Posted by Chris M Friday, December 9, 2005

Morphology on Titan

Last January, the Cassini spaceprobe acquired amazing photographs and other science data from Saturn''s moon Titan. It now appears that even river morphology of Titan resembles that of earth.
There are only three parameters that differ significantly between Earth and Titan, Parker said. First is the acceleration due to gravity – on Titan it is about one-seventh the value on Earth. Second is the viscosity of flowing fluid – the viscosity of liquid methane on Titan is about one-fifth that of water on Earth. Third is the submerged specific gravity of sediment – the value on Titan is about two-thirds of that on Earth.
“What this means is that for the same discharge of liquid methane as to water, the channel characteristics on Titan should be remarkably similar to those on Earth,” Parker said. “However, because of the smaller acceleration due to gravity, channel slopes on Titan should be wider, deeper and less steep than those on Earth.”
Wildcards that make Parker’s predictions tentative include a freeze-thaw process of methane that might not be analogous to the freeze-thaw process of water on Earth, and the formation of hydrocarbons on Titan that might add a kind of cohesion not encountered on Earth. “The interaction of sunlight with a hydrocarbon rich atmosphere could possibly precipitate very sticky compounds that could give streams on Titan a degree of cohesion that makes them behave differently,” Parker said.

Here are some examples of Titan images that appear to be similar to structures on earth.
Dune on Titan
Canyons on Titan
Rivers on Titan

Posted by Chris M Tuesday, June 21, 2005

The lizard vs the....swirly spiral thing

On Friday Slashdot picked up the story about the conflict between Debian and Mozilla. The situation involves Mozilla's trademark policy and The Debian Free Software Guidelines (DFSG). Mozilla says
Our code is free, but we do strictly enforce our trademark rights, we must, in order to keep them valid. Our trademarks include, among others, the names Mozilla, Firefox, Thunderbird, Bugzilla and XUL, as well as the Mozilla logo, Firefox logo, Thunderbird logo and the red lizard logo. This means that, while you have considerable freedom to redistribute and modify our software, there are tight restrictions on your ability to use the Mozilla name and logos, even when built into binaries that we provide.

Basically, you are allowed to change/use their code, but you can not release it using the Mozilla name. The logic behind this is, if joe developer releases his own version of Firefox that is not of high quality, Mozilla will get "a bad name". Now enters Debian. Debian uses Mozilla code, and modifies it to include in their operating system. Debian is known for their quality software, so Mozilla waves their normal policy specifically, and only for Debian. However, DFSG says in article 8
License Must Not Be Specific to Debian. The rights attached to the program must not depend on the program''s being part of a Debian system. If the program is extracted from Debian and used or distributed without Debian but otherwise within the terms of the program''s license, all parties to whom the program is redistributed should have the same rights as those that are granted in conjunction with the Debian system.

This says that if Debian gets certain rights, those rights must be passed on to everyone using Debian. If Debian uses the Mozilla trademark and doesn''t pass it on, Debian is violating its own guidelines. If Debian doesn''t use the Mozilla trademark, they will have to name it something different and it will be a splinter in the FOSS community. To those whom ask "why does this matter", if Debian were to agree to this Knoppix, Mepis, Ubuntu, and every other Debian based operating system could not use the Mozilla trademark. Lets hope Mozilla comes to develop a trademark policy that is in-line with the concept of freedom.