Lunar Reconnaissance Orbiter Overview: The Instrument Suite and Mission

NASA’s Lunar Precursor Robotic Program (LPRP), formulated in response to the President’s Vision for Space Exploration, will execute a series of robotic missions that will pave the way for eventual permanent human presence on the Moon. The Lunar Reconnaissance Orbiter (LRO) is first in this series of LPRP missions, and plans to launch in October of 2008 for at least one year of operation. LRO will employ six individual instruments to produce accurate maps and high-resolution images of future landing sites, to assess potential lunar resources, and to characterize the radiation environment. LRO will also test the feasibility of one advanced technology demonstration package. The LRO payload includes: Lunar Orbiter Laser Altimeter (LOLA) which will determine the global topography of the lunar surface at high resolution, measure landing site slopes, surface roughness, and search for possible polar surface ice in shadowed regions, Lunar Reconnaissance Orbiter Camera (LROC) which will acquire targeted narrow angle images of the lunar surface capable of resolving meter-scale features to support landing site selection, as well as wide-angle images to characterize polar illumination conditions and to identify potential resources, Lunar Exploration Neutron Detector (LEND) which will map the flux of neutrons from the lunar surface to search for evidence of water ice, and will provide space radiation environment measurements that may be useful for future human exploration, Diviner Lunar Radiometer Experiment (DLRE) which will chart the temperature of the entire lunar surface at approximately 300 meter horizontal resolution to identify cold-traps and potential ice deposits, Lyman-Alpha Mapping Project (LAMP) which will map the entire lunar surface in the far ultraviolet. LAMP will search for surface ice and frost in the polar regions and provide images of permanently shadowed regions illuminated only by starlight. Cosmic Ray Telescope for the Effects of Radiation (CRaTER), which will investigate the effect of galactic cosmic rays on tissue-equivalent plastics as a constraint on models of biological response to background space radiation. The technology demonstration is an advanced radar (mini-RF) that will demonstrate X- and S-band radar imaging and interferometry using light weight synthetic aperture radar. This paper will give an introduction to each of these instruments and an overview of their objectives.     

A model for the evolution of the on-orbit man-made debris environment

A model for the evolution of the low Earth orbit man-made debris population is presented and the results of several test cases discussed. Debris sources include normal operations in space, explosions occurring on spacecraft in orbit, and collisions between objects in orbit; the stochastic occurrence of these deposition events is modeled using Monte Carlo techniques. A technique for discriminating between objects populating long-life vs rapid-decay orbits is discussed and applied to the analysis of debris contributions from collisions of comparable sized objects. In varying degrees, each of the cases presented indicate there is cause for concern for spacecraft and space operations from the 1990s onward-man-made debris will play a role which may vary from presenting a considerable hazard to certain operations or certain spacecraft to effectively prohibiting the use of certain spaceccraft or space operations.     

正确的程序及维护,轻松降低切割的成本

随着材料科技高歌猛进的步伐,材质各异、品种繁多的新型金属加工材料逐渐成为工业界的新宠,他们在给制造商带来更高竞争力、更大利益的同时也给从事金属加工业者带去新的技术挑战。     

Measuring Black Hole Spin Using X-Ray Reflection Spectroscopy

I review the current status of X-ray reflection (a.k.a. broad iron line) based black hole spin measurements. This is a powerful technique that allows us to measure robust black hole spins across the mass range, from the stellar-mass black holes in X-ray binaries to the supermassive black holes in active galactic nuclei. After describing the basic assumptions of this approach, I lay out the detailed methodology focusing on “best practices” that have been found necessary to obtain robust results. Reflecting my own biases, this review is slanted towards a discussion of supermassive black hole (SMBH) spin in active galactic nuclei (AGN). Pulling together all of the available XMM-Newton and Suzaku results from the literature that satisfy objective quality control criteria, it is clear that a large fraction of SMBHs are rapidly-spinning, although there are tentative hints of a more slowly spinning population at high (M>5×10⁷ M _⊙) and low (M<2×10⁶ M _⊙) mass. I also engage in a brief review of the spins of stellar-mass black holes in X-ray binaries. In general, reflection-based and continuum-fitting based spin measures are in agreement, although there remain two objects (GRO J1655–40 and 4U 1543–475) for which that is not true. I end this review by discussing the exciting frontier of relativistic reverberation, particularly the discovery of broad iron line reverberation in XMM-Newton data for the Seyfert galaxies NGC 4151, NGC 7314 and MCG–5-23-16. As well as confirming the basic paradigm of relativistic disk reflection, this detection of reverberation demonstrates that future large-area X-ray observatories such as LOFT will make tremendous progress in studies of strong gravity using relativistic reverberation in AGN.     

