  Space weathering is a process that changes the surface of airless planetary
bodies. Prime space weathering agents are solar wind irradiation and
micrometeoroid bombardment. These processes alter planetary reflectance spectra
and often modify their compositional diagnostic features. In this work we
focused on simulating and comparing the spectral changes caused by solar wind
irradiation and by micrometeoroid bombardment to gain a better understanding of
these individual space weathering processes. We used olivine and pyroxene
pellets as proxies for planetary materials. To simulate solar wind irradiation
we used hydrogen, helium, and argon ions with energies from 5 to 40 keV and
fluences of up to $10^{18}$ particles/cm$^2$. To simulate micrometeoroid
bombardment we used individual femtosecond laser pulses. We analysed the
corresponding evolution of different spectral parameters, which we determined
by applying the Modified Gaussian Model, and we also conducted principal
component analysis. The original mineralogy of the surface influences the
spectral evolution more than the weathering agent, as seen from the diverse
evolution of the spectral slope of olivine and pyroxene upon irradiation. The
spectral slope changes seen in olivine are consistent with observations of
A-type asteroids, while the moderate to no slope changes observed in pyroxene
are consistent with asteroid (4) Vesta. We also observed some differences in
the spectral effects induced by the two weathering agents. Ions simulating
solar wind have a smaller influence on longer wavelengths of the spectra than
laser irradiation simulating micrometeoroid impacts. This is most likely due to
the different penetration depths of ions and laser pulses. Our results suggest
that in some instances it might be possible to distinguish between the
contributions of the two agents on a weathered surface.
