  Here we report a comparison between reflectance spectroscopy of meteorites
under asteroidal environment (high vacuum and temperature) and Main Belt and
Near Earth Asteroids spectra. Focusing on the OH absorption feature around
3{\mu}m, we show that the asteroidal environment induces a reduction of depth
and width of the band, as well as a shift of the reflectance minimum. We then
decompose the OH feature into several components with a new model using
Exponentially Modified Gaussians. Unlike previous studies, we confirme the link
between these components, the aqueous alteration history and the amount of
water molecules inside of the sample, using the shape of this spectral feature
only. We then apply this deconvolution model to asteroids spectra which were
obtained with a space-borne telescope and two space probes, and find a strong
similarity with the components detected on meteorites, and among asteroids from
a same type. Based on the conclusions drawn from our meteorites experiment, we
suggest to use the 3-{\mu}m band as a tracer of the alteration history of the
small bodies. Using the 3-{\mu}m band only, we show that Ryugu has been heavily
altered by water, which is consistent with its parent body being covered with
water ice, then went through a high temperature sequence, over 400{\deg}C. We
also point out that the 3-{\mu}m band of Bennu shows signs of its newly
discovered surface activity.
