It’s huge, expensive, and years late—but the SLS rocket is finally here

On Friday morning, NASA's titanic Space Launch System reached the launch pad. The rocket is not yet ready to fly, and it may not lift off the planet for several more months. But as the fully assembled, skyscraper-sized rocket rolled into a serene Florida evening on Thursday at Kennedy Space Center, no one could deny that it is finally here.

Frankly, it is hard to know how to feel about this rocket. Certainly, one cannot help but be awed by a rocket that is as tall as a US football field is long. Designing, building, and testing such a large and complex machine represents a significant engineering achievement. But it's impossible to have a rational discussion about the Space Launch System rocket and its payload, the Orion spacecraft, without considering its enormous expense, ongoing delays, and looming obsolescence.

One thing seems clear: although this fully stacked SLS rocket and Orion crew capsule have set the stage for the uncrewed Artemis I test launch later this year, the rollout does not mark the end of the beginning for this launch system. Rather, it's the beginning of the end. This is probably the last gasp of the Apollo era of NASA that has gripped the space agency for six decades.

The good

The SLS rocket and Orion have appeared in NASA PowerPoint presentations for so long that it's good to finally see the real thing. The rocket and spacecraft looked brilliant as they rolled into the sunset after moving out of the Vehicle Assembly Building at Kennedy Space Center. About 11 hours later, the stack arrived at Launch Complex 39B, seemingly no worse for wear.

During the next week or so, engineers and technicians will prepare the vehicle for a critical fueling test known as a "wet dress rehearsal," during which the rocket will be loaded with chilled propellants and brought down to within seconds of engine ignition. This is a not-insignificant test, as it will involve a complicated interplay between the newly assembled rocket, spacecraft, launch tower, ground systems, and flight software.

If all goes well, the test should happen during the first week of April. It will likely take several days, or perhaps longer if technical issues occur. After this test, the rocket will roll back to the Vehicle Assembly Building to be outfitted with pyrotechnics and for other final tasks. The rocket could potentially be back on the pad for a launch attempt in early June.

This is a big, brawny rocket that is 100 percent American made. If the SLS rocket passes its flight test later this year, it will give NASA and the Western world a powerful heavy-lift vehicle (Europe is a partner on the Orion spacecraft, and dozens of nations have signed up for the space agency's Artemis Moon program). And at least until SpaceX's Starship vehicle comes online, the SLS rocket will provide an unparalleled heavy-lift capability for exploration purposes.

Many people have worked very hard to get the rocket and spacecraft to this point. This is no small feat in a large bureaucracy like NASA. Congratulations, all.