Availability and Delta-V Requirements for Delivering Water Extracted from Near-Earth Objects to Cis-Lunar Space


We have calculated the number of water-bearing near-Earth objects as a function of return-trip delta-v (ΔvRT). First, we combined a model of the near-Earth object's (NEO) orbit and size-frequency distribution with other measurements of their provenance, and the taxonomic distribution of asteroids in the NEO's main belt sources, to calculate the taxonomic distribution of NEOs as a function of their orbital elements and size. Our calculations are in agreement with recent measurements of the ratio of C- and S-complex bodies within the population of small NEOs. Then we developed a simplified mission model to calculate an upper limit on ΔvRT for a mission from an NEO to distant retrograde lunar orbit (DRLO) in cis-lunar space. Combining the first two steps allowed us to develop a synthetic population of low ΔvRT NEOs that includes their taxonomic distribution. Finally, we used measurements of the water-bearing content of the taxonomic classes based on their assumed meteorite associations to calculate the number of water-bearing NEOs as a function of ΔvRT. We find that there are likely thousands of H2O-rich NEOs larger than about 5 m diameter with ΔvRT≲3kms−1 and the number of objects increases as ΔvRT 3. The rapid increase in the number of objects with ΔvRT suggests that in-situ resource utilization (ISRU) of asteroid-derived water can expand quickly throughout the solar system. NEOs with ΔvRT≲3kms−1 tend to be on Earth-like orbits with semi-major axes a∼1au, eccentricities e≳0, and inclinations i≳0⁰. The small, dark, low ΔvRT NEOs are difficult or impossible to detect with Earth-based telescopes because many orbit the Sun interior to Earth's orbit and others have such long synodic periods that they are rarely visible.


Geosciences and Geological and Petroleum Engineering


United States. National Aeronautics and Space Administration


This work was funded in part by grants to Joel Sercel and TransAstra Corporation from the NASA NIAC program (80NSSC18K0110 and 80NSSC18K0111) and to Leslie Gertsch from the NASA ESI program (NNX15AD80G). Karen Morenz's work was funded by the University of Toronto Dean's International Initiatives Fund.

Keywords and Phrases

ISRU; Near-Earth object; NEO; Taxonomy; Water-mining

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Article - Journal

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© 2018 Elsevier, All rights reserved.

Publication Date

15 Sep 2018