Path visualization: a method for objective measurement of spatial visualization

ABSTRACT

The ability to mentally represent spatial information is a fundamental cognitive process. To many people, this process feels a bit like visual perception, hence the term ‘spatial visualization’. In this paper, we describe a method for measuring the accuracy of spatial visualization, specifically visualization of a complex path in imaginary space. A critical feature of this method (called Path Visualization) is that it relies on the detection of intersections in a visualized path. Intersection detection is an inherently spatial task that requires a spatial representation. In this paper, we show how the Path Visualization method works, and how it can be customized to address several key research issues in human spatial cognition.     

Synergistic use of debris environment models for flexible, very-long term projections

Long-term debris environment projections are of great importance for assessing the necessity and effectiveness of debris mitigation measures. Two types of models have been developed to predict these environments. Environment evolution models like the EVOLVE code are using detailed mission model data to input spacecraft, upper stages, and operational debris into specific orbits at specific times; debris from fragmentations are placed in orbits defined by the state vector of the fragmenting object(s) and the breakup model. The second type, typified by the CHAIN program, uses a particle-in-box model that bins the environment in size and altitude rather than following the orbit evolution of individual debris fragments. A 3-Step approach using both the EVOLVE and CHAIN model in a synergistic way was used to increase the reliability of long term environment projections. EVOLVE historical projections 1957–1995 could be validated by comparison to measurements. The comparison of 100 year projection runs of EVOLVE and CHAIN for different traffic scenarios showed a good agreement. In this paper, for the first time, CHAIN projections up to 10,000 years, based on validated boundary conditions derived by EVOLVE are presented, indicating clearly the need of early implementation of effective mitigation measures to prevent exponential population growth by collisional cascading effects.     

High spectral resolution line profiles and images of comet Halley

High-spectral-resolution line profiles and images of comet Halley were obtained in 1986 at the National Solar Observatory McMath telescope, using a dual-etalon Fabry-Perot spectrometer. The spectrometer was designed to obtain data in four distinct modes: (1) high-resolution (R = 200,000) scanning, (2) high-resolution imaging, (3) moderate resolution (R = 30,000) scanning, and (4) moderate resolution imaging. This paper describes the instrument and some examples of data obtained in the high-resolution scanning mode.     

Test of galactic cosmic-ray source models – Working Group Report

The main features of cosmic-ray source models and acceleration processes are reviewed, with special emphasis on the possible observational tests, through both composition analysis and multi-wavelength studies of supernova remnants. Non-linear effects in the context of supernova-induced diffusive shock acceleration are discussed, as well as collective acceleration effects induced by multiple supernova explosions inside superbubbles.     

Identification of a discrete-time dynamical system

A novel generalized minimum variance (GMV) system identification algorithm is developed, and its performance is gauged against the established generalized least squares (GLS) estimation algorithm. The emphasis of the proposed GMV algorithm is on the rigorous treatment of measurement noise for dynamical system identification. A careful analysis of the measurement situation on hand yields a novel fixed-point calculation-based parameter estimation algorithm. The novel and established algorithms are compared in carefully performed and reproducible experiments which include measurement noise. Differences are apparent under small (measurement) sample operation, whereas under sufficient excitation, the algorithms produce statistically similar results     

Conversations with John H. Glenn Jr. Interview by Frank Sietzen Jr

Senator Glenn is interviewed about his experiences on Friendship 7 and the Shuttle Discovery, expectations of early astronauts, lunar missions, the International Space Station, international dimensions of space activities, public confidence in NASA, attracting young people to the aerospace industry, highlights of his career, and the future of flight.