SEARCH · Search NASA
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.
The Galileo spacecraft has been subjected to the charged particle environment around Jupiter since 1995. There have been numerous system failures attributable to radiation effects. We summarize those failures, their causes and any associated fixes.
A slow-scan television camera called the solid-state imaging subsystem (SSI), built for the Galileo Jupiter Orbiter, is described. The SSI consists of a 1500-mm focal-length telescope coupled to a camera head housing a 800 x 800-element charge-coupled device (CCD) detector based on 'virtual-phase' charge transfer technology. The CCD detector provides broadband sensitivity over 100 times that of a comparable vidicon-tube camera, while also yielding improved resolution, linearity, geometric fidelity, and spectral range. The system noise floor is 30 electrons, which results in a dynamic range of about 3500. Saturation of the detector with 9000-A light, followed by a high-speed erasure cycle prior to exposing each image, stabilizes the detector quantum efficiency at its maximum level for wavelengths beyond 7000 A. An optical schematic diagram of the SSI is included.
From orbit around Jupiter, the Galileo spacecraft will take the closest look ever at the planet and its natural satellites.
This video contains Galileo probe animation, mission diagrams, and testing and manufacturing footage.
In the Galileo Optical Experiment (GOPEX), optical transmissions were beamed to the Galilieo spacecraft by Earth-based transmitters at Table Mountain Observatory (TMO), California, and Starfire Optical Range (SOR), New Mexico. The demonstration took place over an eight-day period (December 9 through December 16) as Galileo receded from Earth on its way to Jupiter. At 6 million kilometers (15 times the Earth-Moon distance), the laser beam sent from Table Mountain Observatory eight days after Earth flyby covered the longest known range for laser transmission and detection.
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.
The Galileo spacecraft is now on its three-year direct Earth-to-Jupiter transfer trajectory. Jupiter arrived (Probe entry) is scheduled for 2:05 pm PST, December 7, 1995. The Galileo Probe will be the first human-made object to enter the atmosphere of an outer planet, while the Orbiter will be the first artificial satellite of an outer planet. A two-year Jupiter orbital mission is planned. Following launch on October 18, 1989, Galileo spent just over three years executing its Venus-Earth-Earth Gravity Assist (VEEGA) mission phase to achieve the heliocentric energy necessary to reach Jupiter. Midway through its Earth-to-Earth leg, on October 29, 1991, Galileo became the first spacecraft to encounter an asteroid. Six months earlier in April 1991, the spacecraft's high-gain antenna (HGA) failed to deploy properly. The special guidance, navigation, and control (GN&C) problems associated with a 20-month campaign of maneuvers to free the stuck antenna and successfully perform the asteroid encounter without it are described. The overall mission and spacecraft status are also reported.
Two full scale mockups of the Centaur upper stage were designed, fabricated and delivered to NASA. One was the Centaur Weightless Environment Training Facility (WETF) trainer and the other was the Centaur 1-G mockup. The Centaur upper stage booster is designed to carry the spacecraft Galileo to Jupiter, and the spacecraft Ulysses to an orbit around the Sun after launch from the Space Shuttle. The flight vehicle has several Extravehicular Activity (EVA) contingency tasks that require crew training. This need for crew training generated the requirement for the Centaur WETF crew trainer, which is high fidelity in areas of expected crew interface. During the production of the Centaur WETF crew trainer, the need for a jumper cable from Centaur to the Orbiter was identified. This EVA contingency task would be the installation of a cable from the Orbiter cargo bay sill to various command data boxes on Centaur to allow crew control deployment should a failure occur. This task required the upgrading of volumetric boxes on the trainer to a high fidelity configuration including electrical connector installation and cable routing.
This video is a compilation of three short videos related to the Galileo mission. The first section shows animation of the descent of the Galileo probe into the atmosphere of Jupiter. It includes cutaway views of the atmosphere showing the different layers. This descent will represent the first entry into the atmosphere of an outer planet in our solar system. A second section shows some live shots of the development and drop chute tests of the Galileo spacecraft. A third section is an animation that shows the Probe mission. It shows visualizations from the launch, including the Venus flyby, the separation of the probe and the orbiter, and the trajectory of the planetary arrival. It also shows the descent of the probe into the atmosphere.
The GOPEX (Galileo Optical communications from an Earth-based transmitter) demonstration was performed from transmitter sites at Table Mountain Observatory, CA and Starfire Optical Range, NM. The experiment was done over an eight day period, December 9 through December 16 as Galileo receded from Earth on its way to Jupiter. At a range of 6 million kilometers (15 times the Earth-Moon distance), the transmission from Table Mountain Observatory eight days after Earth-flyby represents the longest range for laser transmission and detection.
The Galileo spacecraft is now on its three-year direct Earth-to-Jupiter transfer trajectory.
