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NASA NTRSDate not supplied

TechEdSat 7, 10, 13, 15: Exo-brake Experiments on the ISS, First Virgin Orbit, and First Firefly-Alpha Test Flights.

The TechEdSat flight series (TES-n), developed by the Nano Orbital Workshop (NOW) group at NASA Ames, has been studying cube satellite re-entry technologies with a focus on Exo-Brake drag device research. An exo-atmospheric braking device, the Exo-Brake uses the tenuous upper atmosphere acting in a free molecular flow regime to enable controllable adjustment of the drag profile of the host spacecraft, currently enabling rapid disposal of small spacecraft after mission conclusion, and eventual targeted de-orbit to a desired entry point at the Von Karman line, or approximately 100km in altitude. The TES-7 mission, flown on the first successful Virgin Orbit flight January 17, 2021, was injected into a 500km, 61-degree inclination orbit, with an expected orbital lifetime of approximately ten years. After successful deployment of a unique hydrogen gas-cell inflation design ‘disposal’-type Mylar Exo-Brake intended to rapidly de-orbit the spacecraft, the maximum expected orbital lifetime of the TES-7 spacecraft was successfully reduced from ten years to 1.3 years, an 87% reduction in orbit lifetime via a passive, fuel-less system. The subsequent TES-13 mission utilized a new, less complex ‘disposal’-type Exo-Brake design made from collapsible rigid struts rather than inflated struts to reduce the engineering, construction, and safety complexities introduced by the prior hydrogen gas inflation design. The rigid strut Exo-Brake design is stowed via rotational compression and deploys using only stored spring energy once released via electronic actuator. This new rotation compression storage design has become the new Exo-Brake design standard used on TES missions thanks to its simplicity. Following on the success of this new Exo-Brake design demonstrated by TES-13, the design was further refined to enabled active manipulation of the Exo-Brake effective drag area though a winch-like system. Both the TES-10 and TES-15 spacecraft were equipped with geometrically similar Exo-Brake devices capable of such active drag modulation, with the intent of studying the operational impact of having such devices on cube satellite missions. To increase the survival time of the Exo-Brake at low altitudes and thus gain more experiment time and better guidance capability, TES-15 was equipped with a modulated Exo-Brake constructed from 3M™ Nextel™ 440 ceramic oxide fiber, the same fabric material used in the Space Shuttle TPS system, rather than Mylar. After launching on Alpha Flight 2 October 1st, 2022, Firefly’s first successful launch, TES-15 met the same modulation restrictions as TES-10, with modulation prohibited above 200km to avoid possible collision with other spacecraft. In this case, a low deployment orbit caused an extremely short mission life, which, coupled with delayed spacecraft identification, exacerbated collision concerns and caused performance data of the high-temperature Exo-Brake design to be inconclusive. As such, the Nano Orbital Workshop has taken a new approach of only conducting modulated Exo-Brake research on missions deploying below ISS altitude to avoid collision avoidance restrictions, and is working to improve spacecraft identification and location reporting techniques to increase experiment durations. Upcoming TES mission will therefore use one of two classes of Exo-Brake depending on their target altitude, as to be described in the submission.

M Murbach↗

NASA NTRSDate not supplied

TechEdSat 7, 10, 13, 15: Exo-brake Experiments on the ISS, First Virgin Orbit, and First Firefly-Alpha Test Flights

Marcus Murbach↗

NASA NTRS1994

Design of the MESUR/pathfinder microrover

The use of unmanned robotic vehicles to assist in the exploration of Mars and other planets has been of interest to the National Aeronautics and Space Administration (NASA) for several decades and has been the focus of an ongoing research program at the Jet Propulsion Laboratory (JPL) for a similar period of time. As a result of these research activities, JPL is in the process of designing and building a small (7-9 kg) microrover to be flown aboard the Mars Environmental Survey Mission (MESUR)/Pathfinder spacecraft, which is tentatively to be launched to Mars in late 1997. The microrover will perform a variety of technology experiments designed to provide information critical to the design of future planetary rovers. In addition, the microrover will perform several science and lander related experiments using specialized onboard instruments. To enable the microrover to perform these experiments at selected target areas and at the same time deal with the long time delays (and limited communications bandwidth), a control/navigation approach combining the use of operator-designated waypoints and onboard behavior control has been adopted. The design of the MESUR/Pathfinder microrover and the overall manner in which it is controlled are described herein.

