Skip to navigation | Skip to content

Saturn probe plops into mud

Titan's landing spot

Huygens probably landing here, mission scientists say (Image: ESA/NASA/JPL/University of Arizona)

Huygens' seven-year journey to Saturn's moon Titan did not end with a thud, or even a splash, but with a plop, as the saucer-shaped golden probe settled upon a lunar surface with the consistency of mud.

Researchers believe the probe sank about 15 centimetres into the soil upon touchdown.

"That landing was a lot friendlier than we anticipated, " says Huygens science team member Charles See. "I think the biggest surprise is that we survived landing and that we lasted so long."

Dangling beneath parachutes, Huygens dropped through Titan's thick atmosphere on Friday to find orange skies, winds more than 25 kilometres per hour, frigid temperatures and strong evidence of liquids on the surface.

Scientists know it is not water, at -179° C water would be as hard as rock, but strongly suspect Titan has rivers and lakes of methane, ethane and other hydrocarbons. At that temperature these would act like water on Earth.

So far, the Huygens researchers have found nothing to dispel the notion that Titan serves as a living model of primordial Earth, a time machine that may help scientists unravel how life formed here.

Though Titan is less than half the size of Earth, it is larger than the planets Mercury and Pluto, and it is the only moon in the solar system that has a sizeable atmosphere. Like Earth, Titan's atmosphere is nitrogen-based.

As Huygens descended, it shot pictures and collected science data of the surrounding area, which turned out to be hilly, with patches of light- and dark-toned areas.

Scientists believe the light areas could be hills of ice. The dark threads possibly could be drainage channels for liquids.

The images also reveal what scientists believe to be shorelines. In addition, the probe's landing site was ringed with smooth, spherical rocks that suggest softening by liquid.

"We're seeing a lot of evidence for the role of liquids," says Professor Jonathan Lunine, a University of Arizona planetary scientist and member of the Cassini science team.

Cassini, which is six months into a four-year study of Saturn, carried Huygens to the ringed planet for its descent to Titan's surface.

The landing was the most distant and difficult ever attempted.

"All of us continue to be amazed as we watch the solar system unveiled and see how different each of these bodies are," says NASA's space sciences chief Al Diaz. "It challenges our preconceptions that all these planets are static places."

Analysis of the Huygen data will continue for months, if not years, scientists say.

Tags: science-and-technology, astronomy-space