Images of Saturn's moon

January 15, 2005 - 3:07PM
A European Space Agency image after the Huygens space probe beamed data including this image back to earth through its Cassini mothership orbiting Saturn's moon Titan.

Photo: AP

The world's first glimpse of the surface of the Saturnian moon Titan revealed an unexpected mix of icy land and liquid when the Huygens space probe touched down.

The first three photos of Titan, Saturn's largest moon, showed what appeared to be boulders of ice, drainage channels, shorelines and islands, reminding scientists of both Earth and Mars.

''I think none of us would have expected ... this kind of unveiling, but it is pretty consistent with the surprises we've seen before,'' said Al Diaz, NASA's associate administrator for science.

The $US3 billion ($A3.92 billion) Cassini-Huygens mission, a joint project of NASA and the European and Italian space agencies, was launched in 1997 from Cape Canaveral, Florida, to study Saturn, its rings, moons and magnetosphere.

In December, the Saturn explorer Cassini dropped off Huygens for a three-week journey toward Titan, culminating in the probe's parachute-slowed plunge to the moon's surface.

Huygens took more than two hours to float to the surface, where it defied expectations of a quick death and continued to transmit for at least two hours.

One picture showed a vista eerily similar to shots of Mars, with a wide-open plain studded with rocky objects.

''We think probably they're not silicate rocks,'' said Marty Tomasko, principal investigator for one of the descent instruments, on a European Space Agency broadcast from its operations centre in Germany.

''They may well be large ice boulders.''

Another image showed drainage channels that scientists said might carry leaks from canyons, while a third picture had bright areas and dark patches, including one mitten-shaped area.

''They're very suggestive of areas that either have flooded or are flooded at the moment,'' Tomasko said.

Titan is believed to have liquid methane and ethane on its surface, but the moon's heavy fog blanket made it unclear what Huygens would encounter when it reached its landing site.

Scientists said there had been problems retrieving data from one wind experiment but held out hopes they could get the information from a different study.

''We can say this afternoon, we have ... a scientific success,'' said Jean-Jacques Dordain, director-general of the European Space Agency (ESA).

Given the sensitive nature of the mission, Cassini quadruple-recorded the data from the 320 kg Huygens.

Scientists expect to spend years poring over the results.

''It's got to be unravelled, got to be put together and then scientists being scientists are going to argue about what it means as we piece together our place in the universe and how we came to be,'' said David Southwood, ESA's director of scientific programs.

Scientists believe the organic chemical reactions taking place on Titan resemble the processes that gave rise to life on Earth four billion years ago.

Titan's atmosphere is mostly nitrogen, like Earth's, but its surface temperatures of about minus 180 degrees Celsius make it inhospitable to life.

The saucer-shaped probe was designed to rotate on its way down, taking high-definition, panoramic images of Titan's thick, smoggy atmosphere and landscape.

Along with six scientific instruments that measure the components of Titan's atmosphere, Huygens carries a sound recorder and lamp to look for signs of surface liquid.

Titan, believed to be the only moon in the solar system with an atmosphere, is larger than Mercury and Pluto.

Some science team members monitoring the flight have waited decades to see the first of 750 planned images and other scientific readings from the moon, which has a yellow sky.

Huygens was named for the Dutch scientist who discovered Titan in 1655, NASA officials said.

- Reuters