Today's exploration level was 20 so I tried to start exploration but could not.
The shipyard level must be at least 13 to do the exploration.
Fortunately, I am able to start the exploration by tomorrow because I have raised Shipyard skill.
Shipyard skills are now 12 levels and tomorrow will be 13 levels.
It would be great if there was a rare planet on the nearby planet.
I am going to continue collecting resources to make space ship by raising Shipyard skill.
I think it is possible to make several spaceships, but the exploration is a day that I really look forward to.