A European spacecraft has plunged onto the Saturn moon Titan for the first close-up look of a celestial body scientists say may give clues to what Earth might have been like billions of years ago. The craft pierced Titan's murky atmosphere and is expected to transmit its first images from Titan's surface soon.
After a seven-year ride to Saturn on the U.S. Cassini spacecraft, the European Space Agency's Huygens probe is finally at its destination.
"We have a signal, meaning that we know that Huygens is alive. So the dream is alive," said the agency's director general, Jean Jacques Dordain.
Huygens separated from Cassini on Christmas Day and moved gradually toward Titan for the final, blazing descent Friday at 28,000 kilometers per hour. It deployed two parachutes to slow it and a heat shield to protect it from searing friction with the moon's atmosphere.
U.S. space agency official Al Diaz told a news conference at European Space Agency mission control in Darmstadt, Germany that Huygens signal means this engineering process worked as designed.
"It means that probably one of the most difficult entry activities ever done has just been accomplished successfully,” he noted. “Otherwise, the parachute would not have triggered the transmitter and the transmitter would not be sending a signal."
On its two-and-a-half hour journey down to Titan's surface, Huygens was to collect data on the moon's obscuring atmosphere, whose methane and nitrogen composition is believed to have been similar to that of the young Earth before oxygen and eventually life appeared. If it survived the collision with Titan's surface, it was to have spent another two hours transmitting images to the Cassini orbiter for relay back to Earth.
Mission controllers will not know how this part of the project went until Cassini turns back to Earth to send the data later Friday. But European Space Agency science director David Southwood says he is elated at the progress so far.
"As far as I'm concerned, the baby is out of the womb, but we've yet to count the fingers and toes,” he said. “So we've still got along way to go, but it's a major step, a major engineering step that was very critical. You can probably detect a certain relief on my face. That's real.”
So little is known about Titan's surface because of its atmospheric shroud that mission scientists could not say before the descent whether Huygens would land on solid ground or liquid. They speculate that it could hit solid methane ice, rock, or a chemical sea.
Whatever the case, scientists will have to piece together the data, which mission operations chief Claudio Sollazzo says will come down in batches.
"For us, it's a bit like when you collect pieces of a jigsaw puzzle, and then you have to put it all together, and only at the end you see the figure, the image," he said.
After the U.S. Cassini orbiter relays the signals from Huygens, it will return to its normal orbit. It arrived in August for a four-year mission to study Saturn.