The Apollo Number: space suits, self-support, and the walk-run
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 wal...
| Main Authors: | , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
Public Library of Science
2010
|
| Online Access: | http://hdl.handle.net/1721.1/54794 |
| _version_ | 1826211143380631552 |
|---|---|
| author | McGee, Jeremy Carr, Christopher E. |
| 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 McGee, Jeremy Carr, Christopher E. |
| author_sort | McGee, Jeremy |
| 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 = v[superscript 2]/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* (0.36±0.11, mean±95% CI) and Ap* (0.68±0.20).
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 | 2024-09-23T15:01:38Z |
| format | Article |
| id | mit-1721.1/54794 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T15:01:38Z |
| publishDate | 2010 |
| publisher | Public Library of Science |
| record_format | dspace |
| spelling | mit-1721.1/547942022-10-02T00:01:50Z The Apollo Number: space suits, self-support, and the walk-run McGee, Jeremy Carr, Christopher E. Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Carr, Christopher E. Carr, Christopher E. 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 = v[superscript 2]/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* (0.36±0.11, mean±95% CI) and Ap* (0.68±0.20). 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. 2010-05-14T18:24:02Z 2010-05-14T18:24:02Z 2009-08 2009-07 Article http://purl.org/eprint/type/JournalArticle 1932-6203 http://hdl.handle.net/1721.1/54794 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 en_US http://dx.doi.org/10.1371/journal.pone.0006614 PLoS ONE Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf Public Library of Science PLoS |
| spellingShingle | McGee, Jeremy Carr, Christopher E. The Apollo Number: space suits, self-support, and the walk-run |
| title | The Apollo Number: space suits, self-support, and the walk-run |
| title_full | The Apollo Number: space suits, self-support, and the walk-run |
| title_fullStr | The Apollo Number: space suits, self-support, and the walk-run |
| title_full_unstemmed | The Apollo Number: space suits, self-support, and the walk-run |
| title_short | The Apollo Number: space suits, self-support, and the walk-run |
| title_sort | apollo number space suits self support and the walk run |
| url | http://hdl.handle.net/1721.1/54794 |
| work_keys_str_mv | AT mcgeejeremy theapollonumberspacesuitsselfsupportandthewalkrun AT carrchristophere theapollonumberspacesuitsselfsupportandthewalkrun AT mcgeejeremy apollonumberspacesuitsselfsupportandthewalkrun AT carrchristophere apollonumberspacesuitsselfsupportandthewalkrun |