Since the landing on the lunar surface, the lunar regolith has begun to interact in different ways with landed elements, such as the wheels of a rover, astronaut suits, drills, and plants for extracting oxygen or manufacturing objects. Therefore, a strong effort has been required on Earth to fully characterise these kinds of interactions and regolith utilisation methods. This operation can only be performed by using regolith simulants, soils that are reproduced with the Earth's rocks and minerals to match the real features. This article presents the main guidelines and tests for obtaining the properties of a generic simulant in terms of composition, physical and mechanical properties, solid-fluid interaction, and thermal properties. These parameters are needed for the designing and testing of payloads under development for planned lunar surface missions. The same tests can be performed on lunar, martian, or asteroid simulants/soils, both in laboratory and in situ. A case study is presented on the lunar simulant NU-LHT-2M, representative of the lunar highlands. The tests are performed in the context of an in situ resource utilisation (ISRU) process that aims to extract oxygen from the lunar regolith using a low-temperature carbothermal reduction process, highlighting the main regolith-related criticalities for an in situ demonstrator plant.

Incorporation of in situ resource utilization (ISRU) and the production of mission-critical consumables for propulsion, power, and life support into mission architectures can greatly reduce the mass, cost, and risk of missions, leading to a sustainable and affordable approach to human exploration beyond Earth. ISRU and its products can also greatly affect how other exploration systems are developed, including determining which technologies are important or enabling. Although the concept of lunar ISRU has existed for more than 40 years, the technologies and systems had not progressed much past simple laboratory proof-of-concept tests. With the release of the Vision for Space Exploration in 2004 with the goal of harnessing the Moon's resources, the National Aeronautics and Space Administration (NASA) initiated the ISRU project in the Exploration Technology Development Program (ETDP) to develop the technologies and systems needed to meet this goal. In the 5 years of work in the ISRU Project, significant advancements and accomplishments occurred in several important areas of lunar ISRU. Also, two analog field tests held in Hawaii in 2008 and 2010 demonstrated all the steps in ISRU capabilities required, along with the integration of ISRU products and hardware with propulsion, power, and cryogenic storage systems. This paper will review the scope of the ISRU Project in the ETDP, ISRU incorporation, development strategies used by the ISRU project, and ISRU development and test accomplishments over the 5 years of funded project activity. DOI: 10.1061/(ASCE)AS.1943-5525.0000208. (C) 2013 American Society of Civil Engineers.