Large software installers are often split into smaller "parts" (part01, part02, etc.) to make them easier to download or share. To extract the contents, you generally need all parts (usually through the final part) saved in the same folder.
The string v0.990.45.1940 identifies a specific beta or early-access build of SpaceEngine. About SpaceEngine SpaceEngine.v0.990.45.1940.part03.rar
Downloading split RAR parts from unofficial sources carries a high risk of containing malware or bundled "adware." Large software installers are often split into smaller
If even one part (like part01 or part02) is missing or corrupted, the entire installation will fail to extract. SpaceEngine.v0.990.45.1940.part03.rar