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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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NASA NTRS2004

Development of a State Machine Sequencer for the Keck Interferometer: Evolution, Development and Lessons Learned using a CASE Tool Approach

This paper presents a discussion of the evolution of a sequencer from a simple EPICS (Experimental Physics and Industrial Control System) based sequencer into a complex implementation designed utilizing UML (Unified Modeling Language) methodologies and a CASE (Computer Aided Software Engineering) tool approach. The main purpose of the sequencer (called the IF Sequencer) is to provide overall control of the Keck Interferometer to enable science operations be carried out by a single operator (and/or observer). The interferometer links the two 10m telescopes of the W. M. Keck Observatory at Mauna Kea, Hawaii. The IF Sequencer is a high-level, multi-threaded, Hare1 finite state machine, software program designed to orchestrate several lower-level hardware and software hard real time subsystems that must perform their work in a specific and sequential order. The sequencing need not be done in hard real-time. Each state machine thread commands either a high-speed real-time multiple mode embedded controller via CORB A, or slower controllers via EPICS Channel Access interfaces. The overall operation of the system is simplified by the automation. The UML is discussed and our use of it to implement the sequencer is presented. The decision to use the Rhapsody product as our CASE tool is explained and reflected upon. Most importantly, a section on lessons learned is presented and the difficulty of integrating CASE tool automatically generated C++ code into a large control system consisting of multiple infrastructures is presented.

interferometer↗
NASA NTRS2004

Mars Reconnaissance Orbiter Navigation

Mars Reconnaissance Orbiter will launch in August 2005 at Cape Canaveral Air Force Station. The heavyweight spacecraft will use a Lockheed-Martin Atlas V-401 launch vehicle. It will be the first mission in a low Mars Orbit to characterize the surface, subsurface, and atmospheric properties. The intensive science operation imposes a great challenge for Navigation to satisfy the stringent requirements. This paper describes navigation key requirements, major challenges, and the sophisticated dynamic modeling. It also details navigation strategy and processes for various mission phases. Mars Reconnaissance Orbiter will return significant amount of scientific data in support of the objectives set by the Mars Exploration Program. A robust and precise navigation is the key to the success of this mission.

navigation↗
NASA NTRS2004

Science Opportunity Analyzer (SOA): Not Just Another Pretty Face

This viewgraph presentation reviews the Science Opportunity Analyzer (SOA). For the first time at JPL, the Cassini mission to Saturn is using distributed science operations for sequence generation. This means that scientist at other institutions has more responsibility to build the spacecraft sequence. Tools are required to support the sequence development. JPL tools required a complete configuration behind a firewall, and the tools that the user community had developed did not interface with the JPL tools. Therefore the SOA was created to bridge the gap between the remote scientists and the JPL operations teams. The presentation reviews the development of the SOA, and what was required of the system. The presentation reviews the functions that the SOA performed.

mission planning↗
NASA NTRS2007

Hemispheric and Topographic Asymmetry of Magnetospheric Particle Irradiation for Icy Moon Surfaces

All surfaces of icy moons without significant atmospheres, i.e. all except Titan in the giant planet systems, are irradiated by hot plasma and more energetic charged particles from the local magnetospheric environments. This irradiation can significantly impact the chemical composition, albedo, and detectable presence of signs of life on the sensible surfaces, while also limiting lifetimes and science operations of orbital spacecraft for extreme radiation environments as at Europa. Planning of surface remote sensing and lander operations, and interpretation of remote sensing and in-situ measurements, should include consideration of natural shielding afforded by the body of the moon, by any intrinsic or induced magnetic fields as at Ganyrnede, and by topographic structures.

Cooper, John F.↗
NASA NTRS2009

UAVSAR: Airborne L-band Radar for Repeat Pass Interferometry

The primary objectives of the UAVSAR Project were to: a) develop a miniaturized polarimetric L-band synthetic aperture radar (SAR) for use on an unmanned aerial vehicle (UAV) or piloted vehicle. b) develop the associated processing algorithms for repeat-pass differential interferometric measurements using a single antenna. c) conduct measurements of geophysical interest, particularly changes of rapidly deforming surfaces such as volcanoes or earthquakes. Two complete systems were developed. Operational Science Missions began on February 18, 2009 ... concurrent development and testing of the radar system continues.

