Huygens lands on Titan, and the data floweth
At an emotional press conference, the Huygens mission team announced that their probe has started to send experimental data back from the surface of Saturnian moon, Titan. The Huygens probe is the first man-made object to land on the surface of Titan, and is the most distant controlled descent mission undertaken.
The first images show channels on the surface of Titan, which suggests some liquid flowed on the surface at some point. The European Space Agency will post images on its website as they are processed, so watch this space for updates.
ESA director General Jean-Jacques Dordain told a press conference in Darmstadtm Germany: "This morning we had an engineering success, this afternoon, we can say we are a scientific success."
The assembled scientists and journalists clapped and cheered. The news was beamed to a parallel press conference in the UK by video link: the notoriously grumpy British press joined in the applause, too.
The probe began transmitting data to Cassini four minutes after entering the moon's atmosphere. The carrier signal was picked up this morning by the Green Bank radio telescope in West Virginia. This confirmed that at least two of the craft's chutes had opened successfully, because the transmitter wouldn't start sending its data until the main chute was deployed.
Claudio Sollazzo, Huygens operations manager, said the probe's descent had matched the scientists' profile of the atmosphere very well: "We got a very good correspondence."
After 147 minutes, scientists detected a 20Hz shift in the frequency of the carrier signal, indicating, perhaps, that the probe had landed. Hugens was still signalling five and a half hours after its first transmisison. Although Cassini was long since over the horizon and no longer receiving data, this signal suggests that the craft had landed on solid ground. If it had landed in liquid, scientists say, it was unlikely to transmit for very long.
Once Cassini passed over the horizon it turned its antenna back to Earth and began relaying the data back to the team at mission control.
Alphonso Diaz, NASA associate administrator of science, was close to tears as he congratulated ESA on a successful misison. "We [NASA] have delivered the probe, we've delivered the data, now it is up to ESA again."
The science team left the playback of the data before it was finished so that they could break the news. "When we left it, Huygens was spinning 3.6 times per minute, and was 50km above the surface," said Jean-Pierre Lebreton, ESA Huygens mission manager.
He revealed that there was a problem with one of the probes communication channels, but explained that this did not affect the science, or the data that was being sent back to Earth. This is because identical data should be transmitted over both channels. The only exception is the Doppler Wind Experiment, which relies solely on the carrier signal from the faulty channel. However, Radio telescopes on Earth can still provide much of the same data.
Now the team must analyse the data, and reconstruct the images from the probe's camera. Professor Colin Pilinger was reluctant to call the mission a total success until he could see data from the science packages coming through. "It is always the same. The scientists are always the last to know," he said. ®
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