Stone, Henry W.↗

NASA NTRS1990

The Astro-1 Observatory mission

This paper describes the NASA's Astro-1 Observatory mission. The three ultraviolet (UV) telescopes and one X-ray telescope that make up this Spacelab mission will observe objects in the solar system, including comets and the outer planets, objects within the Milky Way Galaxy, and high-energy extragalactic objects such as quasi-stellar objects and active galaxies. While briefly discussing the science objectives of the mission, the paper focuses on the history of the mission, the Spacelab hardware assembled by the George C. Marshall Space Flight Center (MSFC) to carry the telescopes into orbit, and the complexities of the systems supporting that payload. Also discussed are the dimensions and capabilities of the Hopkins Ultraviolet Telescope, the Ultraviolet Imaging Telescope, the Wisconsin Ultraviolet Photopolarimeter Experiment, and the Broad Band X-Ray Telescope, all of which will coobserve a number of targets to generate comprehensive data in both the ultraviolet and X-ray ranges of the spectrum. The Astro-1 mission operations are described, and the cooperative functions of other NASA centers are reported.

Jones, Jack↗

NASA NTRS2006

International Polar Year Observations From the International Space Station

Astronauts aboard the International Space Station (ISS) have several opportunities each day to observe and document high-latitude phenomena. Although lighting conditions, ground track and other viewing parameters change with orbital precessions and season, the 51.6 degree orbital inclination and 400 km altitude of the ISS provide the crew an excellent vantage point for collecting image-based data for IPY investigators. To date, the database of imagery acquired by the Crew Earth Observations (CEO) experiment aboard the ISS (http://eol.jsc.nasa.gov) contains more than 12,000 images of high latitude (above 50 degrees) events such as aurora, mesospheric clouds, sea-ice, high-latitude plankton blooms, volcanic eruptions, and snow cover. The ISS Program will formally participate in IPY through an activity coordinated through CEO entitled Synchronized Observations of Polar Mesospheric Clouds, Aurora and Other Large-scale Polar Phenomena from the ISS and Ground Sites. The activity will augment the existing collection of Earth images taken from the ISS by focusing astronaut observations on polar phenomena. NASA s CEO experiment will solicit requests by IPY investigators for ISS observations that are coordinated with or complement ground-based polar studies. The CEO imagery website (http://eol.jsc.nasa.gov) will provide an on-line form for IPY investigators to interact with CEO scientists and define their imagery requests. This information will be integrated into daily communications with the ISS crews about their Earth Observations targets. All data collected will be cataloged and posted on the website for downloading and assimilation into IPY projects.

Pettit, Donald R.↗

NASA NTRS1990

Technology for an intelligent, free-flying robot for crew and equipment retrieval in space

Crew rescue and equipment retrieval is a Space Station Freedom requirement. During Freedom's lifetime, there is a high probability that a number of objects will accidently become separated. Members of the crew, replacement units, and key tools are examples. Retrieval of these objects within a short time is essential. Systems engineering studies were conducted to identify system requirements and candidate approaches. One such approach, based on a voice-supervised, intelligent, free-flying robot was selected for further analysis. A ground-based technology demonstration, now in its second phase, was designed to provide an integrated robotic hardware and software testbed supporting design of a space-borne system. The ground system, known as the EVA Retriever, is examining the problem of autonomously planning and executing a target rendezvous, grapple, and return to base while avoiding stationary and moving obstacles. The current prototype is an anthropomorphic manipulator unit with dexterous arms and hands attached to a robot body and latched in a manned maneuvering unit. A precision air-bearing floor is used to simulate space. Sensor data include two vision systems and force/proximity/tactile sensors on the hands and arms. Planning for a shuttle file experiment is underway. A set of scenarios and strawman requirements were defined to support conceptual development. Initial design activities are expected to begin in late 1989 with the flight occurring in 1994. The flight hardware and software will be based on lessons learned from both the ground prototype and computer simulations.

