The Broad Band X-Ray Telescope

The Broad-Band X-Ray Telescope (BBXRT) has been designed to perform high sensitivity, moderate resolution spectrophototnetry of X-ray sources in the 0.3–12 keV band from the Shuttle. It consists of a coaligned pair of high throughput, conical X-ray imaging mirrors, with a cryogenically-cooled, multiple element, Si(Li) spectrometer at the focus of each. On axis, BBXRT will have an effective area of 580 cm² at 2 keV and 250 cm² at 7 keV, and a spectral resolution of 110 eV at 2 keV and 150 eV at 7 keV. A 10⁴ s observation with BBXRT will allow a determination of the continuum spectral shape for sources near the Einstein deep survey limit.     

Analysis of solar degradation to TDRS S-band phased array antenna

A study of the distribution of gain-to-noise-temperature (G/T) values for the Tracking and Data Relay Satellite (TDRS) satellite is described. The statistics of the G/T values are determined by a Monte Carlo simulation of the orbital geometry of the Sun and Moon, and the gain and noise temperature calculations is included. The results and their underlying assumptions are described     

Gene Transfer and the Reconstruction of Life’s Early History from Genomic Data

The metaphor of the unique and strictly bifurcating tree of life, suggested by Charles Darwin, needs to be replaced (or at least amended) to reflect and include processes that lead to the merging of and communication between independent lines of descent. Gene histories include and reflect processes such as gene transfer, symbioses and lineage fusion. No single molecule can serve as a proxy for the tree of life. Individual gene histories can be reconstructed from the growing molecular databases containing sequence and structural information. With some simplifications these gene histories can be represented by furcating trees; however, merging these gene histories into web-like organismal histories, including the transfer of metabolic pathways and cell biological innovations from now-extinct lineages, has yet to be accomplished. Because of these difficulties in interpreting the record retained in molecular sequences, correlations with biochemical fossils and with the geological record need to be interpreted with caution. Advances to detect and pinpoint transfer events promise to untangle at least a few of the intertwined histories of individual genes within organisms and trace them to the organismal ancestors. Furthermore, analysis of the shape of molecular phylogenetic trees may point towards organismal radiations that might reflect early mass extinction events that occurred on a planetary scale.     

Systems integration, user interface design, and tower air trafficcontrol

Tower air traffic control is currently performed using several unintegrated systems. While each of these systems supports performing an isolated task, the compilation of tools presents a number of challenges. This paper reports ways in which the Tower Control Computer Complex (TCCC) will support and enhance user management of numerous systems. Areas that will be notably improved include the consistency in the user interface of the air traffic control toolset, the task of manually integrating tools and information, toolset alert management, and toolset organization and administration     

The Seed Population for Energetic Particles Accelerated by CME-Driven Shocks

Understanding properties of solar energetic particle (SEP) events associated with coronal mass ejections has been identified as a key problem in solar-terrestrial physics. Although recent CME shock acceleration models are highly promising, detailed agreement between theoretical predictions and observations has remained elusive. Recent observations from ACE have shown substantial enrichments in the abundances of ³He and He⁺ ions which are extremely rare in the thermal solar wind plasma. Consequently, these ions act as tracers of their source material, i.e., ³He ions are flare suprathermals and He⁺ ions are interstellar pickup ions. The average heavy ion composition also exhibits unsystematic differences when compared with the solar wind values, but correlates significantly with the ambient suprathermal material abundances. Taken together these results provide compelling evidence that CME-driven shocks draw their source material from the ubiquitous but largely unexplored suprathermal tail rather than from the more abundant solar wind peak. However, the suprathermal energy regime has many more contributors and exhibits much larger variability than the solar wind, and as such needs to be investigated more thoroughly. Answers to fundamental new questions regarding the preferred injection of the suprathermal ions, the spatial and temporal dependence of the various sources, and the causes of their variability and their effects on the SEP properties are needed to improve agreement between the simulations and observations.     

Magnetar descendants in HMXBs?

We investigate the relation between the pulse and orbital periods in high-mass X-ray binaries (HMXBs), in order to find the candidates of magnetar descendants in HMXBs. We suggest that magnetar descendants can be found among the HMXBs with relatively shorter orbital periods and longer pulse periods.     

Limitations of radiometer performance in spherically invariantnoise

The radiometer is a common method for detection of unknown signals in noise. Most analyses of radiometer performance are based on assumptions of stationary Gaussian noise with known marginal statistics. In this note, we use a spherically invariant noise model to derive simple expressions for radiometer performance degradation in noise variance uncertainty. Numerical examples are provided to show that channel uncertainty imposes a substantial penalty in detection performance     

Overcoming barriers to space travel

This viewpoint argues that the barriers preventing human expansion into space are not scientific but political and legal - an inability to secure funding; artificially high costs created by punitive insurance premiums and excessive bureaucracy; and uncertainty and disagreement about the extent and implications of legal regulation of space activities. Construction on Earth of a ‘metanation’ to oversee the governance of outer space is advocated as a possible solution.     

Clover development during spaceflight: a model system.

The development of legume root nodules was studied as a model system for the examination of gravitational effects on plant root development. In order to examine whether rhizobial association with clover roots can be achieved in microgravity, experiments were performed aboard the KC-135 parabolic aircraft and aboard the sounding rocket mission Consort 3. Binding of rhizobia to roots and the initial stages of root nodule development successfully occurred in microgravity. Seedling germination experiments were performed in the sliding block device, the Materials Dispersion Apparatus, aboard STS-37. When significant hydration of the seeds was achieved, normal rates of germination and seedling development were observed.     

Instrumentation for plant health and growth.

Comprehensive spectroscopic monitoring of plant health and growth in bioregenerative life support system environments is possible using a variety of spectrometric technologies. Absorption spectrometry and atomic emission spectrometry in combination allow for direct, on-line, reagentless monitoring of plant nutrients from nitrate and potassium to micronutrients such as copper and zinc. Fluorometric spectrometry is ideal for the on-line detection, identification and quantification of bacteria and fungi. Liquid Atomic Emission Spectrometry (LAES) is a new form of spectrometry that allows for direct measurement of atomic emission spectra in liquids. An electric arc is generated by a pair of electrodes in the liquid to provide the energy necessary to break molecular bonds and reduce the substance to atomic form. With a fiber probe attached to the electrodes, spectral light can be transmitted to a photodiode array spectrometer for light dispersion and analysis. Ultraviolet (UV) absorption spectrometry is a long-established technology, but applications typically have required specific reagents to produce an analyte-specific absorption. Nitrate and iron nutrients have native UV absorption spectra that have been used to accurately determine nutrient concentrations at the +/- 5% level. Fluorescence detection and characterization of microbes is based upon the native fluorescent signatures of most microbiological species. Spectral and time-resolved fluorometers operating with remote fiber-optic probes will be used for on-line microbial monitoring in plant nutrient streams.