  The detection of gravitational waves from binary neuron star merger GW170817
and electromagnetic counterparts GRB170817 and AT2017gfo kick-started the field
of gravitational wave multimessenger astronomy. The optically red to near
infra-red emission (`red' component) of AT2017gfo was readily explained as
produced by the decay of newly created nuclei produced by rapid neutron capture
(a kilonova). However, the ultra-violet to optically blue emission (`blue'
component) that was dominant at early times (up to 1.5 days) received no
consensus regarding its driving physics. Among many explanations, two leading
contenders are kilonova radiation from a lanthanide-poor ejecta component or
shock interaction (cocoon emission). In this work, we simulate AT2017gfo-like
light curves and perform a Bayesian analysis to study whether an ultra-violet
satellite capable of rapid gravitational wave follow-up, could distinguish
between physical processes driving the early `blue' component. We find that a
Dorado-like ultra-violet satellite, with a 50 sq. deg. field of view and a
limiting magnitude (AB) of 20.5 for a 10 minute exposure is able to distinguish
radiation components up to at least 160 Mpc if data collection starts within
3.2 or 5.2 hours for two possible AT2017gfo-like light curve scenarios. We also
study the degree to which parameters can be constrained with the obtained
photometry. We find that, while ultra-violet data alone constrains parameters
governing the outer ejecta properties, the combination of both ground-based
optical and space-based ultra-violet data allows for tight constraints for all
but one parameter of the kilonova model up to 160 Mpc. These results imply that
an ultra-violet mission like Dorado would provide unique insights into the
early evolution of the post-merger system and its driving emission physics.
