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| Jupiter Europa Orbiter Mission Study 2008: Final Report |
JEO is the NASA Element of the Europa Jupiter System Mission (EJSM). The objective of this study, to assess the science merit, technical risk and qualitative assessment of relative cost of alternative architectural implementations as applied to a first dedicated mission to Europa, was accomplished by 1) reviewing results from previous and current studies and 2) examining alternative architectural options relative to the science objectives defined by the 2007 EE SDT.
This report summarizes a number of Europa mission and system concepts studied over the last decade as well as the results from assessing alternative architectural options in light of current science requirements. |
| Publication date: 30 Jan 2009 |
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| Payload Definition Document for Marco Polo |
| This document is a compilation of the model payload of MarcoPolo. Besides its primary goal to return a sample to Earth, a suite of scientifically important instruments has been selected by the MarcoPolo Science Study Team (SST). The payload elements are selected as such that they serve and accomplish the scientific goals as identified in the Science Requirements Document (AD1). The definition of the instrumentation was fully supported by individual members of the SST. Further information was obtained through the instrument DOI studies. This document will guide the spacecraft design and mission architecture throughout the assessment study.
[This is an abbreviated version of the original document abstract.] |
| Publication date: 30 Jan 2009 |
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| Energetic ion dynamics of the inner magnetosphere revealed in coordinated Cluster-Double Star observations |
| Since early 2004 the Chinese spacecraft Tan Ce 1 (TC-1), first component of the Double Star (DSP) mission, has been on an equatorial elliptical orbit (13.4 RE apogee), allowing the study of the dynamics of the Earth's magnetosphere in conjunction with the four European Cluster spacecraft (19.6 RE apogee). The Cluster and Double Star spacecraft orbits are such that the spacecraft are almost in the same meridian, allowing conjugate studies. The four Cluster spacecraft highly eccentric polar orbit at 4 RE perigee permits them to sample the ring current, the radiation belts, and the outer plasmasphere from south to north, almost following the same magnetic flux tube (latitudinal profile), whereas TC-1, with its very low-perigee equatorial orbit, gives the plasma profile across L shells. Coordinated ion measurements provided by the Cluster Ion Spectrometry and Hot Ion Analyzer instruments onboard Cluster and TC-1, respectively, obtained during quiet conditions, disturbed geomagnetic conditions, and an intense storm, are used to analyze crossings of the plasmasphere and the ring current region. Multiple narrow ion energy bands ("nose-like" structures) are simultaneously observed by both Cluster and TC-1. These observations reveal the large-scale character of these structures and pose a challenge for the simulation and modeling of the inner magnetosphere populations. |
| Publication date: 27 Jan 2009 |
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| Mirror waves and mode transition observed in the magnetosheath by Double Star TC-1 |
| The Double Star TC-1 magnetosheath pass on 26 February 2004 is used to investigate magnetic field fluctuations. Strong compressional signatures which last for more than an hour have been found near the magnetopause behind a quasi-perpendicular bow shock. These compressional structures are most likely mirror mode waves. There is a clear wave transition in the magnetosheath which probably results from the change of the interplanetary magnetic field (IMF) cone angle. The wave characteristics in the magnetosheath are strongly controlled by the type of the upstream bow shock. |
| Publication date: 22 Jan 2009 |
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| EJSM NASA/ESA joint summary report |
Prepared by:
Joint Jupiter Science Definition Team
NASA/ESA Study TeamThe Europa Jupiter System Mission (EJSM) is a joint endeavour by ESA and NASA. This Joint Summary Report (JSR) is intended to provide a high-level description of the following: the science rationale and goals; the mission concept; the NASA and ESA responsibilities and interdependencies; the role of other space agencies; and the costs, schedule, and management approach. The JSR also describes the membership and roles of the JSDT and the engineering study teams that supported them and provides a guide to the extensive documentation that has been developed for the mission concept.
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| Publication date: 20 Jan 2009 |
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| Observations of Turbulence Generated by Magnetic Reconnection |
| Spacecraft observations of turbulence within a magnetic reconnection (guide field ~0) ion diffusion region are presented. In the inertial subrange, electric and magnetic fluctuations both followed a -5/3 power law; at higher frequencies, the spectral indices were -1 and -8/3, respectively. The dispersion relation was found to be consistent with fast-mode-whistler waves rather than kinetic Alfvén-ion cyclotron waves. Lower hybrid waves, which could be enhanced by whistler mode conversion, were observed, but the associated anomalous resistivity was not found to significantly modify the reconnection rate. |
| Publication date: 20 Jan 2009 |
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| TSSM NASA/ESA joint summary report |
Prepared by:
Joint Titan Saturn System Mission Science Definition Team,
ESA Study Team,
NASA Study Team
The Titan Saturn System Mission (TSSM) is a joint endeavour by ESA and NASA.
This Joint Summary Report (JSR) is intended to provide a high level description of the science rationale and goals; the mission concept; the NASA and ESA responsibilities and interdependencies; the role of other space agencies; and the costs, schedule and management approach. It also describes the membership and roles of the JSDT and the engineering study teams that supported them and a guide to the extensive documentation that has been developed for the mission concept.