Moes, Timothy R.↗
NASA NTRS2010

Comparisons of the Flare Irradiance Spectral Model (FISM) to Preliminary SDO EVE Data

The Solar Dynamics Observatory (SDO) launched February 11,2010 from Kennedy Space Center and started normal science operations in April 2010. One of the instruments onboard SDO, the EUV Variability Experiment (EVE), will measure the solar EUV irradiance from 0.1-105 nm with 0.1 nm spectral resolution as well as a measure of the broad-band Lyman-Alpha emission (121.6 nm), all with less than 10 percent uncertainties. One of the biggest improvements of EVE over its predecessors is its ability to continuously measure the complete spectrum every 10 seconds, 24 hours a day, 7 days a week. This temporal coverage and cadence will greatly enhance the knowledge of the solar EUV variations during solar flares. This paper will present a comparison of the Flare Irradiance Spectral Model (FISM), which can produce an estimated EUV spectrum at 10 seconds temporal resolution, to the preliminary results from SDO EVE. The discussion will focus on the short-term EUV flare variations and evolution.

Chamberlin, Phillip↗
NASA NTRS2010

Flare Comparisons of the Flare Irradiance Spectral Model (FISM) to Preliminary SDO EVE Data

The Solar Dynamics Observatory (SDO) launched February 11, 2010 from Kennedy Space Center and started normal science operations in April 2010. One of the instruments onboard SDO, the EUV Variability- Experiment (EVE), will measure the solar EUV irradiance from 0.1-105 nm with 0.1 nm spectral resolution as well as a measure of the broad-band Lyman-Alpha emission (121.0 rim), all with less than 10 percent uncertainties. One of the biggest improvements of EVE over its predecessors is its ability to continuously measure the complete spectrum ever y 10 seconds, 24 hours a day, 7 days a week. This temporal coverage and cadence will greatly enhance the knowledge of the solar EUV variations during solar flares. This paper will present a comparison of the Flare Irradiance Spectral Model (FISM), which can produce an estimated EUV spectrum at 10 seconds temporal resolution, to the preliminary flare observation results from SDO EVE. The discussion will focus on the short-term EUV flare variations and evolution.

Chamberlon, Phillip C.↗
NASA NTRS2010

The Kepler Full Frame Images

NASA's exoplanet discovery mission Kepler provides uninterrupted 1-min and 30-min optical photometry of a 100 square degree field over a 3.5 yr nominal mission. Downlink bandwidth is filled at these short cadences by selecting only detector pixels specific to 105 preselected stellar targets. The majority of the Kepler field, comprising 4 x 10(exp 6) m_v < 20 sources, is sampled at much lower 1-month cadence in the form of a full-frame image. The Full Frame Images (FFIs) are calibrated by the Science Operations Center at NASA Ames Research Center. The Kepler Team employ these images for astrometric and photometric reference but make the images available to the astrophysics community through the Multimission Archive at STScI (MAST). The full-frame images provide a resource for potential Kepler Guest Observers to select targets and plan observing proposals, while also providing a freely-available long-cadence legacy of photometric variation across a swathe of the Galactic disk.

Dotson, Jessie L.↗
NASA NTRS2009

The Kepler Project: Mission Update

Kepler is a Discovery-class mission designed to determine the frequency of Earth-size planets in and near the habitable zone of solar-like stars. The instrument consists of a 0.95 m aperture photometer designed to obtain high precision photometric measurement of > 100,000 stars to search for patterns of transits. The focal plane of the Schmidt-telescope contains 42 CCDs with at total of 95 mega pixels that cover 116 square degrees of sky. The photometer was launched into an Earth-trailing heliocentric orbit on March 6, 2009, finished its commissioning on May 12, and is now in the science operations mode. During the commissioning of the Kepler photometer, data were obtained at a 30 minute cadence for 53,000 stars for 9.7 days. Although the data have not yet been corrected for the presence of systematic errors and artifacts, the data show the presence of hundreds of eclipsing binary stars and variable stars of amazing variety. To provide some estimate of the capability of the photometer, a quick analysis of the photometric precision was made. Analysis of the commissioning data also show transits, occultations and light emitted from the known exoplanet HAT-P7b. The data show a smooth rise and fall of light: from the planet as it orbits its star, punctuated by a drop of 130 +/- 11 ppm in flux when the planet passes behind its star. We interpret this as the phase variation of the dayside thermal emission plus reflected light from the planet as it orbits its star and is occulted. The depth of the occultation is similar in amplitude to that expected from a transiting Earth-size planet and demonstrates that the Mission has the precision necessary to detect such planets.

Borucki, William J.↗
NASA NTRS2010

Dedicated Deployable Aerobraking Structure

A dedicated deployable aerobraking structure concept was developed that significantly increases the effective area of a spacecraft during aerobraking by up to a factor of 5 or more (depending on spacecraft size) without substantially increasing total spacecraft mass. Increasing the effective aerobraking area of a spacecraft (without significantly increasing spacecraft mass) results in a corresponding reduction in the time required for aerobraking. For example, if the effective area of a spacecraft is doubled, the time required for aerobraking is roughly reduced to half the previous value. The dedicated deployable aerobraking structure thus enables significantly shorter aerobraking phases, which results in reduced mission cost, risk, and allows science operations to begin earlier in the mission.

