Tidal Friction Heating on Early Earth and Mars?

[earthseed]

There is strong evidence for liquid water on both Earth and Mars early in their history, even though the sun was at least 30% weaker at the time. It is difficult to conjure up a realistic atmosphere to create a greenhouse effect sufficient to compensate for the lack of solar energy. However, at least on Earth, there may be another source of heating. After its formation the moon was much close to the Earth, and has been receding ever since. Tidal friction could warm the Earth's surface, much as Jupiter does for Io and Europa. This rather obscure page states:<blockquote><em>Another contribution to the thermal equilibrium of the earth's surface is presented by D.L. Turcotte, J.L. Cisne, and J.C. Nordman (1977. On the evolution of the lunar orbit. Icarus 30:254). They have calculated that tidal heating in the past from the moon, when it would have been closer to the earth, could have significantly raised the temperature of the earth's surface. Actually, the problem is too much heat. At a separation of 10 earth radii (the present separation is about 60 earth radii) the energy dissipation from tidal friction would have been equal to the solar flux.</em></blockquote><br />This may be an overstatement, according to this source:<blockquote><em>To account for the disparity between the compositional evidence suggesting that the moon formed as a contemporary of the earth and that tidal evolution places the two bodies in proximity rather recently, Opik (1972) suggested that the moon existed transiently as a circurnterrestrial ring similar to but more massive than the rings of Saturn and coagulated first into a set of small moons and then through several fragmentations coagulated into its present form. He suggests that the original orbit of the moon was at 5 earth radii and that in this synchronous or nearly synchronous orbit tidal friction was minimal. A simpl</em></blockquote>

 

[vogon13]

The tidal heating effect and acceleration of the moon in its' orbit will strongly correlate. A period of high tidal heating of earth will also be a period when the moon will recede from the earth most rapidly. The heating can be looked at as self limiting to a degree (sorry 'bout the pun).<br /><br />Additionally, there will be (presumably) a period shortly after the moon's formation when I expect it to not be tide locked (as it is now) to the earth. During this 'spin down' period, the moon will also experience tidal heating.<br /><br />If the moon's orbit is eccentric, the tidal effects will persist after tide lock for the moon occurs.<br /><br />A possible evolution of the moons' orbit into a path more aligned with the ecliptic (assuming the initial orbit wasn't) is also expected, and this would effect the 'tail off' of the tidal effects.<br /><br />{note: that last effect is probably pretty tiny, but I ain't doin' the math on that!}<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[vogon13]

Fun speculation:<br /><br />If the moons' origin was a fairly messy process, (safe bet) perhaps the moon had a satellite or two of its own at one time. Maybe we can find a hint of them somewhere?<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[mikeemmert]

Sorry, vogon:<br /><br />http://tinyurl.com/djzvs<br /><br />This article is about the Hill sphere, also known as the Roche sphere. This is the sphere around an object orbiting another larger object in which stable orbits are possible. This sphere includes the L1 and L2 points.<br /><br />"Formula and examples<br />If the mass of the smaller body is m, and it orbits a heavier body of mass M at a distance a, the radius r of the Hill sphere of the smaller body is<br /><br />r = a times cuberoot (m/3M)<br /><br /><br /> "For example, the Earth (5.97×1024 kg) orbits the Sun (1.99×1030 kg) at a distance of 149.6 Gm. The Hill sphere for Earth thus extends out to about 1.5 Gm (0.01 AU). The Moon's orbit, at a distance of 0.370 Gm from Earth, is comfortably within the gravitational sphere of influence of Earth and is therefore not at risk of being pulled into an independent orbit around the Sun..."<br /><br />"An astronaut could not orbit the Space Shuttle (mass = 104 tonnes), if the orbit is 300 km above the Earth, since the Hill sphere is only 120 cm in radius, much smaller than the shuttle itself. In fact, in any low Earth orbit, a spherical body must be 800 times denser than lead in order to fit inside its own Hill sphere, or else it will be incapable of supporting an orbit. A spherical geostationary satellite would need to be more than 5 times denser than lead to support satellites of its own; such a satellite would be 2.5 times denser than iridium, the densest naturally-occurring material on Earth. Only at twice the geostationary distance could a lead sphere possibly support its own satellite; the moon itself must be at least 3 times the geostationary distance, or 2/7 its present distance, to make lunar orbits possible..."<br /><br />I ran into this in conjuction with my Neptune/Sun Lagrange point project (see "2003 UB313 is the lost moon of Triton" ). I ran into a problem with it, though. I was doing GravitySimulations of a

 

[mlorrey]

You are lacking crucial knowledge and making unwarranted assumptions. I suggest you obtain a copy of Martyn Fogg's seminal textbook "Terraforming". In it, you will find out that the early Earth had an atmosphere 52 times denser than the current one (its all in the limestone bedrock now), while Mars had something about half that of the current terran atmosphere. Mars atmo evaporated to space and became embedded in carbonate rocks.

