  With the recent announcement by NASA's Planetary Science and Astrobiology
Decadal Survey 2023-2032, a priority flagship mission to the planet Uranus is
anticipated. Here, we explore the prospects of using the mission's radio
Doppler tracking equipment to detect gravitational waves (GWs) and other
analogous signals related to dark matter (DM) over the duration of its
interplanetary cruise. By employing a methodology to stack tracking data in
combination with Monte-Carlo Markov-Chain parameter recovery tests, we show
that the mission will be sensitive to GWs over the wide frequency range of
$3\times 10^{-9}$ Hz to $10^{-1}$ Hz, provided that tracking data is taken
consistently over a large fraction of the cruise duration. Thus, the mission
has the potential to fill the gap between pulsar timing and
space-based-interferometry GW observatories. Within this assumption, we
forecast the detection of $\mathcal{\mathcal{O}}(1 - 100)$ individual massive
black hole binaries using two independent population models. Additionally, we
determine the mission's sensitivity to both astrophysical and primordial
stochastic gravitational wave backgrounds, as well as its capacity to test, or
even confirm via detection, ultralight DM models. In all these cases, the
tracking of the spacecraft over its interplanetary cruise would enable coverage
of unexplored regions of parameter space, where signals from new phenomena in
our Universe may be lurking.
