Section 1216.305 - Actions normally requiring an environmental assessment (EA)(a) NASA shall prepare an EA, which complies with 40 CFR 1501.5 , when a proposed action is not categorically excluded and is not likely to have significant effects or when the significance of the effects is unknown. NASA shall consider the potentially affected environment and degree of the effects of the action when determining whether to prepare an EA.(b) NASA actions normally requiring an EA include:(1) Altering the ongoing operations at a NASA Center where the significance of the environmental effect(s) is unknown.(2) Construction or modifications of facilities that represent a major change to an existing master plan and could result in a change in the environmental effect(s).(3) Actions that are expected to result in major changes to established land use.(4) Launching a spacecraft containing a space nuclear system. Space nuclear systems include radioisotope power systems, such as radioisotope thermoelectric generators and radioisotope heater units, and fission systems used for surface power and spacecraft propulsion. 89 FR 25502 , Apr. 11, 2024