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Doppler data generated with the Cassini spaceraft's radio carrier waves at X and Ka band can be used to determine the quadrupole moments of Rhea's gravitational field.
Radio Doppler data generated by the Deep Space Network (DSN) from five encounters of the Galileo spacecraft with Callisto, Jupiter's outermost Galilean satellite, have been used to determine the quadrupole moments of the satellite's external gravitational field.
By utilizing a crossed electron beam collision geometry, a combination of time-of-flight (TOF) and quadrupole mass spectrometers, and the relative flow technique1 normalized values of cross sections and appearance energies (AP) were obtained for the formation of singly and multiply ionized species resulting from the ionization and dissociation of C2H2. Details ont he apparatus and technique have been published previously.2,3.
The spin-induced quadrupole moment of a rapidly rotating star changes the orbital dynamics in a binary system, giving rise to advance (or regression) of periastron and precession of the orbital plane. We show that these effects are important in the recently discovered radio pulsar/mail sequence star binary system PSR J0045-7319, and reliably account for the observed peculiar timing residuals. Precise measurements of the apsidal motion and orbital plane precession can yield valuable information on the internal structure and rotation of the star. The detection of orbital precession implies that the spin of the companion star is not aligned with the orbital angular momentum, and suggests that the supernova gave the pulsar a kick out of the original orbital plane. Excitations of g-mode oscillations near periastron (the dynamical tide) can induce measurable changes in the orbital period and eccentricity at each passage for this system. We also discuss the spin-orbit coupling effects for the accreting X-ray pulsars and the other know radio pulsar/main sequence binary, PSR B1259-63.
The heterogeneous reaction of gaseous chlorine nitrate and solid sodium chloride was investigated over a temperature range of 220 - 300 K in a flow-tube reactor interfaced with a differentially pumped quadrupole mass spectrometer.
Aircraft on approach in high-drag and high-lift configuration create unsteady flow structures which inherently generate noise. For devices such as flaps, spoilers and the undercarriage there is a strong correlation between overall noise and drag such that, in the quest for quieter aircraft, one challenge is to generate drag at low noise levels. This paper presents a rigorous aero-acoustic assessment of a novel drag concept. The idea is that a swirling exhaust flow can yield a steady, and thus relatively quiet, streamwise vortex which is supported by a radial pressure gradient responsible for pressure drag. Flows with swirl are naturally limited by instabilities such as vortex breakdown. The paper presents a first aero-acoustic assessment of ram pressure driven swirling exhaust flows and their associated instabilities. The technical approach combines an in-depth aerodynamic analysis, plausibility arguments to qualitatively describe the nature of acoustic sources, and detailed, quantitative acoustic measurements using a medium aperture directional microphone array in combination with a previously established Deconvolution Approach for Mapping of Acoustic Sources (DAMAS). A model scale engine nacelle with stationary swirl vanes was designed and tested in the NASA Langley Quiet Flow Facility at a full-scale approach Mach number of 0.17. The analysis shows that the acoustic signature is comprised of quadrupole-type turbulent mixing noise of the swirling core flow and scattering noise from vane boundary layers and turbulent eddies of the burst vortex structure near sharp edges. The exposed edges are the nacelle and pylon trailing edge and the centerbody supporting the vanes. For the highest stable swirl angle setting a nacelle area based drag coefficient of 0.8 was achieved with a full-scale Overall Sound Pressure Level (OASPL) of about 40dBA at the ICAO approach certification point.
We present post-Newtonian-inspired initial data for non-spinning black-hole binaries, suitable for numerical evolution with punctures. We revisit the work of Tichey et al. and explicitly calculate remaining integral terms.Thereby we improve the accuracy in the far zone, by including realistic gravitational waves in the initial data. We investigate the behavior of this data both at the center of mass and in the far zone, demonstrating agreement of the transverse-traceless parts of the new metric with quadrupole-approximation waveforms. An advantage of these data is that they can be used for numerical evolutions to make a direct connection between the merger waveforms and the post-Newtonian inspiral waveforms.
