  In this paper we investigate in detail the correspondence between E10 and
Romans' massive deformation of type IIA supergravity. We analyse the dynamics
of a non-linear sigma model for a spinning particle on the coset space
E10/K(E10) and show that it reproduces the dynamics of the bosonic as well as
the fermionic sector of the massive IIA theory, within the standard truncation.
The mass deformation parameter corresponds to a generator of E10 outside the
realm of the generators entering the usual D=11 analysis, and is naturally
included without any deformation of the coset model for E10/K(E10). Our
analysis thus provides a dynamical unification of the massless and massive
versions of type IIA supergravity inside E10. We discuss a number of additional
and general features of relevance in the analysis of any deformed supergravity
in the correspondence to Kac-Moody algebras, including recently studied
deformations where the trombone symmetry is gauged.