Erickson, J. D.↗

NASA NTRS1992

Joint Langley Research Center/Jet Propulsion Laboratory CSI experiment

This paper describes a joint Control Structure Interaction (CSI) experiment in which Jet Propulsion Laboratory (JPL) damping devices were incorporated into the Langley Research Center (LaRC) Phase 0 Testbed. The goals of the effort were twofold: (1) test the effectiveness of the JPL structural damping methods in a new structure and (2) assess the feasibility of combining JPL local control methods with the LaRC multiple input multiple output global control methods. Six dampers (2 piezoelectric active members, 4 viscous dampers), placed in three different regions of the structure, produced up to 26 dB attenuation in target modes. The combined control strategy in which the JPL damping methods contributed local control action and the LaRC control scheme provided global control action, produced and overall control scheme with increased stability margins and improved performance. This paper presents an overview of the technologies contributed from the two centers, the strategies used to combine them, and results demonstrating the success of the damping and cooperative control efforts.

Neat, Gregory W.↗

NASA NTRS2021

Enabling High-Contrast Imaging of Binary Stars With the Roman Space Telescope Coronagraph Instrument

A large fraction of Sun-like stars is contained in binary systems, in fact within 10 pc there are 67 FGK stars, out of which 42 belong to a multi-star system, and 28 have companion leak that is greater than 1e-9 contrast, assuming typical Hubble-quality space optics. Currently, those binary stars are not included in the Roman Space Telescope Coronagraph Instrument target list, but they could be observed if high-contrast imaging around binary star systems using Roman was possible. The Multi-Star Wavefront Control (MSWC) algorithm can be used to suppress companion star leakage. If the targets have angular separations larger than the Nyquist controllable region of the Deformable Mirror, MSWC must operate in its Super-Nyquist (SN) mode. This mode requires a target star replica within the SN region in order to provide the ability to null speckles at SN angular separations. For the case of Roman, more than half of the targets that can be observed using MSWC, including Alpha Centauri, have angular separations larger than the Nyquist controllable region of the 48x48 actuator Deformable Mirror (DM) to be used. In this paper, we describe how super-Nyquist MSWC can be implemented in Roman CGI adding a mild grating on a replica of the Wide-field Shaped Pupil mask, which would use a spare space in the Shaped Pupil Active Mechanism. We present the feasibility analysis, simulation results, and discuss the latest results on MSWC experiment from three different laboratories at NASA Ames, the Jet Propulsion Laboratory, and the Subaru telescope.

Prada, Camilo Mejia↗

NASA NTRS1995

Comments on the Rotational State and Non-Gravitational Forces of Comet 46/WIRTANEN

We apply our experience of modeling the rotational state and non-gravitational forces of comet 1 P/Halley and other comets to comet 46P/Wirtanen. While the paucity of physical data on 46P/Wirtanen makes this process somewhat speculative, this comet's place as target for the important Rosetta mission gives significance to such a study. Our arguments are based on the summary of observational data provided by Jorda and Rickman (1995) and a comparative study of the behavior of other periodic comets. We find 46P/Wirtanen to have a level of surface activity relative to its mass that is dynamically more akin to that found in comet 1 P/Halley than in a typical periodic comet. We show through an illustrative numerical example that this apparent fact should likely lead to an excited spin state for this comet and that significant changes in the spin period could occur in a single pass through perihelion. We argue that the available observations are not sufficient to substantiate the claim of Jorda and Rickman (1995) that the nucleus is undergoing retrograde rotation and it is possible that the rotation is either prograde as well as retrograde. The substantial requirements that must be placed on any future observing program necessary to determine the precise rotational state are outlined. We advocate an extended (approx. two month) southern hemisphere observing campaign to determine the nuclear rotational state in 1996 if possible before activity turns on.

