Exploration of Saturn

The exploration of Saturn has been solely done by robotic probes. Like all gas giants, there is no solid surface for a solid probe to land on. Most missions therefore have been flybys, although the Cassini–Huygens spacecraft is currently in orbit.

Flybys

Pioneer 11 flyby

Pioneer 11 image of Saturn.

Saturn was first visited by Pioneer 11 in September 1979. It flew within 20,000 km of the top of the planet's cloud layer. Low-resolution images were acquired of the planet and a few of its moons; the resolution of the images was not good enough to discern surface features. The spacecraft also studied the rings; among the discoveries were the thin F-ring and the fact that dark gaps in the rings are bright when viewed towards the Sun, or in other words, they are not empty of material. Pioneer 11 also measured the temperature of Titan at 250 K.

Voyager

The probes Voyager 1 and Voyager 2 flew past Saturn in the early 1980s, studying the planet, its rings and its moons. Voyager 2 went on to study Uranus and Neptune.

Cassini orbiter

Saturn eclipses the Sun, as seen from Cassini.

On July 1, 2004, the Cassini–Huygens spacecraft performed the SOI (Saturn Orbit Insertion) maneuver and entered into orbit around Saturn. Before the SOI, Cassini had already studied the system extensively. In June 2004, it had conducted a close flyby of Phoebe, sending back high-resolution images and data.

The orbiter completed two Titan flybys before releasing the Huygens probe on December 25, 2004. Huygens descended onto the surface of Titan on January 14, 2005, sending a flood of data during the atmospheric descent and after the landing. During 2005 Cassini conducted multiple flybys of Titan and icy satellites.

On March 10, 2006, NASA reported that the Cassini probe found evidence of liquid water reservoirs that erupt in geysers on Saturn's moon Enceladus.

On September 20, 2006, a Cassini probe photograph revealed a previously undiscovered planetary ring, outside the brighter main rings of Saturn and inside the G and E rings.

In July 2006, Cassini saw the first proof of hydrocarbon lakes near Titan's north pole, which was confirmed in January 2007. In March 2007, additional images near Titan's north pole discovered hydrocarbon "seas", the largest of which is almost the size of the Caspian Sea.

As of 2009 the probe has discovered and confirmed four new satellites. Its primary mission ended in 2008 when the spacecraft completed 74 orbits around the planet. In 2010, the probe began its first extended mission, the Cassini Equinox Mission. It is now currently on its second mission extension, the Cassini Solstice Mission, expected to last through September 2017.

For the latest information and news releases, see Cassini website.

Future missions

The Titan Saturn System Mission (TSSM) is a joint NASA/ESA proposal for an exploration of Saturn and its moons Titan and Enceladus, where many complex phenomena have been revealed by the recent Cassini–Huygens mission. TSSM was competing against the Europa Jupiter System Mission proposal for funding. In February 2009 it was announced that ESA/NASA had given the EJSM mission priority ahead of TSSM, although TSSM will continue to be studied for a later launch date. The Titan Saturn System Mission (TSSM) was created by the merging of the ESA's Titan and Enceladus Mission (TandEM) with NASA's Titan Explorer 2007 flagship study.

References

• Hannu Karttunen, et al. (1996), Fundamental Astronomy (3rd ed.), New York: Springer, ISBN 978-3-540-60936-0, http://books.google.com/books?id=rn7vAAAAMAAJ, retrieved February 21, 2012. 
• NASA/JPL–Caltech (October 18, 2010 [last update]). "Voyager Science Results: Saturn". voyager.jpl.nasa.gov. http://voyager.jpl.nasa.gov/science/saturn.html. Retrieved February 21, 2012. 

External links

• NASA's Cassini mission to Saturn