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	<title>News Watch &#187; Dave Mosher</title>
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		<title>Missing Martian Atmosphere: Clues In Earth&#8217;s Cold Plasma?</title>
		<link>http://newswatch.nationalgeographic.com/2012/01/26/martian-missing-atmosphere-cold-plasma/</link>
		<comments>http://newswatch.nationalgeographic.com/2012/01/26/martian-missing-atmosphere-cold-plasma/#comments</comments>
		<pubDate>Thu, 26 Jan 2012 16:22:59 +0000</pubDate>
		<dc:creator>Dave Mosher</dc:creator>
				<category><![CDATA[Breaking Orbit]]></category>
		<category><![CDATA[NatGeo News Watch]]></category>
		<category><![CDATA[Planets]]></category>
		<category><![CDATA[Space]]></category>
		<category><![CDATA[atmosphere]]></category>
		<category><![CDATA[cold plasma]]></category>
		<category><![CDATA[mars]]></category>
		<category><![CDATA[space weather]]></category>

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		<description><![CDATA["Invisible" veils of cold plasma discovered around Earth might tell us something about how Mars lost its atmosphere, experts say.]]></description>
				<content:encoded><![CDATA[<p style="text-align: center"><a rel="attachment wp-att-34243" href="http://newswatch.nationalgeographic.com/?attachment_id=34243"><img class="size-medium wp-image-34243 aligncenter" src="http://newswatch.nationalgeographic.com/files/2012/01/cluster-spacecraft-590x421-480x342.jpg" alt="" width="480" height="342" /></a><br />
<em>Illustration courtesy J. Huart, ESA</em></p>
<p>It&#8217;s  been an incredible week for space weather, thanks to a nasty sunspot  that hurled a cloud of superheated gas and charged particles <a href="http://newswatch.nationalgeographic.com/2012/01/23/solar-storm-hits-earth/">toward the  Earth</a>.</p>
<p>But  some cooler space weather news has snuck into the mix: <a href="http://news.nationalgeographic.com/news/2012/01/120125-solar-storm-cold-plasma-earth-space-science/">&#8220;Invisible&#8221;  veils of cold plasma were discovered around Earth</a>, and they might tell  us something about Mars&#8217;s missing atmosphere.</p>
<p>First, a little bit more on the discovery.</p>
<p>Two  space scientists poring over data from the European Space Agency&#8217;s  Cluster II satellites—four spacecraft which zip around Earth in an  elliptical orbit—found evidence of positively charged, slow-moving  (hence &#8220;cold&#8221;) plasma particles as far as 60,000 miles (100,000  kilometers) above Earth&#8217;s surface.</p>
<p>That&#8217;s  about a quarter of the way to the moon, and a region where few  researchers suspected any cold plasma lurked. But nobody needs to be  hard on themselves, said space scientist Mats André of the Swedish  Institute of Space Physics (and leader of the new study about the plasma  in Geophysical Research Letters). That&#8217;s because cold plasma is really, really tough to detect.</p>
<p>The  invisibility of cold matter has a lot to do with like charges repelling  like charges. Sunlight in space strips away electrons from atoms,  ionizing any &#8220;naked&#8221; matter out there to have a positive charge. That  includes spacecraft (like Cluster II satellites) and atmospheric gas at  the edge of Earth&#8217;s atmosphere (which creates cold plasma).</p>
<p>Like  a magnet&#8217;s north pole near another magnet&#8217;s north pole, the spacecraft  and cold plasma repel and never meet. &#8220;Hot&#8221; plasma, on the other hand,  is moving fast enough to ignore any magnetic repulsion with a  spacecraft, so it&#8217;s detectable.</p>
<p>Without some clever analysis, cold plasma just doesn&#8217;t seem to be out there.</p>
<p>But  André knew two things. First, that a spacecraft zooming through cold  plasma—if it existed—would create a shockwave (i.e. cold plasma  piling in front and zipping around to the back). Second, moving charged  particles emit electric fields.</p>
<p>André  and his colleague paired these facts up to &#8220;see&#8221; the subtle shockwaves  in Cluster II&#8217;s data. The results imply cold matter constitutes between  50 and 70 percent of all charged particles in Earth&#8217;s magnetic field!  That&#8217;s quite a jump from zero percent.</p>
<p>The  sudden abundance of cold plasma means a few things. Space weather  forecasts stand to improve, as cold plasma particles probably interact  with incoming hot matter from solar storms—and that dynamic is  missing from computer models. Another effect is that the Earth is  bleeding off roughly 2.2 pounds (1 kilogram) of atmospheric gas <em>every second</em>.</p>
<p>When  you look at planets with thin atmospheres like Mars (which has just 1  percent the atmospheric pressure of Earth), scientists like André  begin to wonder what role the &#8220;blood loss&#8221; of cold plasma plays in  killing atmospheres.</p>
<p style="text-align: center"><a rel="attachment wp-att-34333" href="http://newswatch.nationalgeographic.com/?attachment_id=34333"><img class="aligncenter size-full wp-image-34333" src="http://newswatch.nationalgeographic.com/files/2012/01/mars-atmosphere-plasma-blog.jpg" alt="" width="480" height="348" /></a><br />
<em>Illustration couretsy NASA/JPL-Caltech</em></p>
<p>Despite  having half the solar intensity, the rate of loss may be about the same  as it is at Earth (about one Chihuahua&#8217;s weight every second).</p>
<p>&#8220;There  are all kinds of ways to get rid of a planet&#8217;s atmosphere—big  asteroid impacts, loss of a dynamo, and so on,&#8221; André said. &#8220;Well, this  is certainly one of them when you apply it over billions of years of  time. I don&#8217;t know how important it is, but this is on my short list.&#8221;</p>
<p>While no one knows for certain how Mars lost its atmosphere, we now have a chilly new suspect.</p>
<p><em><a href="http://davemosher.com/">Dave Mosher</a> is a freelance journalist obsessed with space, physics,  biology, technology and more. He lives in New York City and you can stalk him on Twitter as <a href="http://www.twitter.com/davemosher">@davemosher</a>.</em></p>
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