RESUMO
An imaging photopolarimeter aboard Pioneer 11, including a 2.5-centimeter telescope, was used for 2 weeks continuously in August and September 1979 for imaging, photometry, and polarimetry observations of Saturn, its rings, and Titan. A new ring of optical depth < 2 x 10(-3) was discovered at 2.33 Saturn radii and is provisionally named the F ring; it is separated from the A ring by the provisionally named Pioneer division. A division between the B and C rings, a gap near the center of the Cassini division, and detail in the A, B, and C rings have been seen; the nomenclature of divisions and gaps is redefined. The width of the Encke gap is 876 +/- 35 kilometers. The intensity profile and colors are given for the light transmitted by the rings. A mean particle size less, similar 15 meters is indicated; this estimate is model-dependent. The D ring was not seen in any viewing geometry and its existence is doubtful. A satellite, 1979 S 1, was found at 2.53 +/- 0.01 Saturn radii; the same object was observed approximately 16 hours later by other experiments on Pioneer 11. The equatorial radius of Saturn is 60,000 +/- 500 kilometers, and the ratio of the polar to the equatorial radius is 0.912 +/- 0.006. A sample of polarimetric data is compared with models of the vertical structure of Saturn's atmosphere. The variation of the polarization from the center of the disk to the limb in blue light at 88 degrees phase indicates that the density of cloud particles decreases as a function of altitude with a scale height about one-fourth that of the gas. The pressure level at which an optical depth of 1 is reached in the clouds depends on the single-scattering polarizing properties of the clouds; a value similar to that found for the Jovian clouds yields an optical depth of 1 at about 750 millibars.
RESUMO
For 2 weeks continuous imaging, photometry, and polarimetry observations were made of Jupiter and the Galilean satellites in red and blue light from Pioneer 11. Measurements of Jupiter's north and south polar regions were possible because the spacecraft trajectory was highly inclined to the planet's equatorial plane. One of the highest resolution images obtained is presented here along with a comparison of a sample of our photometric and polarimetric data with a simple model. The data seem consistent with increased molecular scattering at high latitudes.
RESUMO
Pioneer 10 images of Jupiter show bright nuclei in the equatorial zone that appear to be thermally driven sources of cloud plume formations.
RESUMO
A 2.5-centimeter telescope aboard Pioneer 10 is capable of making two-dimensional spin-scan maps of intensity and polarization in red and blue light at high spatial resolution. During the recent flyby of Jupiter, a large quantity of imaging and polarimetric data was obtained on Jupiter and the Galilean satellites over a wide range of phase angles.
RESUMO
The ozone and oxygen in the earth's atmosphere prevent all ground-based observing at wavelengths shorter than about 3000 A. With the largest available balloons and a large telescope one can get sufficiently above the ozone to make precise polarization measurements of stars and planets near 2820 A and 2200 A. Two telescope/gondola systems are in operation. The first actually is a prototype for spacecraft but it is also used on balloons, mounted in a gondola of the National Center for Atmospheric Research. It has two 7.5-cm reflecting telescopes (7.5 cm is the diameter of the primary mirror). The second system has a 71-cm Cassegrain reflector, two vidicon cameras, command and telemetry by radio link, and a startracker that guides the stabilized platform (+/-1 min of arc). The first measurements made were of the polarization of the moon at 2900 A in December 1965, and of interstellar polarization at 2820 A and 2200 A in May 1966.
