<blockquote><font class="small">In reply to:</font><hr /><p>Calli, Cydonia was an original landing option/choice for the viking missions. There is absolutely no good reason NOT to land at Cydonia and answer the question. Did you see where they landed Pathfinder? Jagged, sharp rocks were everywhere! <p><hr /></p></p></blockquote><br /><br />Yeah, Cydonia was on the very long "wish list" for landing spots. It got rejected for a variety of reasons, among them the fact that there were too many mesas and other large scale features within the landing ellipse.<br /><br />Pathfinder did indeed land on a rock-strewn plain. But there are several crucial points that need to be made here.<br /><br />1) The jagged boulders at the Pathfinder landing site aren't visible from orbit. You can't really tell if there are going to be rocks like that. All you can do is try to avoid the large scale features like hills, valleys, canyons, mountains, mesas, and so forth. Remember that Opportunity's serendipitous "hole in one" was pure luck. That crater wasn't even known about prior to Opportunity's landing. I think you'll agree with me that the "Face" is a lot bigger than any of those rocks. <img src="/images/icons/wink.gif" /> Really, Pathfinder's site is pretty flat compared to Cydonia.<br /><br />2) The Vikings could afford a wider variety of landing sites for several reasons: they were not dependent on good sunlight, they didn't rely on airbags for landing and instead had much more powerful descent engines, and they were descending from Mars orbit and thus were coming down a lot more slowly.<br /><br />3) The Vikings had smaller landing ellipses. This relates to the point above, that they were coming from Mars orbit. All subsequent lander missions have been from heliocentric orbit, which is a lot faster and more difficult to aim.<br /><br />4) Pathfinder came within a hairsbreadth of failure due to all of those sharp rocks, and testing revealed more and more potential weaknesses in the landing system f <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em> -- The Tenth Doctor, "Blink"</font></p> </div>