Starship Asterisk*

wolfie138 wrote:alright, as someone not too well-versed in chemistry : if it's raining methane etc, how come the lightning wouldn't ignite it and cause a big explosion? :-/

Guest wrote:if there are rocks on Titan made of typical earth-like materials - sulfates, silicates, carbonates, nitrates etc, the effect of lightning could produce oxygen. No explosion, since amounts would be small. However, with methane, nitrogen AND oxygen, all kinds of important life-chemicals could then be generated.

Deep in some Titanic cracks, some primitive life form may be lurking!

neufer wrote:

jabm67 wrote:

booky1@earthlink.net wrote:
Titan is NOT in the equatorial ring plane except twice a month (one titan revolution). So you could often see the rings at a low angle.

Pushing a few numbers around, I think that from the points where Titan has the greatest displacement out of the ring plane, the rings would have an angular thickness of a couple of minutes of arc. That's below the limit of unaided vision.

One should distinguish seeing from resolving.

One has no trouble 'seeing' Saturn from Earth with unaided vision
though it is never more than a third of a minute of arc in diameter.

http://en.wikipedia.org/wiki/Great_Wall_of_China#Visibility_from_low_earth_orbit wrote:
<<Based on the optics of resolving power...
[a line] object of reasonable contrast to its surroundings which is 1 arc-minute wide would be visible to the unaided eye.

Astronaut William Pogue thought he had seen the Great Wall of China [5 to 9 m wide] from Skylab [440 km] but discovered he was actually looking at the Grand Canal of China near Beijing. He spotted the Great Wall with binoculars, but said that "it wasn't visible to the unaided eye.">>

CharlieNNC wrote:Whoa big fella!.. I agree with the other comment. Lightning in a nitrogen rich atmosphere with a methane river? Uhhh...nitromethane...the fuel that's burned in top fuel dragsters, and give it a spark with a bolt of lightning? Sounds like the ultimate combustion chamber to me. Always wondered if scientists ever think about things like sending a probe to gaseous planets with a Zippo installed, and see if it would ignite. Perhaps the EPA already has rules about lighting foreign planets.

• Nitromethane isn't just nitrogen and methane together.

• Nitromethane is burned with air in race cars - the fuel is combined with oxygen. Ever notice they have carburetors?

• If ever we should land on a life-bearing planet, in which free oxygen has accumulated because of Photosynthesis or something, it may well be that we might accidentally light something on fire with the ship's retrorockets. But in such an environment it's not hard to imagine that lightning, volcanic activity, an incoming meteor, or SOME other source of heat will have beat us to the punch and the whole planet is simply not likely to suddenly burn up.

APOD Robot wrote: It s Raining on Titan

Explanation: It's been raining on Titan. In fact, it's likely been raining methane on Titan and that's not an April Fools' joke. The almost familiar scene depicted in this artist's vision of the surface of Saturn's largest moon looks across an eroding landscape into a stormy sky. That scenario is consistent with seasonal rain storms temporarily darkening Titan's surface along the moon's equatorial regions, as seen by instruments onboard the Cassini spacecraft. Of course on frigid Titan, with surface temperatures of about -290 degrees F (-180 degrees C), the cycle of evaporation, cloud formation, and rain involves liquid methane instead of water. Lightning could also be possible in Titan's thick, nitrogen-rich atmosphere.

http://www.planetary.org/blog/article/00003040/ wrote:
Titan's lack of lightning
The Planetary Society Blog
By Emily Lakdawalla May. 19, 2011

<<It's a fact of life in science that not all of your hypotheses will turn out to be correct (or even verifiable at all). But there's a bias toward the publication of positive results -- the discovery of this, or the proof of that. So I always find it refreshing to read a publication about hypotheses that didn't work out. A recent paper in Geophysical Research Letters by Georg Fischer and Don Gurnett describes "The search for Titan lightning radio emissions," a search that wound up fruitless.

It wasn't for lack of searching. Fischer and Gurnett used the Radio and Plasma Wave Science (RPWS) instrument, which can detect high-frequency radio emissions, from a total of 72 Titan flybys. RPWS has three perpendicular, 10-meter antennas and doesn't need to be pointed, so it doesn't interfere with the acquisition of data from other instruments (except in terms of how much of Cassini's precious onboard memory is needed to store the data). So RPWS could theoretically operate continuously for as much as 24 hours around Cassini's closest approach to Titan on each of those flybys. It wasn't used quite that much, but Cassini has listened for lightning on Titan for more than 600 hours. That is a lot of observation time.

Given the fact that Titan has convective clouds that produce rainfall, it really ought to have lightning. If Titan's lightning is as intense as Earth lightning, it would be detectable as "bursty" signals in the data within 35 Titan radii (or about 90,000 kilometers). Now, RPWS did record some bursts during one Titan flyby, but Fischer and Gurnett show that these bursts came from Saturn rather than Titan. Bursts from Titan would increase in intensity as Cassini approached Titan, and decrease as it flew away from Titan after the flyby, but all bursts recorded during Titan flybys did not change in intensity with Cassini's changing distance from Titan. Even more conclusive evidence that the bursts came from Saturn is that a burst shut off sharply as Cassini got very close to Titan and the big moon occulted a known storm-producing region on Saturn's disk.

Of course, the problem with a negative result is that it's difficult to prove a negative conclusively. Sure, they didn't find any evidence for lightning in 72 flybys. But it could just be a very rare event. There were a few "weak sporadic bursts" that they could not positively attribute to either Saturn or the Sun, but because of the many possible sources of radio bursts in the Saturn system, "a positive identification of Titan lightning still needs great care....we should demand at least a few dozen of intense bursts with a clear fall-off in intensity with distance to Titan for a positive identification of Titan lightning." Also, there are places in the solar system where there definitely is lightning that doesn't produce high-frequency radio emissions, notably Jupiter.

Why does anybody even care about lightning? Because of the Dr. Frankenstein-like spark it could give to the brew of organic materials floating in Titan's atmosphere. Lightning would efficiently produce hydrogen cyanide and cyanogen, materials that we think of as poisons but which form building blocks for more complex compounds that we think are necessary for carbon-based life, including amino acids. Even without mentioning life, the compounds that lightning would create in Titan's atmosphere are important to scientists trying to understand Titan's atmospheric chemistry -- how the atmosphere evolved, and how it affects Titan's weather and climate.>>

neufer wrote:

http://www.planetary.org/blog/article/00003040/ wrote:
Titan's lack of lightning
The Planetary Society Blog
By Emily Lakdawalla May. 19, 2011

• Geophysical Reasearch Letters 38 L08206 (28 Apr 2011) DOI: 10.1029/2011GL047316