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Hydrated minerals are tracers of early solar system history and have been proposed as a possible focus for economic activity in space. Near-Earth objects (NEOs) are important to both of these, especially the most accessible members of that community. Because there are very few identified hydrated NEOs, we use the Ch spectral class of asteroids as a proxy for hydrated asteroids and use published work about NEO delivery, main-belt taxonomic distributions, NEO taxonomic distributions, and observed orbital distributions to estimate the number of hydrated asteroids with different threshold sizes and at different levels of accessibility. We expect 5327 Ch asteroids to be present in the known population of NEOs >1-km diameter, and using two different approaches to estimate accessibility we expect 179 of them to be more accessible on a round trip than the surface of the Moon. If there is no need to define a minimum size, we expect 700350 hydrated objects that meet that accessibility criterion. While there are few unknown NEOs larger than 1km, the population of smaller NEOs yet to be discovered could also be expected to contain proportionally many hydrated objects. Finally, we estimate that hydrated NEOs are unlikely to bring enough water to account for the ice found at the lunar poles, though it is possible that asteroid-delivered hydrated minerals could be found near their impact sites across the lunar surface. Plain Language Summary We know that some asteroids formed with water ice, and that early in solar system history that ice melted and reacted with rock to create hydrated minerals, which have water as part of their structure. Asteroidal hydrated minerals are particularly interesting because they often are found along with organic materials, and it is thought that asteroids may have been important for bringing water and organic materials to the early Earth via impacts. Hydrated minerals are also of interest to asteroid mining companies, which hope to make their extraction and processing as the basis for their business. For these reasons, we are interested in understanding how common hydrated asteroids are in the population of objects with orbits like the Earth's. There are a few different ways we can make the calculation, but all of the estimates suggest that hydrated asteroids are more common than we would think from the pieces that fall to Earth, and that dozens of them are larger than 1 km in diameter and take less fuel for a round-trip spacecraft than to the surface of the Moon.

来源平台：JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS