JonClarke:<br />Remember that SSTO is much easier on Mars than on earth, orbital velocity is only 5 km/s.<br /><br />Me:<br />Correct, which means the design will be scaled to operate on mars and as such, will require propellant loads consistent with the vehicles size. The DC-X or Delta Clipper could probably almost go to orbit from mars and return to the surface. If a DC-Y were built for mars, then additional payload capacity would be present.<br /><br />JonClarke:<br />Surface yes, but why in orbit?<br /><br />Me:<br />If used repeatedly, the vehicle will be in orbit when it prepares to land. It will be at maximum propellant load for landing, and then subsequent return to orbit where a propellant depot would be required to allow repeated landing and orbital return cycles.<br /><br />JonClarke:<br />"But then, anything mars will involve more than what is generally anticipated or proposed in mars mission plans." <br /><br />Meaning?<br /><br />Me:<br />Just that anything we plan to do, we almost always run into some unanticipated bumps in the road. This really applies to just about any major planning. But where mars is concerned, when plans reach the public, they almost always show only the main gist of the plan. An example being a mars lander on the cover of a magazine with an astronaut outside. Unless the magazine goes into great detail, and the plan itself includes great detail, the public only gets a general idea of what to expect.<br /><br />We always here the tagline in books and movies..."Things didn't go according to plan". We hear it so much, its cliche. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>