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NASA NTRS1991

Magellan, Galileo, and Ulysses

A combination of sophisticated computer animation and shuttle footage describe the missions of Ulysses, Galileo, and Magellan satellites to the solar system. Ulysses, launched in October 1990 by the European Space Agency, will study the sun. Galileo, launched in October 1989, will probe the Jovian system by releasing a probe that will descend into Jupiter's atmosphere and by using 12 instruments which will study Jupiter's 16 moons, its atmosphere, and its radiation and magnetic fields. Magellan, released from Space Shuttle Atlantis in May 1989, uses a synthetic aperture radar to probe through Venus' dense atmosphere to map its planetary surface. A computer animation simulates flying over the surface of Venus.

Source record↗
NASA NTRS1983

Return to Jupiter - Project Galileo

The mission profile, instrumentation, and mission objectives of the Galileo probe are described. Scheduled for Shuttle launch in 1986, with a boost from the Centaur upper stage, the probe will require over 2 yr to reach the Jovian system. An atmospheric entry probe will be released during Jupiter approach, and the orbiting module will relay the temperature, pressure, radio signals, spectroscopy, magnetometry, and particle counts, originating from the parachuting probe. The orbiting module will then continue on to a series of flybys and orbits around the Jovian moons by using a gravity assist from Jupiter after each pass of a moon. The orbiter will record spectrometric, radiometric, dust, visual, magnetic, and radio propagation data. The television camera is a CCD device with 640,000 diodes forming an 800 x 800 array in one square centimeter.

Johnson, T. V.↗
NASA NTRS2000

The Cassini/Huygens Flyby of Jupiter

At the and of the year 2000 the Cassini/Huygens spacecraft will fly by the planet Jupiter at a range of 137 jovian radii. A preliminary assessment has indicated that the instruments aboard Cassini/Huygens can make measurements that will make unique contributions to audio of the jovian system. In this presentation we will discuss the status of the plans for observations of the jovian system by Cassini/Huygens. We shall also consider the possibilities for observations carried out in cooperation with the Galileo spacecraft presently in orbit about Jupiter, with other spacecraft, and with various observatories on the ground.

Matson, Dennis L.↗
NASA NTRS1999

Pump Effects in Planetary Mass Spectrometers

Mass spectrometers provide a useful tool in solar system exploration since fundamental questions of Solar System formation and evolution may be constrained by models based on the chemical and isotopic data provided by these instruments. For example, comparison of such data between the atmospheres of the terrestrial planets enables an understanding of mechanisms of atmospheric loss to space and production sources such as from planetary outgassing and from infall from objects such as comets. Over the past 25 years, mass spectrometers have been sent to Mars, Venus, Comet Halley, and Jupiter and are presently in transit to the Saturnian system to sample the atmosphere of Saturn's moon Titan. The quality of data derived from a very small, lightweight, and rugged instrument is constrained not only by the mass analyzer itself, but also by the performance of its gas sampling and pumping systems. A comparison of several planetary mass spectrometer experiments is provided with a focus on the demands placed on the gas processing and pumping systems. For example, the figure below is a mass spectrum from deep in the atmosphere of Jupiter obtained from a quadrupole mass spectrometer developed in the early 1980's for the Galileo Probe (Niemann et al., Space Sci. Rev., 60, 111-142 (1992)). Measurements of Jovian noble gases and other species with this system is described.

