A CIVILIZATION on MARS? 1B/200M Years Ago? (Pt. 5)

[JonClarke]

Steve<br /><br />There sure are some great place names in Oz, some aboriginal (like Tabberabbera or Porongurup ), some European (like Ouse - pronounced Ooze - and Nowhere Else).<br /><br />The continent is certainly old and quite dry. However, the antiquity of the landscape has its challenges though, much of it is very deeply weathered to depths of 100 m or more, so tat the parent material is almost unrecognisable.<br /><br />Shark Bay gets all the glorry, but stromatloites, admittedly not as fine are not uncommon in many other saline lakes and lagoons.<br /><br />Jon<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

Density of earth is 5.52 <br />Venus 5.25. <br />Mars 3.95. <br /><br />My understanding of these numbers is that this is largely due to differences in density due to different degrees of graviational compression because of their different radii. Venus has a slightly smaller radius, is therefore slightly less compressed, and therefore only has a slightly smaller bulk density. Mars is significantly smaller in radii, and compression and bulk density are correspondingly smaller.<br /><br />Which mentals are essential traces for life (at least terrestrial like? Mg and Fe are present at the % level on the surface of Mars. I don't know about some of the others - Cu, Co, V, Zn - but Cu, Co and Zn are typically common in mafic minerals and therefore should be common on Mars. I will try and dig up some whole rock geochem on the SNC meteorites and the lander data. V is lithophile and therefore might be relatively low in martian crustal rocks. Any others?<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

Although an oxygen caused mass extinction is a nice hypothesis there is no evidence for it what so ever in the fossil record. There is a good section this in in Nick Lane's "Oxygen: the molecule that made the world", a reasonably accessible popular book.<br /><br />Similarly the taxa sail right through supposed snowball earth epoch without any drops in divesity. This is good evidence that the snowball was not as global as some have argued.<br /><br />Incidently, the methane era was early Archaean. Snowball earth, if it existed, was Late Proterozoic, nearly 2 Gy later.<br /><br />Jon<br /> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[mental_avenger]

IMO, it is more likely that there were several rather severe ice ages that lasted long enough to bring glaciers to the equator. These could have been caused by major impacts or major volcanic activity, but only had to last perhaps 10,000 – 50,000 years. <div class="Discussion_UserSignature"> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="2" color="#ff0000"><strong>Our Solar System must be passing through a Non Sequitur area of space.</strong></font></p> </div>

 

[maxtheknife]

Jon.... We waited all this time for that?<br /><br />Way to substantiate your contentions. You're a real pro.

 

[telfrow]

Yes, Max, he is. <br /><br />And speaking of waiting, we're still waiting on the answers to a number of questions...the full Malin quote...the ortho/non-ortho nature of the illustrations at TEM...the pot calling the kettle black..to name just a few. <div class="Discussion_UserSignature"> <strong><font color="#3366ff">Made weak by time and fate, but strong in will to strive, to seek, to find and not to yeild.</font> - <font color="#3366ff"><em>Tennyson</em></font></strong> </div>

 

[centsworth_II]

<font color="yellow">"Although an oxygen caused mass extinction is a nice hypothesis there is no evidence for it what so ever in the fossil record." -- JonClarke</font><br /><br />When I said: "It is THE theory that fits the current fossil and geologic evidence." I was refering to the mass production of oxygen by cycanobacteria. This is the one facet of the "snowball" theory that I see as mainstream. Everything else in the theory I agree is very speculative.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[JonClarke]

Well Max, I could post two pages of notes detailing the poor organisation, the mixing of fact, deduction, and speculation, the reliance on unsubtantiated and unsubstantiable unpublished material, etc. but I doubt that people are interested. <br /><br />But at least I have read the material. You don't seem to, as shown by your assertion that Malin was ignoring specific articles of the Cydonites when they were written years after his article. <br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

Anglo-AMERICAN Telescope?????????????<br /><br />Wash your mouth out with industrial strength cleaner!!!!<br /><br />It's the Anglo-AUSTRALIAN Telescope, thank you <img src="/images/icons/smile.gif" /><br /><br />http://www.aao.gov.au/<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

