This paper first presents a double-node upset (DNU) protected and sextuple cross-coupled static-random-access memory (SRAM) cell, i.e., SCCS-18T, for aerospace applications. The cell can recover from each possible single-node upsets (SNUs) as well as partial DNUs due to its formed large feedback loop that can retain values and intercept errors. To improve DNU self-recoverability, an enhanced version of the SCCS-18T cell, namely SCCS-18T-EV, is proposed. Due to the new formed structure, the SCCS-18T-EV can recover from more DNUs. Since parallel access transistors are used, the proposed cells have optimized read/write performance. Simulation results demonstrate the node-upset tolerance as well as the optimized operation performance of the proposed SCCS-18T and SCCS-18T-EV cells compared to existing SRAM cells.