Doctoral Dissertations


Masafumi Iai

Keywords and Phrases

In-Situ Resource Utilization (ISRU)


"As humanity's activities expand to the Moon, Mars, and other extra-terrestrial bodies, it will be necessary to use local resources rather than bringing everything from the Earth. This concept is called In-Situ Resource Utilization (ISRU), which starts with excavation and earthmoving. The present study focuses on loosening and moving of the lunar regolith by a ripper (or rake) and a wide blade with consideration of gravel content. After characterizing the lunar regolith and two of its simulants (JSC-1A and FJS-1), the relationship between the excavation energy and different conditions, namely gravel content, relative density, and tine spacing on a rake, is investigated with scaled experiments. Geotechnical properties of JSC-1A were determined, in addition to the simulants' stress-strain relationships over a wide range of relative density (13% to near 100%). Gravel content of the lunar regolith, often overlooked in previous studies, is estimated based on the data of 11 Apollo cores, which reveals the maximum local gravel content is about 30% by weight. Also the grain size distribution of the lunar regolith up to 1 m grains is created by combining the data from Apollo and Surveyor missions. In the experiments, gravel (2 mm - 10 mm) is added to JSC-1A. In addition, a math model of the ripping force is developed as a function of material density, which could be the basis of an instrumented-ripper technique for detailed mapping of construction. Prior ripping decreases total excavation energy by up to 20% if the relative density is ≥ 60% and the gravel content is ≤ 10%. The optimal tine spacing for JSC-1A at a penetration depth of 30 mm is 30 mm. Even a gravel content of 5% increases the reaction force on excavation tools, which underlines the necessity of consideration of gravel content for lunar excavation planning"--Abstract, page iii.


Gertsch, Leslie S.

Committee Member(s)

Cawlfield, Jeffrey D.
Luna, Ronaldo
Rogers, J. David
Maerz, Norbert H.


Geosciences and Geological and Petroleum Engineering

Degree Name

Ph. D. in Geological Engineering


Missouri University of Science and Technology

Publication Date

Fall 2010


xiii, 215 pages

Note about bibliography

Includes bibliographical references (pages 203-214).


© 2010 Masafumi Iai, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Subject Headings

Excavation -- Methodology
Lunar soil -- Analysis
Soil ripping
Space mining

Thesis Number

T 9698

Print OCLC #


Electronic OCLC #