Space exploration is a risky business and things don't always go according to plan. But fortunately for Jean-Pierre Lebreton and an international team of more than 100 scientists, their mission was a success.

They have published the first papers from the Cassini–Huygens mission to Titan, Saturn's largest moon (see pages 758–802). Titan's environment is thought to be similar to that on Earth before life emerged. Scientists landed a probe on Titan to learn more about the composition and properties of its atmosphere and surface, hoping to provide clues about Earth's primeval conditions. Thanks to the success of this mission, “we know we have the data we need to fulfil our objectives, which were set out 20 years ago”, says Lebreton, project scientist with the European Space Agency (ESA) and the mission's manager.

The idea for the mission came about not long after Voyagers I and II returned images of Titan in the early 1980s. ESA, NASA and the Italian Space Agency launched the Cassini orbiter and the Huygens probe as a joint mission in 1997. The spacecraft took seven years to reach Titan.

For Lebreton and his colleagues, 14 January 2005 was judgement day: the day that the probe would descend through Titan's thick atmosphere and land on its surface. It would collect data for six experiments during the descent and on the surface, and transmit them to Earth through the Cassini orbiter.

That day, excitement and nerves pervaded the mission control centre in Darmstadt, Germany. The last time the scientists had heard from the Huygens probe had been three weeks earlier. “We were hoping for the best, but were also prepared for something terrible — such as never hearing from the probe again,” says Lebreton. In fact, at around 11:20 local time, they received the first signals from the probe, indicating that it was working properly. “It was very emotional,” says Lebreton. “Some people were crying.”

Data began streaming in by the early evening and scientists were at the ready to analyse it. But they were anxious to see the first images of Titan's surface, which finally arrived at around 20:45. Seeing pictures of the desert-like landscape, “was the most rewarding moment of the day”, says Lebreton.

The only major hitch was losing one of the two radio links between the probe and the orbiter. The receiver for ‘channel A’ on the orbiter did not turn on during the probe's descent, because its ‘switch-on’ command was never included in the sequence loaded on to the orbiter for this mission. Scientists lost data because of this missing channel, but managed to salvage some through ‘channel B’. A network of radio telescopes on Earth picked up faint signals directly from the probe and gave scientists the information they needed to complete the experiments.

But in other ways the mission far exceeded scientists' expectations. For example, they received data from the probe on Titan's surface for 72 minutes. “We would have been happy with three,” says Lebreton.

Analysis of the bonanza of data is ongoing and will continue for years to come, he says. “We still have a lot to learn.” But they've already overcome the biggest hurdle: getting the data in the first place.