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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Vacuum Deployment and Testing of a 4-Quadrant Scalable Inflatable Solar Sail System

Solar sails reflect photons streaming from the sun and transfer momentum to the sail. The thrust, though small, is continuous and acts for the life of the mission without the need for propellant. Recent advances in materials and ultra-low mass gossamer structures have enabled a host of useful missions utilizing solar sail propulsion. The team of L'Garde, Jet Propulsion Laboratories, Ball Aerospace, and Langley Research Center, under the direction of the NASA In-Space Propulsion office, has been developing a scalable solar sail configuration to address NASA s future space propulsion needs. The baseline design currently in development and testing was optimized around the 1 AU solar sentinel mission. Featuring inflatably deployed sub-T(sub g), rigidized beam components, the 10,000 sq m sail and support structure weighs only 47.5 kg, including margin, yielding an areal density of 4.8 g/sq m. Striped sail architecture, net/membrane sail design, and L'Garde's conical boom deployment technique allows scalability without high mass penalties. This same structural concept can be scaled to meet and exceed the requirements of a number of other useful NASA missions. This paper discusses the interim accomplishments of phase 3 of a 3-phase NASA program to advance the technology readiness level (TRL) of the solar sail system from 3 toward a technology readiness level of 6 in 2005. Under earlier phases of the program many test articles have been fabricated and tested successfully. Most notably an unprecedented 4-quadrant 10 m solar sail ground test article was fabricated, subjected to launch environment tests, and was successfully deployed under simulated space conditions at NASA Plum Brook s 30m vacuum facility. Phase 2 of the program has seen much development and testing of this design validating assumptions, mass estimates, and predicted mission scalability. Under Phase 3 a much larger 20 m square test article including subscale vane has been fabricated and tested. A 20 m system ambient deployment has been successfully conducted after enduring Delta-2 launch environment testing. The program will culminate in a vacuum deployment of a 20 m subscale test article at the NASA Glenn s Plum Brook 30 m vacuum test facility to bring the TRL level as close to 6 as possible in 1 g. This focused program will pave the way for a flight experiment of this highly efficient space propulsion technology.

Lichodziejewski, David↗
NASA NTRS2003

Multifunctional Inflatable Structure Being Developed for the PowerSphere Concept

The continuing development of microsatellites and nanosatellites for low Earth orbits requires the collection of sufficient power for instruments onboard a low-weight, low-volume spacecraft. Because the overall surface area of a microsatellite or nanosatellite is small, body-mounted solar cells cannot provide enough power. The deployment of traditional, rigid, solar arrays necessitates larger satellite volumes and weights, and also requires extra apparatus for pointing. One solution to this power choke problem is the deployment of a spherical, inflatable power system. This power system, termed the "PowerSphere," has several advantages, including a high collection area, low weight and stowage volume, and the elimination of solar array pointing mechanisms.

Peterson, Todd T.↗
NASA NTRS1971

The Effects of Parachute System Mass and Suspension-Line Elastic Properties on the LADT #3 Viking Parachute Inflation Load

Analytical calculations have considered the effects of 1) varying parachute system mass, 2) suspension-line damping, and 3) alternate suspension-line force-elongation data on the canopy force history. Results indicate the canopy force on the LADT #3 parachute did not substantially exceed the recorded vehicle force reading and that the above factors can have significant effects on the canopy force history. Analytical calculations have considered the effects of i) varying parachute system mass, 2) suspension line damping, and 3) different suspension-line force-elongation data on the canopy force history. Based on the results of this study the following conclusions are drawn: Specifically, 1. At the LADT #3 failure time of 1.70 seconds, the canopy force ranged anywhere from 15.7% below to 2.4% above the vehicle force depending upon the model and data used. Therefore, the canopy force did not substantially exceed the recorded vehicle force reading. 2. At a predicted full inflation time of 1.80 seconds the canopy force would be greater than the vehicle force by from 1.1% to 10.6%, again depending upon the model and data used. Generally, 3. At low altitudes, enclosed and apparent air mass can significantly effect the canopy force calculated and should, therefore, not be neglected. 4. The canopy force calculations are sensitive to decelerator physical properties. In this case changes in the damping and/or force-elongation characteristics produced significant changes in the canopy force histories. Accurate prediction of canopy force histories requires accurate inputs in these areas.

