MSL update

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JonClarke

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MSL landing site downselections have taken place. <br /><br />The six remaining sites are: Nili Fossae Trough, Mawrth Vallis, Southwest Meridiani Clays (a.k.a. Runcorn Crater), Jezero Crater (a.k.a. Nili Fossae Crater), Holden Crater, and Terby Crater.<br /><br /><i>All along, MSL has been touted for its capability to land in places that the Mars Exploration Rovers could not hope to reach -- inside a canyon, maybe, or within a steep-walled crater; the cameras would gaze upon dramatic terrain like that found in America's desert southwest. Once landed, MSL is supposed to be able to rove 10, maybe even 20 kilometers or more over its lifetime, so it could potentially land in a less-interesting place and drive into rugged, rocky exposures of ancient rocks, places that will also produce spectacular landscape photos... But as MSL's development has progressed, the engineers have been getting more conservative... we heard how it could not tolerate low temperatures... we heard that "go-to" sites -- where the interesting stuff lies at the end of a long initial traverse -- may be considered too risky. We heard that MSL will probably be able to drive no more each day than Spirit and Opportunity could, limited by battery power to 100 to 150 meters at most each day. We heard that the landing ellipse is a little larger than previously thought, making some of the proposed sites too tight a squeeze into narrow spaces; and that the site may be required, late in the game, possibly even after launch, to have a much larger safe landing ellipse, forcing the mission to consider sites that are off of this list of six... there is only one proposed site that we are sure is "safe" by every definition, one called "North Meridiani."</i><br /><br />http://www.planetary.org/blog/article/00001212/<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>
 
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h2ouniverse

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Hi Jon,<br /><br />Do you know whether they will drill? And how deep?
 
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JonClarke

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Unlike ExoMars, MSL does not carry a drill. <br /><br />With the new latitudinal constraints of 30 degrees either side of the equator it would appear that the RTG offers no improvment in this respect compared to the solar arrays of Exomars. This is quite disapointing as the original specs said it could go 60 degrees north or south. <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>
 
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3488

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You would have thought that with RTGs, MSL could have landed just about anywhere.<br /><br />Even so, there is still a lot of interesting terrain with the 30th parallels on Mars.<br /><br />Does anyone know why the latitude limitations? If solar pwered, yes, that makes sense, <br />but not if RTG powered.<br /><br />After all Viking 2 landed at 48 degrees north. Pheonix is headed for approx 69 degrees North<br />& she is solar powered.<br /><br />Andrew Brown. <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>
 
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mi2again

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Lubrication of actuators is the issue that is reducing the latitudes. Too cold
 
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h2ouniverse

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Btw, why is latitude such a factor for use of Solar Array? Attenuation by the very thin martian atmosphere should not be that severe, even at say 70° of inclination. If the Solar Array can be orientated normal to solar flux...<br />Am I missing a point?
 
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JonClarke

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Hi Andrew<br /><br />if you read the article the latitude restrictions from from heating requirements. While the interior of the rover is warmed by waste heat from the RTGs, the external sensors etc. use electric heaters, which come from the batteries. There is only os much power to go round. Even at the Holden crater site (the mostly southerly target still left), there is only enough power to operate MSL for a few hours a day. the rest of the time it's just trying to stay warm.<br /><br />Viking could go further north because they did not have to move. They may have had more power too, with two RTGs apiece.<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>
 
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JonClarke

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Solar power attenuation comes from several sources - atmospheric absorbtion, suspended dust, deposied dust, and incidence angle. the last is the killer for high latitudes, at 50 degrees north or south you need twice the area you would at the equator. For a stationary lander but for a vehicle you could do this, or tilt the arrays, which helps to some extent. But rovers have higher power requirments and fixed sizes for arrays for stability reasons. Tilting them is a problem for rovers because you have effectively a large sail on the rover as a result. Plus tilted arrays on a rover would then have to rotate to track the sun, which adds weight and complexity. I have read an article about a porous array for a polar rover which would offer less wind resistance, which might work.<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>
 
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3488

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Possible landing sites for MSL from Mars Odyssey THEMIS.<br /><br />Andrew Brown. <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>
 
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3488

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An important development here.<br /><br />MSL Parachute being tested (1).<br /><br />MSL Parachute being tested (2).<br /><br />Andrew Brown. <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>
 
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JonClarke

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The most locations on Mars can be found at http://pubs.usgs.gov/imap/i2782/i2782_sh1.pdf (2.12 MB) - it's searchable<br /><br />Images of four of the candidate sites can be found by following the links in this story: http://space.newscientist.com/article/dn12873-prime-landing-sites-chosen-for-biggest-martian-rover.html<br /><br />Other can be found at http://marsoweb.nas.nasa.gov/landingsites/<br /><br />Jon<br /><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>
 
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