Samarasinha, Nalin H.↗

NASA NTRS2002

Three-Dimensional Stress Fields and Slip Systems for Single Crystal Superalloy Notched Specimens

Single crystal superalloys have become increasingly popular for turbine blade and vane applications due to their high strength, and creep and fatigue resistance at elevated temperatures. The crystallographic orientation of a single crystal material greatly affects its material properties, including elastic modulus, shear modulus, and ductility. These directional properties, along with the type of loading and temperature, dictate an anisotropic response in the yield strength, creep resistance, creep rupture ductility, fatigue resistance, etc. A significant amount of research has been conducted to determine the material properties in the <001> orientation, yet the material properties deviating from the <001> orientation have not been assessed for all cases. Based on the desired application and design criteria, a crystal orientation is selected to yield the maximum properties. Currently, single crystal manufacturing is able to control the primary crystallographic orientation within 15 of the target orientation, which is an acceptable deviation to meet both performance and cost guidelines; the secondary orientation is rarely specified. A common experiment is the standard load-controlled tensile test, in which specimens with different orientations can be loaded to observe the material response. The deformation behavior of single-crystal materials under tension and compression is known to be a function of not only material orientation, but also of varying microdeformation (i.e. dislocation) mechanisms. The underlying dislocation motion causes deformation via slip, and affects the activation of specific slip systems based on load and orientation. The slip can be analyzed by observing the visible traces left on the surface of the specimen from the slip activity within the single crystal material. The goal of this thesis was to predict the slip systems activated in three-dimensional stress fields of a notched tensile specimen, as a function of crystal orientation, using finite element analysis without addressing microstructural deformation mechanisms that govern their activation. Out of three orientations tested, the specimen with a [110] load orientation and a [001] growth direction had the lowest maximum resolved shear stress; this specimen orientation appears to be the best design candidate for a tensile application.

Magnan, Shannon M.↗

NASA NTRSDate not supplied

Anisotropic Goal-Based Mesh Adaptation Metric Clarification and Development

Adaptive unstructured mesh techniques have a limited, but growing impact on production analysis workflows to control discretization error for reliable simulation results. Multiple independent implementations of flow solvers, anisotropic metric construction methods, and anisotropic mesh adaptation mechanics have matured. Goal-based metrics target estimated error in output functions, such as lift and drag, through the guidance of an adjoint solution. A unification of goal-based anisotropic metrics is presented for steady viscous flows, which is an active area of research. These goal-based metrics drive robust and efficient anisotropic mesh adaptation for the calculation of output functions. The super-convergent functional output error behavior of stabilized finite-element methods is exploited without a formal proof, and evidence of super-convergence is shown in numerical experiments. Mesh adapted drag and lift outputs for two simple bodies in compressible viscous flow show convergence of error to less than a single drag count. Asymptotic behavior established for relatively coarse meshes shows the efficiency of this goal-based metric when compared to solution interpolation error control and expert-guided meshing. Anisotropic mesh adaptation techniques are applied to a transport aircraft in a high-lift configuration where variation between approaches decreases with mesh refinement, but asymptotic behavior is not observed with available resources.

goal-based↗

NASA NTRS1988

A stereo triangulation system for structural identification: Analytical and experimental results

Identification of large space structures' distributed mass, stiffness, and energy dissipation characteristics poses formidable analytical, numerical, and implementation difficulties. Development of reliable on-orbit structural identification methods is important for implementing active vibration suppression concepts which are under widespread study in the large space structures community. Near the heart of the identification problem lies the necessity of making a large number of spatially distributed measurements of the structure's vibratory response and the associated force/moment inputs with sufficient spatial and frequency resolution. In the present paper, we discuss a method whereby tens of active or passive (retro-reflecting) targets on the structure are tracked simultaneously by the focal planes of two or more video cameras mounted on an adjacent platform. Triangulation (optical ray intersection) of the conjugate image centroids yield inertial trajectories of each target on the structure. Given the triangulated motion of the targets, we apply and extend methodology developed by Creamer, Junkins, and Juang to identify the frequencies, mode shapes, and updated estimates for the mass/stiffness/damping parameterization of the structure. The methodology is semi-automated, for example, the post experiment analysis of the video imagery to determine the inertial trajectories of the targets typically requires less than thirty minutes of real time. Using methodology discussed herein, the frequency response of a large number of points on the structure (where reflective targets are mounted) on the structure can be determined from optical measurements alone. For comparison purposes, we also utilize measurements from accelerometers and a calibrated impulse hammer. While our experimental work remains in a research stage of development, we have successfully tracked and stereo triangulated 20 targets (on a vibrating cantilevered grid structure) at a sample frequency of 200 HZ, and have established conclusively the feasibility and desirability of this approach. We discuss, in summary, recent advances in analog and digital video processing methodology, actuation methods, and bring them to bear on the structural identification problem. We include a brief discussion of our experimental hardware and some recent experimental results which support the practical feasibility of this structural vibration sensing approach.

