European-U.S. Team Penetrates the Outer Solar System

PASADENA, California, January 19, 2004 (ENS) - This time next year, if all goes well, the European Space Agency’s Huygens spaceprobe will be descending through the thick atmosphere of Saturn’s largest moon, Titan, becoming the first spacecraft to land on a body in the outer solar system.

Titan is one of the most mysterious objects in the solar system. It is the second largest moon, only Jupiter's Ganymede is bigger, and it is the only one with a methane rich, nitrogen atmosphere. Experts think that its atmosphere resembles that of a very young Earth. The Huygens' mission is to discover what clues Titan can yield about how life began on Earth.

Saturn shown in a natural color image composed from exposures taken by Cassini's narrow angle camera on November 9, 2003, from a distance of 111.4 million kilometers (69.2 million miles). (Photo courtesy NASA)

Cassini/Huygens, the largest interplanetary spacecraft ever built, is named for 17th century Dutch astronomer Christiaan Huygens, who is credited with the discovery of Saturn's rings and its largest moon, Titan.

The Cassini-Huygens mission is a cooperative mission of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Lab, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Office of Space Science, Washington, DC.

Cassini will enter Saturn orbit on July 1, 2004, scientists predict. In early 2005, while the Cassini orbiter continues to explore Saturn and its rings, the Huygens probe will be released to parachute through the atmosphere of Titan.

The Huygens probe can withstand temperatures of up to 18,000°C in front of the heat shield, space scientists say. The heat generated as Huygens travels through Titan's thick gas atmosphere will be immense.

After a descent of about 137 minutes, the probe will crash land on Titan's the surface at about five to six meters per second. Scientists hope that the probe will survive this impact for at least a few minutes and that the instruments will be able to make direct measurements of the state and composition of the landing site surface.

Saturn's moon Titan (Photo courtesy NASA)

If the spaceprobe survives the impact with Titan's surface, it will continue to send information back to the Cassini orbiter until its batteries expire or it is out of range.

Jean-Pierre Lebreton, Huygens project scientist, says it is possible that the spaceprobe could land in a methane ocean. "Just imagine!" he said. "We could be landing in an ocean! It would be really exciting, the first landing in an ocean outside the Earth!"

In January 2005, Huygens will parachute below the clouds to see what is really going on.

The path of Cassini/Huygens so far has touched three planets - Venus, Earth and Jupiter. The reason for the fly-bys was to gain the "kick" from the planets' gravitational fields to reach Saturn, Lebreton explained. "Naturally, we took our chance to examine every planet and we collected a lot of new scientific data."

When Cassini/Huygens reached Jupiter it found the Galileo probe still operative around Jupiter. "Using the two probes, the Hubble Space Telescope, the Chandra X-ray Observatory, and radio telescopes in California, we made a once-in-a-lifetime set of observations of Jupiter's surroundings," said Lebreton.

"We detected an aurora caused by particle streams coming from the solar wind," he explained. "This flow affected Jupiter's magnetosphere, making it contract. Although we had suspected this might happen, we had never observed it before."

"Without using both probes, Lebreton said, "it would have been impossible to prove the magnetosphere can be influenced like that by the solar wind. It showed that testing our instruments is more than just routine work. It gives you results that make you sit up and it keeps your team on the ball."

To keep its Earth bound team on the ball, the European Space Agency will host a conference in Noordwijk, The Netherlands from April 13 through 17 ommemorating the achievements of Christiaan Huygens on the occasion of his 375th birthday which falls on April 14.