  We investigated the reliability of the genetic algorithm which will be used
to invert the photometric measurements of asteroids collected by the European
Space Agency Gaia mission. To do that, we performed several sets of simulations
for 10 000 asteroids having different spin axis orientations, rotational
periods and shapes. The observational epochs used for each simulation were
extracted from the Gaia mission simulator developed at the Observatoire de la
C\^{o}te d'Azur, while the brightness was generated using a Z-buffer standard
graphic method. We also explored the influence on the inversion results of
contaminating the data set with Gaussian noise with different $\sigma$ values.
The research enabled us to determine a correlation between the reliability of
the inversion method and the asteroid's pole latitude. In particular, the
results are biased for asteroids having quasi-spherical shapes and low pole
latitudes. This effect is caused by the low lightcurve amplitude observed under
such circumstances, as the periodic signal can be lost in the photometric
random noise when both values are comparable, causing the inversion to fail.
Such bias might be taken into account when analysing the inversion results, not
to mislead it with physical effects such as non-gravitational forces. Finally,
we studied what impact on the inversion results has combining a full lightcurve
and Gaia photometry collected simultaneously. Using this procedure we have
shown that it is possible to reduce the number of wrong solutions for asteroids
having less than 50 data points. The latter will be of special importance for
planning ground-based observations of asteroids aiming to enhance the
scientific impact of Gaia on Solar system science.
