Illustration of the European Radiation Sensors Array (ERSA), a space weather measurement instrument that will be part of the planned Lunar Gateway, or simply Gateway, space station. ERSA will measure solar wind (energetic particles from the sun) to determine the risk posed to astronauts and their equipment. The Gateway is a small space station that will orbit the Moon and is planned for launch no earlier than 2025. It is a joint programme between the USA (NASA), Europe (ESA), Japan (JAXA), Canada (CSA) and the UAE (Mohammed Bin Rashid Space Centre). It will act as a staging post for missions to the Moon and Mars, and as a communications relay and scientific laboratory.