Mahaffy, Paul↗
NASA NTRS1974

Pioneer Odyssey: Encounter with a Giant

Ancient peoples, perhaps thousands of years ago, undoubtedly conceived the idea of "reaching out" to Jupiter, the largest and most brilliant of the "wandering stars." But for mankind to stretch across the half billion miles to the giant planet of the Solar System many advances in technical and organizational fields of human endeavor had to be made. Outreach to Jupiter did not become a serious possibility until the Pioneer F and G Project was formed by NASA early in 1968. And then man began to design an extension of his senses that would probe the environs of the giant of the Solar System, a truly pioneer odyssey into the virtually unknown regions beyond the orbit of Mars. In the ensuing year. a dedicated and cooperative effort of several thousand people in Govern­ment, university, and private industrial organiza­tions converted the idea into a reality. Less than twelve generations after Galileo first saw the banded disc of Jupiter and the flickering dots of its large satellites in the newly invented telescope, mankind sent a machine to make observations within that Jovian system. The two Pioneer spacecraft for the mission to Jupiter each weighed only about 570 pounds, yet carried eleven highly sophisticated instruments capable of operating unattended for many year in space. The spacecraft consumes less electrical power than a standard 100 watt lamp yet is able to accept instructions from Earth to control numerous operating modes of its scientific payload, process observations from these scientific instruments and format the observations into information usable on Earth. Even more remarkable. the space­craft transmits a radio signal of only 8 watts power - equal to a nightlight - yet the information carried by the radio signal is received back on Earth from a distance of several billion miles. The Pioneer mission could not have been a success without the special engineering, scientific and management organization created for its accomplishment. This organization was rather unique in that it first had to meet a launch date target relatively quickly and then had to function for an extremely long mission operational time, far longer than any previous mission to planets. The first task was thus to organize so that the mission could be planned and the spacecraft designed and fabricated to be ready for launch within a few weeks of a 30-month target for completion. The program also produced an organization that planned mission operations to such detail that more than 16,000 commands were transmitted flawlessly to the distant spacecraft during Jupiter encounter. And each command reached the spacecraft within one second of the planned time despite the more than 90 minutes required for the radio message to travel from Earth to the space­craft and for the spacecraft to return a confirma­tion to controllers back on Earth. The organization for Pioneer also determined the required flight path from Earth to Jupiter with such precision, and controlled the launch vehicle with such accuracy, that 21 months after launch the spacecraft was able to fly behind Jupiter's satellite lo, thereby providing the first measurement that indicated the possibility of a tenuous atmosphere about this large satellite. Finally, the Pioneer organization processed and analyzed each year sufficient information from the spacecraft to fill a book having about 3 million pages and reduced this avalanche of data from space into summaries of manageable size. And all this organization depended on people, consisted of people: the people who really made this whole mission possible. Pioneer has always depended on the dedication of many individuals from many organizations throughout the world to achieve its scientific objectives, and, as evidenced by the success of the Pioneer series, this dependence is completely justified. Relatively few individuals have an opportunity during their lives to participate in such a challenging, historic, pioneering effort; and still fewer are able to enjoy the rewards of such an activity. We who have worked on Pioneer 10 and its sister spacecraft, Pioneer 11, consider ourselves fortunate to be in both classes. For the opportunity we thank the people of the United States of America, who have supported our country's space effort and its spreading of human awareness of a vast and intriguing universe in which our own unique planet Earth is only one of myriads of worlds. This volume describing the mission to Jupiter and its results is one of the many rewards for our effort which we share with you, the reader.

Fimmel, Richard O.↗
NASA NTRS2011

A Deterministic Electron, Photon, Proton and Heavy Ion Radiation Transport Suite for the Study of the Jovian System

A deterministic suite of radiation transport codes, developed at NASA Langley Research Center (LaRC), which describe the transport of electrons, photons, protons, and heavy ions in condensed media is used to simulate exposures from spectral distributions typical of electrons, protons and carbon-oxygen-sulfur (C-O-S) trapped heavy ions in the Jovian radiation environment. The particle transport suite consists of a coupled electron and photon deterministic transport algorithm (CEPTRN) and a coupled light particle and heavy ion deterministic transport algorithm (HZETRN). The primary purpose for the development of the transport suite is to provide a means for the spacecraft design community to rapidly perform numerous repetitive calculations essential for electron, proton and heavy ion radiation exposure assessments in complex space structures. In this paper, the radiation environment of the Galilean satellite Europa is used as a representative boundary condition to show the capabilities of the transport suite. While the transport suite can directly access the output electron spectra of the Jovian environment as generated by the Jet Propulsion Laboratory (JPL) Galileo Interim Radiation Electron (GIRE) model of 2003; for the sake of relevance to the upcoming Europa Jupiter System Mission (EJSM), the 105 days at Europa mission fluence energy spectra provided by JPL is used to produce the corresponding dose-depth curve in silicon behind an aluminum shield of 100 mils ( 0.7 g/sq cm). The transport suite can also accept ray-traced thickness files from a computer-aided design (CAD) package and calculate the total ionizing dose (TID) at a specific target point. In that regard, using a low-fidelity CAD model of the Galileo probe, the transport suite was verified by comparing with Monte Carlo (MC) simulations for orbits JOI--J35 of the Galileo extended mission (1996-2001). For the upcoming EJSM mission with a potential launch date of 2020, the transport suite is used to compute the traditional aluminum-silicon dose-depth calculation as a standard shield-target combination output, as well as the shielding response of high charge (Z) shields such as tantalum (Ta). Finally, a shield optimization algorithm is used to guide the instrument designer with the choice of graded-Z shield analysis.

