Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Jupiter”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

XMM-Newton X-Ray Observation of Jupiter

Soft X-ray emission has been observed from the disk of both Jupiter and Saturn as well as from the auroral regions of these planets. The low-latitude disk emission as observed by ROSAT, the Chandra X-Ray Observatory, and XMM-Newton appears to be uniformly distributed across the disk and to be correlated with solar activity. These characteristics suggest that the disk x-rays are produced by: (1) the elastic scattering of solar X-rays by atmospheric neutrals and (2) the absorption of solar X-rays in the carbon K-shell followed by fluorescent emission. The carbon atoms are found in methane molecules located below the homopause. In this paper we present the results of calculations of the scattering albedo for soft x-rays. We also show the calculated x-ray intensity for a range of atmospheric abundances for Jupiter and Saturn and for a number of solar irradiance spectra. The model calculations are compared with recent x-ray observations of Jupiter and Saturn. We conclude that the emission of soft x-rays from the disks of Jupiter and Saturn can be largely explained by the scattering and fluorescence of soft x-rays. We suggest that measured x-ray intensities from the disk regions of Jupiter

Waite, J. Hunter↗
NASA NTRS2006

Low- to Mid-Latitude X-Ray Emission from Jupiter

The Chandra X-ray Observatory (CXO) observed Jupiter during the period 2003 February 24-26 for approx.40 hours (4 Jupiter rotations), using both the spectroscopy array of the Advanced CCD Imaging Spectrometer (ACIS-S) and the imaging array of the High-Resolution Camera (HRC-I). Two ACIS-S exposures, each approx.8.5 hr long, were separated by an HRC-I exposure of approx.20 hr. The low- to mid-latitude non-auroral disk X-ray emission is much more spatially uniform than the auroral emission. However, the low- to mid-latitude X-ray count rate shows a small but statistically significant hour angle dependence, and is higher in regions of relatively low surface magnetic field strength, confirming ROSAT results. In addition, the spectrum from the low surface field region shows an enhancement in the energy band 1.14- 1.38 keV, perhaps partly due to line emission from that region. Correlation of surface magnetic field strength with count rate is not found for the 2000 December HRC-I data, at a time when solar activity was high. The low- to mid-latitude disk X-ray count rate observed by the HRC-I in the 2003 February observation is about 50% of that observed in 2000 December, roughly consistent with a decrease in the solar activity index (F10.7 cm flux) by a similar amount over the same time period. The low- to mid-latitude X-ray emission does not show any oscillations similar to the -45 minute oscillations sometimes seen from the northern auroral zone. The temporal variation in Jupiter's non-auroral X-ray emission exhibits similarities to variations in solar X-ray flux observed by GOES and TIMED/SEE. The two ACIS-S 0.3-2 keV low- to mid-latitude X-ray spectra are harder than the auroral spectrum, and are different from each other at energies above 0.7 keV, showing variability in Jupiter s non-auroral X-ray emission on a time scale of a day. The 0.3-2.0 keV X-ray power emitted at low- to mid-latitudes is 0.21 GW and 0.39 GW for the first and second ACIS-S exposures, respectively. We suggest that X-ray emission from Jupiter's disk may be largely generated by solar X-rays resonantly and fluorescently scattered in its upper atmosphere, especially at times of high incident solar X-ray flux. However, the correlation of higher count rate with low surface magnetic-field strength indicates the presence of some secondary component, possibly ion precipitation from radiation belts closer to the planet than elsewhere at low- to mid-latitudes.

