The Cassini Visual And Infrared Mapping Spectrometer (Vims) Investigation

The Cassini visual and infrared mapping spectrometer (VIMS) investigation is a multidisciplinary study of the Saturnian system. Visual and near-infrared imaging spectroscopy and high-speed spectrophotometry are the observational techniques. The scope of the investigation includes the rings, the surfaces of the icy satellites and Titan, and the atmospheres of Saturn and Titan. In this paper, we will elucidate the major scientific and measurement goals of the investigation, the major characteristics of the Cassini VIMS instrument, the instrument calibration, and operation, and the results of the recent Cassini flybys of Venus and the Earth–Moon system.This revised version was published online in July 2005 with a corrected cover date.     

The giant planets and their satellites: Report on the Cospar Symposium,Ottawa, Canada,May 18–21, 1982

A $\text{Symposium on the Giant Planets and Their Satellites}$ was presented in conjunction with the Twenty-fourth Plenary Meeting of the Committee on Space Research. This paper summarizes the talks presented and places the remaining papers of this volume in context.     

Implications of Rotation, Orbital States, Energy Sources, and Heat Transport for Internal Processes in Icy Satellites

Internal processes in icy satellites, e.g. the exchange of material from the subsurface to the surface or processes leading to volcanism and resurfacing events, are a consequence of the amount of energy available in the satellites’ interiors. The latter is mainly determined shortly after accretion by the amount of radioactive isotopes incorporated in the silicates during the accretion process. However, for satellites—as opposed to single objects—important contributions to the energy budget on long time-scales can come from the interaction with other satellites (forcing of eccentricities of satellites in resonance) and consequently from the tidal interaction with the primary planet. Tidal evolution involves both changes of the rotation state—usually leading to the 1:1 spin orbit coupling—and long-term variations of the satellite orbits. Both processes are dissipative and thus connected with heat production in the interior. The way heat is transported from the interior to the surface (convection, conduction, (cryo-) volcanism) is a second main aspect that determines how internal processes in satellites work. In this chapter we will discuss the physics of heat production and heat transport as well as the rotational and orbital states of satellites. The relevance of the different heat sources for the moons in the outer solar system are compared and discussed.     

Evolution of Icy Satellites

Evolutionary scenarios for the major satellites of Jupiter, Saturn, Neptune, and Pluto-Charon are discussed. In the Jovian system the challenge is to understand how the present Laplace resonance of Io, Europa, and Ganymede was established and to determine whether the heat being radiated by Io is in balance with the present tidal dissipation in the moon. In the Saturnian system, Enceladus and Titan are the centers of attention. Tidal heating is the likely source of activity at the south pole of Enceladus, although the details of how the heating occurs are not understood. An evolutionary scenario based on accretion and internal differentiation is presented for Titan, whose present substantial orbital eccentricity is not associated with any dynamical resonance. The source and maintenance of methane in Titan’s present atmosphere remain uncertain. Though most attention on the Saturnian moons focuses on Titan and Enceladus, the mid-size satellites Iapetus, Rhea, Tethys, and the irregular satellite Phoebe also draw our interest. An evolutionary scenario for Iapetus is presented in which spin down from an early rapidly rotating state is called upon to explain the satellite’s present oblate shape. The prominent equatorial ridge on Iapetus is unexplained by the spin down scenario. A buckling instability provides another possible explanation for the oblateness and equatorial ridge of Iapetus. Rhea is the only medium-size Saturnian satellite for which there are gravity data at present. The interpretation of these data are uncertain, however, since it is not known if Rhea is in hydrostatic equilibrium. Pluto and Charon are representative of the icy dwarf planets of the Kuiper belt. Did they differentiate as they evolved, and do either of them have a subsurface liquid water ocean? New Horizons might provide some answers when it arrives at these bodies.     

The Cassini/Huygens Mission to the Saturnian System

The international Cassini/Huygens mission consists of the Cassini Saturn Orbiter spacecraft and the Huygens Titan Probe that is targeted for entry into the atmosphere of Saturn's largest moon, Titan. From launch on October 15, 1997 to arrival at Saturn in July 2004, Cassini/Huygens will travel over three billion kilometers. Once in orbit about Saturn, Huygens is released from the orbiter and enters Titan's atmosphere. The Probe descends by parachute and measures the properties of the atmosphere. If the landing is gentle, the properties of the surface will be measured too. Then the orbiter commences a four-year tour of the Saturnian system with 45 flybys of Titan and multiple encounters with the icy moons. The rings, the magnetosphere and Saturn itself are all studied as well as the interactions among them. This revised version was published online in August 2006 with corrections to the Cover Date.     

The OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS): Spectral Maps of the Asteroid Bennu

The OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) is a point spectrometer covering the spectral range of 0.4 to 4.3 microns (25,000–2300 cm^?1). Its primary purpose is to map the surface composition of the asteroid Bennu, the target asteroid of the OSIRIS-REx asteroid sample return mission. The information it returns will help guide the selection of the sample site. It will also provide global context for the sample and high spatial resolution spectra that can be related to spatially unresolved terrestrial observations of asteroids. It is a compact, low-mass (17.8 kg), power efficient (8.8 W average), and robust instrument with the sensitivity needed to detect a 5% spectral absorption feature on a very dark surface (3% reflectance) in the inner solar system (0.89–1.35 AU). It, in combination with the other instruments on the OSIRIS-REx Mission, will provide an unprecedented view of an asteroid’s surface.     

The NOAA satellites: A largely neglected tool in the land sciences

The NOAA satellite system comprises the polar-orbiting satellites which provide image data twice a day, and the geostationary satellites, which provide image data every 30 minutes. Data is provided in the visible, near infrared, and middle and far thermal infrared at 1 km resolution from the polar-orbiting satellites and in the visible at 1-km resolution and in the far thermal infrared at 8 km resolution from the geostationary satellites. Applications described include monitoring tectonic lineaments in Alaska, monitoring the Greenland Ice Sheet, mapping geomorphology in the Dakotas and monitoring volcano eruptions. Applications of the Heat Capacity Mapping Mission described include discriminating rock types and indications of mineral deposits. Current research into Land Sciences Applications are discussed and recommendations made for further areas of research.