GALILEO Plasma Wave Subsystem (PWS) Experiment
The basic objective of this investigation is the study of plasma waves and radio emissions in the magnetosphere of Jupiter.
The Voyager 1 and 2 flybys of Jupiter have now clearly shown that many complex types of plasma wave and radio-emission phenomena occur in the Jovian magnetosphere. These include electromagnetic whistler mode emissions called chorus and hiss, electromagnetic continuum radiation trapped in the magnetospheric cavity, electrostatic waves associated with harmonics of the electron cyclotron frequency, and a wide variety of escaping radio emissions. Some of these waves, such as the whistler mode emissions, are believed to play an important role in the dynamics of the magnetosphere by controlling the pitch-angle scattering and loss of energetic charged particles. In other cases plasma waves provide an important diagnostic tool by revealing various characteristic frequencies of the plasma, from which quantities such as the electron density can be computed.
Since the Galileo spacecraft will be the first orbiter of Jupiter, this spacecraft will provide a much more comprehensive study of the Jovian magnetosphere than was possible with the previous Pioneer and Voyager flybys of Jupiter. Specifically, the orbit of Galileo will provide a survey of the magnetotail at distances of up to 150 RJ over a range of local times near local midnight, a region that has never previously been explored, repeated passes through the plasma sheet, and the tail lobes, and numerous close flybys of the Galilean satellites. Of particular importance will be a very close pass by the satellite Io.
The Voyager flybys showed that volcanic gases escaping from this moon are the main source of plasma in the Jovian magnetosphere. The primary energization of plasma in the Jovian magnetosphere is believed to occur in a dense plasma torus that surrounds Jupiter near Io's orbit. This energization is associated with many complex plasma wave phenomena, including the generation of intense kilometric and decametric radio emissions. In addition to exploring regions never previously investigated, Galileo, by virtue of its long lifetime in orbit around Jupiter, also provides a unique new capability for carrying out studies of temporal variations on time scales that cannot be investigated with a single flyby.
For example, it is known that the kilometric and decametric radio emissions associated with Io and its plasma torus have temporal variations on time scales of weeks and longer. With Galileo these temporal variations can be monitored over periods of several years and compared with other remote sensing instruments. These measurements should be able to tell us, for example, whether the variations are associated with changes in the volcanoes on Io. Considerable interest also exists in searching for evidence of magnetospheric substorm phenomena, possibly comparable to auroral substorms in the Earth's magnetosphere.
With the Galileo plasma wave instrument, it should be possible to provide remote sensing of substorms in a manner comparable to the remote sensing of terrestrial auroral kilometric radiation, which is known to be closely associated with terrestrial substorms. To carry out comprehensive studies of plasma waves and radio emissions at Jupiter, the Galileo plasma wave instrument incorporates several new features that provide improvements over the previous Voyager 1 and 2 measurements.
These improvements include:
The main instrument package and the electric dipole antenna system were designed and constructed at the University of Iowa, and the search coil magnetic antenna was provided by the "Centre de Recherches en Physique de l'Environnement terrestre et planétaire" (CRPE), then the "Centre d'Etude des environnements Terrestre et Planétaire" (CETP) before joining the "Laboratoire Atmosphères, Observations Spatiales" (LATMOS) in part.
Version:2.4.0
GALILEO Plasma Wave Subsystem (PWS) Experiment
The basic objective of this investigation is the study of plasma waves and radio emissions in the magnetosphere of Jupiter.
The Voyager 1 and 2 flybys of Jupiter have now clearly shown that many complex types of plasma wave and radio-emission phenomena occur in the Jovian magnetosphere. These include electromagnetic whistler mode emissions called chorus and hiss, electromagnetic continuum radiation trapped in the magnetospheric cavity, electrostatic waves associated with harmonics of the electron cyclotron frequency, and a wide variety of escaping radio emissions. Some of these waves, such as the whistler mode emissions, are believed to play an important role in the dynamics of the magnetosphere by controlling the pitch-angle scattering and loss of energetic charged particles. In other cases plasma waves provide an important diagnostic tool by revealing various characteristic frequencies of the plasma, from which quantities such as the electron density can be computed.
Since the Galileo spacecraft will be the first orbiter of Jupiter, this spacecraft will provide a much more comprehensive study of the Jovian magnetosphere than was possible with the previous Pioneer and Voyager flybys of Jupiter. Specifically, the orbit of Galileo will provide a survey of the magnetotail at distances of up to 150 RJ over a range of local times near local midnight, a region that has never previously been explored, repeated passes through the plasma sheet, and the tail lobes, and numerous close flybys of the Galilean satellites. Of particular importance will be a very close pass by the satellite Io.
The Voyager flybys showed that volcanic gases escaping from this moon are the main source of plasma in the Jovian magnetosphere. The primary energization of plasma in the Jovian magnetosphere is believed to occur in a dense plasma torus that surrounds Jupiter near Io's orbit. This energization is associated with many complex plasma wave phenomena, including the generation of intense kilometric and decametric radio emissions. In addition to exploring regions never previously investigated, Galileo, by virtue of its long lifetime in orbit around Jupiter, also provides a unique new capability for carrying out studies of temporal variations on time scales that cannot be investigated with a single flyby.
For example, it is known that the kilometric and decametric radio emissions associated with Io and its plasma torus have temporal variations on time scales of weeks and longer. With Galileo these temporal variations can be monitored over periods of several years and compared with other remote sensing instruments. These measurements should be able to tell us, for example, whether the variations are associated with changes in the volcanoes on Io. Considerable interest also exists in searching for evidence of magnetospheric substorm phenomena, possibly comparable to auroral substorms in the Earth's magnetosphere.
With the Galileo plasma wave instrument, it should be possible to provide remote sensing of substorms in a manner comparable to the remote sensing of terrestrial auroral kilometric radiation, which is known to be closely associated with terrestrial substorms. To carry out comprehensive studies of plasma waves and radio emissions at Jupiter, the Galileo plasma wave instrument incorporates several new features that provide improvements over the previous Voyager 1 and 2 measurements.
These improvements include:
The main instrument package and the electric dipole antenna system were designed and constructed at the University of Iowa, and the search coil magnetic antenna was provided by the "Centre de Recherches en Physique de l'Environnement terrestre et planétaire" (CRPE), then the "Centre d'Etude des environnements Terrestre et Planétaire" (CETP) before joining the "Laboratoire Atmosphères, Observations Spatiales" (LATMOS) in part.
| Role | Person | StartDate | StopDate | Note | |
|---|---|---|---|---|---|
| 1. | PrincipalInvestigator | spase://CNES/Person/CDPP-Archive/Philippe.Louarn | |||
| 2. | CoInvestigator | spase://CNES/Person/CDPP-Archive/William.S.Kurth |