We have recently completed a prototype ion-clock physics package based on Hg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability ~2-3x10-13 at 1 second, averaging to 10-15 at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required for holding 1-2x10-13 at 1 second. This performance was obtained in a sealed vacuum configuration where only a getter pump was used to maintain vacuum. The vacuum tube containing the traps has now been under sealed vacuum conditions for nearly 1.5 years with no measurable degradation of ion trapping lifetimes or clock short-term performance. Because the tube is sealed, the Hg source and Neon buffer gas are held indefinitely, for the life of the tube. There is no consumption of Hg in this system unlike in a Cs beam tube where lifetime is often limited by Cs depletion.
The present invention provides an improved electron ionizer for use in a quadrupole mass spectrometer. The improved electron ionizer includes a repeller plate that ejects sample atoms or molecules, an ionizer chamber, a cathode that emits an electron beam into the ionizer chamber, an exit opening for excess electrons to escape, at least one shim plate to collimate said electron beam, extraction apertures, and a plurality of lens elements for focusing the extracted ions onto entrance apertures.
A power supply for a quadrupole mass spectrometer which operates using an RF signal. The RF signal is controllable via a feedback loop. The feedback loop is from the output, through a comparator, and compared to a digital signal. An air core transformer is used to minimize the weight. The air core transformer is driven via two out of phase sawtooth signals which drive opposite ends of the transformer.
In its tour of the Saturnian system, the spacecraft Cassini is carrying out measurements of the gravity field of Titan, whose knowledge is crucial for constraining the internal structure of the satellite. In the five flybys devoted to gravity science, the spacecraft is tracked in X (8.4 GHz) and Ka band (32.5 GHz) from the antennas of NASA's Deep Space Network. The use of a dual frequency downlink is used to mitigate the effects of interplanetary plasma, the largest noise source affecting Doppler measurements. Variations in the wet path delay are effectively compensated by means of advanced water vapor radiometers placed close to the ground antennas. The first three flybys occurred on February 27, 2006, December 28, 2006, and June 29, 2007. Two additional flybys are planned in July 2008 and May 2010. This paper presents the estimation of the mass and quadrupole field of Titan from the first two flybys, carried out by the Cassini Radio Science Team using a short arc orbit determination. The data from the two flybys are first independently fit using a dynamical model of the spacecraft and the bodies of the Saturnian system, and then combined in a multi-arc solution. Under the assumption that the higher degree harmonics are negligible, the estimated values of the gravity parameters from the combined, multi-arc solution are GM = 8978.1337 +/- 0.0025 km(exp 3) / s(exp 2), J (sub 2) = (2.7221 +/- 0.0185) 10 (exp -5) and C (sub 22) = (1.1159 +/- 0.0040) 10 (exp -5) The excellent agreement (within 1.7 sigma) of the results from the two flybys further increases the confidence in the solution and provides an a posteriori validation of the dynamical model.
The Huygens Probe executed a successful entry, descent and impact on the Saturnian moon of Titan on January 14, 2005. Gas Chromatograph Mass Spectrometer (GCMS) instrument conducted isotopic and compositional measurements throughout the two and one half hour descent from 146 km altitude, and on the surface for 69 minutes until loss of signal from the orbiting Cassini spacecraft. The GCMS incorporated a quadrupole mass filter with a secondary electron multiplier detection system. The gas sampling system provided continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns, a chemical scrubber and a hydrocarbon enrichment cell. The GCMS gas inlet was heated to prevent condensation, and to evaporate volatiles from the surface after impact. Data products from the GCMS included altitude profiles of the major atmospheric constituents dinitrogen (N2) and methane (CH4), isotope ratios of N-14/N-15, C-12/C-13, and D/H, mole fractions of radiogenic argon (Ar-40)and primordial argon Ar-36), and upper limits on the mole fractions of neon, krypton and xenon, which were found to be below the detection limit of the instrument or absent. Surface measurements confirmed the presence of ethane (C2H6) and cyanogen (C2N2). Later data products include the instrument response to surface outgassing of C2N2, C2H6, acetylene (C2H2),and carbon dioxide (CO2). More recent results include the detection of benzene (C6H6) and height profiles of molecular hydrogen (H2). Numerous other trace species evaporating from the surface were also identified using the GCMS data.
