Space Technology Advisory Committee Act of 2021 This bill sets out a process for reviewing applications and licenses for commercial space activities to determine whether an application or license poses a risk to national security or public safety. Specifically, the bill establishes a committee to assist the Federal Aviation Administration, the Department of Transportation, and the Federal Communications Commission review applications and licenses for the use of launch sites, launch and reentry vehicles, commercial spaceports, commercial Earth remote sensing satellites, or commercial satellite communications. For each application or license reviewed by the committee, the Office of the Director of National Intelligence must issue a written assessment of any national security threat related to the application or license.