Bhardwaj, Anil↗
NASA NTRS2006

Low- to Middle-Latitude X-Ray Emission from Jupiter

The Chandra X-ray Observatory (CXO) observed Jupiter during the period 24-26 February 2003 for approx. 40 hours (4 Jupiter rotations), using both the spectroscopy array of the Advanced CCD Imaging Spectrometer (ACIS-S) and the imaging array of the High-Resolution Camera (HRC-I). Two ACIS-S exposures, each -8.5 hours long, were separated by an HRC-I exposure of approx. 20 hours. The low- to middle-latitude nonauroral disk X-ray emission is much more spatially uniform than the auroral emission. However, the low- to middle-latitude X-ray count rate shows a small but statistically significant hour angle dependence and depends on surface magnetic field strength. In addition, the X-ray spectra from regions corresponding to 3-5 gauss and 5-7 gauss surface fields show significant differences in the energy band 1.26-1.38 keV, perhaps partly due to line emission occurring in the 3-5 gauss region but not the 5-7 gauss region. A similar correlation of surface magnetic field strength with count rate is found for the 18 December 2000 HRC-I data, at a time when solar activity was high. The low- to middle-latitude disk X-ray count rate observed by the HRC-I in the February 2003 observation is about 50% of that observed in December 2000, roughly consistent with a decrease in the solar activity index (F10.7 cm flux) by a similar amount over the same time period. The low- to middle-latitude X-ray emission does not show any oscillations similar to the approx. 45 min oscillations sometimes seen from the northern auroral zone. The temporal variation in Jupiter's nonauroral X-ray emission exhibits similarities to variations in solar X-ray flux observed by GOES and TIMED/SEE. The two ACIS-S 0.3-2.0 keV low- to middle-latitude X-ray spectra are harder than the auroral spectrum and are different from each other at energies above 0.7 keV, showing variability in Jupiter's nonauroral X-ray emission on a timescale of a day. The 0.3-2.0 keV X-ray power emitted at low to middle latitudes is 0.21 GW and 0.39 GW for the first and second ACIS-S exposures, respectively. We suggest that X-ray emission from Jupiter's disk may be largely generated by the scattering and fluorescence of solar X rays in its upper atmosphere, especially at times of high incident solar X-ray flux. However, the dependence of count rate on surface magnetic-field strength may indicate the presence of some secondary component, possibly ion precipitation from radiation belts close to the planet.

Bhardwaj, Anil↗
NASA NTRS2009

Jupiter's Mid-Infrared Aurora: Solar Connection and Minor Constituents

High spectral resolution in the 12 pin region of the polar regions of Jupiter reveal unique information on auroral phenomena and upper stratospheric composition. Polar aurorae in Jupiter's atmosphere radiate; throughout the electromagnetic spectrum from X-ray through mid-infrared (mid-IR, 5 - 20 micron wavelength). Voyager IRIS data and ground-based. spectroscopic measurements of Jupiter's northern mid-IR aurora acquired since 1982, reveal a correlation between auroral brightness and solar activity that has not been observed in Jovian aurora at other wavelengths. Over nearly three solar cycles, Jupiter auroral ethane, emission brightness and solar 10.7-cm radar flux and sunspot number are positively correlated with high confidence. Ethane line emission intensity varies over tenfold between low and high scalar activity periods. Detailed measurements have been made using the GSFC HIPWAC spectrometer at the NASA IRTF since the last solar maximum, following the mid-IR emission through the declining phase toward solar minimum. An even more convincing correlation with solar activity is evident in these data. The spectra measured contain features that cannot be attributed to ethane and are most likely spectra of minor constituents whose molecular bands overlap the v9 band of ethane. Possible candidates are allene, propane, and other higher order hydrocarbons. These features appear to be enhanced in the active polar regions. Laboratory measurements at comparable spectral resolution of spectra of candidate molecules will be used to identify the constituents. Current analyses of these results will be described, including planned measurements on polar ethane line emission scheduled through the rise of the next solar maximum beginning in 2009, with a steep gradient to a maximum in 2012. This work is relevant to the Juno mission and to the development of the NASA/ESA Europa Jupiter System Mission.

