<br />many say that the Shuttle is unnecessary because the (2015?) 125 tons payload SDHLV will be a great replacement for heavy payload<br /><br />but many forget that Shuttle is not only an heavy-payload-rocket... Shuttle is able to MOVE its payload from orbit to orbit, assemble it and (if necessary) bring back a payload to earth<br /><br />for THAT reasons the Shuttle weight is 100 tons and its payload only 25 tons (engines, fuel, navigation system, return to earth, wings for landing, reusability, crew, robot-arm, assembly tools, etc.)<br /><br />an HLV may launch 125 tons payload only if it will be a "dumb" 125 tons satellite to be launched in a predefined orbit (how many 125 tons satellites may be launched???)<br /><br />but if we need the SAME work of Progress, cargoCEV and Shuttle, we must add engines, propellant, and navigation system to the HLV payload... this will reduce very much the REAL payload of an HLV as "Shuttle replacement"<br /><br />the Shuttle's total-weight/net-payload ratio is 125tons/25tons<br /><br />with Progress it is 8tons/2.4tons<br /><br />with the unpressurized cargo-CEV (see image below) it will be 19tons/6tons<br /><br />then, as "Shuttle replacement", the 125 tons HLV may send LESS than 40 "net" tons of "Shuttle-like" payload!!!!!!!! ...like two shuttle launches! (but WITHOUT an 8 astronauts crew that need TWO orbital-CEV launches, without robot-arm, etc.)<br /><br />and... just imagine the cost of each SDHLV launch...<br />