Norman, Ryan B.↗
NASA NTRS1983

Galileo Atmospheric Entry Probe System - Design, development, and test

The overall development of the Galileo Atmospheric Entry Probe System is described. The Probe will be carried to Jupiter by the Galileo Orbiter and released on an entry trajectory 150 days before entry. A complement of seven science instruments will measure the near-Jupiter radiation field and the characteristics of the Jovian atmosphere from a distance of about 5 Jupiter radii above the 1-bar level down to levels in the 10-20-bar range. Probe data are to be transmitted to earth via the Orbiter. System requirements are discussed. Probe design features and those features of the development test program peculiar to entry probes are described.

Givens, J. J.↗
NASA NTRS1983

Galilean satellite remote sensing by the Galileo Jupiter Orbiter

The derivation of a mission design strategy for the Galileo Jupiter Orbiter which best satisfies the requirements for remote sensing of the surfaces of the Galilean satellites during a 20-month orbital tour of the Jovian system is described. The celestial mechanics of a spacecraft orbiting about Jupiter and interacting with the Galilean satellites is discussed. A satellite tour strategy designed to optimize the accomplishment of remote sensing, field and particle science, and radio science objectives is developed. Finally, an assessment is made of how well these objectives can be met given the spacecraft, the capabilities of the scientific instruments, and the structure of the satellite tour.

Yeates, C. M.↗
NASA NTRS1985

Galileo

The Galileo consists of two main parts: a Jupiter orbiter and a probe. After a 1000 day journey, the Galileo will assume orbit around the giant planet, an orbit which will last for 200 days, in the hopes of astronomers. The orbit will carry the Galileo past its four Jovian satellites--Io, Europa, Ganymede, and Callisto - a combined total of 11 times. This will enable scientists to study the atmosphere of not only the largest planet in the solar system, but its large moons as well. Sometime in August of 1988, the Galileo will approach Jupiter and begin its important activities. Fifty-six days away from planetary encounter, the Galileo will release the probe which will continue the trip to Jupiter and enter the atmosphere. As it descends through the atmosphere, the probe will unfurl a parachute to slow its speed as it broadcasts information back to the waiting orbiter, which will in turn relay it back to the waiting scientists on Earth. The probe's descent time is expected to be approximately 15 min before Jupiter's pressure and heat overwhelm the probe's protection. However, scientists are hopeful that the probe will survive longer than 15 min, possibly up to 60 min.

Hwang, C.↗
NASA NTRS2001

A Global Magnetohydrodynamic Model of Jovian Magnetosphere

The goal of this project was to develop a new global magnetohydrodynamic model of the interaction of the Jovian magnetosphere with the solar wind. Observations from 28 orbits of Jupiter by Galileo along with those from previous spacecraft at Jupiter, Pioneer 10 and 11, Voyager I and 2 and Ulysses, have revealed that the Jovian magnetosphere is a vast, complicated system. The Jovian aurora also has been monitored for several years. Like auroral observations at Earth, these measurements provide us with a global picture of magnetospheric dynamics. Despite this wide range of observations, we have limited quantitative understanding of the Jovian magnetosphere and how it interacts with the solar wind. For the past several years we have been working toward a quantitative understanding of the Jovian magnetosphere and its interaction with the solar wind by employing global magnetohydrodynamic simulations to model the magnetosphere. Our model has been an explicit MHD code (previously used to model the Earth's magnetosphere) to study Jupiter's magnetosphere. We continue to obtain important insights with this code, but it suffers from some severe limitations. In particular with this code we are limited to considering the region outside of 15RJ, with cell sizes of about 1.5R(sub J). The problem arises because of the presence of widely separated time scales throughout the magnetosphere. The numerical stability criterion for explicit MHD codes is the CFL limit and is given by C(sub max)(Delta)t/(Delta)x less than 1 where C(sub max) is the maximum group velocity in a given cell, (Delta)x is the grid spacing and (Delta)t is the time step. If the maximum wave velocity is C(sub w) and the flow speed is C(sub f), C(sub max) = C(sub w) + C(sub f). Near Jupiter the Alfven wave speed becomes very large (it approaches the speed of light at one Jovian radius). Operating with this time step makes the calculation essentially intractable. Therefore under this funding we have been designing a new MHD model that will be able to compute solutions in the wide parameter regime of the Jovian magnetosphere.

