QUESTION:
Very briefly, can you explain why the second stage temporarily shuts down at
9 minutes 20 seconds after launch and starts up again about an hour later?

ANSWER from David Dubov:
The first burn of the second stage is used to place the spacecraft in a low
parking orbit around the Earth. It then coasts until it gets to the right
point in its orbit to do the burn to go to Mars. The second stage then
ignites again to begin pushing the spacecraft towards Mars. The third stage
finishes off the job because the second stage fuel tanks are nearly empty.