Galileo is now enroute to Jupiter to do its intensive and comprehensive investigation of the Jupiter System. The Galileo Spacecraft consists of a Jupiter Orbiter and an Atmospheric Entry Probe. The Galileo mission at Jupiter is described. The design and operation of the Probe and Orbiter are discussed in some detail. The history of the many Shuttle upper stage changes Galileo experienced during development is outlined. The VEEGA trajectory Galileo is flying to achieve enough energy to reach Jupiter is explained. Science of opportunity on the circuitous VEEGA route is identified. Galileo Mission Operations are described. The paper concludes with an inflight mission status statement.
The Voyager 1 spacecraft flew by Jupiter on March 5, 1979. Spacecraft navigation was performed with radio tracking data from NASA's Deep Space Network. In the years since then, there has been a great deal of progress in the definition of celestial reference frames and in determining the orbit and orientation of the Earth. Using these improvements, the radio metric range and Doppler data acquired from the Voyager 1 spacecraft near its encounter with Jupiter have been reanalyzed to determine the plane-of-sky position of Jupiter with much greater accuracy than was possible at the time of the encounter. The position of Jupiter at the time of encounter has been determined with an accuracy of 40 nrad in right ascension and 140 nrad in declination with respect to the celestial reference frame defined by the International Earth Rotation Service. This position estimate has been done to improve the ephemeris of Jupiter prior to the upcoming encounter of the Galileo spacecraft with Jupiter.
Explore the source record for details and available documents.
The plasma science (PLS) Instrument on the Galileo spacecraft (orbiting Jupiter from December 1995 to September 2003) measured properties of the ions that were trapped in the magnetic field. The PLS data provide a survey of the plasma properties between approx. 5 and 30 Jupiter radii [R(sub J)] in the equatorial region. We present plasma properties derived via two analysis methods: numerical moments and forward modeling. We find that the density decreases with radial distance by nearly 5 orders of magnitude from approx. 2 to 3000 cm(exp.-3) at 6R(sub j) to approx. 0.05cm(sub -3) at 30 R(sub j). The density profile did not show major changes from orbit to orbit, suggesting that the plasma production and transport remained constant within about a factor of 2. The radial profile of ion temperature increased with distance which implied that contrary to the concept of adiabatic cooling on expansion, the plasma heats up as it expands out from Io's orbit (where TI is approx.60-80 eV) at approx. 6R(sub j) to a few keV at 30R(sub j).There does not seem to be a long-term, systematic variation in ion temperature with either local time or longitude. This latter finding differs from earlier analysis of Galileo PLS data from a selection of orbits. Further examination of all data from all Galileo orbits suggests that System Ill variations are transitory on timescales of weeks, consistent with the modeling of Cassini Ultraviolet Imaging Spectrograph observations. The plasma flow is dominated by azimuthal flow that is between 80% and 100% of corotation out to 25 R(sub j).
The Galileo spacecraft reached Jupiter on December 8, 1995. During its six year voyage Galileo encountered six celestial bodies.
The National Aeronautics and Space Administration (NASA) launched the Jet Propulsion Laboratory's (JPL) two Voyager spacecraft to Jupiter in 1977, each using three radioisotope thermoelectric generators (RTGs) supplied by the Department of Energy (DOE) for onboard electric power. In 1986 NASA will launch JPL's Galileo spacecraft to Jupiter equipped with two DOE supplied RTGs of an improved design. NASA and JPL are also responsible for obtaining a single RTG of this type from DOE and supplying it to the European Space Agency as part of its participation in the International Solar Polar Mission. As a result of these missions, JPL has been deeply involved in space nuclear safety as a user. This paper will give a brief review of the user contributions by JPL - and NASA in general - to the nuclear safety processes and relate them to the overall nuclear safety program necessary for the launch of an RTG. The two major safety areas requiring user support are the ground operations involving RTGs at the launch site and the failure modes and probabilities associated with launch accidents.
Two of the many performance requirements of the zinc orthotitanate (ZOT) ceramic thermal control paint covering parts of the Jupiter-bound Galileo spacecraft are that it be sufficiently electrically conductive so as to prevent electrostatic discharge (ESD) damage to onboard electronics and that it adhere to and protect the substrate from corrosion in terrestrial environments. The bulk electrical resistivity of ZOT on an aluminum substrate was measured over the ranges 22 C to 90 C and 0 percent RH to 100 percent RH, and also in soft (10 (minus 2) Torr) and hard (10 (minus 7) Torr) vacuums. No significant temperature dependence was evident, but measured resistivity values ranged over 9 orders of magnitude: 10 to the 5th power ohm-cm at 100 percent RH greater than 10 to the 12th power ohm-cm in a hard vacuum. The latter value violates the ESD criterion for a typical 0.019 cm thick coating. The corrosion study involved exposing typical ZOT substrate combinations to two moisture environments - 30 C/85 percent RH and 85 C/85 percent RH - for 2000 hours, during which time the samples were periodically removed for front-to-back electrical resistance and scratch/peel test measurements. It was determined that the ZOT/Al and ZOT/Mg systems are stable (no ZOT delamination), although some corrosion (oxide formation) and resistivity increases observed among the ZOT/Mg samples warrant that exposure of some parts to humid environments be minimized.