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At least 865 records · Page 48

Aerodynamic Heating and Deceleration During Entry into Planetary Atmospheres

Dr. Chapman's lecture examines the physics behind spacecraft entry into planetary atmospheres. He explains how scientists determine if a planet has an atmosphere and how scientists can compute deceleration when the atmospheric conditions are unknown. Symbols and equations used for calculations for aerodynamic heating and deceleration are provided. He also explains heat transfer in bodies approaching an atmosphere, deceleration, and the use of ablation in protecting spacecraft from high temperatures during atmospheric entry.

Chapman, Dean R.↗

The Solar Cycle

Sunspots provided the first evidence for the 11-year cycle of solar activity and continue to provide key indicators of the level and nature of solar activity. Solar flares, prominence eruptions, and coronal mass ejections increase in frequency as the number of sunspots increases during the rising phase of the solar cycle. The total irradiance of the Sun and its irradiance in ultraviolet light and x-rays also increase as the sunspot number increases. On the other hand, the flux of galactic cosmic rays reaching Earth decreases as the sunspot number increases. These changes in the heliospheric environment produce significant effects on our environment. Our technological assets, in space, in the air, and on the ground, can be adversely affected by solar activity. Satellite drag, single-event upsets in electronic components, radio communication outages, power outages, and terrestrial climate can all be influenced by solar activity. In this lecture I will describe many of the significant characteristics of the solar cycle, their roots in solar magnetism, the mechanisms of the Sun's magnetic dynamo, and predictions for the amplitude and timing of next solar cycle.

Hathaway, D. H.↗

Transition Zone Modeling

This lecture reviews current practice as well as new modeling ideas for the calculation of at least skin friction and heat transfer between the onset and end of transition.

Reshotko, Eli↗

Seven Key Principles of Program and Project Success: A Best Practices Survey

The National Aeronautics and Space Administration (NASA) Organization Design Team (ODT), consisting of 20 seasoned program and project managers and systems engineers from a broad spectrum of the aerospace industry, academia, and government, was formed to support the Next Generation Launch Technology (NGLT) Program and the Constellation Systems Program. The purpose of the ODT was to investigate organizational factors that can lead to success or failure of complex government programs, and to identify tools and methods for the design, modeling, and analysis of new and more-efficient program and project organizations. The ODT conducted a series of workshops featuring invited lectures from seasoned program and project managers representing 25 significant technical programs spanning 50 years of experience. The result was the identification of seven key principles of program success that can be used to help design and operate future program organizations. This paper presents the success principles and examples of best practices that can significantly improve the design of program, project, and performing technical line organizations, the assessment of workforce needs and organization performance, and the execution of programs and projects.

Bilardo, Vincent J.↗

The Beginning and End of the Universe

Cosmology is the scientific study of how the Universe began more than 13 billion years ago, how its properties have changed, and what its future might be. The balance of forces and energy cause the Universe to expand, first accelerating, then decelerating and then accelerating again. Within this overall structure, the interplay of atoms and light with the mysterious dark matter and dark energy causes stars and galaxies to form and evolve, leading to galaxies like our own home, the Milky Way. Observational cosmology uses telescopes on Earth and in space to reach back in time to find the faint remaining echoes of the Big Bang and to trace the formation and evolution of the galaxies and structures that fill the Universe. In this lecture, Dr. Gardner will give an overview of cosmology, outlining the 13-billion year history of the Universe, and highlighting the very rapid progress this field has made in the last decade. He will discuss the role that NASA space telescopes have played in this progress and will continue to play in the years to come. He will give a time-based history of the Universe, discussing the successive processes that formed matter, particles, atoms, stars and galaxies. In particular, he will focus on cosmological inflation, the rapid accelerated expansion that marks the beginning of the Universe, and dark energy, a tenuous substance that overcomes gravity and whose properties will determine its final fate.

