Did Mars ever have a large moon?

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<p><strong><font size="2">Poster BSJ raised a very interesting speculative point on Why is the Earth's interior still hot thread in Earth Sciences. Also click on the link. Leads to a NOVA episode exploring this possibility.<br /> </font></strong></p><p><strong><font size="2">Actual post below:</font></strong></p><img class="PluckUserAvatar" src="http://sitelife.space.com/ver1.0/Content/images/store/3/15/f3a9b01c-3a77-432e-afd3-5780fd40a687.Small.jpg" alt="" /> <div id="forumPostAuthor[3]" class="Discussion_UserName"> <font size="2" color="#800000">BSJ</font> </div> <div class="Discussion_UserInfo"><font size="2" color="#800000"> First post: 11/26/2008<br /> Last post: 1/16/2009<br /> Total posts: 18 </font></div> <font size="2" color="#800000"><span style="font-size:7.5pt;font-family:Verdana">Watch this Nova episode.&nbsp; http://www.pbs.org/wgbh/nova/mars/program.html (I believe it was the <strong>End of an Atmosphere</strong> section in particular)</span></font> <p><font size="2" color="#800000"><span style="font-size:7.5pt;font-family:Verdana">It explains that Mars once had a large moon which caused or helped extend the presence a&nbsp;molten core. Thereby giving the planet a magnetosphere.&nbsp;<span>&nbsp;This&nbsp;</span>allowed Mars to hold its atmosphere. They think the moon crashed into the planet and either blew away the atmosphere or in its <span style="font-size:7.5pt;font-family:Verdana">absence</span> the core froze and the solar winds carried&nbsp;it away.</span></font></p><p><font size="2" color="#800000"><span style="font-size:7.5pt;font-family:Verdana">The constant deformation caused by our moon has to be keeping the core molten.</span></font></p><p><font size="2" color="#800000"><span style="font-size:7.5pt;font-family:Verdana">As our moon moves away from us this will lesson the deformation;&nbsp;and we know how that turns out for a planet...</span></font></p><p><font size="2"><strong>My own response:&nbsp;</strong></font></p><p><font size="2"><strong>IMO & AFAIK, the MERs (mostly MER B Opportunity) & Mars Phoenix Lander have confrmed that Mars has tremendous obliquity swings, continuing to through the present time. MER B Opportunity has found evidence of this happenning in ancient times, certainly back to the Noachian (Jon Clarke may pull me up on this) & Phoenix Mars Lander revealing further evidence in far more recent times, even ongoing (one example of the synergy between the MERs & Phoenix).<br /></strong></font></p><p><font size="2"><strong>This to me, particularly the information regarding the older terrain in Meridiani, being surveyed by Opportunity rules out Mars ever having a large moon. I would not rule out Mars having many other small moons, in the remote past like Phobos & Deimos, the current martian natural satellites, but a large moon I doubt it.</strong></font></p><p><font size="2"><strong>Andrew Brown.&nbsp;</strong></font></p> <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>