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Titan's Surface Revealed
MattKeeler writes "NASA's running a story on the recent findings of Cassini, the satellite orbiting Titan, one of Saturn's giant moons. New images reveal details of the moon's surface and a variety of materials that cover it."
For a millisecond, I thought I was looking at a picture of an inhabitable world. That's one misleading photo, imho... Not to mention, heavily pixilated.
The dangers of knowledge trigger emotional distress in human beings.
The idea of Titan holding the key to our understanding of pre-life earth has always been interesting, but a little too optimistic.
I mean, isn't Europa the one that's supposed to develop life?
I was wondering, that bit about the cloud, do they mean that the ring of sky that Titan has traced around Saturn has thus far gotten 'dense' enough that its a single 'cloud', encompassing both Saturn and the rings?
Kind of a 'ring of Titan' that has captured the planet and its lesser minions?
If so, thats pretty interesting. Might be useful to know how that works, if we're going to get any terraforming done in the next 100 years.
; -- the corruption of government starts with its secrets. a truly free people keep no secrets. --
Actually, that was my post that I AC'd. It is an interesting point, don't I deserve a chance to get some karma for it this time?
On the 0th day, God created C
The full text of this article from The Economist follows. The original content is subscriber-only; it is reproduced here in the hope and expectation that you will find it useful.
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Coding theory
Not the usual channels
Jul 1st 2004
From The Economist print edition
[Image]
How to transmit information reliably
ON JULY 1st, a spacecraft called Cassini went into orbit around Saturn--the first probe to visit the planet since 1981. While the rockets that got it there are surely impressive, just as impressive, and much neglected, is the communications technology that will allow it to transmit its pictures millions of kilometres back to Earth with antennae that use little more power than a light-bulb.
To perform this transmission through the noisy vacuum of space, Cassini employs what are known as error-correcting codes. These contain internal tricks that allow the receiver to determine whether what has been received is accurate and, ideally, to reconstruct the correct version if it is not.
Such codes go back to 1948, the year when Claude Shannon, universally regarded as the father of coding theory, published a paper which showed the maximum theoretical rate at which information can be transmitted without error. But it is only recently that real codes have started to approach Shannon's theoretical limit. Those on Cassini, while powerful, still have some way to go, because the probe is limited to the technology available when it was built in the mid-1990s. But developments in coding theory made at the time Cassini was being assembled are now coming to fruition. As a result, as well as spacecraft, tomorrow's consumer-electronic devices, from mobile phones to high-definition televisions, will be able to receive and transmit data at something close to Shannon's limit.
Turbo coding, as the first of the new techniques to come on stream is known, was invented by Alain Glavieux and Claude Berrou, two researchers at the Ecole Nationale Supérieure des Télécommunications de Bretagne in Brest, France. It is now being deployed in third-generation (3G) mobile-telephone networks, and will allow wireless access from 3G phones to be over ten times faster than from an old-fashioned dial-up line.
Turbo-charged transmission
Turbo coding takes one of the techniques deployed on Cassini--known as convolution coding--and doubles it. Convolutional codes work by adding some of the bits (the ones and zeros of binary arithmetic) from a block of data, and transmitting that sum alongside the raw data. The decoder then works backwards, to make sure the sums add up correctly. If they do not, it knows there has been a mistake and fiddles with the appropriate bits to try to correct the errors. Unfortunately, it does not always succeed.
What Dr Glavieux and Dr Berrou showed was that combining two convolutional codes would yield a dramatic improvement in performance--one that would go almost all the way to the Shannon limit. To do this, you have to shuffle the bits in each block of data at random. Each block is then broadcast twice--once unshuffled and once shuffled. One convolutional decoder works on the unshuffled data, and the other on the shuffled data. The shuffling means that an error which affects one block will not affect the other at the same place in the sequence.
If the two decoders disagree about a particular bit in the message because transmission noise has introduced errors, they consult one another by feeding their "opinions" about the error to each other, along with a measure of how confident each is about its opinion. Each decoder then uses the other's input to make a decision, and the process is repeated until they agree with each other.
This feedback loop has proved to be
Where is the ethical question? First of all, the idea that there is life on Titan is just speculation. Second, we are just taking pictures from outside the atmosphere at this point, no need to get excited just yet. Lastly, are you really saying we should base our ethics in regards to this on a science fiction television show? Think about what you are saying for a moment, not within the context of Star Trek, but within the context of real scientific possibilities that could await us.
Vast, complex hydrocarbon rafts in a methane sea... could we have an embryonic Solaris in our system? Or not so embryonic? These dreams... where do they come from...
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make install -not war
Huygens doesn't really have a landing site. It's supposed to do all its science while parachuting. If it happens to not land in a methane ocean, or whatever, and instead survives on the ground, that's a bonus. In which case its batteries would die in 1/2 hour or so.
As the orbit parameters for Cassini are still up in the air pending future TCMs (trajectory correction maneuvers), I would guess the parameters for Huygens' "launch" are still up in the air as well - and thus adjustable.
I don't have any official answers. But almost certainly Huygens' atmospheric entry point can be adjusted.