dilution rate/culture volume), and an 8.5 ft(exp -1) ratio of light surface to liquid culture volume. Optimum pH and concentrations of the constituents of the growth medium were determined in corollary test-tube studies. Other test-tube studies showed that the nutrient medium used for mass culture could be stored up to five weeks at 25 C or at refrigerator temperature (4 C) with little change in nitrogen-urea level. Algal suspensions stored at 4 C remained viable for periods of at least 12 weeks; growth resumed after a lag period when stored suspensions were cultured at 39 C. Streptomycin was found suitable for controlling a blue-green containment.

ALGAE↗

NASA NTRS1971

Dynamic responses of railroad car models to vertical and lateral rail inputs

Simplified dynamic models were applied in a study of vibration in a high-speed railroad car. The mathematical models used were a four-degree-of-freedom model for vertical responses to vertical rail inputs and a ten-degree-of-freedom model for lateral response to lateral or rolling (cross-level) inputs from the rails. Elastic properties of the passenger car body were represented by bending and torsion of a uniform beam. Rail-to-car (truck) suspensions were modeled as spring-mass-dashpot oscillators. Lateral spring nonlinearities approximating certain complicated truck mechanisms were introduced. The models were excited by displacement and, in some cases, velocity inputs from the rails by both deterministic (including sinusoidal) and random input functions. Results were obtained both in the frequency and time domains. Solutions in the time domain for the lateral model were obtained for a wide variety of transient and random inputs generated on-line by an analog computer. Variations in one of the damping properties of the lateral car suspension gave large fluctuations in response over a range of car speeds for a given input. This damping coefficient was significant in reducing lateral car responses that were higher for nonlinear springs for three different inputs.

Sewall, J. L.↗

NASA NTRS1972

Aeolian processes on Mars - Erosive velocities, settling velocities, and yellow clouds.

Extremely high atmospheric wind velocities are needed to erode particulate matter on Mars. Settling velocities are roughly equivalent to terrestrial settling velocities for clay to fine sand-size particles; suspension transport may be dominant for fine particles on Mars. Yellow clouds suggest that required threshold erosion velocities are reached and that a great deal of fine-grained material is carried in suspension. Yellow cloud origins are concentrated over the southern latitudes and areas of major topographic relief. The cloud distribution pattern suggests that high threshold velocities are attained by transient atmospheric disturbances such as slope winds and dust devils.-

Arvidson, R. E.↗

NASA NTRS1972

Scanning mirror for infrared sensors

A high resolution, long life angle-encoded scanning mirror, built for application in an infrared attitude sensor, is described. The mirror uses a Moire' fringe type optical encoder and unique torsion bar suspension together with a magnetic drive to meet stringent operational and environmental requirements at a minimum weight and with minimum power consumption. Details of the specifications, design, and construction are presented with an analysis of the mirror suspension that allows accurate prediction of performance. The emphasis is on mechanical design considerations, and brief discussions are included on the encoder and magnetic drive to provide a complete view of the mirror system and its capabilities.

Anderson, R. H.↗

NASA NTRS1973

Satellite studies of suspended matter and aquatic interfaces in Delaware Bay

The author has identified the following significant results. Three successful ERTS-1 satellite passes have produced synoptic imagery showing distribution of suspended matter and aquatic interfaces over Delaware Bay and adjacent Atlantic coastal regions. The interfaces are a major hydrographic feature in Delaware Bay and frequently include regions of high convergence. In the upper and middle bay the interfaces tend to align along the flow axis of the river and parallel to the shoreline. A correlation has been found between the concentration of sand particles in suspension and the depth, suggesting that most of the heavier particles are lifted into temporary suspension over shoals and shallow areas by currents and waves. The second type of interface is primarily a tidal intrusion of shelf water into the bay during incipient flood tide, with associated discontinuities in salinity and temperature. The convergence properties of such fronts attract heavy accumulations of foam which were found to contain strong concentrations of heavy metals and other toxic substances.

Klemas, V.↗

NASA NTRS1973

The use of superconductivity in magnetic balance design

The magnetic field and field gradient requirements for magnetic suspension in a Mach 3, 6-in. diameter wind tunnel are stated, along with the power requirements for gradient coil pairs wound of copper operating at room temperature and aluminum cooled to 20 K. The power dissipated is large enough that the use of superconductivity in the coil design becomes an attractive alternative. The problems of stability and ac losses are outlined along with the properties of stabilized superconductors. A brief review of a simplified version of the critical state model of C. P. Bean is presented, and the problems involved in calculations of the ac losses in superconducting coils are outlined. A summary of ac loss data taken on pancake coils wound of commercially available Nb3Sn partially stabilized tape is presented and shown as leading to the U.Va. gradient coil design. The actual coil performance is compared with predictions based on the BNL results. Finally, some remarks are presented concerning scaling of the ac losses to larger magnetic suspension systems as well as prospects for improved performance using newer multifilament superconductors.

Moss, F. E.↗

NASA NTRS1973

Distribution and movement of suspended sediment in the Gulf of Mexico off the Texas coast

ERTS-1 imagery has proven very useful in studies of the distribution of suspended sediment in the Gulf of Mexico off the Texas coast. Moreover, by using suspended matter concentrations as tags on water masses, much information on water movement can be obtained. The utility of suspended sediment as a tracer is dependent on the sediment remaining in suspension long enough to travel an appreciable distance or to be visible on successive images. Although the evidence is not conclusive, it seems likely that much of the suspended sediment in Gulf of Mexico nearshore waters during normal seastate conditions has remained in suspension since the time of its entry into the Gulf of Mexico through rivers and tidal inlets.

Hunter, R. E.↗

NASA NTRS1973

Development of the Viking parachute configuration by wind tunnel investigation.

Several experimental investigations to obtain the drag performance of 10% scale-model disk-gap-band-type parachute assemblies trailing in the Viking forebody wake were conducted over the range of Mach 0.2 to 2.6. The wind-tunnel tests varied both the canopy trailing distance and ratio of suspension line length to canopy diameter. The data obtained permitted optimization of both parameters. Parachute drag performance in the forebody wake is markedly degraded transonically beginning at Mach 0.6, reaching a minimum value at Mach 1.0, then approaches the subsonic value for the selected configuration as Mach number is increased to 1.4. Further increase in Mach number causes the drag coefficient to again decline. A 20% increase in parachute-alone transonic drag coefficient was obtained by increasing suspension-line length ratio from 1.16 to 1.73.

Steinberg, S.↗