Solar Wind Stripping Mars atmosphere

[MeteorWayne]

<div id="post-270042" class="postcolor">http://www.marsdaily.com/reports/Solar_Win...sphere_999.html<br /><br />The solar wind is stripping away chunks of Martian atmosphere. Martian air detaches from the planet and tumbles into deep space. It explains why Mars has so little air. Billions of years ago, Mars had a lot more air, primarily carbon dioxide, than it does today. Ancient Martian lakebeds and river channels tell of a planet covered by abundant water and thick atmosphere.<br /><br />The atmosphere of Mars was once as thick as Earth&rsquo;s. Today all those lakes and rivers are dry and the Martian atmospheric pressure is less than 1% that of Earth at sea level. A cup of water anywhere on the Martian surface would boil quickly and violently because of the super-low air pressure.<br /><br />There are several possible reasons for the reduction. An asteroid hitting Mars long ago might have blown away some of the planet's atmosphere in a single violent upheaval. Or the loss might have been slow and gradual from billions of years of relentless sand blasting by the solar wind particles. A new possibility is a daily ripping process intermediate between the great cataclysm and slow erosion models.<br /><br />Mars has a very strange magnetic field. Instead of a global bubble like Earth&rsquo;s, the Martian fields looks like a dozen magnetic umbrellas that sprout from the ground and reach beyond the top of the Martian atmosphere. These umbrellas cover about 40% of the surface, mainly in the southern hemisphere. Researchers thought for years the umbrellas protected pockets of Martian atmosphere beneath them from erosion by the solar wind. The opposite can be true as well. The umbrellas are where coherent chunks of air are tearing away.<br /><br />They had measurements from 25,000 orbits. During one of those orbits, MGS passed through the top of a magnetic umbrella. The umbrella's magnetic field had linked up with the magnetic field in the solar wind. Global Surveyor&rsquo;s readings are consistent with magnetic reconnection. The fields joined, wrapping around a gas packet at the Martian atmosphere top, forming a magnetic capsule a thousand kilometers wide and trapping ionized air inside. Solar wind pressure made the capsule to pinch off and it blow away, taking the air with it. There are a dozen more examples. The magnetic capsules plasmoids blow over the South Pole, mainly because most of the umbrellas are located in the southern hemisphere. Researchers are still not sure how often the plasmoids form or how much gas each one contains.<br /><br />Scientists did not design the Mars Global Surveyor to study the phenomenon. It was only equipped to sense electrons, not heavier ions that would make up the bulk of any trapped gas. Ions and electrons do not always behave the same way. In addition, MGS sampled the umbrellas at fixed altitudes at the same local time each day. They need more data from many altitudes and times to understand these dynamic events. NASA has a new mission named MAVEN, short for &ldquo;Mars Atmosphere and Volatile Evolution&rdquo;. MAVEN is an upper atmosphere orbiter currently approved for launch to Mars in 2013.<br /><br />NASA specifically designed the probe to study atmospheric erosion. MAVEN will detect electrons, ions, and neutral atoms. It will measure both magnetic and electric fields. It will and travel around Mars in an elliptical orbit, piercing magnetic umbrellas at different altitudes, angles, and times of day; and it will explore regions both near and far from the umbrellas, giving researchers the complete picture they need. If magnetized chunks of air are truly tearing free, MAVEN will see it happening and measure the rate.<br /></div><p>&nbsp;</p><p>MW, PS thanx to Proplyd</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[3488]

<p><font size="2"><strong>Thanks Wayne,</strong></font></p><p><font size="2"><strong>I still think also that the cessation of widepread volcanism & the collapse of the global magnetosphere are jointly responsible. As you said, approx 40 % of the southern hemisphere still appears to be covered by local magnetism, & really that is really not nearly enough & those magnetic 'bubbles' are rather weak also.</strong></font></p><p><font size="2"><strong>I wonder if either of the MERs are within one of these 'bubbles' & also if the MERs along with the late Phoenix Mars Lander have / are providing clues as to the time scales involved?</strong></font></p><p><font size="2"><strong>Perhaps comparing the cratering density with the reduction of wide spread volcanism (I don't mean localised volcanism, cinder cones, etc, I mean the big stuff that created Olympus Mons, the other Tharsis shields, Elysium, etc).<br /></strong></font></p><p><font size="2"><strong>I am of the opinion that the rot started as soon as the global magnetosphere collapsed & major volcanism ceased. What would be most interesting is to get a time scale, perhaps a sliding scale matching up, the reduction in volcanism, the reduction in the rate of small crater erosion, drying up of hydrological features (Mars Pathfinder data from Ares Vallis may need reviewing in this task) & the thinning atmosphere.</strong></font></p><p><font size="2"><strong>I think already we are most of the way there, but MAVEN, MSL & ExoMars will certainly help in filling up whats left. </strong></font></p><p><font size="2"><strong>Also isn't it postulated that much of the lowlands of Northern Mars, are actually part of a gigantic impact basin? </strong></font></p><p><font size="2"><strong>Perhaps Viking 2 data in Utopia Planitia needs to be reviewed also in context with the recent Phoenix data from Scandia Colles.<br /></strong></font></p><p><font size="2"><strong>Great topic Wayne, absolutely fascinating stuff. I have also thanked Proplyd.<br /></strong></font></p><p><font size="2"><strong>Andrew Brown. <br /></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>