  In recent years, cold atoms could prove their scientific impact not only on
ground but in microgravity environments such as the drop tower in Bremen,
sounding rockets and parabolic flights. We investigate the preparation of cold
atoms in an optical dipole trap, with an emphasis on evaporative cooling under
microgravity. Up to $ 1\times10^{6} $ rubidium-87 atoms were optically trapped
from a temporarily dark magneto optical trap during free fall in the droptower
in Bremen. The efficiency of evaporation is determined to be equal with and
without the effect of gravity. This is confirmed using numerical simulations
that prove the dimension of evaporation to be three-dimensional in both cases
due to the anharmonicity of optical potentials. These findings pave the way
towards various experiments on ultra-cold atoms under microgravity and support
other existing experiments based on atom chips but with plans for additional
optical dipole traps such as the upcoming follow-up missions to current and
past spaceborne experiments.