Kostiuk, Theodore↗
NASA NTRS2012

Assessing the Time Variability of Jupiter's Tropospheric Properties from 1996 to 2011

We acquired and analyzed mid-infrared images of Jupiter's disk at selected wavelengths from NASA's Infrared Telescope Facility (IRTF) from 1996 to 2011, including a period of large-scale changes of cloud color and albedo. We derived the 100-300 mbar temperature structure, together with tracers of vertical motion: the thickness of a 600- mbar cloud layer, the 300-mbar abundance of the condensable gas NH3, and the 400- mbar para- vs. ortho-H2 ratio. The biggest visual change was detected in the normally dark South Equatorial Belt (SEB) that 'faded' to a light color in 2010, during which both cloud thickness and NH3 abundance rose; both returned to their pre-fade levels in 2011, as the SEB regained its normal dark color. The cloud thickness in Jupiter's North Temperate Belt (NTB) increased in 2002, coincident with its visible brightening, and its NH3 abundance spiked in 2002-2003. Jupiter's Equatorial Zone (EZ), a region marked by more subtle but widespread color and albedo change, showed high cloud thickness variability between 2007 and 2009. In Jupiter's North Equatorial Belt (NEB), the cloud thickened in 2005, then slowly decreased to a minimum value in 2010-2011. No temperature variations were associated with any of these changes, but we discovered temperature oscillations of approx.2-4 K in all regions, with 4- or 8-year periods and phasing that was dissimilar in the different regions. There was also no detectable change in the para- vs. ortho-H2 ratio over time, leading to the possibility that it is driven from much deeper atmospheric levels and may be time-invariant. Our future work will continue to survey the variability of these properties through the Juno mission, which arrives at Jupiter in 2016, and to connect these observations with those made using raster-scanned images from 1980 to 1993 (Orton et al. 1996 Science 265, 625).

Orton, G. S.↗
NASA NTRS2009

An Overview of the Jupiter Europa Orbiter Concept's Europa Science Phase Orbit Design

Jupiter Europa Orbiter (JEO), the proposed NASA element of the proposed joint NASA-ESA Europa Jupiter System Mission (EJSM), could launch in February 2020 and conceivably arrive at Jupiter in December of 2025. The concept is to perform a multi-year study of Europa and the Jupiter system, including 30 months of Jupiter system science and a comprehensive Europa orbit phase of 9 months. This paper provides an overview of the JEO concept and describes the Europa Science phase orbit design and the related science priorities, model pay-load and operations scenarios needed to conduct the Europa Science phase. This overview is for planning and discussion purposes only.

Lock, Robert E.↗
NASA NTRS1993

Determination of Radio-Frame Position for Earth and Jupiter from Ulysses Encounter Tracking

Radio metric tracking data acquired from the Ulysses spacecraft about its encounter with Jupiter in February 1992 allow an accurate measurement of some components of the orbital elements describing the positions of the Earth and Jupiter with respect to extragalactic radio sources. Range and Doppler data acquired from the Earth while the spacecraft is far from any planet provide an estimate of the spacecraft trajectory relative to the orbit of the Earth. Doppler data near Jupiter provide an accurate position determination of the spacecraft with respect to Jupiter. Very Long Baseline Interferometry observations of the spacecraft with respect to the distant radio sources provide a direct measure of the spacecraft position in the radio reference frame. Combining these measurements provides a means to estimate the locations of the Earth and Jupiter in the radio reference frame.

McElrath, T.P.↗
NASA NTRS2019

Solar Power System and Radioisotope Thermoelectric Generation Technologies at Jupiter-Saturn-Uranus Environments: New Insights and Paradigms