Giersch, Louis R.↗
NASA NTRS2009

Implementation and Comparison of Acoustic Travel-Time Measurement Procedures for the Helioseismic and Magnetic Imager Time-Distance Helioseismology Pipeline

The Helioseismic and Magnetic Imager (HMI) instrument on board the Solar Dynamics Observatory (SDO) satellite is designed to produce high-resolution Doppler velocity maps of oscillations at the solar surface with high temporal cadence. To take advantage of these high-quality oscillation data, a time-distance helioseismology pipeline has been implemented at the Joint Science Operations Center (JSOC) at Stanford University. The aim of this pipeline is to generate maps of acoustic travel times from oscillations on the solar surface, and to infer subsurface 3D flow velocities and sound-speed perturbations. The wave travel times are measured from cross covariances of the observed solar oscillation signals. For implementation into the pipeline we have investigated three different travel-time definitions developed in time-distance helioseismology: a Gabor wavelet fitting (Kosovichev and Duvall, 1997), a minimization relative to a reference cross-covariance function (Gizon and Birch, 2002), and a linearized version of the minimization method (Gizon and Birch, 2004). Using Doppler velocity data from the Michelson Doppler Imager (MDI) instrument on board SOHO, we tested and compared these definitions for the mean and difference travel-time perturbations measured from reciprocal signals. Although all three procedures return similar travel times in a quiet Sun region, the method of Gizon and Birch (2004) gives travel times that are significantly different from the others in a magnetic (active) region. Thus, for the pipeline implementation we chose the procedures of Kosovichev and Duvall (1997) and Gizon and Birch (2002). We investigated the relationships among these three travel-time definitions, their sensitivities to fitting parameters, and estimated the random errors they produce

Couvidat, S.↗
NASA NTRS2010

A Framework for Propagation of Uncertainties in the Kepler Data Analysis Pipeline

The Kepler space telescope is designed to detect Earth-like planets around Sun-like stars using transit photometry by simultaneously observing 100,000 stellar targets nearly continuously over a three and a half year period. The 96-megapixel focal plane consists of 42 charge-coupled devices (CCD) each containing two 1024 x 1100 pixel arrays. Cross-correlations between calibrated pixels are introduced by common calibrations performed on each CCD requiring downstream data products access to the calibrated pixel covariance matrix in order to properly estimate uncertainties. The prohibitively large covariance matrices corresponding to the ~75,000 calibrated pixels per CCD preclude calculating and storing the covariance in standard lock-step fashion. We present a novel framework used to implement standard propagation of uncertainties (POU) in the Kepler Science Operations Center (SOC) data processing pipeline. The POU framework captures the variance of the raw pixel data and the kernel of each subsequent calibration transformation allowing the full covariance matrix of any subset of calibrated pixels to be recalled on-the-fly at any step in the calibration process. Singular value decomposition (SVD) is used to compress and low-pass filter the raw uncertainty data as well as any data dependent kernels. The combination of POU framework and SVD compression provide downstream consumers of the calibrated pixel data access to the full covariance matrix of any subset of the calibrated pixels traceable to pixel level measurement uncertainties without having to store, retrieve and operate on prohibitively large covariance matrices. We describe the POU Framework and SVD compression scheme and its implementation in the Kepler SOC pipeline.

Clarke, Bruce D.↗
NASA NTRS2010

New Results on High Energy Cosmic Ray Electrons Observed with Fermi LAT and Their Implications on the Origin of Cosmic Rays

The Large Area Telescope on-board the Fermi Gamma-Ray Space Telescope has collected more than 10 million cosmic ray electrons with energy above 7 GeV since its science operation on orbit. High energy electrons rapidly lose their energy by synchrotron radiation on Galactic magnetic fields and by inverse Compton scattering on the interstellar radiation field. The typical distance over which a 1 TeV electron loses half its total energy is estimated to be 300-400 pc.This makes them a unique tool for probing nearby Galactic space. Observed spectrum has a harder spectral index than was previously reported and suggests the presence of nearby sources of high energy electrons. One of viable candidates are nearby pulsars, possibly some of recently discovered by Fermi. At the same time the dark matter origin of such sources cannot be ruled out. I will also report our current upper limits on cosmic ray electrons anisotropy which helps to set constraints on their local sources.

