Answer
The reports are sent to Earth every 24 hours according to Earth clocks.
Work Step by Step
Let $\Delta t_0$ be the interval in the spaceship frame.
Let $\Delta t$ be the interval in the Earth frame.
We can find the interval measured in the Earth frame:
$\Delta t = \frac{\Delta t_0}{\sqrt{1-\frac{v^2}{c^2}}}$
$\Delta t = \frac{12~h}{\sqrt{1-\frac{(0.87~c)^2}{c^2}}}$
$\Delta t = \frac{12~h}{\sqrt{0.2431}}$
$\Delta t = 24~h$
The reports are sent to Earth every 24 hours according to Earth clocks.