Walker, Raymond J.↗
NASA NTRS1984

Development of a bipropellant propulsion module for the Galileo spacecraft

The bipropellant engine retropropulsion module (RPM) of the Jupiter-exploration Galileo spacecraft provides attitude control, trajectory correction, a deep space velocity increment, a spacecraft deflection maneuver for an entry capsule, a retromaneuver for Jupiter approach, and a 'perijove raise' maneuver for the Jovian system tour of the spacecraft. Attention is given to the design features and performance capabilities of the RPM, which uses a set of 12 10-N thrusters in conjunction with a 400-N engine. Tanks contain 935 kg of propellant to satisfy mission requirements.

Hagenest, W.↗
NASA NTRS2003

The Galileo Probe: How it Has Changed Our Understanding of Jupiter

The Galileo Mission to Jupiter, which arrived in December of 1995, provided the first study by an orbiter, and the first in-situ sampling via an entry probe, of an outer planet atmosphere. The rationale for an entry probe is that, even from an orbiter, remote sensing of the jovian atmosphere could not adequately retrieve the information desired. This paper provides a current summary of the most significant aspects of the data returned from the Galileo entry probe. As a result of the probe measurements, there has been a reassessment of our understanding of outer planet formation and evolution of the solar system. The primary scientific objective of the Galileo probe was to determine the composition of the jovian atmosphere, which from remote sensing remained either very uncertain, or completely unknown, with respect to several key elements. The probe found that the global He mass fraction is. significantly above the value reported from the Voyager Jupiter flybys but is slightly below the protosolar value, implying that there has been some settling of He to the deep jovian interior. The probe He measurements have also led to a reevaluation of the Voyager He mass fraction for Saturn, which is now determined to be much closer to that of Jupiter. The elements C, N, S, Ar, Kr, Xe were all found to have global abundances approximately 3 times their respective solar abundances. This result has raised a number of fundamental issues with regard to properties of planetesimals and the solar nebula at the time of giant planet formation. Ne, on the other hand, was found to be highly depleted, probably as the result of it being carried along with helium as helium settles towards the deep interior. The global abundance of O was not obtained by the probe because of the influence of local processes at the probe entry site (PES), processes which depleted condensible species, in this case H2O, well below condensation levels. Other condensible species, namely NH3 and H2S, were similarly affected but attained their deep equilibrium mixing ratios before the maximum depth sampled by the probe. Processes that might be capable of producing such effects on the condensibles are still under investigation. Measured isotopic ratios of noble gases and other heavy elements are solar, and (D + (Sup 3)He)/H is the same to within measurement uncertainties as in the local interstellar medium. No thick clouds were detected, and in particular no significant water cloud, but the PES location clearly affected the probe measurements of clouds. In fact, the probe data must be understood in the context of the location of the PES, which was within what is termed a 5 micron hot spot, a local clearing in the clouds that is bright near the 5 microns spectral region. The thermal structure at the PES was determined from approximately 1000 km above the 1 bar pressure level (10(exp -9 bars)) to 132 km 1 bar (22bars). The probe showed the atmosphere to have a generally sub-adiabatic temperature gradient (static stability) of = 0.1 K/km to as deep as the probe made measurements. In the upper atmosphere the probe derived a maximum positive vertical temperature gradient of approximately 5 K/km, and maximum temperature of = 900 K. The energy sources producing the warm upper atmosphere have yet to be completely identified. At first glance, Doppler tracking of the probe indicates that the long observed cloud level zonal winds extend to levels at least as deep as the probe made measurements. Zonal wind increases from = 80 m/s at pressures less than a bar to about 180 m/s near 5 bars, and remains approximately constant with depth thereafter. However, there is a question as to whether the winds measured from probe tracking are representative of the general wind field, or are considerably influenced by localized winds associated with the PES.

Young, Richard E.↗
NASA NTRS1997

Final Galileo Propulsion System In-Flight Characterization

The Galileo Retro-Propulsion Module (RPM) performed excellently throughout the ambitious, eight-year Galileo Jupiter mission. The RPM is a state-of-the-art, pressure-fed, bipropellant propulsinon system, provided to NASA by the Federal Republic of Germany.