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| Publication date: 19 Jan 2009 |
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| A binary origin for 'blue stragglers' in globular clusters |
| Blue stragglers in globular clusters are abnormally massive stars that should have evolved off the stellar main sequence long ago. There are two known processes that can create these objects: direct stellar collisions and binary evolution. However, the relative importance of these processes has remained unclear. In particular, the total number of blue stragglers found in a given cluster does not seem to correlate with the predicted collision rate, providing indirect support for the binary-evolution model. Yet the radial distributions of blue stragglers in many clusters are bimodal, with a dominant central peak: this has been interpreted as an indication that collisions do dominate blue straggler production, at least in the high-density cluster cores. Here we report that there is a clear, but sublinear, correlation between the number of blue stragglers found in a cluster core and the total stellar mass contained within it. From this we conclude that most blue stragglers, even those found in cluster cores, come from binary systems. The parent binaries, however, may themselves have been affected by dynamical encounters. This may be the key to reconciling all of the seemingly conflicting results found to date. |
| Publication date: 15 Jan 2009 |
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| Molecular conductance of a contact-free labyrinth seal used for the contamination control of a cryogenic space instrument |
| This study presents the molecular conductance measurement of a labyrinth seal introduced for the Contamination Control Cover which is protecting the cryogenic optical surfaces of the mid-infrared instrument of the James Webb Space Telescope against molecular contaminants from the environment. The conductance has been measured in the molecular pressure regime between 10-7 and 10-3 mbar within a temperature range of 300 K and 10 K for several typical omponents of the expected residual gas such as H2O, NH3, CO2, H2, NO, alcohols and hydrocarbons as well as standard gases such as N2 and He. The measurements have been repeated with a thin orifice to verify the systematics. The results are well consistent with numerically derived values and demonstrate a robust understanding of the design and performance of the labyrinth seal. |
| Publication date: 15 Jan 2009 |
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| SPICA Cryogenic Telescope Assembly - Science Requirements Document |
| This Science Requirements Document focuses on the SPICA Telescope Assembly, one of the contributions under study by ESA for its partner agency role in the JAXA led SPICA mission. This document
will be the basis for the ESA Telescope Definition Document, and will be applicable to the SPICA
Telescope Assembly Interface Control Document.
The Science Requirements defined in this document address exclusively those aspects that have an
impact on the SPICA Telescope Assembly specification. This document does not intend to cover
all the Science Requirements of the SPICA mission, which are addressed in JAXA documents and
are under the responsibility of JAXA.
This document aims at showing clearly the links between Science Requirements, performance
requirements and the Telescope scientific requirements, in order to help understand, trace and
support the analysis of the relation between the telescope assembly specifications on the scientific
objectives of the mission.
[This is an abbreviated version of the original document abstract.] |
| Publication date: 15 Jan 2009 |
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| Status of the JWST/MIRI Focal Plane System and Cooler |
| AAS Meeting #213, #426.10
The Mid-Infrared Instrument (MIRI) is a multipurpose imager, coronagraph, and spectrometer for the James Webb Space Telescope. It provides wavelength coverage from 5 through 28 microns and is an integral contributor to all four of JWST's primary science themes. MIRI is being developed as a partnership between NASA and ESA, with JPL providing the Focal Plane System (FPS, consisting of the detectors, control electronics, and flight software) and the cooler, and a consortium of European astronomical institutes providing the optical bench and structure.
The flight FPS is being prepared for delivery to the European Consortium for its integration into the optical bench, while the cooler is nearing its Critical Design Review. We describe the capabilities of the FPS and cooler, present test results and the predicted sensitivity performance of the FPS, and update the current status of each these systems.
The research described in this poster was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. |
| Publication date: 15 Jan 2009 |
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| The Potential Of JWST Mid-infrared Instrument (MIRI) Followup Of The Spitzer Sage Survey Of The Large Magellanic Cloud |
| AAS Meeting #213, #426.12 The recycling of matter between the interstellar medium (ISM) and stars are key evolutionary drivers of a galaxy's baryonic matter. The Spitzer and JWST/MIRI wavelengths provide a sensitive probe of circumstellar and interstellar dust and hence, allow us to study the physical processes of the ISM, the formation of new stars and the injection of mass by evolved stars and their relationships on the galaxy-wide scale. We have performed a uniform and unbiased imaging survey of the Large Magellanic Cloud (LMC, 7x7 degrees), using the IRAC (3.6, 4.5, 5.8 and 8 microns) and MIPS (24, 70, and 160 microns) instruments on board the Spitzer Space Telescope (Spitzer) in order to survey the agents of a galaxy's evolution (SAGE): the ISM, young stellar objects (YSOs) and dusty evolved stars (Meixner et al. 2006). Initial results from SAGE have revealed >1000 new YSOs (Whitney et al. 2008), a detailed map of the dust and ISM mass (Bernard et al. 2008) and estimates of the dusty mass-loss return (Srinivsan et al., submitted) of the 30,000 dusty evolved stars (Blum et al. 2006). Here we describe how the powerful capabilities of the JWST MIRI can be used to followup these new discoveries of SAGE-LMC and also how SAGE-like studies can be extended to nearby galaxies.
