Launcher size optimization for a crewed Mars mission

Several proposals exist for human Mars mission architectures. An important question to resolve is to determine the most appropriate size of the launcher to minimize the costs, without compromising with risks, efficiency and future developments. Strategic choices are proposed. A fundamental choice is the direct to surface option, one that greatly simplifies the architecture of the mission and avoids a complex and costly LEO assembly of a giant vehicle. The second is aerocapture for Mars orbit insertion. The third is the choice of the EDL systems with highest TRL in order to minimize the risks of the mission and at the same time to avoid possible cost overruns due to qualification issues. Minimization is achieved for a crew of three. It is shown that an LEO capacity of the order of 100–110 tonnes is sufficient to carry out a Mars mission using 5 heavy launchers. This result is of particular interest for the countries currently developing super heavy launchers with such capacity, like the Starship and SLS in the USA, Long March 9 in China and similar developments in Russia. If Europe were also interested in the design of a super heavy launcher, it is shown here that it could be based on Vulcain or Prometheus engines. As the mission is rather simple and optimized with high TRL, the mission could be affordable. A roadmap is also suggested with appropriate preparatory missions for a human Mars exploration program.