Complex sentence: Prior to the release of information about its mission, NASA correctly identified that it had been a test of a spacecraft intended for manned Lunar flights, however they were unsure whether it was intended to reach the Moon itself.
Split into simpler sentences: Prior to the release of information about its mission, NASA correctly identified that it had been a test of a spacecraft intended for manned Lunar flights. However, they were unsure whether it was intended to reach the Moon itself.