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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 829 records · Page 46
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NASA NTRS2015

The Evolution of Failure Analysis at NASA's Kennedy Space Center and the Lessons Learned

The United States has had four manned launch programs and three station programs since the era of human space flight began in 1961. The launch programs, Mercury, Gemini, Apollo, and Shuttle, and the station programs, Skylab, Shuttle-Mir, and the International Space Station (ISS), have all been enormously successful, not only in advancing the exploration of space, but also in advancing related technologies. As each subsequent program built upon the successes of previous programs, they similarly learned from their predecessors' failures. While some failures were spectacular and captivated the attention of the world, most only held the attention of the dedicated men and women working to make the missions succeed.

metallography↗
NASA NTRS2016

Modeling a Miniaturized Scanning Electron Microscope Focusing Column - Lessons Learned in Electron Optics Simulation

This presentation discusses work done to assess the design of a focusing column in a miniaturized Scanning Electron Microscope (SEM) developed at the NASA Marshall Space Flight Center (MSFC) for use in-situ on the Moon-in particular for mineralogical analysis. The MSFC beam column design uses purely electrostatic fields for focusing, because of the severe constraints on mass and electrical power consumption imposed by the goals of lunar exploration and of spaceflight in general. The resolution of an SEM ultimately depends on the size of the focused spot of the scanning beam probe, for which the stated goal here is a diameter of 10 nanometers. Optical aberrations are the main challenge to this performance goal, because they blur the ideal geometrical optical image of the electron source, effectively widening the ideal spot size of the beam probe. In the present work the optical aberrations of the mini SEM focusing column were assessed using direct tracing of non-paraxial rays, as opposed to mathematical estimates of aberrations based on paraxial ray-traces. The geometrical ray-tracing employed here is completely analogous to ray-tracing as conventionally understood in the realm of photon optics, with the major difference being that in electron optics the lens is simply a smoothly varying electric field in vacuum, formed by precisely machined electrodes. Ray-tracing in this context, therefore, relies upon a model of the electrostatic field inside the focusing column to provide the mathematical description of the "lens" being traced. This work relied fundamentally on the boundary element method (BEM) for this electric field model. In carrying out this research the authors discovered that higher accuracy in the field model was essential if aberrations were to be reliably assessed using direct ray-tracing. This led to some work in testing alternative techniques for modeling the electrostatic field. Ultimately, the necessary accuracy was attained using a BEM/Fourier series hybrid approach. The presentation will give background remarks about the MSFC mini Lunar SEM concept and electron optics modeling, followed by a description of the alternate field modeling techniques that were tried, along with their incorporation into a ray-trace simulation. Next, the validation of this simulation against commercially available software will be discussed using an example lens as a test case. Then, the efficacy of aberration assessment using direct ray-tracing will be demonstrated, using this same validation case. The discussion will include practical error checks of the field solution. Finally, the ray-trace assessment of the MSFC mini Lunar SEM concept will be shown and discussed. The authors believe this presentation will be of general interest to practitioners of modeling and simulation, as well as those with a general optics background. Because electron optics and photon optics share many basic concepts (e.g., lenses, images, aberrations, etc.), the appeal of this presentation need not be restricted to just those interested in charged particle optics.

Modeling Miniaturizing Scanning↗
NASA NTRS2016

A Tale of Two Chambers: Iterative Approaches and Lessons Learned from Life Support Systems Testing in Altitude Chambers

With a brand new fire set ablaze by a serendipitous convergence of events ranging from a science fiction novel and movie ("The Martian"), to ground-breaking recent discoveries of flowing water on its surface, the drive for the journey to Mars seems to be in a higher gear than ever before. We are developing new spacecraft and support systems to take humans to the Red Planet, while scientists on Earth continue using the International Space Station as a laboratory to evaluate the effects of long duration space flight on the human body. Written from the perspective of a facility test director rather than a researcher, and using past and current life support systems tests as examples, this paper seeks to provide an overview on how facility teams approach testing, the kind of information they need to ensure efficient collaborations and successful tests, and how, together with researchers and principal investigators, we can collectively apply what we learn to execute future tests.

Callini, Gianluca↗
NASA NTRS2016

Unique Results and Lessons Learned from the TSS Missions

In 1924, Irvin Langmuir and H. M. Mott-Smith published a theoretical model for the complex plasma sheath phenomenon in which they identified some very special cases which greatly simplified the sheath and allowed a closed solution to the problem. The most widely used application is for an electrostatic, or "Langmuir," probe in laboratory plasma. Although the Langmuir probe is physically simple (a biased wire) the theory describing its functional behavior and its current-voltage characteristic is extremely complex and, accordingly, a number of assumptions and approximations are used in the LMS model. These simplifications, correspondingly, place limits on the model's range of application. Adapting the LMS model to real-life conditions is the subject of numerous papers and dissertations. The Orbit-Motion Limited (OML) model that is widely used today is one of these adaptions that is a convenient means of calculating sheath effects. The OML equation for electron current collection by a positively biased body is simply: I is approximately equal to A x j(sub eo) x 2/√𝜋(phi)(exp ½) where A is the area of the body and phi is the electric potential on the body with respect to the plasma. Since the Langmuir probe is a simple biased wire immersed in plasma, it is particularly tempting to use the OML equation in calculating the characteristics of the long, highly biased wires of an Electric Sail in the solar wind plasma. However, in order to arrive at the OML equation, a number of additional simplifying assumptions and approximations (beyond those made by Langmuir-Mott-Smith) are necessary. The OML equation is a good approximation when all conditions are met, but it would appear that the Electric Sail problem lies outside of the limits of applicability.

