Why Titan And Not Mars?

[dragon04]

It's on the order of 5 times less massive. It's only 76% the size.<br /><br />Yet Titan has an atmosphere 60 times more dense than earth and Mars has essentially NO atmosphere.<br /><br />I've read that Mars lost its atmosphere to space due to insufficient mass to retain it. I've read that due to the lack of a strong magnetic field that Mars lost its atmosphere to solar wind over the past 3 billion or so years.<br /><br />Given the above stated facts and theories, how is it that Titan retains a very dense atmosphere and Mars does not?<br /><br />On the surface (no pun intended) it would be easy to postulate that Titan is a much younger body. But somehow that doesnt seem right.<br /><br />Could some cataclysmic impact have vented Mars' atmosphere and Titan have been spared the same fate?<br /><br />Anybody wanna help me out and take a stab at a possible explanation?<br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[nexium]

The strength of the solar wind decreaces as the square of the distance, so it is about 60 times stronger at Mars distance than Titan distance. The temperature k at the top of Mars atmosphere is about double the temperature k at the top of the Titian atmosphere which also increases loss of voitiles from the top of the Mars atmosphere. The old atmosphere of Mars may have been mostly helium and hydrogen compounds and free hydrogen which are more easily lost to solar wind. Free oxygen from the water vapor that lost it's hydrogen may have combined chemically with surface rocks of Mars. Methane and some other hydro-carbons of Titan have a very strong molecular bond, not as easily broken by ionizing radiation. Mars may have out gassed most of it's volitiles 4.5 billion years ago while Titan has been releaceasing it's volitiles at about a constant rate for the past 4.6 billion years. A large impactor may have stripped Mars of much of it's atmosphere sometime in the last billion years. Titan may have less atmosphere than we presently believe. Some of these reasons are likely wrong, so don't hesitate to refute, embellish and/or comment. Neil

 

[jiminy]

i just watched the live canadian discovery ch, tonights headlines were, renewable source of methane found on mars, they interviewed an expert from nasa and he claims that they found methane in heavy concentration esp around deep valleys or mountain ranges they said that its possible it is caused by some sort of life forms or volcanic activity and as far we know there is no vol activity on mars, mars has a layer of permafrost a few hundred metres thick and there could be liquid water underneath this permafrost which could support microbial life he claims that once the mathane gas hits the bottom of the permafrost if it cant go up it will go sideways and will finally reache the surface on the slopes of mountains or hills with deep valleys some of it can escape thru vents in the permafrost if there is any vents for it to escape, it also said that methane had been dicovered on mars before but not in this quanity. i went to their website www.discovery.ca but didnt see anything about it there only yesterdays report, they did say at the first of the show this news just came in as the show was beginning to go on the airso maybe it hasnt made it to their website yet, what i would like to know is this new news or old news the 2 hosts seemed pretty excited about it, they also mentioned rememberance day/veterns day so it must be an updated show and not a repeat. can anyone else shed some light on this?

 

[silylene old]

I hate being a grammer critic, but a 400 word paragraph would be a lot easier to read with more than two sentances. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[yurkin]

It’s really quite simple.<br /><br />Titan is a lot colder then Mars. Therefore the atoms that make up Titan’s atmosphere are less energetic then those on Mars. So Titan’s relatively small gravity is strong enough to hold them down. Whereas Mars cannot even with its stronger gravity.<br />

 

[peteb]

<blockquote><font class="small">In reply to:</font><hr /><p>Yet Titan has an atmosphere 60 times more dense than earth<p><hr /></p></p></blockquote><br /><br />The best determinations so far are that the surface pressure is about 1.5 bars and, given Titan's 1/7 gravity compared to Earth, the mass density of the atmosphere at the surface is ~4X Earth's .<br />http://www.lpi.usra.edu/meetings/outerplanets2001/pdf/4003.pdf

 

[dragon04]

My mistake. I meant to say Titan's atmospheric pressure was 60% greater than earth's.<br /><br />http://solarsystem.nasa.gov/planets/profile.cfm?Object=Sat_Titan<br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>