Gardner, Jonathan P.↗

The Beginning and End of the Universe

Cosmology is the scientific study of how the Universe began more than 13 billion years ago, how its properties have changed, and what its future might be. The balance of forces and energy cause the Universe to expand, first accelerating, then decelerating and then accelerating again. Within this overall structure, the interplay of atoms and light with the mysterious dark matter and dark energy causes stars and galaxies to form and evolve, leading to galaxies like our own home, the Milky Way. Observational cosmology uses telescopes on Earth and in space to reach back in time to find the faint remaining echoes of the Big Bang and to trace the formation and evolution of the galaxies and structures that fill the Universe. In this lecture, Dr. Gradner will give an overview of cosmology, outlining the 13-billion year history of the Universe, and highlighting the very rapid progress this field has made i the last decade. He will discuss the role that NASA space telescopes have played in this progress and wil continue to play in the years to come. He will give a time-based history of the Universe, discussing the successive processes that formed matter, particles, atoms, stars and galaxies. In particular, he will focus on cosmological inflation, the rapid accelerated expansion that marks the beginning of the Universe, and dark energy, a tenuous substance that overcomes gravity and whose properties will determine its final fate.

Gardner, Jonathan↗

The Cosmic Odyssey of Dust

We will present models for the evolution of dust in high redshift galaxies and in galaxies in the local universe. Galaxies at very high redshift, when the universe was less than one billion years old, contain massive quantities of dust that could only have for~nedin the explosion of core-collapse supernovae. These same objects are also the main source of grain destruction during the later, remnant phase of their evolution. These galaxies offer therefore a unique opportunity for examining the effect of massive stars on the formation and destruction of interstellar dust, and the lecture will present a model for the evolution of dust in these very young galaxies. Spectral and photometric observations of nearby galaxies show a correlation between the strength of their mid-IR aromatic features, attributed to PAH molecules, and their metal abundance, leading to a deficiency of these features in low-metallicity galaxies. We show the observed correlation represents a trend of PAH abundance with galactic age, reflecting the delayed injection of carbon dust into the ISM by AGB stars in the final post-AGB phase of their evolution. We also show that larger dust particles giving rise to the far-IR emission follow a distinct evolutionary trend closely related to the injection of dust by massive stars into the ISM.

Dwek, Eli↗

The Global Aerosol System As Viewed By MODIS Today

The MODerate resolution Imaging Spectroradiometer (MODIS) aerosol algorithms have been working steadily since early 2000 to transform the MODIS-measured spectral solar reflectance from the Earth's surface and atmosphere into a variety of aerosol products. In this lecture I will proceed through a survey of these products, answering the following questions as I proceed. What are the products? How do they compare with ground truth? How do we use these products to describe the global aerosol system? Are aerosols increasing or decreasing? How do aerosols affect climate and clouds?

Remer, Lorraine↗

Mars Exploration Rovers: 4 Years on Mars

This January, the Mars Exploration Rovers "Spirit" and "Opportunity" are starting their fifth year of exploring the surface of Mars, well over ten times their nominal 90-day design lifetime. This lecture discusses the Mars Exploration Rovers, presents the current mission status for the extended mission, some of the most results from the mission and how it is affecting our current view of Mars, and briefly presents the plans for the coming NASA missions to the surface of Mars and concepts for exploration with robots and humans into the next decade, and beyond.

Landis, Geoffrey A.↗

Exploring Venus

With a temperature higher than the inside of your oven and atmospheric pressure equal to that a kilometer under the ocean, the surface of Venus is one of the most hostile environments in the solar system, and Venus exploration presents a challenge to technology. This lecture presents mission trade-offs and discusses a proposed mission concept for rover and aircraft based exploration of the surface and atmosphere of Venus. Several approaches to the technology, electronics, mechanical parts, and power systems, are discussed.

Landis, Geoffrey A.↗

Taking the Measure of the Universe

The cosmic microwave background (CMB) radiation is the oldest light in the universe - it is literally the remnant heat left over from the Big Bang. This fossil relic has survived largely intact and it provides us with a unique probe of conditions in the early universe, long before any stars or galaxies had formed. NASA has now flown two satellites devoted to studying the CMB: 'COBE' and 'WMAP'. In this lecture I will describe what we have learned from these missions including: evidence for the Big Bang itself; new measurements of the age, shape, and content of the universe; and new evidence that all structure in the universe emerged from microscopic quantum fluctuations in the primordial soup.