Stone, Nobie H.↗
NASA NTRS2016

Unique Results and Lessons Learned From the TSS Missions

The Tethered Satellite System (TSS) Space Shuttle missions, TSS-1 in 1993 and TSS-1R in 1996, were the height of space tether technology development in the U.S. Altogether, the investment made by NASA and the Italian Space Agency (ASI) over the thirteen-year period of the TSS Program totaled approximately $400M-exclusive of the two Space Shuttle flights provided by NASA. Since those two pioneering missions, there have been several smaller tether flight experiments, but interest in this promising technology has waned within NASA as well as the DOD agencies. This is curious in view of the unique capabilities of space tether systems and the fact that they have been flight validated in earth orbit and shown to perform better than the preflight dynamic or electrodynamic theoretical predictions. While it is true that the TSS-1 and TSS-1R missions experienced technical difficulties, the causes of these early developmental problems are now known to have been engineering design flaws, material selection, and procedural issues that (1) are unrelated to the basic viability of space tether technology, and (2) can be readily corrected. The purpose of this paper is to review the dynamic and electrodynamic fundamentals of space tethers and the unique capabilities they afford (that are enabling to certain types of space missions); to elucidate the nature, cause, and solution of the early developmental problems; and to provide an update on progress made in development of the technology.

Stone, Nobie H.↗
NASA NTRS2016

Challenges of Designing a 13-Hz High-Load Vibration Isolation System with Tight Volume Constraints: Lessons Learned and Path Forward

This paper describes the design of a passive isolation system using D-struts (Registered TradeMark) to isolate an optical payload from aircraft-borne jitter with challenging stroke per volume requirements. It discusses the use of viscoelastic-coated D-struts® that meet the customer performance and outgassing specification, NASA-1124. The result was a relatively soft isolation system, (where the first mode was 13 Hz), with each individual strut capable of withstanding loads on the order of magnitude of 623 N (140 lbf), weighing less than 910 g (2 lbm), fitting in a volume 5.1 cm (2 inches) in diameter and 12-cm (4.7-inches) long and capable of performing up to 1000 Hz without nonlinearities.

Dearing, Stella↗
NASA NTRS2016

APM for a Constellation Intersatellite Link - EM Qualification and Lessons Learned

For an Intersatellite Link (ISL) of a future constellation program, a study phase was initiated by ESA to design a mechanism for Radio Frequency communication. Airbus DS Friedrichshafen (ADSF) proposed a design based on the Antenna Pointing Mechanism (APM) family with modifications that met the stated needs of the constellation. A qualification program was started beginning in September 2015 to verify the launch and thermal loads and the equipment performance (Radio Frequency, Pointing, Microvibration and Magnetic Moment). Technical challenges identified with the Engineering Model will be discussed within this paper.

Hartel, Frank↗
NASA NTRS2016

Over Target Baseline: Lessons Learned from the NASA SLS Booster Element

Goal of the presentation is to teach, and then model, the steps necessary to implement an Over Target Baseline (OTB). More than a policy and procedure session, participants will learn from recent first hand experience the challenges and benefits that come from successfully executing an OTB.

Carroll, Truman J.↗
NASA NTRS2016

A Year in Space: Early Results and Lessons Learned from the First Year-Long Expedition Aboard the International Space Station

Two ISS crewmembers recently completed the first year-long orbital stay in two decades. International cooperation was central to the success of Mikhail Kornienko from Russia and Scott Kelly from the United States. Their expedition leveraged current mission experience and capitalized on recent advances in health monitoring technology. This unique effort began in 2012 when the program managers of the ISS partner nations adopted two separate goals: greater multilateral cooperation to increase efficiency of inflight research and a year-long expedition to gain familiarity with in-flight durations approaching that required for a Mars mission. These goals were unified when a set of bilateral Russian and American human research investigations was assigned to the year-long mission, augmented by additional investigations from Europe and Japan. For example, Kelly was assigned 18 investigations (twice the complement on standard six-month missions) including two joint U.S.-Russian studies, and two Russian and two Japanese studies. The core set of American investigations was a repetition of six studies Kelly had done on his previous six-month ISS mission, to allow a direct comparison of physiological and behavioral responses of the longer and shorter durations in this single individual. The remainder of his assignments plus those of Kornienko were drawn from currently active national investigations documenting human adaptation to long-duration spaceflight factors or effectiveness of countermeasures against known deleterious adaptations. The two joint U.S.-Russian investigations were the flagship biomedical studies of the year-long expedition. The "Fluid Shifts" study collocated American research equipment alongside a Russian operational stressor device to document the pattern and impacts of the headward fluid shift long known to occur in weightlessness, including its role in ocular changes recently observed in some astronauts. The "Field Test" study investigated the ability of the astronaut and cosmonaut to perform rudimentary tasks requiring sensorimotor coordination immediately after landing to define human capabilities soon after landing on Mars after an extended transit. Both investigations were highly successful in large part to the thorough integration of the implementation processes of the two partners. Kelly's assignment as the one-year crewmember also provided a serendipitous opportunity for the "Twins Study" comparing changes in his body at the genetic level with those occurring on Earth in his identical twin brother Mark Kelly. Data analysis from this expedition will commence in earnest after frozen in-flight samples are delivered to Earth in May aboard a commercial cargo spacecraft. Detailed results are expected in early 2017. Preliminary results and implementation improvements will be reviewed in this presentation.

Charles, J. B.↗