Season 5 is a modded single-player game in Science mode, and one goal of the season is that no kerbal dies. This stream opens in the VAB with Science9, the rocket that carried Jebediah to the Mun last time, and turns it into a bigger robot rocket, Science10, for a trip past Minmus. Getting it off the pad takes four tries. Out near Minmus it loses contact with home, but it runs its experiments anyway, comes back into range and splashes down in Kerbin's ocean.
Too heavy to fly
The top of Science9 stays and the rest goes. "We're going to scrap all the bottom part." The commentary pokes through the new parts first, including a science container, then builds down: big fuel tanks, engines, decouplers, winglets and a ring of side stacks with cones on top. The crew window shows the Mk1 Command Pod with an empty seat. "This is going to be unmanned to start." The name changes to Science10, and the goal is a Minmus encounter and back.
The first launch goes nowhere. "So it doesn't get off the ground." The stack is rebuilt and tried again, then half the bottom fuel tanks come off. On the third try Science10 sits on the pad for over a minute before it starts to rise, and then it slows. "Clearly too heavy." With nobody aboard, the commentary goes back to the Space Center and takes more tanks off the inner stage.
Fourth time up
The fourth launch rises slowly out of its own smoke and keeps going. "Okay, so far so good. This seems like a lot better than the last one." The ring of engines pushes it up, a little wobbly, and it reaches orbit around Kerbin with tanks still left.
Minmus is on a tilted orbit, so the first maneuver lines Science10 up with it. Then comes a long transfer burn. "It's a minute burn." The map shows an encounter with Minmus, and a path that swings straight back toward Kerbin afterward.
No signal at Minmus
On the way out, the signal readout at the top of the screen turns into a question mark. "Yeah, no signal to the probe." Science10 can no longer be steered, but its experiments still run: a materials study, a temperature scan, a goo observation and a pressure scan, all "while in space high over Minmus".
The return path was already set by the encounter. "I'm glad I planned ahead for that." Back near Kerbin, the signal comes back weak and then full. A viewer suggests switching on the map's signal routes, and green lines link Science10 to home. The commentary blames "a little wimpy antenna" and plans relay satellites for the next robot trips.
Splashdown
A retrograde burn pulls the orbit in. "Wow, these engines are really powerful." The spare fuel is dropped, and Science10 burns into the atmosphere. During the long fall, the commentary reads the KSPedia pages for Kerbal Planetary Base Systems: habitats, corridors and deployable parts for a future base.
The parachutes open over the ocean. On the way down the Communotron 16 antenna is extended, and the capsule splashes down. "I didn't know that there was an extended antenna."
Where it ends
The Mission Summary for Science10 lists 6 experiments recovered and 152.5 science earned, for 227. The materials study from high over Minmus is worth 62.5 of that. In the tech tree the next nodes cost 160, and nothing is bought. "I could just bank it for now." The next plan, per the commentary, is the same trip with a kerbal aboard, then longer missions. The stream ends at the Space Center with 227.1 science and no kerbal lost.