The Thermal and Evolved Gas Analyzer (TEGA) instrument scheduled to fly onboard the 2007 Mars Phoenix Scout Mission will perform differential scanning calorimetry (DSC) and evolved gas analysis (EGA) of soil samples and ice collected from the surface and subsurface at a northern landing site on Mars. We have been developing a sample characterization data library using a laboratory DSC integrated with a quadrupole mass spectrometer to support the interpretations of TEGA data returned during the mission. The laboratory TEGA test-bed instrument has been modified to operate under conditions similar to TEGA, i.e., reduced pressure (e.g., 100 torr) and reduced carrier gas flow rates. We have previously developed a TEGA data library for a variety of volatile-bearing mineral phases, including Fe-oxyhydroxides, phyllosilicates, carbonates, and sulfates. Here we examine the thermal and evolved gas properties of samples that contain organics. One of the primary objectives of the Phoenix Scout Mission is to search for habitable zones by assessing organic or biologically interesting materials in icy soil. Nitrogen is currently the carrier gas that will be used for TEGA. In this study, we examine two possible modes of detecting organics in geologic samples; i.e., pyrolysis using N2 as the carrier gas and combustion using O2 as the carrier gas.
Space flight mass spectrometers contribute our understanding of the origin and evolution of our solar system and even of life itself. This fundamental role has motivated increasing interest in miniature mass spectrometry for planetary missions. Several remarkable new instruments are en route or under development to investigate the composition of planetary bodies such as Mars and comets. For instance, the Sample Analysis at Mars (SAM) suite on the 2009 Mars Science Laboratory (MSL) mission includes a quadrupole mass spectrometer with a sophisticated gas processing system as well as pyrolysis and chemical derivatization protocols for solid samples. Future missions will require even lighter, lower power, and yet more capable mass spectrometers, particularly to analyze samples in situ on planetary surfaces. We have been developing laser-based mass spectrometers for elemental and organic/molecular analysis of rock, ice, or fine particle samples. These typically use time-of-flight (TOF) mass analyzers, which are readily miniaturized and can detect both atomic species and complex organics that occur in a variety of planetary materials. For example, nonvolatile polycyclic aromatic hydrocarbons and kerogen-like macromolecular carbon are found in some carbonaceous meteorites, which derived from asteroid parent bodies. A single focused laser pulse is able to volatilize and ionize some of these compounds for direct TOF analysis. While this is possible without any sample preparation or contact, sensitivity and quantitative performance can improve significantly with some sample handling. As such we have also been examining robotic mechanisms and protocols to accompany space flight mass spectrometers. In addition, sensors in early development may significantly improve these capabilities, via use of techniques such as switchable polarity, ambient pressure, or resonant ionization; tandem mass spectrometry (TOF or ion trap); and chemical imaging.
The Huygens Probe executed a successful entry, descent and impact on the Saturnian moon of Titan on January 14, 2005. The Gas Chromatograph Mass Spectrometer (GCMS) instrument conducted isotopic and compositional measurements throughout the two and one half hour descent from 146 km altitude, and on the surface for 69 minutes until loss of signal from the orbiting Cassini spacecraft. The GCMS incorporated a quadrupole mass filter with a secondary electron multiplier detection system. The gas sampling system provided continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns, a chemical scrubber and a hydrocarbon enrichment cell. The GCMS gas inlet was heated to prevent condensation, and to evaporate volatiles from the surface after impact. Data products from the GCMS included altitude profiles of the major atmospheric constituents dinitrogen (N2) and methane (CH4), isotope ratios of 14N/15N, 12C/13C, and D/H, mole fractions of radiogenic argon (40Ar) and primordial argon (36Ar), and upper limits on the mole fractions of neon, krypton and xenon, which were found to be absent. Surface measurements confirmed the presence of ethane (C2H6) and cyanogen (C2N2). Later data products expanded atmospheric profiles to include the surface response of C2N2. C2H6, acetylene (C2H2), and carbon dioxide (CO2). More recent results include the profiles of benzene (C6H6) and molecular hydrogen (H2). The GCMS data are being further analyzed to obtain higher precision results and to identify other trace species ion the atmosphere and evaporating from the surface.
