The robot probe Huygens has beamed its first discoveries back to Earth, after successfully landing on Saturn鈥檚 giant moon, Titan.
The first actual data from the European Space Agency鈥檚 Huygens probe, relayed via NASA鈥檚 Cassini spacecraft, reached ESA鈥檚 control centre in Darmstadt, Germany, at 1618 GMT, prompting cheers and embraces in the control room.
鈥淲e are the first visitors of Titan,鈥� said Jean-Jacques Dourdain, ESA鈥檚 director general. 鈥淭he scientific data we are collecting now will unveil the secrets of this new world.鈥�
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At 1038 GMT, the Green Bank radio telescope in West Virginia, US, picked up a faint carrier signal from Huygens after it entered Titan鈥檚 atmosphere. Mission scientists met the news of this first signal with some emotion. 鈥淚鈥檝e seen people with tears in their eyes,鈥� said ESA scientist Mike McKay from the control room.
Green Bank and the Parkes dish in Australia then tracked the signal from Huygens, and found that it kept transmitting for at least two hours after it had landed on the Titan鈥檚 surface. The probe, launched from Earth seven years ago and now sitting on the ice or tar, or even liquid surface of a moon in the outer solar system, has accomplished the hardest part of its mission. Over the next few days, scientists will begin to unravel data gathered by Huygens array of instruments.
Titan鈥檚 terrain
The probe was released from its mothership, Cassini, on 25 December, 2004. A few days beforehand, Cassini had put itself on a collision course with Titan to aim Huygens at the moon and then on Christmas morning a spring-loaded mechanism gave the probe a gentle push off and a slow spin to keep it stable.
Huygens then hurtled towards Titan, with its power switched off to conserve its batteries. Just about four and a half hours before arrival, in the small hours of Friday morning, three separate onboard timers woke Huygens up.
The probe鈥檚 parachutes deployed within minutes of hitting Titan鈥檚 upper atmosphere. Cameras should have scanned the surface and the skies, capturing highly detailed pictures of Titan鈥檚 terrain.
鈥淔rom the descent, we may see features smaller than one metre across,鈥� says Martin Tomasko of the University of Arizona, US, and head of the imaging team. And as Huygens will get views from different angles, scientists should be able to reconstruct a 3D picture of Titan鈥檚 terrain. 鈥淲e鈥檒l be able to paint a pretty complete picture of the surface鈥� says Tomasko.
Two instruments should also analyse the gases and particles in the atmosphere. Titan has been likened to a version of the early Earth in deep freeze, so the organic chemistry of its atmosphere could reveal something about the origins of life on Earth.