Power system selection for outer planet destinations, such as Jupiter, Saturn, and Uranus and beyond, is complex, involving and dependent on many interdisciplinary factors such as power system mass, specific power, cost, mechanical and electrical integration, and natural radiation environment. Low solar irradiance at Jupiter, Saturn, and Uranus systems (i.e., 50, 15, and 4 W/m2 , respectively) makes solar power systems challenging in mechanical / electrical integration and accommodating radiation environments. More costly radioisotope thermoelectric generator (RTG) systems can help proposed missions overcome radiation environment and spacecraft control challenges at Jupiter, Saturn, and Uranus. NASA’s Jet Propulsion Laboratory (JPL) has recently made significant strides in demonstrating high-efficiency, radiation-hard solar cell technologies for low-irradiance, low-temperature (LILT) applications, and high-efficiency thermoelectric (TE) materials and modules for higher-specific-power RTGs. Stateof-art multi-junction solar cells now routinely demonstrate high efficiencies of 30-34% at LILT (9.5AU and -165°C), making solar arrays a viable option for many near-term Saturn mission concepts. Emerging technologies like LILToptimized solar cells have recently demonstrated even higher efficiencies of 37% at 9.5AU and -165°C and 30% lower mass than the state-of-art, offering the prospect of ~3W/kg array-level, end-of-life specific powers under Saturn conditions. Having already demonstrated the tremendous utility of RTGs on Mars and in deep-space missions (e.g., Galileo at Jupiter, New Horizons at Pluto), NASA is now developing and demonstrating new TE materials and modules (e.g., skutterudites, La3-x Te4, and Zintls) for increasing RTG specific power (up to >8.5 W/kg), which strongly impacts an RTG’s mass, fuel utilization, and modularity in the power system trade domain. New accomplishments in both areas highlight the renewed requisite for updated comparisons and trade-offs in power output, specific power and mass, cost, mechanical and electrical integration, new technology timelines, and natural radiation impacts between new LILT-optimized photovoltaic technologies and next-generation RTG technologies. This work discusses and demonstrates how new LILT-based technologies are now allowing one to consider and design solar power systems for Saturn orbit and beyond, and are changing the potential cost-mass trade-offs between emerging solar power technologies and newly-envisioned RTG technologies. Key updated system mass and cost trade-offs between high-performance LILT solar technologies and new RTG technologies are presented, reinforcing and refining power selection criteria supporting possible future NASA deep-space science and exploration missions to Mars, the Jupiter system (Europa, Ganymede), the Saturn system (Titan, Enceladus), Uranus, and beyond. Key trade-offs in other above-mentioned interdisciplinary factors between these two power technologies are also discussed.

Bairstow, Brian K.↗
NASA NTRS2023

A High-Eccentricity Warm Jupiter Orbiting TOI-4127

We report the discovery of TOI-4127 b, which is a transiting, Jupiter-sized exoplanet on a long period (P=56.39879 +0.00010 -0.00010 days) and a high-eccentricity orbit around a late F-type dwarf star. This warm Jupiter was first detected and identified as a promising candidate from a search for single-transit signals in TESS Sector 20 data and was later characterized as a planet following two subsequent transits (TESS Sectors 26 and 53) and follow-up ground-based RV observations with the NEID and SOPHIE spectrographs. We jointly fit the transit and RV data to constrain the physical (R p =1.096 +0.039 -0.032 R J , M p =2.30 +0.11 -0.11 M J ) and orbital parameters of the exoplanet. Given its high orbital eccentricity (𝓮=0.7471 +0.0078 -0.0086 ), TOI-4127 b is a compelling candidate for studies of warm Jupiter populations and of hot Jupiter formation pathways. We show that the present periastron separation of TOI-4127 b is too large for high-eccentricity tidal migration to circularize its orbit, and that TOI-4127 b is unlikely to be a hot Jupiter progenitor unless it is undergoing angular momentum exchange with an undetected outer companion. Although we find no evidence for an external companion, the available observational data are insufficient to rule out the presence of a perturber that can excite eccentricity oscillations and facilitate tidal migration.

