You cannot send a probe to the Moon or Mars until you have completed the specific "Mission to [Planet]" research project. Once researched, select the planet and use the launch button at the bottom center of the screen.
Use the Advice mission with a high-Science councilor to boost a nation's research output. If you control a major power like the US, run Welfare to reduce unrest and Knowledge to boost long-term research points. Transitioning to Space Terra.Invicta.v0.3.35.Early.Access.zip
For a deeper look at navigating the complex UI and mastering the 100-hour-plus tutorial, check out this guide: You cannot send a probe to the Moon
For , the early game is all about establishing a foothold on Earth and preparing for the jump into space. This specific version introduced key quality-of-life updates, such as the ability to mark obsolete projects and ship parts to declutter your menus. Core Early Game Strategy If you control a major power like the