ESA Document - Emits - ESA

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Figure 2-42: Radial acceleration depending on rotational radius and angular velocity
Two options are considered:
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 86 of 423
Option 1: Rotation of two end masses at the extremities of a long structure. Additional structure
is required, as well a propulsion system to spin the vehicle, power, avionics, and tether or truss
deployment mechanisms. The increase in the dry mass of the spacecraft is estimated to be 20%.
Option 2: Take advantage of the existing design of the entire vehicle (THM, Propulsion Stages
and MEV) and its configuration and rotate it. With the current design, however, the comfort zone
cannot be achieved.
In both cases the complexity of the configuration is increased and some operational constraints
are introduced, because no EVA is possible while the spacecraft is spinning. Therefore this
option was rejected.
2.7.14.1.2 Shor- arm centrifuge
The short-arm centrifuge option results more realistic, simple and effective. From a practical
perspective, it is very likely that humans do not need gravity (or a fraction of it) 24 hours a day
to remain healthy. If intermittent gravity is proven to be sufficient, an on-board centrifuge
presents a realistic near-term opportunity for providing artificial gravity.
For the purpose of this study, a 4.5-metre diameter, two-man balanced centrifuge was
considered. It incorporates an exercise cycle or treadmill and has a spin rate of 21 rpm for 1g at
the feet and 13 rpm for 0.38g. This centrifuge would have a mass of about 450 kg and would be
used in combination with 2 flywheel crew exercise devices to minimise muscle deconditionning.