Hinshaw, Gary↗

Interstellar Propulsion Research: Realistic Possibilities and Idealistic Dreams

Though physically possible, interstellar travel will be exceedingly difficult. Both the known laws of physics and the limits of our current understanding of engineering place extreme limits on what may actually be possible. Our remote ancestors looked at the night sky and assumed those tiny points of light were campfires around which other tribes were gathered -- and they dreamed of someday making the trip to visit them. In our modern era, we've grown accustomed to humans regularly traveling into space and our robots voyaging ever-deeper into the outer edges of our solar system. Traveling to those distant campfires (stars) has been made to look easy by the likes of Captains Kirk and Picard as well as Han Solo and Commander Adama. Our understanding of physics and engineering has not kept up with our imaginations and many are becoming frustrated with the current pace at which we are exploring the universe. Fortunately, there are ideas that may one day lead to new physical theories about how the universe works and thus potentially make rapid interstellar travel possible -- but many of these are just ideas and are not even close to being considered a scientific theory or hypothesis. Absent any scientific breakthroughs, we should not give up hope. Nature does allow for interstellar travel, albeit slowly and requiring an engineering capability far beyond what we now possess. Antimatter, fusion and photon sail propulsion are all candidates for relatively near-term interstellar missions. The plenary lecture will discuss the dreams and challenges of interstellar travel, our current understanding of what may be possible and some of the "out of the box" ideas that may allow us to become an interstellar species someday in the future.

Johnson, Les↗

Sunspots, Space Weather and Climate

Four hundred years ago this year the telescope was first used for astronomical observations. Within a year, Galileo in Italy and Harriot in England reported seeing spots on the surface of the Sun. Yet, it took over 230 years of observations before a Swiss amateur astronomer noticed that the sunspots increased and decreased in number over a period of about 11 years. Within 15 years of this discovery of the sunspot cycle astronomers made the first observations of a flare on the surface of the Sun. In the 150 years since that discovery we have learned much about sunspots, the sunspot cycle, and the Sun s explosive events - solar flares, prominence eruptions and coronal mass ejections that usually accompany the sunspots. These events produce what is called Space Weather. The conditions in space are dramatically affected by these events. Space Weather can damage our satellites, harm our astronauts, and affect our lives here on the surface of planet Earth. Long term changes in the sunspot cycle have been linked to changes in our climate as well. In this public lecture I will give an introduction to sunspots, the sunspot cycle, space weather, and the possible impact of solar variability on our climate.

Hathaway, David H.↗

Environmental Control and Life Support System (ECLSS) System Engineering Workshop

This slide presentation begins with a recap on a previous lecture on the ECLSS subsystems, and the various types (i.e., Non-regenerative vs Regenerative, open loop vs closed loop, and physical-chemical vs bioregenerative) It also recaps the Equivalent system mass (ESM) metric. The presentation continues with a review of the ECLSS of the various NASA manned space exploration programs from Mercury, to the current planned Altair lunar landing, and Lunar base operations. There is also a team project to establish the ESM of two conceptualized missions.

Peterson, Laurie J.↗

Infectious Considerations in Space Flight

Slightly more than 500 people have flown in space, most of them for short periods of time. The total number of person years in space is small. Given this fact, and given rigorous astronaut screening, it is not surprising that the accumulated infectious disease experience in space is also small, and mostly, theoretical. As the human space presence expands, we may expect mission length, total accumulated person years and the environmental complexity to increase. Add to the mix both changes in human immunity and microbial virulence, and it becomes realistic to consider infectious scenarios and the means to mitigate them. This lecture will cover the inhabited space environment from the perspective of host-microbe interactions, current relevant research, and the current countermeasures used. Future challenges will be discussed and there will be opportunity to ask questions about Space Operations. The audience is encouraged to think about what medical tools you would choose to have in different types of mission, what you would be willing to leave behind, and how you would compensate for the necessary trade offs in mission design.