Junkins, J. L.↗

NASA NTRS1990

Effects of zero gravity on myofibril content and isomyosin distribution in rodent skeletal muscle

The purpose of this experiment was to investigate the effects of 12.5 days of zero gravity (0 g) exposure (Cosmos 1887 Biosputnik) on the enzymatic properties, protein content, and isomyosin distribution of the myofibril fraction of the slow-twitch vastus intermedius (VI) and the fast-twitch vastus lateralis (VL) muscles of adult male rats. Measurements were obtained on three experimental groups (n = 5 each group) designated as flight group (FG), vivarium control (VC), and synchronous control (SC). Body weight of the FG was significantly lower than that of the two control groups (P less than 0.05). Compared with the two control groups, VI weight was lower by 23% (P less than 0.10), whereas no such pattern was apparent for the VL muscle. Myofibril yields (mg protein/g muscle) in the VI were 35% lower in the FG than in controls (P less than 0.05), whereas no such pattern was apparent for the VL muscle. When myofibril yields were expressed on a muscle basis (mg/g x muscle weight), the loss of myofibril protein was more exaggerated and suggests that myofibril protein degradation is an early event in the muscle atrophy response to 0 g. Analysis of myosin isoforms indicated that slow myosin (Sm) was the primary isoform lost in the calculated degradation of total myosin. No evidence of loss of the fast isomyosins was apparent for either muscle following spaceflight. Myofibril ATPase activity of the VI was increased in the FG compared with controls, which is consistent with the observation of preferential Sm degradation. These data suggest that muscles containing a high percentage of slow-twitch fibers undergo greater degrees of myofibril protein degradation than muscles containing predominantly fast-twitch fibers in response to a relatively short period of 0 g exposure, and the primary target appears to be the Sm molecule.

NASA Program Flight↗

NASA NTRS2003

MRO's High Resolution Imaging Science Experiment (HiRISE): Education and Public Outreach Plans

The High Resolution Imaging Experiment, described by McEwen et al. and Delamere et al., will fly on the Mars 2005 Orbiter. In conjunction with the NASA Mars E/PO program, the HiRISE team plans an innovative and aggressive E/PO effort to complement the unique high-resolution capabilities of the camera. The team is organizing partnerships with existing educational outreach programs and museums and plans to develop its own educational materials. In addition to other traditional E/PO activities and a strong web presence, opportunities will be provided for the public to participate in image targeting and science analysis. The main aspects of our program are summarized.

V C Gulick↗

NASA NTRS2014

Role of Oxidative Damage in Radiation-Induced Bone Loss

During prolonged spaceflight, astronauts are exposed to both microgravity and space radiation, and are at risk for increased skeletal fragility due to bone loss. Evidence from rodent experiments demonstrates that both microgravity and ionizing radiation can cause bone loss due to increased bone-resorbing osteoclasts and decreased bone-forming osteoblasts, although the underlying molecular mechanisms for these changes are not fully understood. We hypothesized that excess reactive oxidative species (ROS), produced by conditions that simulate spaceflight, alter the tight balance between osteoclast and osteoblast activities, leading to accelerated skeletal remodeling and culminating in bone loss. To test this, we used the MCAT mouse model; these transgenic mice over-express the human catalase gene targeted to mitochondria, the major organelle contributing free radicals. Catalase is an anti-oxidant that converts reactive species, hydrogen peroxide into water and oxygen. This animal model was selected as it displays extended lifespan, reduced cardiovascular disease and reduced central nervous system radio-sensitivity, consistent with elevated anti-oxidant activity conferred by the transgene. We reasoned that mice overexpressing catalase in mitochondria of osteoblast and osteoclast lineage cells would be protected from the bone loss caused by simulated spaceflight. Over-expression of human catalase localized to mitochondria caused various skeletal phenotypic changes compared to WT mice; this includes greater bone length, decreased cortical bone area and moment of inertia, and indications of altered microarchitecture. These findings indicate mitochondrial ROS are important for normal bone-remodeling and skeletal integrity. Catalase over-expression did not fully protect skeletal tissue from structural decrements caused by simulated spaceflight; however there was significant protection in terms of cellular oxidative damage (MDA levels) to the skeletal tissue. Furthermore, we used an array of countermeasures (Antioxidant diets and injections) to prevent the radiation-induced bone loss, although these did not prevent bone loss, analysis is ongoing to determine if these countermeasure protected radiation-induced damage to other tissues.