 

[bonzelite]

milkee, that's an extremely fascinating bit of information. thanks for that. <img src="/images/icons/smile.gif" />

 

[earthseed]

I know I am lacking crucial knowledge, that is why I am asking this question here. However, when looking for basic science, I am not going to use a book advocating some glorious megaproject. Science tends to get shaped to fit the author's goal. Quoting the density of the early atmosphere to two significant figures does not increase my confidence - there is no way that is known to that degree of accuracy.<br /><br />I take it that the thick carbon dioxide atmosphere was supposed to be sufficient to warm the early Earth, and will do the trick on Mars in the future. Funny how efficient carbon dioxide is in this forum, while over in Environment no amount of anthropogenic carbon dioxide will make any difference to climate. The problem is the greenhouse response to concentration is logarithmic, so piling on the carbon dioxide stops making much difference.

 

[mikeemmert]

Well, this post might be a little more fun than the last. The Moon can have moons today - it's far enough away from the Earth - but could not have back in the distant past when it was closer to Earth as in the original post of this thread. The Moon can start to have moons (surface-skimming moons) when it is > 110,000 km.<br /><br />But it <font color="red">CAN <font color="white">have objects at the <font color="red">Lagrange points! <font color="white">L4 and L5. I couldn't tell you what size they'd be.<br /><br />I got such a simulation going on my dinky little computer. Unfortunately, the Earth has likely never been uniform in it's mass distribution, which I can't simulate on MDLC. That might tend to make the Lagrange points unstable.<br /><br />Where are these things now? Aitken Basin? Some other crater? I don't see anything I could call Lagrange scars because they're all too small...</font></font></font></font>

 

[vogon13]

Objects closer or further than the moon would at least be possible temporarily in stable orbits.<br /><br />How about objects in resonant orbits exterior to the moons orbit?<br /><br />As the moon recedes from earth, objects in exterior resonant orbits would plausibly be pushed higher too?<br /><br />Could they be pushed 'out of' earth's Hill sphere?<br /><br />{btw, if you compare the contemporary value of the force of the sun/moon attraction to the value of the earth/moon attraction, I think you will be rather surprised}<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[mikeemmert]

Hi, vogon. I just took a look at my Gravity simulation of the Earth/Moon system early in it's history(Moon about 2/7 of it's present distance from Earth). I put a ring of material interior to the Moon. Now, this was a retry because on the last one I hit the wrong button and only put an object at the L5 point.<br /><br />This simulation was not done in the base simulation with the other 8 planets (that simulation considers Pluto a planet, that's another thread). Just the Earth, Moon, and fourty moonlets. I gave the moonlet a tiny amount of mass, much smaller than the mass I gave L5 (less than 1% of the Moon's mass).<br /><br />Well, I'm lazy...not my main project (many mumbled excuses)... I put the machine on "don't plot". If the machine has to create a display for your monitor, it slows it way down.<br /><br />When I got back, most of the inner ring was gone, as I expected. The Moon had moved in slightly from 110,000 km (just outside the Hill sphere radius) to 108,000 and change (just inside the Hill sphere radius). The L5 orbited at 21,000,000 (that's tweny one million) kilometers, way outside of the Moon's orbit and way outside of the Earth/Sun Hill sphere radius, which answers your question. Three little moonlets were left orbiting inside the moon and about a half a dozen were on wide/escape orbits.<br /><br />All this within a mere 62 years.<br /><br />Thanks for getting me to do this exercise. Great insights into my project.

 

[nexium]

My guess is an unknown source of heat for the interior of planets. Main stream opinion is 1 A sun with decreasing energy output 2 gravitational commpression 3 radioactive isotopes account for the most of the heat the first half billion years. If Earth acquired it's moon by collision with a Mars size body 4 the surface was likely melted rock temperature for no more than a million years. Life may have begun in rare cool spots even before the 2nd bombardment ended. If the moon was at approximately geo sychronous altitude = 36,000 kilometers, tidal heating would have been tiny but 5 increasing rapidly as the moon moved quickly away. By the end of the first billon years, the Moon was likely more than half it's present distance and no longer warming Earth significantly. This is where the 6 unknown source is needed, to keep Earth warm, until the first ice age about one billion years ago.<br />Green house gases may have 7 warmed Earth and Mars 5 degrees c = 9 degrees f at times. but, my guess this is not enough nor does the timing fit main stream theory.<br />1 The sun has provided 99%? of the heat budget of Earth the most recent billion years.<br />Because this is excessively complex, my guess is the main stream theory has one or more errors, but I don't know what they are. Neil