Colin<br /><br />With respect to methane, please note that it 's Kasting who argues that Archaean methane was about 1000 X present atmospheric levels. Current leverls are 1.6 ppm. That is 0.1%, enough to play a significant role, enough to be the dominant greenhouse gas, but not enough to be the dominant constituent of the earth's secondary atmosphere.<br /><br />As for rocky accretion of planetisimals in the inner solar system, the models are well constrained by meteorites and studies of extra-solar protoplanetary disks. the formation of the inner solar systems would be contemporaneous with the period of peak stellar outflow (the T-Tauri wind) and therefore is unlikely to have done through a mini-gas giant phase. It isn't enough to say that such a phase is logical, you have to look at the evidence, and the evidence is that the chondritic meteorites experienced very high heating during this time, enough to strip away any primary atmosphere in the inner solar systems as it formed.<br /><br />It is absolutely essential to get your time frame right in this discussion. The T Tauri phase applies to the first 100 My of the sun's history. This is before and during the final accretion of the inner planets. The loss of primary terrestrial and martian atmospheres is indicated by the quite different noble gas ratios of earth and Mars compared to solar abundances. <br /><br />Kasting's hypothesised methane era would have occurred after this time say from 4.5 or 4.6 Ga. It is proposed to get round the faint early sun paradox. <br /><br />The methane era came to an end with the oxygenation of the atmosphere, sometime between 2.3 and 1.8 Ga. So it lasted for 2.3-2.8 Gy, over half the earth's history.<br /><br />Interestingly there is evidence of glaciation at roughly (within a few hundred My!) the end of the proposed methane era. However it is only found at Gowganda in Canada and there is no other evidence for coaeval glaciation anywhere else in the world. There is no evidence for <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

Colin:<br /><br />The core has very little influence on the composition (as opposed to the preservation) of the atmosphere.<br /><br />Agruing that the sun was still collapsing as late as 2.3 Ga is completely contrary to what we understand about stellar formation. Once the the protosolar dusk becomes graviationally unstable it collapses quite quickly (less than 1 My), leading to ignition. <br /><br />Again, meteorite chemistry and mineralogy point to very strong heating in the protosolar nebular consistent with this.<br /><br />The presence of possible photosynthetic organisms in sediments as old as 3.5 Ga (the Warrawoona supergroup fossils) indicates that there was strong sunlight. This is inconsistent with a thick atmosphere or a feeble sun.<br /><br />Should should take theis discussion to the space science and astronomy board under a relevant title so that more people can contribute.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[yevaud]

Ahh, that makes a certain amount of sense, but the graphic is misleading. Remember that it's really subtending a part of an arc. What you should show (I understand simple typing can't accurately represent this) is a wedge shape, with asteroidal and cometary bodies falling inwards towards the tip of the wedge.<br /><br />Which will raise the probability of Earth being hit. We circle the sun faster than Mars, and inward falling bodies are converging towards the sun. If you look at that picture analytically, you'll se that our probability of being hit is higher than that. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[yevaud]

I actually meant something like this (sorry for the quick and dirty paint illustration):<br /><br />As you can see, Earth subtends a smaller portion of the arc than Mars does. Infalling material is attracted towards the primary, and Earth is in the way.<br /><br />As well, Mars has a longer orbital period, whereas Earth will enter the same area twice as many times. While Mars dwells in the that arc for twice as long as Earth, you'll note that the fact actually lessens the chance of an impact, not increases it.<br /><br />Also, infalling material will have gained greater velocity hence greater kinetic energy for any hypothetical impact on Earth.<br /><br />Edit: dang. Sorry...thought the image was small enough that it wouldn't extend beyond the margins. *Blah*<br /> <br />I'd believe that overall, it means that the chances of Earth vs Mars receiving an impact are likely near-identical. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[yevaud]

Not all infalling material approaches the sun in an elliptical orbit, by any means. Frequently, it just falls inwards. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[yevaud]

http://www7.nationalacademies.org/ssb/sssbch2.html<br /><br />Not quite. Thse sort of dynamics don't require an elliptical orbit (I suppose this is near-impossible to show using paint).<br /><br />While there's some elliptical behaviour (after all, asteroidal material is usually derived from the Belt, which is in elliptical orbit around the sun), there are many different perturbative events. And those events are where the asteroidal material begin their journey inwards.<br /><br />No single vector is preferential to any other. <br /><br />Edit: have to pick this up tonight. Must be at work in an hour. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[JonClarke]

Anglo American mine just about everything as well as diamonds <img src="/images/icons/smile.gif" /><br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[yevaud]

It's an interesting question, Colin. The Terminal Bombardment Phase ended around 4.5 GY ago. And Mars, to whatever extent, was as affected as Earth.<br /><br />Now though, our chances of a mass-extinction event are 1 out of 100,000,000 - and the last was 65,000,000 years ago.<br /><br />I'm not certain anyone has actually worked out what the odds of a similar Martian event are. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[mental_avenger]

