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The Near Infrared Mapping Spectrometer performed spectral studies of Jupiter and the Galilean satellites during the June 1996 perijove pass of the Galileo spacecraft.
The Galileo mission includes an Io flyby, insertion in Jupiter orbit, and ten close satellite flybys at altitudes as low as 250 km. The required orbit determination and navigation are described.
The Galileo mission operations concept is undergoing substantial redesign while the spacecraft is on its way to Jupiter, necessitated by the deployment failure of the High Gain Antenna.
In April 1991, Galileo's X-band high gain antenna failed to deploy. An alternate approach which utilizes the spacecraft's S-band low gain antenna was conceived and is in development.
The Galileo mission operations concept is undergoing substantial redesign, necessitated by the deployment failure of the High Gain Antenna, while the spacecraft is on its way to Jupiter.
The galileo spacecraft was launched on October 18, 1989 towards Jupiter using the Venus-Earth-Earth Gravity Assist (VEEGA) trajectory.
The application of high-accuracy S/S-band (2.1 GHz uplink/2.3 GHz dowlink) ranging to orbit determination with relatively short data arcs is investigated for the approach phase of each of the Galileo spacecraft's two Earth encounters (8 December 1990 and 8 December 1992).
The Galileo RetroPropulsion Module (RPM) has performed excellently throughout the first three years of mission operations. The RPM is a state-of-the-art, pressure-fed, bipropellant propulsion system, provided to NASA by the Federal Republic of Germany.
After the Galileo High Gain Antenna (HGA) failed to deploy in 1991, the Jet Propulsion Laboratory(JPL) faced the challenge of implementing a science-rich mission with a Low-Gain Antenna (LGA), at data rates that were almost four orders of magnitude less than originally planned.
Doppler data generated with the Galileo spacecraft's radio carrier wave during two Europa encounters on 19 December 1996 (E4) and 20 February 1997 (E6) were used to measure Euroapa's external gravitational field. The measurements indicate that Europa has a predominantly water ice-liquid outer shell about 100 to 200 klilometers thick and a deep interior with a density in excess of about 4000 kilograms per cubic meter.
The orbital tour trajectory that was selected for the Galileo mission includes ten close flybys of the Galilean satellites Europa, Ganymede, and Callisto, additional distant flybys of these satellites, lo torous observations, and many other events that provide broad opportunities for scientific observations.
On May 23, 1996, Galileo successfully switched to a new telecommunication mode with upgraded software on the spacecraft and comprehensively revised ground equipment. The new link offers multiple techniques (arraying, error-correcting coding, data compression, etc) to maximize the data return, while applying automation to minimize the complexity and cost of operations.
The Galileo spacecraft performed six radio occultaion observations of Jupiter's Galilean satellite Europa (J2) during its tour of the Jovian system.
Galileo's accomplishment of a science-rich mission through a low-gain antenna was made possible by a coordinated efforts of the Deep Space Network Support team, the spacecraft designers, and the science principal investigators.
Galileo infrared observaitons of Jupiter have been perfomed with two instruments, the Near Infrared Mapping Spectrometer (NIMS) and the Photo-Polarimeter Radiometer (PPR).
During this past year, the Galileo Orbiter has performed the large majority of its primary scientific mission in the Jupiter System-eigh of the eleven orbits and seven of the ten close satellite encounters and the deep penetration of the magnetotail.
Radio Doppler data from four encounters of the Galileo Orbiter with the jovian moon Europa have been used to refine models of Europa's interior.
In 1996 during the first four orbits of the satellite tour the Galileo ultraviolet spectrometer (UVS) (1130-4320 A) and extreme ultraviolet spectrometer (EUVS)(540-1280 A) performed near-simultaneous observations of the Jupiter aurora in both the north and south polar regions.