http://www.c3.lanl.gov/~cjhamil/SolarSystem/titan.html (Einblicke ins Internet, 10/1995)Saturn VI
Although Titan is classified as a moon, it is larger than the planets Mercury and Pluto. It has a planet-like atmosphere which is more dense than those of Mercury, Earth, Mars and Pluto. The atmospheric pressure near the surface is about 1.6 bars, 60 percent greater than Earth's. Titan's air is predominantly made up of Nitrogen with other hydrocarbon elements which give Titan its orange hue. These hydrocarbon rich elements are the building blocks for amino acids necessary for the formation of life. Scientists believe that Titan's environment may be similar to that of the Earth's before life began putting oxygen into the atmosphere.
Titan's surface temperature appears to be about -178° C (-289° F). Methane appears to be below its saturation pressure near Titan's surface; rivers and lakes of methane probably don't exist, in spite of the tantalizing analogy to water on Earth. On the other hand, scientists believe lakes of ethane exist, and methane is probably dissolved in the ethane. Titan's methane, through continuing photochemistry, is converted to ethane, acetylene, ethylene, and (when combined with nitrogen) hydrogen cyanide. The last is an especially important molecule; it is a building block of amino acids.
The Voyager spacecraft were not able to penetrate the thick layers of clouds but they did reveal that Titan is one of the more interesting places in the solar system. What kind of landscape lies below the layers of clouds? What mysteries are held beneath these orange curtains? These questions will have to wait until future spacecraft are launched to visit this unusual moon. In October of 1997, the Cassini spacecraft is planed to be launched for a rendezvous with Saturn in June 2004. Later that year it will release the European-built Huygens probe for a descent through Titan's atmosphere. Cassini will have more than 30 encounters with Titan in which radar will be used to map out its surface similar to the radar mapping of Venus by Magellan.
Discovered by ............................ Christiaan Huygens Date of discovery ...................................... 1655 Mass (kg) .......................................... 1.35e+23 Mass (Earth = 1) ................................. 2.2590e-02 Equatorial radius (km) ................................ 2,575 Equatorial radius (Earth = 1) .................... 4.0373e-01 Mean density (gm/cm^3) ................................. 1.88 Mean distance from Saturn (km) .................... 1,221,850 Rotational period (days) ........................... 15.94542 Orbital period (days) .............................. 15.94542 Mean orbital velocity (km/sec) ......................... 5.58 Orbital eccentricity ................................. 0.0292 Orbital inclination .................................... 0.33° Escape velocity (km/sec) ............................... 2.65 Visual geometric albedo ................................ 0.21 Magnitude (Vo) ......................................... 8.28 Mean surface temperature ............................. -178°C Atmospheric pressure (bars) ............................. 1.5
Titan
(GIF, 104K)
Opaque layers of clouds prevented
Voyager from seeing Titan's surface
during its 1980 flyby. The clouds over the southern hemisphere are
lighter in color than over the northern hemisphere.
There is a dark hood over the north pole.
(Credit: Calvin J. Hamilton, Los Alamos National Laboratory)
Titan Looking Back
(GIF, 29K)
This view of Titan was taken from a position looking almost directly
back toward the Sun. Titan's hydrocarbon-rich nitrogen atmosphere
scatters sunlight in a forward direction over the limb around the
entire disk. The surface of Titan is obscured due to a deep cloud layer.
The only visible markings are the dark north polar hood and a difference
in the brightness and color in the north and south hemispheres.
(Courtesy NASA/JPL).
Mercator Map Of Titan
(GIF, 154K;
caption)
For the first time scientists have made images of the surface of
Titan. They
mapped light and dark features over the surface of the
satellite during nearly a complete 16-day rotation. One
prominent bright area they discovered is a surface feature
2,500 miles across, about the size of the continent of
Australia. This view of Titan is a Mercator projection with
latitude ranging from 40° south to 50° north and longitude
ranging from 0° to 360° (E longitude increasing to the right).
This image was constructed from images taken by the Hubble
Space Telescope during 14 observing runs between Oct. 4 - 18, 1994.
The WideField/Planetary Camera 2 was used at near-infrared wavelengths
(between .85 and 1.05 microns). Titan's haze is
transparent enough in this wavelength range to allow
mapping of surface features according to their reflectivity.
Four Views of Titan
(GIF, 125K;
caption)
This image shows four views of Titan by mapping the Mercator Map
onto a globe at four different orientations.
Huygens
(GIF, 80K)
This artist's rendering shows the European Space Agency's Huygens
probe descending into the atmosphere of Saturn's moon Titan after
being released by NASA's Cassini spacecraft. Planned for launch
in October 1997, Cassini will reach Saturn in June 2004 and will
release the Huygens probe later that year.
(Courtesy NASA/ESA).
Huygens on Titan's Surface
(GIF, 58K)
This artist's rendering shows the Huygens
probe on the surface of Saturn's moon Titan after being released
by NASA's Cassini spacecraft.
(Courtesy NASA/ESA).
Burnham, Robert, "Hubble Maps Titan's Hidden Landscape," Astronomy, 44-45, February 1995.
Saturn
Rhea
Hyperion
