The Apollo Number: Space Suits, Self-Support, and the Walk-Run Transition
Background: How space suits affect the preferred walk-run transition is an open question with relevance to human biomechanics and planetary extravehicular activity. Walking and running energetics differ; in reduced gravity (,0.5 g), running, unlike on Earth, uses less energy per distance than walk...
| Main Authors: | , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
2010
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| Online Access: | http://hdl.handle.net/1721.1/52418 |
| _version_ | 1826204367450013696 |
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| author | Carr, Christopher E. McGee, Jeremy |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Carr, Christopher E. McGee, Jeremy |
| author_sort | Carr, Christopher E. |
| collection | MIT |
| description | Background: How space suits affect the preferred walk-run transition is an open question with relevance to human
biomechanics and planetary extravehicular activity. Walking and running energetics differ; in reduced gravity (,0.5 g),
running, unlike on Earth, uses less energy per distance than walking.
Methodology/Principal Findings: The walk-run transition (denoted *) correlates with the Froude Number (Fr = v2/gL,
velocity v, gravitational acceleration g, leg length L). Human unsuited Fr* is relatively constant (,0.5) with gravity but
increases substantially with decreasing gravity below ,0.4 g, rising to 0.9 in 1/6 g; space suits appear to lower Fr*. Because
of pressure forces, space suits partially (1 g) or completely (lunar-g) support their own weight. We define the Apollo Number
(Ap = Fr/M) as an expected invariant of locomotion under manipulations of M, the ratio of human-supported to total
transported mass. We hypothesize that for lunar suited conditions Ap* but not Fr* will be near 0.9, because the Apollo
Number captures the effect of space suit self-support. We used the Apollo Lunar Surface Journal and other sources to
identify 38 gait events during lunar exploration for which we could determine gait type (walk/lope/run) and calculate Ap.
We estimated the binary transition between walk/lope (0) and run (1), yielding Fr* (0.3660.11, mean695% CI) and Ap*
(0.6860.20).
Conclusions/Significance: The Apollo Number explains 60% of the difference between suited and unsuited Fr*, appears to
capture in large part the effects of space suits on the walk-run transition, and provides several testable predictions for space
suit locomotion and, of increasing relevance here on Earth, exoskeleton locomotion. The knowledge of how space suits
affect gait transitions can be used to optimize space suits for use on the Moon and Mars. |
| first_indexed | 2024-09-23T12:53:31Z |
| format | Article |
| id | mit-1721.1/52418 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T12:53:31Z |
| publishDate | 2010 |
| record_format | dspace |
| spelling | mit-1721.1/524182022-09-28T10:42:33Z The Apollo Number: Space Suits, Self-Support, and the Walk-Run Transition Carr, Christopher E. McGee, Jeremy Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Carr, Christopher E. Carr, Christopher E. McGee, Jeremy Background: How space suits affect the preferred walk-run transition is an open question with relevance to human biomechanics and planetary extravehicular activity. Walking and running energetics differ; in reduced gravity (,0.5 g), running, unlike on Earth, uses less energy per distance than walking. Methodology/Principal Findings: The walk-run transition (denoted *) correlates with the Froude Number (Fr = v2/gL, velocity v, gravitational acceleration g, leg length L). Human unsuited Fr* is relatively constant (,0.5) with gravity but increases substantially with decreasing gravity below ,0.4 g, rising to 0.9 in 1/6 g; space suits appear to lower Fr*. Because of pressure forces, space suits partially (1 g) or completely (lunar-g) support their own weight. We define the Apollo Number (Ap = Fr/M) as an expected invariant of locomotion under manipulations of M, the ratio of human-supported to total transported mass. We hypothesize that for lunar suited conditions Ap* but not Fr* will be near 0.9, because the Apollo Number captures the effect of space suit self-support. We used the Apollo Lunar Surface Journal and other sources to identify 38 gait events during lunar exploration for which we could determine gait type (walk/lope/run) and calculate Ap. We estimated the binary transition between walk/lope (0) and run (1), yielding Fr* (0.3660.11, mean695% CI) and Ap* (0.6860.20). Conclusions/Significance: The Apollo Number explains 60% of the difference between suited and unsuited Fr*, appears to capture in large part the effects of space suits on the walk-run transition, and provides several testable predictions for space suit locomotion and, of increasing relevance here on Earth, exoskeleton locomotion. The knowledge of how space suits affect gait transitions can be used to optimize space suits for use on the Moon and Mars. 2010-03-09T18:07:26Z 2010-03-09T18:07:26Z 2009-08 2009-04 Article http://purl.org/eprint/type/JournalArticle 1932-6203 http://hdl.handle.net/1721.1/52418 Carr CE, McGee J (2009) The Apollo Number: Space Suits, Self-Support, and the Walk-Run Transition. PLoS ONE 4(8): e6614. doi:10.1371/ journal.pone.0006614 19672305 en_US http://dx.doi.org/10.1371/journal.pone.0006614 PLoS ONE Creative Commons Attribution http://creativecommons.org/licenses/by/2.5/ application/pdf PLoS |
| spellingShingle | Carr, Christopher E. McGee, Jeremy The Apollo Number: Space Suits, Self-Support, and the Walk-Run Transition |
| title | The Apollo Number: Space Suits, Self-Support, and the Walk-Run Transition |
| title_full | The Apollo Number: Space Suits, Self-Support, and the Walk-Run Transition |
| title_fullStr | The Apollo Number: Space Suits, Self-Support, and the Walk-Run Transition |
| title_full_unstemmed | The Apollo Number: Space Suits, Self-Support, and the Walk-Run Transition |
| title_short | The Apollo Number: Space Suits, Self-Support, and the Walk-Run Transition |
| title_sort | apollo number space suits self support and the walk run transition |
| url | http://hdl.handle.net/1721.1/52418 |
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