Exoplanet astronomy↗
NASA NTRS2004

Radiation analysis for manned missions to the Jupiter system

An analysis for manned missions targeted to the Jovian system has been performed in the framework of the NASA RASC (Revolutionary Aerospace Systems Concepts) program on Human Exploration beyond Mars. The missions were targeted to the Jupiter satellite Callisto. The mission analysis has been divided into three main phases, namely the interplanetary cruise, the Jupiter orbital insertion, and the surface landing and exploration phases. The interplanetary phase is based on departure from the Earth-Moon L1 point. Interplanetary trajectories based on the use of different propulsion systems have been considered, with resulting overall cruise phase duration varying between two and five years. The Jupiter-approach and the orbital insertion trajectories are considered in detail, with the spacecraft crossing the Jupiter radiation belts and staying around the landing target. In the surface exploration phase the stay on the Callisto surface is considered. The satellite surface composition has been modeled based on the most recent results from the GALILEO spacecraft. In the transport computations the surface backscattering has been duly taken into account. Particle transport has been performed with the HZETRN heavy ion code for hadrons and with an in-house developed transport code for electrons and bremsstrahlung photons. The obtained doses have been compared to dose exposure limits. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

NASA Center LaRC↗
NASA NTRS1994

(abstract) Short Time Period Variations in Jupiter's Synchrotron Radiation

The long term time variability of Jupiter's synchrotron radiation on yearly time scales has been established for some time. For many years, theorists have speculated about the effects variations in the solar wind, solar flux, Io, the Io torus, and Jupiter's magnetic field have on the ultra-relativistic electron population responsible for the emission. Early observational results suggested the additional possibility of a short term time variability, on timescales of days to weeks. In 1989 a program designed to investigate the existence of short term time variability using the 85 foot Hat Creek radio telescope operating at 1400 MHz was initiated. The availability of a dedicated telescope provided the opportunity, for the first time, to obtain numerous observations over the full Jupiter rotation period. These and future observations will enable two important studies, characterization and confirmation of possible short term variations, and the investigation of the stability of Jupiter's synchrotron emission beaming curve. Analysis of Hat Creek observations and early results from the Maryland Point Naval research Laboratory will be presented.

telescope magnetic field↗
NASA NTRS2015

Study of Power Options for Jupiter and Outer Planet Missions

Power for missions to Jupiter and beyond presents a challenging goal for photovoltaic power systems, but NASA missions including Juno and the upcoming Europa Clipper mission have shown that it is possible to operate solar arrays at Jupiter. This work analyzes photovoltaic technologies for use in Jupiter and outer planet missions, including both conventional arrays, as well as analyzing the advantages of advanced solar cells, concentrator arrays, and thin film technologies. Index Terms - space exploration, spacecraft solar arrays, solar electric propulsion, photovoltaic cells, concentrator, Fresnel lens, Jupiter missions, outer planets.

jupiter↗
NASA NTRS2017

Coloring Jupiter's Clouds: Radiolysis of Ammonium Hydrosulfide (NH4SH)

Here we present our recent studies on the color and spectral reflectance changes induced by approximately 0.9 megaelectronvolts proton irradiation of ammonium hydrosulfide, NH4SH, a compound predicted to be an important tropospheric cloud component of Jupiter and other giant planets. Ultraviolet-visible spectroscopy was used to observe and identify reaction products in the ice sample and digital photography was used to document the corresponding color changes at 10-160 degrees Kelvin. Our experiments clearly show that the resulting color of the sample depends not only on the irradiation dose but also the irradiation temperature. Furthermore, unlike in our most recent studies of irradiation of NH4SH at 120 degrees Kelvin, which showed that higher irradiation doses caused the sample to appear green, the lower temperature studies now show that the sample becomes red after irradiation. However, comparison of these lower temperature spectra over the entire spectral range observed by HST (Hubble Space Telescope) shows that even though the color and spectrum resemble the color and spectrum of the GRS (Jupiter’s Great Red Spot), there is still enough difference to suggest that another component may be needed to adequately fit spectra of the GRS and other red regions of Jupiter's clouds. Regardless, the presence of NH4SH in the atmosphere of Jupiter and other gas giants, combined with this compound's clear alteration via radiolysis, suggests that its contribution to the ultraviolet-visible spectra of any of these object's clouds is significant.

ultraviolet-visible spectroscopy↗
NASA NTRS1997

Galileo at Jupiter: First Results

On the 7th of December, 1995 the Galileo spacecraft arrived at Jupiter. It began its mission by collecting data radioed from the Probe as it descended into Jupiter's atmosphere. A Short time later it fired its main engine for about 45 minutes, slowing the craft enough to be captured by Jupiter's gravity. The vessel named for the discovery of Jupiter's natural satellites thus became the first known artificial satellite of the giant planet.