Talay, Theodore A.↗
NASA NTRS2007

Inflatable Aerocapture Decelerators for Mars Orbiters

A multi-disciplinary research program was recently completed, sponsored by NASA Marshall Space Flight Center, on the subject of aerocapture of spacecraft weighing up to 5 metric tons at Mars. Heavier spacecraft will require deployable drag area beyond the dimensional limits of current and planned launch fairings. This research focuses on the approach of lightweight inflatable decelerators constructed with thin films, using fiber reinforcement and having a temperature limitation of 500 C. Trajectory analysis defines trajectories for a range of low ballistic coefficients for which convective heat flux is compatible with the material set. Fluid-Structure Interaction (FSI) tools are expanded to include the rarified flow regime. Several non-symmetrical configurations are evaluated for their capability to develop lift as part of the necessary trajectory control strategy. Manufacturing technology is developed for 3-D stretch forming of polyimide films and for tailored fiber reinforcement of thin films. Finally, the mass of the decelerator is estimated and compared to the mass of a traditional rigid aeroshell.

Brown, Glen J.↗
NASA NTRS2007

Cosmological Inflation: A Personal Perspective

We present a review of the sequence of events/circumstances that led to the introduction of interplay between the physics associated with phase transitions in the early universe and their effects on its dynamics of expansion with the goal of resolving the horizon problem that it has since become known as Cosmological Inflation. We then provide a brief review of the fundamentals and the solutions of a theory of gravity based on local scale invariance, known as Weyl gravity that have been elaborated by the presenter and his collaborator P. D. Mannheim. We point out that this theory provides from first principles for a characteristic universal acceleration, whose value appears to be in agreement with observations across a vast range of length scales in the universe.

Kazanas, Demosthenes↗
NASA NTRS2008

Cosmological Inflation: A Personal Perspective

We present a brief review of Cosmological Inflation from the personal perspective of the speaker who almost 30 years ago proposed a way of resolving the problem of Cosmological Horizon by employing certain notions and developments from the field of High Energy Physics. Along with a brief introduction of the Horizon and Flatness problems of standard cosmology, this lecture concentrates on personal reminiscing of the notions and ideas that prevailed and influenced the author's thinking at the time. The lecture then touches upon some more recent developments related to the subject including exact solutions to conformal gravity that provide a first principles emergence of a characteristic acceleration in the universe and concludes with some personal views concerning the direction that the cosmology field has taken in the past couple of decades and certain speculations some notions that may indicate future directions of research.

Kazanas, Demos↗
NASA NTRS2008

Cosmological Inflation: A Personal Perspective

We present a review of the sequence of events/circumstances that led to the introduction of interplay between the physics associated with phase transitions in the early universe and their effects on its dynamics of expansion with the goal of resolving the horizon problem that it has since become known as Cosmological Inflation. We then provide a brief review of the fundamentals and the solutions of a theory of gravity based on local scale invariance, known as Weyl gravity that have been elaborated by the presenter and his collaborator P. D. Mannheim. We point out that this theory provides from first principles for a characteristic universal acceleration, whose value appears to be in agreement with observations across a vast range of length scales in the universe.

Kazanas, Demos↗
NASA NTRS2009

Test Plan for the Technology Maturation of Supersonic Inflatable Aerodynamic Decelerators

Supersonic inflatable aerodynamic decelerators (IADs) are drag devices intended to be deployed at high Mach numbers. In the application considered here they assist in the descent and landing of spacecraft on Mars. Although promising, present IAD technology is not yet sufficiently mature for use in the near future. This paper describes a technology maturation plan for tension cone IADs using subscale test articles to reduce development costs. As envisioned, the proposed test plan includes three phases: wind tunnel tests (subsonic), unpowered high-altitude flight tests (transonic), and powered high-altitude tests (supersonic). This test plan is based on a building block approach in which successful completion of each phase adds to the understanding of the behavior of IADs and reduces the risk of the subsequent, more expensive phases. By properly scaling the IADs, test articles of the same size and nearly the same construction can be used for all three phases. The final phase is a dynamically scaled flight test with IAD deployment at the same Mach number as the full-scale vehicle on Mars. Two full-scale example cases are presented: one for a single-stage system (15 m dia. IAD to subsonic retropropulsion), and another for a two-stage system (10.5 m dia. IAD to subsonic parachute). Using scale factors of 0.333 and 0.476 yield subscale test IADs of 5 m dia. The dynamically scaled powered flight test starts at Mach 4 and an altitude of 33.5 km. Existing balloons and rocket motors are shown to be adequate to meet the required test conditions.