Moiseev, Alexander↗
NASA NTRS2010

Fermi Gamma-Ray Space Telescope Science Overview

After more than 2 years of science operations, the Fermi Gamma-ray Space Telescope continues to survey the high-energy sky on a daily basis. In addition to the more than 1400 sources found in the first Fermi Large Area Telescope Catalog (I FGL), new results continue to emerge. Some of these are: (1) Large-scale diffuse emission suggests possible activity from the Galactic Center region in the past; (2) a gamma-ray nova was found, indicating particle acceleration in this binary system; and (3) the Crab Nebula, long thought to be a steady source, has varied in the energy ranges seen by both Fermi instruments.

Thompson, David J.↗
NASA NTRS2011

Analysis of XMM-Newton Data from Extended Sources and the Diffuse X-Ray Background

Reduction of X-ray data from extended objects and the diffuse background is a complicated process that requires attention to the details of the instrumental response as well as an understanding of the multiple background components. We present methods and software that we have developed to reduce data from XMM-Newton EPIC imaging observations for both the MOS and PN instruments. The software has now been included in the Science Analysis System (SAS) package available through the XMM-Newton Science Operations Center (SOC).

Snowden, Steven↗
NASA NTRS2010

Quick Attach Docking Interface for Lunar Electric Rover

The NASA Lunar Electric Rover (LER) has been developed at Johnson Space Center as a next generation mobility platform. Based upon a twelve wheel omni-directional chassis with active suspension the LER introduces a number of novel capabilities for lunar exploration in both manned and unmanned scenarios. Besides being the primary vehicle for astronauts on the lunar surface, LER will perform tasks such as lunar regolith handling (to include dozing, grading, and excavation), equipment transport, and science operations. In an effort to support these additional tasks a team at the Kennedy Space Center has produced a universal attachment interface for LER known as the Quick Attach. The Quick Attach is a compact system that has been retro-fitted to the rear of the LER giving it the ability to dock and undock on the fly with various implements. The Quick Attach utilizes a two stage docking approach; the first is a mechanical mate which aligns and latches a passive set of hooks on an implement with an actuated cam surface on LER. The mechanical stage is tolerant to misalignment between the implement and the LER during docking and once the implement is captured a preload is applied to ensure a positive lock. The second stage is an umbilical connection which consists of a dust resistant enclosure housing a compliant mechanism that is optionally actuated to mate electrical and fluid connections for suitable implements. The Quick Attach system was designed with the largest foreseen input loads considered including excavation operations and large mass utility attachments. The Quick Attach system was demonstrated at the Desert Research And Technology Studies (D-RA TS) field test in Flagstaff, AZ along with the lightweight dozer blade LANCE. The LANCE blade is the first implement to utilize the Quick Attach interface and demonstrated the tolerance, speed, and strength of the system in a lunar analog environment.

Schuler, Jason M.↗
NASA NTRS2010

Using Multi-Core Systems for Rover Autonomy

Task Objectives are: (1) Develop and demonstrate key capabilities for rover long-range science operations using multi-core computing, (a) Adapt three rover technologies to execute on SOA multi-core processor (b) Illustrate performance improvements achieved (c) Demonstrate adapted capabilities with rover hardware, (2) Targeting three high-level autonomy technologies (a) Two for onboard data analysis (b) One for onboard command sequencing/planning, (3) Technologies identified as enabling for future missions, (4)Benefits will be measured along several metrics: (a) Execution time / Power requirements (b) Number of data products processed per unit time (c) Solution quality

multi-core↗
NASA NTRS2011

When A Standard Candle Flickers

The Crab Nebula is the only hard X-ray source in the sky that is both bright enough and steady enough to be easily used as a standard candle. As a result, it has been used as a normalization standard by most X-ray/gamma ray telescopes. Although small-scale variations in the nebula are well-known, since the start of science operations of the Fermi Gamma-ray Burst Monitor (GBM) in August 2008 a 7% (70 mcrab) decline has been observed in the overall Crab Nebula flux in the 15-50 keV band, measured with the Earth occultation technique. This decline is independently confirmed in the 15-50 keV band with three other instruments: the Swift Burst Alert Telescope (Swift/BAT), the Rossi X-ray Timing Explorer Proportional Counter Array (RXTE/PCA), and the INTErnational Gamma-Ray Astrophysics Laboratory Imager on Board INTEGRAL (IBIS). A similar decline is also observed in the 3 - 15 keV data from the RXTE/PCA and in the 50 - 100 keV band with GBM, Swift/BAT, and INTEGRAL/IBIS. The change in the pulsed flux measured with RXTE/PCA since 1999 is consistent with the pulsar spin-down, indicating that the observed changes are nebular. Correlated variations in the Crab Nebula flux on a 3 year timescale are also seen independently with the PCA, BAT, and IBIS from 2005 to 2008, with a flux minimum in April 2007. As of August 2010, the current flux has declined below the 2007 minimum.

Wilson-Hodge, Colleen A.↗