Complex sentence: The Little Joe 2 was a test of the Mercury capsule for the first Little Joe animal flight, carrying the Rhesus monkey Sam (Macaca mulatta) close to the edge of space.
Split into simpler sentences: The Little Joe 2 was a test of the Mercury capsule. It was the first Little Joe animal flight, carrying the Rhesus monkey Sam (Macaca mulatta) close to the edge of space.