Kelly, Jenny R.↗
NASA NTRS2009

Flight Dynamics of an Aeroshell Using an Attached Inflatable Aerodynamic Decelerator

An aeroelastic analysis of the behavior of an entry vehicle utilizing an attached inflatable aerodynamic decelerator during supersonic flight is presented. The analysis consists of a planar, four degree of freedom simulation. The aeroshell and the IAD are assumed to be separate, rigid bodies connected with a spring-damper at an interface point constraining the relative motion of the two bodies. Aerodynamic forces and moments are modeled using modified Newtonian aerodynamics. The analysis includes the contribution of static aerodynamic forces and moments as well as pitch damping. Two cases are considered in the analysis: constant velocity flight and planar free flight. For the constant velocity and free flight cases with neutral pitch damping, configurations with highly-stiff interfaces exhibit statically stable but dynamically unstable aeroshell angle of attack. Moderately stiff interfaces exhibit static and dynamic stability of aeroshell angle of attack due to damping induced by the pitch angle rate lag between the aeroshell and IAD. For the free-flight case, low values of both the interface stiffness and damping cause divergence of the aeroshell angle of attack due to the offset of the IAD drag force with respect to the aeroshell center of mass. The presence of dynamic aerodynamic moments was found to influence the stability characteristics of the vehicle. The effect of gravity on the aeroshell angle of attack stability characteristics was determined to be negligible for the cases investigated.

Cruz, Juan R.↗
NASA NTRS2009

Primordial Inflation Polarization Explorer: Status and Plans

The Primordial Inflation Polarization Explorer is a balloon-borne instrument to measure the polarization of the cosmic microwave background in order to detect the characteristic signature of gravity waves created during an inflationary epoch in the early universe. PIPER combines cold /I.G K\ optics, 5120 bolometric detectors, and rapid polarization modulation using VPM grids to achieve both high sensitivity and excellent control of systematic errors. I will discuss the current status and plans for the PIPER instrument.

Kogut, Alan↗
NASA NTRS2009

Apparatus for integrating a rigid structure into a flexible wall of an inflatable structure

For an inflatable structure having a flexible outer shell or wall structure having a flexible restraint layer comprising interwoven, load-bearing straps, apparatus for integrating one or more substantially rigid members into the flexible shell. For each rigid member, a corresponding opening is formed through the flexible shell for receiving the rigid member. A plurality of connection devices are mounted on the rigid member for receiving respective ones of the load-bearing straps. In one embodiment, the connection devices comprise inner connecting mechanisms and outer connecting mechanisms, the inner and outer connecting mechanisms being mounted on the substantially rigid structure and spaced along a peripheral edge portion of the structure in an interleafed array in which respective outer connecting mechanisms are interposed between adjacent pairs of inner connecting mechanisms, the outer connecting mechanisms projecting outwardly from the peripheral edge portion of the substantially rigid structure beyond the adjacent inner connecting mechanisms to form a staggered array of connecting mechanisms extending along the panel structure edge portion. In one embodiment, the inner and outer connecting mechanisms form part of an integrated, structure rotatably mounted on the rigid member peripheral edge portion.

Johnson, Christopher J.↗
NASA NTRS2010

Modular Habitats Comprising Rigid and Inflatable Modules

Modular, lightweight, fully equipped buildings comprising hybrids of rigid and inflatable structures can be assembled on Earth and then transported to and deployed on the Moon for use as habitats. Modified versions of these buildings could also prove useful on Earth as shelters that can be rapidly and easily erected in emergency situations and/or extreme environments: examples include shelters for hurricane relief and for Antarctic exploration.

Kennedy, Kriss J.↗
NASA NTRS2010

Foam rigidized inflatable structural assemblies

An inflatable and rigidizable structure for use as a habitat or a load bearing structure is disclosed. The structure consists of an outer wall and an inner wall defining a containment member and a bladder. The bladder is pressurized to erect the structure from an initially collapsed state. The containment member is subsequently injected with rigidizable fluid through an arrangement of injection ports. Exhaust gases from the curing rigidizable fluid are vented through an arrangement of exhaust ports. The rate of erection can be controlled by frictional engagement with a container or by using a tether. A method for fabricating a tubular structure is disclosed.

Tinker, Michael L.↗
NASA NTRS2000

A Shielding Model for an Inflatable Vehicle, TransHab, and the Associated Astronaut Space Radiation Risk Assessment

TransHab, a habitable inflatable structure, has been proposed as a possible module for the International Space Station that provides significant increase in the available volume compared with the US Hab module and fo r a human Mars mission . A study was undertaken to understand and provide design inputs for crew radiation exposures. The results show that the current design provides sufficient shielding to assure that the crew exposures are below the crew exposure limits currently adopted for the ISS. In addition, the shielding provides adequate protection from the largest solar particle events (SPEs) observed during the last 40 years.

