Flying to (hypothetical) Planet 9: Why visit it, how could we get there and would it surprise us like Pluto?

In a recent study submitted to Earth and Planetary Astrophysics, an international team of researchers discuss the various mission design options for reaching a hypothetical Planet 9, also known as "Planet X," which state-of-the-art models currently estimate to possess a semi-major axis of approximately 400 astronomical units (AU). The researchers postulate that sending a spacecraft to Planet 9 could pose scientific benefits much like when NASA's New Horizons spacecraft visited Pluto in 2015. But...