The H2GO project presents the design of H2ERMES, a reusable launch vehicle developed to autonomously deliver liquid hydrogen (LH2) to orbital fuel depots, supporting the advancement of nuclear thermal rocket (NTR) propulsion for deep space missions. The vehicle, optimized for environmental and economic sustainability, features a reusable second stage with novel technologies, including a regeneratively cooled heat shield, aerospike-effect propulsion, and cryogenic LH2 storage integrated with structural elements. H2ERMES is designed for 25 or more missions with minimal refurbishment, meeting stringent performance, safety, and sustainability requirements. A comprehensive systems engineering approach defined user and stakeholder requirements, conducted risk analyses, and performed extensive subsystem trade-offs. The final design includes high-efficiency LH2 tanks, a 24-chamber aerospike engine using an expander bleed cycle, actively cooled heat shield, autonomous docking systems, and reliable recovery mechanisms. The project addresses growing market needs for sustainable space infrastructure, with first operational flights planned by 2032 to enable economical, reusable, and low-emission LH2 transport to orbit.