Haddon, Robert↗

Laboratory for Atmospheres 2008 Technical Highlights

The 2008 Technical Highlights describes the efforts of all members of the Laboratory for Atmospheres. Their dedication to advancing Earth Science through conducting research, developing and running models, designing instruments, managing projects, running field campaigns, and numerous other activities, is highlighted in this report. The Laboratory for Atmospheres (Code 613) is part of the Earth Sciences Division (Code 610), formerly the Earth Sun Exploration Division, under the Sciences and Exploration Directorate (Code 600) based at NASA s Goddard Space Flight Center in Greenbelt, Maryland. In line with NASA s Exploration Initiative, the Laboratory executes a comprehensive research and technology development program dedicated to advancing knowledge and understanding of the atmospheres of Earth and other planets. The research program is aimed at understanding the influence of solar variability on the Earth s climate; predicting the weather and climate of Earth; understanding the structure, dynamics, and radiative properties of precipitation, clouds, and aerosols; understanding atmospheric chemistry, especially the role of natural and anthropogenic trace species on the ozone balance in the stratosphere and the troposphere; and advancing our understanding of physical properties of Earth s atmosphere. The research program identifies problems and requirements for atmospheric observations via satellite missions. Laboratory scientists conceive, design, develop, and implement ultraviolet, infrared, optical, radar, laser, and lidar technology for remote sensing of the atmosphere. Laboratory members conduct field measurements for satellite data calibration and validation, and carry out numerous modeling activities. These modeling activities include climate model simulations, modeling the chemistry and transport of trace species on regional-to-global scales, cloud-resolving models, and development of next-generation Earth system models. Interdisciplinary research is carried out in collaboration with other laboratories and research groups within the Earth Sciences Division, across the Sciences and Exploration Directorate, and with partners in universities and other Government agencies. The Laboratory for Atmospheres is a vital participant in NASA s research agenda. Our Laboratory often has relatively large programs, sizable satellite missions, and observational campaigns that require the cooperative and collaborative efforts of many scientists. We ensure an appropriate balance between our scientists responsibility for these large collaborative projects and their need for an active individual research agenda. This balance allows members of the Laboratory to continuously improve their scientific credentials. Members of the Laboratory interact with the general public to support a wide range of interests in the atmospheric sciences. Among other activities, the Laboratory raises the public s awareness of atmospheric science by presenting public lectures and demonstrations, by making scientific data available to wide audiences, by teaching, and by mentoring students and teachers. The Laboratory makes substantial efforts to attract new scientists to the various areas of atmospheric research. We strongly encourage the establishment of partnerships with Federal and state agencies that have operational responsibilities to promote the societal application of our science products. This report describes our role in NASA s mission, gives a broad description of our research, and summarizes our scientists major accomplishments during calendar year 2008. The report also contains useful information on human resources, scientific interactions, and outreach activities.

Cote, Charles E.↗

Creep Forming of Carbon-Reinforced Ceramic-Matrix Composites

A set of lecture slides describes an investigation of creep forming as a means of imparting desired curvatures to initially flat stock plates of carbon-reinforced ceramic-matrix composite (C-CMC) materials. The investigation is apparently part of a continuing effort to develop improved means of applying small CCMC repair patches to reinforced carbon-carbon leading edges of aerospace vehicles (e.g., space shuttles) prior to re-entry into the atmosphere of the Earth. According to one of the slides, creep forming would be an intermediate step in a process that would yield a fully densified, finished C-CMC part having a desired size and shape (the other steps would include preliminary machining, finish machining, densification by chemical vapor infiltration, and final coating). The investigation included experiments in which C-CMC disks were creep-formed by heating them to unspecified high temperatures for time intervals of the order of 1 hour while they were clamped into single- and double-curvature graphite molds. The creep-formed disks were coated with an oxidation- protection material, then subjected to arc-jet tests, in which the disks exhibited no deterioration after exposure to high-temperature test conditions lasting 490 seconds.

Vaughn, Wallace L.↗

Professor Created On-line Biology Laboratory Course

This paper will share the creation, implementation, and modification of an online college level general biology laboratory course offered for non-science majors as a part of a General Education Curriculum. The ability of professors to develop quality online laboratories will address a growing need in Higher Education as more institutions combine course sections and look for suitable alternative course delivery formats due to declining departmental budgets requiring reductions in staffing, equipment, and supplies. Also, there is an equal or greater need for more professors to develop the ability to create online laboratory experiences because many of the currently available online laboratory course packages from publishers do not always adequately parallel on-campus laboratory courses, or are not as aligned with the companion lecture sections. From a variety of scientific simulation and animation web sites, professors can easily identify material that closely fit the specific needs of their courses, instructional environment, and students that they serve. All too often, on-campus laboratory courses in the sciences provide what are termed confirmation experiences that do NOT allow students to experience science as would be carried out by scientists. Creatively developed online laboratory experiences can often provide the type of authentic investigative experiences that are not possible on-campus due to the time constraints of a typical two-hour, once-per-week-meeting laboratory course. In addition, online laboratory courses can address issues related to the need for students to more easily complete missing laboratory assignments, and to have opportunities to extend introductory exercises into more advanced undertakings where a greater sense of scientific discovery can be experienced. Professors are strongly encourages to begin creating online laboratory exercises for their courses, and to consider issues regarding assessment, copyrights, and Intellectual Property concerns.

Bowman, Arthur W.↗