We investigated the abundances of amino acids and amines, as well as their enantiomeric composition in water extracts of comet Wild 2 exposed aerogel and aluminum foils returned by Stardust using liquid chromatography with UV fluorescence detection and time of flight-mass spectrometry (LC-FD/ToF-MS). A suite of amino acids and amines including glycine, L-alanine, methylamine (MA), and ethylamine (EA) were identified in the Stardust bulk aerogel. With the exception of MA and EA, all other primary amines detected in comet-exposed aerogels were also present in the aerogel witness tile that was not exposed to Wild 2, suggesting that most amines are terrestrial in origin. The enhanced abundances of MA, EA, and possibly glycine in comet-exposed aerogel compared to controls, coupled with MA to EA ratios (approx.1 to 2) that are distinct from preflight aerogels (approx.7 to lo), suggest that these amines were captured from Wild 2. The presence of cometary amines in Stardust material supports the hypothesis that comets were an important source of prebiotic organics on the early Earth. To better understand their origin, a systematic study of all these species with C, N, and H compound specific isotopic analysis (CSIA) via gas chromatography quadrupole mass spectrometry in with parallel with combustion isotope ratio mass spectrometry (GC-QMS/IRMS) is being conducted. We will discuss our latest C-CSIA measurements and what they indicate about the origin of the amino acids extracted from Stardust samples.
The Gas Chromatograph Mass Spectrometer was one of six instruments on the Cassini-Huygens Probe mission to Titan. The GCMS measured in situ the chemical composition of the atmosphere during the probe descent and served as the detector for the pyrolization products for the Aerosol Collector Pyrolyser (ACP) experiment to determine the composition of the aerosol particles. The GCMS collected data from an altitude of 146 km to ground impact. The Probe and the GCMS survived impact and collected data for 1 hour and 9 minutes on the surface. Mass spectra were collected during descent and on the ground over a range of m/z from 2 to 141. The major constituents of the lower atmosphere were confirmed to be N2 and CH4. The methane mole fraction was uniform in the stratosphere. It increased below the tropopause, at about 32 km altitude, monotonically toward the surface, reaching a plateau at about 8 km at a level near saturation. After surface impact a steep increase of the methane signal was observed, suggesting evaporation of surface condensed methane due to heating by the GCMS sample inlet heater. The measured mole fraction of Ar-40 is 4.3x10(exp -5) and of Ar-36 is 2.8x10(exp -7). The other primordial noble gases were below 10(exp -8) mole fraction. The isotope ratios of C-12/C-13 determined from methane measurements are 82.3 and of N-14/N-15 determined from molecular nitrogen are 183. The D/H isotope ratio determined from the H2 and HD measurements is 2.3x10(exp -4). Carbon dioxide, methane, acetylene and cyanogen were detected evaporating from the surface in addition to methane. The GCMS employed a quadrupole mass filter with a secondary electron multiplier detection system and a gas sampling system providing continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns, a chemical scrubber and a hydrocarbon enrichment cell. The GCMS gas inlet was heated to prevent condensation, and to evaporate volatiles from the surface after impact.
The Gas Chromatograph Mass Spectrometer was one of six instruments on the Cassini-Huygens Probe mission to Titan. The GCMS measured in situ the chemical composition of the atmosphere during the probe descent and served as the detector for the pyrolization products for the Aerosol Collector Pyrolyser (ACP) experiment to determine the composition of the aerosol particles. The GCMS collected data from an altitude of 146 km to ground impact. The Probe and the GCMS survived impact and collected data for 1 hour and 9 minutes on the surface. Mass spectra were collected during descent and on the ground over a range of mlz from 2 to 141. The major constituents of the lower atmosphere were confirmed to be N2 and CH4. The methane mole fraction was uniform in the stratosphere. It increased below the tropopause, at about 32 km altitude, monotonically toward the surface, reaching a plateau at about 8 km at a level near saturation. After surface impact a steep increase of the methane signal was observed, suggesting evaporation of surface condensed methane due to heating by the GCMS sample inlet heater. The measured mole fraction of Ar-40 is 4.3x10(exp -5) and of Ar-36 is 2.8x10(exp -7). The other primordial noble gases were below 10(exp -8) mole fraction. The isotope ratios of C-12/C-13 determined from methane measurements are 82.3 and of N-14/N-15 determined from molecular nitrogen are 183. The D/H isotope ratio determined from the H2 and HD measurements is 2.3x10(exp -4). Carbon dioxide, ethane, acetylene and cyanogen were detected evaporating from the surface in addition to methane. The GCMS employed a quadrupole mass filter with a secondary electron multiplier detection system and a gas sampling system providing continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns, a chemical scrubber and a hydrocarbon enrichment cell. The GCMS gas inlet was heated to prevent condensation, and to evaporate volatiles from the surface after impact.