Advancing Human Spaceflight Act of 2021 This bill establishes programs and policies pertaining to human presence in space. The National Aeronautics and Space Administration (NASA) shall establish a program to develop next-generation space suits and associated technologies, establish an outpost in orbit around the Moon as described in this bill, and submit a plan for achieving a power supply on the Moon. The bill declares that it is U.S. policy to continuously maintain the capability for a continuous human presence in low-Earth orbit through and beyond the useful life of the International Space Station (ISS) and that such capability shall maintain U.S. global leadership and relations with partners and allies, contribute to the general welfare of the United States, and leverage commercial capabilities to promote affordability so as not to preclude a robust portfolio of other human space exploration activities. NASA shall ensure that the ISS remains a viable and productive facility capable of potential U.S. use through at least FY2030. NASA must submit a strategy that includes how it will transition to a successor platform to the ISS. The Office of Science and Technology Policy shall conduct a study on the manner in which NASA funds missions of national need.