The European Space Agency's Huygens probe safely landed on the surface of Saturn's largest moon, Titan, on Friday, sending back a steady stream of data back to Earth.
Huygens' instruments surveyed the moon's atmosphere
Operating in the dark and friendless chill of deep space, the unmanned probe Huygens glided to Titan's surface, relaying its findings to its American mothership Cassini, which then sent the data home to NASA's waiting radio sentinels.
Joy erupted at mission control as the precious data poured in. Scientists and space chiefs have bet more than $3 billion dollars on the Cassini-Huygens project and some have spent a quarter-century of their lives planning it and carrying it out.
Huygens is "a scientific success ... and a fantastic success as well for international cooperation," the director-general of the European Space Agency (ESA), Jean-Jacques Dordain, declared
The probe headed to Titan's surface carrying half a dozen instruments within a clam-like shell to film and measure the moon's weather system and methane-rich atmosphere during a two-and-a-half-hour descent. Its sensors were designed to continue working for just three minutes after it landed on the bone-freezing Titan surface.
ESA workers watch the Huygens landing in the mission control room in Darmstadt Germany.
But delighted scientists said the instruments probably continued to function for at least half an hour after touchdown, possibly providing vital clues as to whether Titan is covered by rock, methane ice or an ocean of chemicals.
"I am sure we have at least 30 minutes of surface science," said Jean-Pierre Lebreton, head of the Huygens mission at ESA.
Titan a mystery
Titan, the largest satellite of Saturn, was chosen for the $3.2-billion (€2.46-billion) transatlantic venture as, intriguingly, it is the only moon in the Solar System that has a substantial atmosphere. Its thick mix of nitrogen and methane is suspected to be undergoing chemical reactions similar to those that unfolded on Earth billions of years ago. That process eventually provided the conditions for life on our planet.
"Titan is a time machine. It will especially provide us with the opportunity to know about the conditions on our early Earth," Alphonso Diaz, NASA Science assistant administrator, said.
Huygen's descent, on a moon 1.5 billion kilometers (940 million miles) from home, was the farthest landing from Earth ever attempted. The operation was fraught with potential hitches, including the risk of a crash or catastrophic malfunction when the 319-kilo (702-pound) craft entered Titan's roiling atmosphere.
The Cassini-Huygens spacecraft returned this image of Saturn on Sunday, May 16, 2004, taken with its imaging science subsystem narrow-angle camera. Enceladus, one of Saturn's 31 known moons, appears near the south pole at the bottom of the image. After a seven-year, 2.2 billion-mile journey, the Cassini spacecraft will fire its engine Wednesday night, June 30, 2004, to slow down, allowing itself to be captured by Saturn's gravity. (AP Photo/NASA/JPL/Space Science Institute, File)
Cassini had given Huygens a piggyback ride to Saturn and its moon system. Their epic seven-year trip, covering 2.1 billion kilometers (1.3 billion miles), culminated last July.
Dordain described Friday's outcome as "a fantastic success for Europe, first of all for European industry which delivered a very complex machine. It worked beautifully with six scientific instruments, in a very harsh environment in order to break the secret of Titan."
But it was also "a fantastic success as well for international cooperation," said Dordain. "We should learn lessons from this success. Lessons don't come only from failure." German Research Minister Edelgard Buhlman was equally overjoyed, hailing the mission as "one of the greatest events in space science and technology."
Clues to life on Earth
The chemical processes believed to be unfolding on Titan may give clues as to how life took root on Earth. But life -- or at least life as we understand it -- is unlikely to exist on Titan itself, given that it is so far from Sun, receiving negligible solar heat and light. The moon's surface temperature is estimated to be -180 Celsius (-292 Fahrenheit).
Purple haze is seen around the Saturn moon Titan on Tuesday, Oct. 26, 2004 as the NASA/ESA/ASI Cassini-Huygens spacecraft makes a fly-by of Saturn's largest moon - the closest ever performed. Data of the fly-by were transmitted by the spacecraft early Wednesday, Oct. 27, 2004
After Friday's dramatic Huygens landing, Cassini will continue its four-year mission to map Saturn, the second largest planet of the Solar System, and its leading satellites.
Huygens is named after the Dutch astronomer Christiaan Huygens, who discovered Titan in 1655. Cassini's name comes from the Italian Jean-Dominique Cassini, who discovered the Saturn's satellites Iapetus, Rhea, Tethys and Dione. In 1675, he discovered what is called the "Cassini Division," the gap between Saturn's rings.