Overview of the Different Devices and Techniques for Simulated Microgravity
Rotating Wall Vessel (RWV)
Aiming to construct a machine that allows the simulation of weightlessness, the RWV was developed. It has been used by the National Aeronautics and Space Administration (NASA) since the early 1990s. The design and principle of the RWV is as follows: A chamber, completely filled with culture medium and a defined number of cells, rotates around an axle and is so subjecting the cells to a continuous free fall. The rotation speed regulates the fall velocity . Due to the continuous free fall, cells are not able to attach to the chamber surface but they attach to each other and form three-dimensional constructs.
A similar design principle is exhibited by the 2D clinostat. The rotation takes place around an axle perpendicular to the gravity force vector. In contrast to the RWV, weightlessness is obtained through vector averaging of the gravity force vector and results below 1g when the clinostat rotates fast enough (40-100 rpm). Rotation samples like cultured cells are centered in the middle of the clinostat. However, a big drawback of the 2D clinostat is the rotation velocity. Is the velocity too high, the clinostat turns into a centrifuge. Furthermore, just cells or plants small enough to fit centered into the rotation axis can be rotated with the clinostat, because any part of a sample larger than the rotation axis would experience centrifugal forces.
The Random Positioning Machine (RPM) simulates low gravity conditions (microgravity).
It was developed by T. Hoson in Japan and manufactured by Dutch Space (former Fokker Space).
The basic principle consists of an inner and an outer frame rotating independently from each
other in random direction. The samples in the centre of the machine experience low gravity
as the gravity vector is averaged to zero over time.
Marcel Egli`s group improved and re-designed the Fokker Space RPM.
Features of the new RPM
* CO2-Incubator with temperature and CO2-level control
* Various operation modes: Random Walk, Swing, Partial gravity, Cyclic operation
* Programmable sequence with programmable start and stop
* Double check with 3D-accelerometer
* Automatic data acquisition and report generation
* Two channels for liquids or pressurized gases
* Wireless access and web service for monitoring purposes
* Visual and acoustic signals (status of machine)
standing in the lab of Marcel Egli (Hochschule Luzern)
standing at University Clinic Magdeburg
Figures courtesy of Dutch space, an EADS Astrium company, the Netherlands
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