It was a long night for NASA's Exploration Ground Systems team at Kennedy Space Center in Florida. Crews worked through the dark to slowly move the Artemis I "mega moon rocket" from its indoor habitat out to the pad at launch complex 39B in preparation for a second try at the critical "wet dress rehearsal" test.

Let's look ahead for a moment. NASA's Artemis program is focused on getting a woman and a person of color onto the surface of the moon, all while building a sustained human presence at our lunar neighbor. Before people go for a ride on the Orion spacecraft -- launched by the jumbo-sized Space Launch System (SLS) mega moon rocket -- NASA needs to prove everything works by sending Orion on an un-crewed trip around the moon. That's the Artemis I mission. 

Now let's wind back. Before Artemis I takes off, SLS needs to pass some tests, notably the wet dress rehearsal, which involves loading propellant into the rocket and going through all the steps for launch without actually launching. NASA tried to run this test in April, but technical problems prevented success. So the agency rolled SLS back into the garage, fixed it up and is trying again.

It's not easy to move a rocket system taller than the Statue of Liberty around. It took eight hours to get SLS back to the launchpad, where it arrived at about 5:20 a.m. PT on Monday. The Exploration Ground Systems group shared some lovely photos of the journey.

Getting SLS into the right position is the just the beginning. 

"Teams will work to secure the Space Launch System rocket and Orion spacecraft and mobile launcher to ground support equipment at the launch pad and ensure that the rocket is in a safe configuration in preparation of the upcoming tanking test," NASA said in a statement Monday.

The agency said it would take about two weeks of prep work before the wet dress rehearsal takes place. If all goes well, the actual Artemis I launch could happen within a couple months, though NASA has identified possible takeoff dates all the way into 2023.