Galileo↗
NASA NTRS1994

Galileo Preparing for Jupiter Arrival

The most critical events of the Galileo mission occur on Jupiter arrival day, December 7, 1995. In chronological order, these one-time events are: a 1000 km flyby of the innermost Galilean satellite Io, the 75-minute Atmospheric Entry Probe mission, and the Orbiter's Jupiter Orbit Insertion (JOI) maneuver. In addition, extensive, unique Orbiter science observations are planned because this is the only time Galileo will encounter Io, fly through the Io torus, and will be so close to Jupiter -- three times closer than at any of the perijove passes in the orbital mission. All of these events occur in what will be by far the most intense radiation environment Galileo will ever see. The focus of this paper is the extraordinary preparations being made to maximize the reliability of the most critical events in order to ensure a successful probe mission and Orbiter Insertion while also gathering unique arrival day Orbiter science. The paper also provides a mission status report including the return of the asteroid Ida data and the Galileo direct line-of-sight observations of Comet Shoemaker-Levy fragments impacting Jupiter in July 1994.

Galileo↗
NASA NTRS1972

Preliminary mission designs for Jupiter orbiter missions

Preliminary designs for unmanned orbital exploration missions to Jupiter are examined, and the operational options and systems requirements consistent with the major scientific goals of the mission are summarized. In general, each mission design provides repeated measurements of the interaction of Jupiter with the solar media, encounters at least two Galilean satellites with multiple encounters with at least one satellite at distances which allow photography with resolutions of at least 10 km; provides at least 10 orbital maps of the field and particle environment surrounding Jupiter, and provides synoptic observations of Jupiter over a range of wavelengths and various degrees of photographic coverage with resolutions of 300 to 30 km.

Swenson, B. L.↗
NASA NTRS1972

A model for Jupiter's proton radiation belt

A model for electron and proton energy and density in Jupiter's radiation belt is proposed. It is assumed that electrons diffuse inward from the solar wind. The Davis and Chang diffusion model, in which there is a very steep L-shell dependence in density and energy, is scaled outwards from the peak of the belts at about 1.5 to 2 Jupiter radii to the magnetopause as defined by the magnetic moment. The energetic electron density is calculated to be one billionth of the density in the solar wind, and that is assumed to be the trapping ratio of Jupiter's synchrotron belts. It is further assumed that the same figures apply to protons. The flux density at 80 MHz was measured by the Culgoora ring to be identical to that at 3000 MHz, implying a constant flux density of the synchrotron source of over 20 or 30 to 1 in frequency. It is suggested that the synchrotron spectrum is flat over more than an order of magnitude of frequency. Jupiter is an enormous synchrotron source and has a strong magnetic field, causing long diffusion times for electrons in the magnetosphere.

Warwick, J.↗
NASA NTRS1972

Energetic protons in Jupiter's radiation belts

Estimates of the location, density, and energy of energetic protons in the Jupiter radiation belts are presented. A model of the Jupiter magnetosphere is developed by scaling from the Earth magnetosphere. Solar wind parameters, and magnetic and electric field characteristics in the magnetosphere are given for the Earth and projected for Jupiter. The upper limit of the number density of energetic protons is calculated to be 310,000/cu m, and the energy density would be about 310,000 MeV/cu m, or 51 nJ/cu m. A magnetic moment of 100 MeV/gauss for solar wind particles, a magnetic field on Jupiter's surface of 10 gauss, and a McIlwain parameter L of 7 are used. Sources of energetic particles are cosmic rays, satellite-magnetosphere interaction, and the solar wind, and their contributions are discussed. The two components of trapped energetic particle drift, one due to corotational and convective fields and the other due to gradients in the magnetic field, are described, and their periods are given.

Brice, N.↗