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Running on the MoonFrancois Decuir
IntroductionIn reduced gravity <0.5g, running requires
less energy than walking
• In space, the pressure inside space suits is high enough that it helps support the total weight
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0006614#pone.0006614.s003
IntroductionSpace suits affect the walk-run transition by
mobility restriction, changes in stability, and increased joint mechanical work
VideoThe pressure in the space suit keeps the knee from buckling. This makes walking expend more energy.
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0006614#pone.0006614.s003
IntroductionFroude Number
By modeling walking as an inverted pendulum, we find that walking occurs only when Fr≤1.
IntroductionApollo Number
The Apollo number is defined as the Froude number multiplied by the inverse of the mass ratio M.
When no space suit is present, M=1 and Ap=Fr
Variablesv=velocityL=hip height or center of mass heightM=ratio of human carried mass to total
transported massg=gravitational accelerationα&β=shape and location of the state transition
PhysiologicalThe physiological variables include the length
of the leg, L, and the mass ratio, M.When attempting to manipulate the Apollo
number, the variable M can be changed. This can give either a higher or lower chance to be in a “run” state.
Important models
Change in M to keep the Apollo number constant.
Probability that gait=1
RecreationMATLAB was used to recreate
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0006614#pone.0006614.s003
Apollo Number
Walk
or R
un
sta
te
Alteration
To allow a shorter astronaut to run at the same speed as a taller astronaut, the weight of the space suit must be altered.
Lower space suit weight/Shorter hip height
Higher space suit weight/ Longer hip height
Ap
ollo
Nu
mb
er
Mass Ratio
PossibilitiesEmergency situation occurs
BenefitsOptimizing space suits for travel to the Moon
and Mars
ConclusionIn a suit with a higher mass, M, the walk-run
transition will occur at lower speedsAs loads reduce the self-support, M, walking
becomes possible at higher velocities
Questions