How a Swedish engineer saved a once-in-a-lifetime mission to Titan (2004)

Post by rayiner » Wed, Mar 26, 2014, 5:24 PM UTC

bdamm wrote: post #39

andyjohnson0 wrote: post #32

Earlier quoted context omitted.

I agree that tribalism probably was one factor that allowed humans to survive to reach the modern era. However, that doesn't mean that it is still a desirable survival trait now that we're in that era. The world is vastly more populated than it was 30,000 years, or even 100 years, ago and the tribes are bigger and have more opportunities for conflict now.

Tribalism is fine. It's nationalism that has proven disastrous.

Post by rayiner » Wed, Mar 26, 2014, 5:46 PM UTC

nitrogen wrote: post #42

rayiner wrote: post #41

Earlier quoted context omitted.

Nationalism is responsible for some of the most technologically advanced societies in recent history (the U.S. and Great Britain). Nationalism is a powerful force for motivating people across class divisions to work together to build things.

Okay, if tribalism is an essential human motivator, let's graduate from nationalism to humanism.

Post by keithpeter » Wed, Mar 26, 2014, 6:35 PM UTC

antimagic wrote: post #25

jessriedel wrote: post #23

Hopefully everyone realized that this article is from 2004 and Huygens completed its descent onto Titan in January 2005. The problem discussed in the article was successfully fixed, saving the mission, but an unrelated problem (also with the telemetry) means a modest chunk of data was lost: > Huygens was programmed to transmit telemetry and scientific data to the Cassini orbiter for relay to Earth using two redundant…

Well, being pedantic for a moment, the problem never was fixed. The flightpath of Cassini was simply altered so that there was negligeable Doppler shift of the radio signal from Huygens, meaning that the inability to handle a Doppler shift. Happily enough this was possible to do without using too much fuel, and indeed Cassini had more fuel available than planned, as the original launch and early course corrections ha…

Post by meric » Wed, Mar 26, 2014, 10:47 PM UTC

saraid216 wrote: post #44

meric wrote: post #35

Earlier quoted context omitted.

You've dismissed someone's carefully thought out reply with not arguments but with a one-liner with a word of jargon, an accusation of someone advancing an ideology through making comments buried many levels deep in random hacker news threads and a dash of sarcasm thrown in for good measure. Go ahead and feel proud you've defended your mind from reasoning another person's thoughts and thinking up a rebuttal based on…

Wow. Self-describing your post as "carefully thought out". Yeah, accuse me of pride. There's "takes one to know one", and then there's this . > thinking up a rebuttal based on reasonable arguments. Your post is rebutted by history. When you have a reasonable argument to make, go ahead and make it. Until then, your wall of sarcastic text is best answered by "a dash of sarcasm".

Post by jimktrains2 » Thu, Mar 27, 2014, 2:09 AM UTC

Serow225 wrote: post #27

jimktrains2 wrote: post #13

Perhaps I missed it when I read the article: Why did he originally have the hunch that the radio wouldn't work when Doppler shifted? Also, I guess something like Manchester encoding wasn't use because of the data rate limitations? IIRC Manchester encoding is self-clocking, which seemed like the issue here.

Take this with a grain of salt because it's been a while since I've done telecom/telemetry stuff, but even with a Manchester-encoded signal, one of the first steps in the demodulation process is clock recovery from the signal. This usually involves some sort of PLL (phase-locked loop), which has parameters to control it's freq tracking range. However there are trade offs for widening the range, in terms of time-to-lo…