Based on that image, I can answer the question of what type of telescope it is. It's not a Newtonian. It's a Cassegrain. These are popular in those sorts of applications because they are much more compact than Newtonians, although they have slightly less performance than comparable Newtonians. But when space and weight are a premium, you end up with more telescope this way.<br /><br />With an apeture of half a meter, this outperforms the vast majority of amateur telescopes.<br /><br />Actual resolution, however, is more complicated than simply the telescope's performance. MRO is moving very fast around Mars, so it also has to compensate for its own motion or the pictures will be blurred. This reduces the resolution to quite a bit less than the theoretical limit for the 'scope, so that's why they sent such a whopping big 'scope. <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>