ABORT OPTIONS FOR POTENTIAL MARS MISSIONS

Mars trajectory design options were examined that would accommodate a premature termination of a nominal manned opposition class mission for opportunities between 2010 and 2025. A successful abort must provide a safe return to Earth in the shortest possible time consistent with m ission constraints. In this study, aborts that provided a minimum incr ease in the initial vehicle mass in low Earth orbit (IMLEO) were ident ified by locating direct transfer nominal missions and nominal mission s including an outbound or inbound Venus swing-by that minimized IMLEO . The ease with which these missions could be aborted while meeting pr opulsion and time constraints was investigated by examining free retur n (unpowered) and powered aborts. Further reductions in trip time were made to some aborts by the addition or removal of an inbound Venus sw ing-by. The results show that, although few free return aborts met the specified constraints, 85% of each nominal mission could be aborted a s a powered abort without an increase in propellant. Also, in many cas es, the addition or removal of a Venus swing-by increased the number o f abort opportunities or decreased the total trip time during an abort .