Table 3.

Synopsis of commonly used facilities for microgravity research.

Devices	Principle	Application	Characteristic	Shortcoming	References
RPM	Randomizing the gravity vector direction and the gravity vector is averaged to nearly zero over time	Osteoblasts; T lymphocytes; adherent cells	Two axes with different speeds and directions	Cell behavior affected by the shear forces and other forces; no gas change	[29,62]
2-D Clinostat		Plants; small organism; unicellular; slow responsive living objects	One axis with fast and constant rotation	Vibration and centrifugal forces may lead to artifacts; no gas change	[63,64,65,66]
RWV (RCCS)		Suspended and anchorage-dependent cells; cell differentiation	Co-culture multiple cell types in a 3D spheroid morphology with low shear force	Lack of measurability; limited transfer of matter; additional environmental conditions such as the mixture	[67,68,69]
Parabolic Flight	Centrifugal forces counteract the gravity vector	Fast events, such as signal transduction, hormone secretion, binding of ligands to cell membranes	By controlling acceleration, creating a centrifugal force; about 25 s microgravity time	External conditions are not easy to control; high cost; short time of microgravity simulation	[25]