Atwell, William↗
NASA NTRS2011

A Focus on Cryogenic Engineering for the Primordial Inflation Polarization Explorer (PIPER) Mission

Cryogenic engineering involves design and modification of equipment that is used under boiling point of nitrogen which is 77 K. The focus of this paper will be on the design of hardware for cryogenic use and a retrofit that was done to the main laboratory cryostat used to test flight components for the Primordial Inflation Polarization Explorer balloon-borne mission. Data from prior tests showed that there was a superfluid helium leak and a total disassemble of the cryostat was conducted in order to localize and fix the leak. To improve efficiency new fill tubes and clamps with modifications were added to the helium tank. Upon removal of the tank, corrosion was found on the flange face that connects to the helium cold plate and therefore had to be fully replaced and copper plated to prevent future corrosion. Indium seals were also replaced for the four fill tubes, a helium level sensor, and the nitrogen and helium tanks. Four additional shielded twisted pairs of cryogenic wire and a wire harness for the Superconducting Quantum Interference Devices (SQUIDs) were added. Finally, there was also design work done for multiple pieces that went inside the cryostat and a separate probe used to test the SQUIDs. Upon successful completion of the cryostat upgrade, tests were run to check the effectiveness and stability of the upgrades. The post-retrofit tests showed minor leaks were still present and due to this, superfluidity has still not been attained. As such there could still be a possibility of a superfluid leak appearing in the future. Regardless, the copper plating on the helium tank has elongated the need to service it by three to five years.

Rosas, Rogelio↗
NASA NTRS2011

Utilizing Photogrammetry and Strain Gage Measurement to Characterize Pressurization of Inflatable Modules

This paper focuses on integrating a large hatch penetration into inflatable modules of various constructions. This paper also compares load predictions with test measurements. The strain was measured by utilizing photogrammetric methods and strain gages mounted to select clevises that interface with the structural webbings. Bench testing showed good correlation between strain data collected from an extensometer and photogrammetric measurements, even when the material transitioned from the low load to high load strain region of the curve. The full-scale torus design module showed mixed results as well in the lower load and high strain regions. After thorough analysis of photogrammetric measurements, strain gage measurements, and predicted load, the photogrammetric measurements seem to be off by a factor of two.

Mohammed, Anil↗
NASA NTRS2005

Multi-Layer Laminated Thin Films for Inflatable Structures

Special-purpose balloons and other inflatable structures would be constructed as flexible laminates of multiple thin polymeric films interspersed with layers of adhesive, according to a proposal. In the original intended application, the laminate would serve as the envelope of the Titan Aerobot a proposed robotic airship for exploring Titan (one of the moons of Saturn). Potential terrestrial applications for such flexible laminates could include blimps and sails. In the original application, the multi-layered laminate would contain six layers of 0.14-mil (0.0036-mm)-thick Mylar (or equivalent) polyethylene terephthalate film with a layer of adhesive between each layer of Mylar . The overall thickness and areal density of this laminate would be nearly the same as those of 1-mil (0.0254-mm)-thick monolayer polyethylene terephthalate sheet. However, the laminate would offer several advantages over the monolayer sheet, especially with respect to interrelated considerations of flexing properties, formation of pinholes, and difficulty or ease of handling, as discussed next. Most of the damage during flexing of the laminate would be localized in the outermost layers, where the radii of bending in a given bend would be the largest and, hence, the bending stress would be the greatest. The adverse effects of formation of pinholes would be nearly completely mitigated in the laminate because a pinhole in a given layer would not propagate to adjacent layers. Hence, the laminate would tend to remain effective as a barrier to retain gas. Similar arguments can be made regarding cracks: While a crack could form as a result of stress or a defect in the film material, a crack would not propagate into adjacent layers, and the adjacent layer(s) would even arrest propagation of the crack. In the case of the monolayer sheet, surface damage (scratches, dents, permanent folds, pinholes, and the like) caused by handling would constitute or give rise to defects that could propagate through the thickness as cracks or pinholes that would render the sheet less effective or ineffective as a barrier. In contrast, because damage incurred during handling of the laminate would ordinarily be limited to the outermost layers, the barrier properties of the laminate would be less likely to be adversely affected. Therefore, handling of the laminate would be easier because there would be less of a need to exercise care to ensure against surface damage.

Yavrouian, Andre↗