Galileo↗
NASA NTRS2003

Photometric Analysis of the Jovian Ring System and Modeling of Ring Origin and Evolution

We have successfully completed the work described in our proposal. The work supported by this grant resulted in the publication of the following paper: Brooks, S. M., L. W. Esposito, M. R. Showalter, and H. B. Throop. 2002. The size distribution of Jupiter's main ring from Galileo imaging and spectroscopy. Icarus, in press. This was also the major part of Dr. Shawn Brooks PhD dissertation. Dr. Brooks gave oral presentations on this work at the Lunar and Planetary Conference, the annual meetings of the Division for Planetary Sciences of the American Astronomical Society, the annual meetings of the European Geophysical Society, the international Jupiter Conference in Boulder, the Jupiter after Galileo and Cassini Conference in Lisbon and to the Working Group in Non-Linear Dynamics in Potsdam, Germany. This work was reviewed in: Esposito, L. W. 2002. Planetary rings. Rep. hog. Phys. 65, 1741-1783. Planetary rings. LASP reprint 874. Online at http://stacks.iop.org/RoPP/65/1741. Dr. Esposito gave presentations at schools and over the internet on the results of this work. Dr. Brooks lectured in undergraduate and graduate classes on Jupiter's rings, and on the meaning of his research. In August 2003, Dr. Shawn Brooks received the Phd degree from the University of Colorado in Astrophysical and Planetary Sciences.

Esposito, L. W.↗
NASA NTRS1979

Galileo to Jupiter: Probing the Planet and Mapping Its Moons

The first project to use the space shuttle as an interplanetary launch vehicle, the Galileo mission is designed to obtain information about the origin and evolution of the solar system by studying large-scale phenomena on Jupiter and its satellites. Aimed towards Mars to obtain gravity assist, the orbiting spacecraft will deploy a probe, which penetrating the Jovian atmosphere, will transmit data for approximately an hour. The spacecraft itself will inspect the atmospheres, ionospheres, and surfaces of Ganymede, Io, Europa, and Callisto, as well as determine their magnetic and gravitational properties. The experiments to be conducted and their scientific objectives are described. Known facts about the Jovian system are reviewed.

Source record↗
NASA NTRS1981

Trends in unmanned planetary entry systems

Entry systems used in unmanned planetary exploration are discussed in terms of future missions and more complex demands made upon the design configurations of orbiters and atmospheric space probes. The presently on-going Galileo project involving a Jupiter orbiter and a probe of the Jovian atmosphere is mentioned, and the difficult entry requirements at a velocity of 48 km/sec and an angle of minus seven to minus 10 degrees into an atmosphere composed largely of hydrogen, are described. Re-entry parameters determined by the respective entry environment, type of entry approach (hyperbolic or elliptical orbit) entry velocity, and guidance technology are given attention. Aerobraking, involving relatively slow circularization of an initial elliptical orbit by repeated passes through the atmosphere, is investigated. Aerocapture, by which vehicles using controlled flight paths through the atmosphere, can go directly from a hyperbolic flyby trajectory to low circular orbit is described. Major attractions of aerobraking and aerocapture are analyzed in terms of modest technology needs and relatively small impact on spacecraft design.

French, J. R.↗
NASA NTRS1999

Jupiter's Deep Flowing Thermocline

The observed banded wind structure of Jupiter and Saturn remains an outstanding problem in planetary fluid dynamics. Both planets exhibit super-rotational equatorial jets (exceeding the underlying rotation of the magnetic fields tied to their deep fluid interiors), with speeds of some 100 and 400m/s, respectively, and counter-flowing lots at higher latitudes;. Recent analyses of the 1995 Galileo probe measurements, Hubble Telescope observations of the 1994 Shoemaker-Levy9 comet crash, and Earth-based infrared mapping provide evidence for a variably stratified, deeply seated flow layer. A now conceptual model for the jovian current system is proposed, in some ways resembling the oceanic thermocline, assuming a mixed distribution of potential vorticity atop a tropospheric wind layer of latitudinally variable stratification. A simple analytic version of the model links the strength, shape, and direction of the alternating zonal currents on Jupiter and Saturn to a single parameter equivalent to the internal deformation scale for an inferred deep stable region.

Allison, Michael↗