How Many Hydrated NEOs Are There?. (arXiv:1812.02285v1 [astro-ph.EP])

How Many Hydrated NEOs Are There?. (arXiv:1812.02285v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Rivkin_A/0/1/0/all/0/1">Andrew S. Rivkin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+DeMeo_F/0/1/0/all/0/1">Francesca E. DeMeo</a>

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 53 $pm$ 27 Ch asteroids to be present in
the known population of NEOs $>$ 1 km diameter, and using two different
approaches to estimate accessibility we expect 17 $pm$ 9 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 700 $pm$ 350 hydrated objects that meet that
accessibility criterion. While there are few unknown NEOs larger than 1 km, 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.

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 53 $pm$ 27 Ch asteroids to be present in
the known population of NEOs $>$ 1 km diameter, and using two different
approaches to estimate accessibility we expect 17 $pm$ 9 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 700 $pm$ 350 hydrated objects that meet that
accessibility criterion. While there are few unknown NEOs larger than 1 km, 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.

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