A fuel tank for a spacecraft stores a liquid fuel and a pressurized
propellant gas that drives the fuel out of the tank through a fuel
extraction arrangement including a reservoir or collection container and
a tank outlet. The collection container bounds a fuel reservoir space
that communicates with the interior space of the tank, and fuel flow
channels connect the reservoir space to an outlet pipe. A side or area of
the collection container opposite the fuel flow channels is provided with
one or more grooves. These structures produce a capillary pumping effect
and use the surface tension to separate the fuel from the propellant gas.