As NASA makes final preparations to send four astronauts on a journey around the moon, a critical test Monday will reveal whether its enormous moon rocket is truly ready to fly. Known as a “wet dress rehearsal,” the test is essentially an elaborate launch day walkthrough. NASA will fully fuel its next-generation Space Launch System rocket , going through each step as it would on the actual day up until roughly 30 seconds before liftoff. The results will allow engineers and mission managers to