The curation of extraterrestrial samples (astromaterials) obtained by sample-return missions take place at facilities specially designed to preserve both the sample integrity and protect the Earth. Astromaterials are classified as either non-restricted or restricted, depending on the nature of the Solar System body. Non-restricted samples include the Moon, asteroids, comets, solar particles and space dust. Restricted bodies include planets or moons suspected to have either past or present habitable environments to microscopic life, and therefore must be treated as extremely biohazardous. Overview Spacecraft instruments are subject to mass and power constraints, in addition of the limitations imposed by the extreme environment of outer space on the sensitive science instruments, so bringing extraterrestrial material to Earth is desired for extensive scientific analyses. For the purpose of planetary protection, astromaterial samples brought to Earth by sample-return missions must be received and curated in a specially-designed and equipped biocontainment facility that must also double as a cleanroom to preserve the science value of the samples. Samples brought from non-restricted bodies such as the Moon, asteroids, comets, solar particles and space dust, are processed at specialized facilities rated Biosafety level-3 (BSL-3). Samples brought to Earth from a planet or moon suspected to have either past or present habitable environments to microscopic life would make it a Category V body, and must be curated at facilities rated Biosafety level-4 (BSL-4), as agreed in the Article IX of the Outer Space Treaty. However, the existing BSL-4 facilities in the world do not have the complex requirements to ensure the preservation and protection of Earth and the sample simultaneously. While existing BSL-4 facilities deal primarily with fairly well-known organisms, a BSL-4 facility focused on extraterrestrial samples must pre-plan the systems carefully while being mindful that there will be unforeseen issues during sample evaluation and curation that will require independent thinking and solutions. A challenge is that, while it is relatively easy to simply contain the samples once returned to Earth, researchers will want to take a portion and perform analyses. During all these handling procedures, the samples would need to be protected from Earthly contamination and from contact with the atmosphere. Non-restricted materials As of 2019, only the Japanese space agency JAXA and the United States space agency NASA operate BSL-3 laboratories in the world exclusively dedicated to the curation of samples from non-restricted bodies. The key feature of JAXA's curation facility, the Extraterrestrial Sample Curation Center,