Technology advancements in recent years have led to an increase in the employment of integrated circuits in space applications. However, these applications operate in a highly radiated environment, causing a high probability of single event upsets (SEU). Continuous transistor scaling exacerbates the situation, as susceptibility to SEUs is increased in advanced process technologies. The most vulnerable of these circuits are memory arrays that cover large areas of the silicon die and often store critical data. Accordingly, maintaining data integrity in light of SEUs has become an integral aspect of memory cell design. This paper introduces recently proposed methods for mitigating SEUs, and reviews the advantages and disadvantages of leading memory radiation hardening solutions. A brief comparison of radiation hardened bitcells is provided, based on Monte Carlo simulations in a 65nm CMOS process under slightly scaled supply voltages.