The SAGE Project is supported by NASA/Spitzer grant 1275598 and MIRI science team work is supported by NASA NAG5-12595. |
| Publication date: 15 Jan 2009 |
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| Kinetic Alfvén Wave Turbulence and Transport through a Reconnection Diffusion Region |
| We demonstrate from observations that kinetic Alfvén waves may play an important role in facilitating magnetic reconnection. These waves radiate outwards from the diffusion region oblique to the magnetic field in a conelike pattern delimited by the X line separatrices with outward energy fluxes equivalent to that contained in the outstreaming ions. It is shown that the wave vectors reverse across the X and symmetry lines and have a large out of plane component. We estimate that these waves drive significant transport through the diffusion region. |
| Publication date: 08 Jan 2009 |
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| Evidence of an extended electron current sheet and its neighboring magnetic island during magnetotail reconnection |
| We have identified a spatially extended electron current sheet (ECS) and its adjacent magnetic island during a magnetotail reconnection event with no appreciable guide field. This finding is based on data from the four Cluster spacecraft and is enabled by detailed maps of electron distribution functions and DC electric fields within the diffusion region. The maps are developed using two-dimensional particle-in-cell simulations with a mass ratio mi/me = 800. One spacecraft crossed the ECS earthward of the reconnection null and, together with the other three spacecraft, registered the following properties: (1) The ECS is colocated with a layer of bipolar electric fields normal to the ECS, pointing toward the ECS, and with a half width less than 8 electron skin depths. (2) In the inflow region up to the ECS and separatrices, electrons have a temperature anisotropy (Te parallel/Te perp. > 1), and the anisotropy increases toward the ECS. (3) Within about 1 ion skin depth (di) above and below the ECS, the electron density decreases toward the ECS by a factor of 3-4, reaching a minimum at edges of the ECS, and has a local distinct maximum at the ECS center. (4) A di-scale magnetic island is attached to the ECS, separating it from another reconnection layer. Our simulations established that the electric field normal to the ECS is due to charge imbalance and is of the ECS scale, and ions exhibit electron-scale structures in response to this electric field. |
| Publication date: 06 Jan 2009 |
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| 18 years of science with the Hubble Space Telescope |
| After several decades of planning, the Hubble Space Telescope (HST) was launched in 1990 as the first of NASA's Great Observatories. After a rocky start arising from an error in the fabrication of its main mirror, it went on to change forever many fields of astronomy, and to capture the public's imagination with its images. An ongoing programme of servicing missions has kept the telescope on the cutting edge of astronomical research. Here I review the advances made possible by the HST over the past 18 years. |
| Publication date: 01 Jan 2009 |
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| Earth's ionospheric outflow dominated by hidden cold plasma |
| The Earth constantly loses matter, mostly in the form of H+ and O+ ions, through various outflow processes from the upper atmosphere and ionosphere. Most of these ions are cold (below 1 eV in thermal energy), but can still escape and travel farther out along the magnetic field lines into the magnetospheric tail lobes. The outflow has previously been measured close to the Earth. To understand what fraction does not return but instead escapes, the measurements should be conducted at larger geocentric distances. However, at high altitudes the cold ions are normally invisible to spacecraft measurements, because the potential of a sunlit spacecraft exceeds the equivalent energy of the ions. Here we show that cold ions dominate in both flux and density in the distant magnetotail lobes, using a new measurement technique on the Cluster spacecraft. The total loss of cold hydrogen ions from the planet is inferred to be of the order of 1026 s-1, which is larger than the previously observed more energetic outflow. Quantification and insight of the loss processes of the Earth's atmosphere and ionosphere are also important for understanding the evolution of atmospheres on other celestial bodies. |
| Publication date: 01 Jan 2009 |
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| Earth's ionospheric outflow dominated by hidden cold plasma |
| The Earth constantly loses matter, mostly in the form of H+ and O+ ions, through various outflow processes from the upper atmosphere and ionosphere. Most of these ions are cold (below 1 eV in thermal energy), but can still escape and travel farther out along the magnetic field lines into the magnetospheric tail lobes. The outflow has previously been measured close to the Earth. To understand what fraction does not return but instead escapes, the measurements should be conducted at larger geocentric distances. However, at high altitudes the cold ions are normally invisible to spacecraft measurements, because the potential of a sunlit spacecraft exceeds the equivalent energy of the ions. Here we show that cold ions dominate in both flux and density in the distant magnetotail lobes, using a new measurement technique on the Cluster spacecraft. The total loss of cold hydrogen ions from the planet is inferred to be of the order of 1026 s-1, which is larger than the previously observed more energetic outflow. Quantification and insight of the loss processes of the Earth's atmosphere and ionosphere are also important for understanding the evolution of atmospheres on other celestial bodies. |
| Publication date: 01 Jan 2009 |
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