Friday, January 14, 2005

Another world

Huygens has reached the surface of Titan, and the images are amazing.

Check, first of all, the European Space Agency's site. Today they only posted three images -- a few more are circulating around the net -- but they are dazzling enough. Drainage channels, an apparent shoreline, what looked like a field of rounded stones. Those stones, by the way, are quite likely to be water ice (essentially a rock at that temperature), and the drainage channels carried methane or ethane. It is a new world, as surprising for its similarities as for its differences.

No sign of life, alas. I did not really expect trees and lizards, of course, but one always wonders. Titan is likely to have a chemical environment almost as complex as the Earth's, and if there is a substantial amount of liquid on its surface, they question will be why life is absent. But we have to understand that the low amount of free energy in that environment is a serious issue. Chemical reactions that are rapid on Earth may be impossibly slow on Titan; chemical bonds that are easily changed around in our environment are much more stable at such low temperatures. You can make up for a lack of thermal energy if you have a source of high energy photons, but sunlight is only 1% as bright at Saturn, and Titan is shrouded by layers of haze.

Nevertheless, Titan's secrets will not all be revealed by Huygens. This is a strange and complex world. We may still be surprised; and we will certainly be back.

All of the data from Huygens has been downlinked already, but it is dribbling out slowly. I'm a bit sorry that the ESA is playing things so close, releasing the images so slowly. We have grown used to the JPL folks, who stoke their servers with millions of pixels a day, showing us the best of what they have almost as soon as they have it. That is a risky sort of science, with public guesswork and public opportunities for failure. I can understand the European desire to be more cautious, but I do prefer the American plan.

Related note: Deep Impact has been launched and is on its way to Comet Tempel 1. Expect fantastic fireworks this July 4.

Update: The ESA had a fascinating press conference this morning -- I woke up early and caught a little of it. There are also more images now on their site. There seems to be some low-lying fog on the coastline, and the "stones" are only a few inches across.


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