oxidative damage↗

NASA NTRS1993

Preliminary analysis of the JAPE ground vehicle test data with an artificial neural network classifier

Remotely sensing and classifying military vehicles in a battlefield environment have been the source of much research over the past 20 years. The ability to know where threat vehicles are located is an obvious advantage to military personnel. In the past active methods of ground vehicle detection such as radar have been used, but with the advancement of technology to locate these active sensors, passive sensors are preferred. Passive sensors detect acoustic emissions, seismic movement, electromagnetic radiation, etc., produced by the target and use this information to describe it. Deriving the mathematical models to classify vehicles in this manner has been, and is, quite complex and not always reliable. However, with the resurgence of artificial neural network (ANN) research in the past few years, developing models for this work may be a thing of the past. Preliminary results from an ANN analysis to the tank signatures recorded at the Joint Acoustic Propagation Experiment (JAPE) at the US Army White Sands Missile Range, NM, in July 1991, are presented.

Larsen, Nathan F.↗

NASA NTRS1992

Availability of the B beta(15-21) epitope on cross-linked human fibrin and its plasmic degradation products

The binding of radiolabeled monoclonal antifibrin antibody 59D8 (specific for fibrin but not fibrinogen) to a series of degraded fibrin clots showed that the availability of the B beta(15-21) epitope (against which 59D8 had been raised) was inversely proportional to the extent of clot lysis. Examination of digest supernatants revealed that the B beta(15-21) epitope was released from clots as a high molecular weight degradation product in the presence of calcium ions but that the generation of low molecular weight peptides occurred in the absence of calcium ions. To address the question of epitope accessibility, we compared levels of fibrin clot binding among four radioactively labeled antibodies: antifibrin monoclonal antibody 59D8, two antifibrinogen monoclonal antibodies that cross-reacted with fibrin, and an affinity-purified polyclonal antifibrinogen antibody. We expected that the antifibrinogen antibodies would show enhanced binding to clots in comparison with the antifibrin antibody. However, the epitope accessibility experiments showed that all four antibody preparations bound fibrin clots at comparable levels. Taken together, these studies demonstrated that one fibrin-specific epitope, B beta(15-21), remains available on clots as they undergo degradation by plasmin and, importantly, that the epitope is not solubilized at a rate faster than the rate at which the clot is itself solubilized. The availability of the B beta(15-21) epitope during the course of plasminolysis assures the potential utility of antifibrin antibodies such as 59D8 for detecting thrombi and targeting plasminogen activators.

NASA Discipline Regulatory Physiology↗

NASA NTRS2007

Swift Multi-wavelength Observing Campaigns: Strategies and Outcomes

The Swift gamma-ray burst explorer has been operating since December 2004 as both a gamma-ray burst (GRB) monitor and telescope and a multi-wavelength observatory, covering the energy range from V band and near UV to hard X rays above 150 keV. It is designed to rapidly repoint to observe newly discovered GRBs, and this maneuverability, combined with an easily changed observing program, allows Swift to also be an effective multiwavelength observatory for non-GRB targets, both as targets of opportunity and pre-planned multi-wavelength observing campaigns. Blazars are particularly attractive targets for coordinated campaigns with TeV experiments since many blazars are bright in both the hard X-ray and TeV energy ranges. Successful coordinated campaigns have included observations of 3C454.3 during its 2005 outburst. The latest Swift funding cycles allow for non- GRB related observations to be proposed. The Burst Alert Telescope on Swift also serves as a hard X-ray monitor with a public web page that includes light curves for over 400 X-ray sources and is used to alert the astronomical community about increased activity from both known and newly discovered sources. This presentation mill include Swift capabilities, strategies and policies for coordinated multi-wavelength observations as well as discussion of the potential outcomes of such campaigns.

Krimm, Hans A.↗