<font color="yellow"> Not all infalling material approaches the sun in an elliptical orbit, by any means. Frequently, it just falls inwards. </font><br /><br />There is no way that can be true in any instance, if the material is falling from the asteroid belt as you illustrate. Currently ALL material that is in this solar system is in orbit about the Sun. In order for any object currently in orbit to plummet straight in towards the Sun, 100% of it’s orbital velocity (no more, no less) would have to be negated by some force, presumably an impact. I see no mechanism that would result in such a negation of orbital velocity. Do you have one handy?<br /> <div class="Discussion_UserSignature"> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="2" color="#ff0000"><strong>Our Solar System must be passing through a Non Sequitur area of space.</strong></font></p> </div>

 

[yevaud]

Ever heard of hyperbolic or parabolic orbits?<br /><br />No single orbital path is preferred to any other. You make it sound as if something begins in an orbital path, it's trapped there forever, and no outside force can ever affect it. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[sinova]

I think I posted once way back on Martian "extinctions," but haven't commented because I know too little on Martian and solar system morphology. Frankly, my impression is that no one knows much definitive about the topic, either. But since we're in the realm where Colin can appropriately say "another argument now occurs to me," here I go:<br /><br />Orbits, shape of orbits, gravity, planet "target" size, sure these have all got to be factors. But the biggest locus seems to me to be atmosphere. Atmosphere is the buffer and defense a planetary body has against surface strikes. I mean, if the Earth's atmosphere were half as thick, how many more and how more severe would meteorite impacts be?<br /><br />Also, atmosphere seems to be the mode of extinctions. The theory goes that it isn't the impact per se that is lethal, not enough organisms are destroyed by primary strike; it is the subsequent spreading of debris and atmospheric opacity that causes deaths in a planetary "winter."<br /><br />Keeping this in mind, the prevalent atmosphere of a planet at the time of the impact would be vital to the viability for life. As a planet's atmosphere evolves, as its biology evolves (if there were any life), one era's "killer asteroid" might be another era's inconvenience.<br /><br />These considerations are more complex and harder to pin down than plotting orbit shapes, for example, but they may be more critical in understanding extinctions.<br />

 

[mental_avenger]

<font color="yellow"> Ever heard of hyperbolic or parabolic orbits? </font><br /><br />ROTFLMAO. That’s a good one. No, I haven’t, because they do not exit. By definition, a hyperbolic or parabolic trajectory would not be an orbit, but would be a one-time pass. As such, any object with a hyperbolic or parabolic trajectory would either come from interstellar space, or have been ejected from its orbit with enough force to eject it from the solar system. Unless you can show a mechanism that would negate enough of an orbiting object’s orbital momentum to send it directly into the Sun, or add enough momentum to eject it from the solar system, your contention is without merit. In any case, such objects, IF they existed, would be so rare as to be inconsequential. <br /><br />BTW, to make this easier for you, both a parabola and a hyperbola are “open” sections of a cone. Basically, when a plane intersects a cone and is not an ellipse, it is a parabola. When a plane intersects a pair of cones (identical cones joined at the apex) it is a hyperbola.<br /> <div class="Discussion_UserSignature"> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="2" color="#ff0000"><strong>Our Solar System must be passing through a Non Sequitur area of space.</strong></font></p> </div>

 

[sinova]

Aw, come on. Isn't being correct enough, you have to laugh about it, TOO?<br /><br />Yes, you got it right, Yevaud got it wrong, but be nice he wasn't being a jerk or anything.<br />

 

[yevaud]

Sure, they don't exist.<br /><br />http://www.hq.nasa.gov/office/pao/History/conghand/traject.htm<br /><br />http://64.233.167.104/search?q=cache:KiTpKhEhvHgJ:berlinadmin.dlr.de/SGF/acm2002/abstracts/pshort/04-17p.pdf+hyperbolic+parabolic+orbit&hl=en&start=15&ie=UTF-8<br /><br />Shall I continue?<br /><br />*Remainder of rant deleted* <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[yevaud]

*Sigh*<br /><br />Once more into the breach, dear friends... <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[yevaud]

Thanks for being so classy about it. I'll be certain to inform my professors in Astronomy and Space Physics that such "orbits" (which, by the way, is what we generically referred to them as) can't exist.<br /><br />Apparently I wasted all of that money going to school for this stuff. Gee. Go figure.<br /><br />As to your question about a force sufficient to eject a body from the solar system, you are aware that solar escape velocity is Sqrt(2) of the circular (eg instantaneous orbital) velocity? It can't happen? Uh huh.<br /><br />Much cometary matter falls inward, both from the Oort cloud and from interstellar space. Asteroidal material can be perturbed by other material in the belt, passing material and comets, and perturbative events caused by Jupiter being in an occasional eccentric orbit.<br /><br />Why is this "impossible," and "never seen?"<br /><br />I don't know where you got your information, but it's without relative merit.<br /><br />And I, on the other hand, won't laugh... <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>