In a microgravity environment liquid can be pumped and positioned by cohesion and adhesion forces. On earth this effect is covered by the hydrostatic pressure so it can only be observed in very fine tubes (so-called capillaries). In this case a finite liquid height resulting from the balance of the capillary force and the weight of the amount of liquid lifted up occurs. If the gravity acceleration tends to zero the liquid height becomes infinite. In surface tension tanks this effect is used to pump propellant via capillary vanes without any additional energy supply.