  Jupiter Trojan asteroids are minor bodies that share Jupiter's orbit around
the Sun. Although not yet well understood in origin and composition, they have
surface properties that, besides being comparable with other populations of
small bodies in the Solar System, hold information that may restrict models of
planetary formation. Due their importance, there has been a significant
increase in an interest in studying this population. In this context arises the
NASA Lucy Mission, with a planned launch of 2021. The Lucy Mission will be the
first one to address a group of 6 objects with the aim of investigating, in
detail, their nature. In order to provide valuable information for mission
planning and maximize the scientific return, we carried out ground based
observations of four targets of the mission. Aimed at looking for variabilities
on the spectra of (3548) Eurybates, (15094) Polymele and (21900) Orus, we
performed rotationally resolved visible spectroscopy of them at SOAR Telescope.
We also analyzed the first visible spectrum obtained for the main belt asteroid
(52246) Donaldjohanson at Gran Telescopio Canarias. The spectra of Orus and
Polymele present rather homogeneous characteristics along the surfaces, and
their taxa correspond with those of the two dominant populations in the Trojan
population, the P- and the D-type group of objects. Spectroscopy of Eurybates,
on the other side, suggests that some variation on the characteristics of the
reflectance of this body could be related with its collisional history.
Donaldjohanson, the only main belt object in the group of targets, shows,
according to our visible spectrum, hints of the presence of hydrated materials.
Lucy mission will investigate the surface composition of these targets and will
shed light on their connections with other minor bodies populations and in
their role on the evolution of the Solar System.
