T-Minus How Long? - When Will Artemis II Launch?

The Space Launch System (SLS) rocket that will carry Artemis II away from Earth is nearly ready for historic launch. The SLS is over 322 feet tall.

The countdown has begun. Part of the groundbreaking Artemis Program, the Artemis II launch is nearly upon us. No later than April of 2026 will Artemis II launch with the first crewed trip to the Moon in over 50 years.

Apollo 17 marked the end of an era in 1972 when it departed from the Moon with the final crew to ever make the voyage. Since then, humans have never strayed farther from Earth than low Earth orbit aboard the International Space Station. But the Artemis II mission, with its crew of four astronauts, is making its final preparations to end that drought with a manned lunar flyby.

As of publishing, NASA is aiming to begin the transportation of Space Launch System rocket and Orion spacecraft that will carry Artemis II to the Moon no later that January 17. The SLS is so massive and expensive that transporting it from its assembly point to the launch pad about four miles away will be a meticulous journey, taking up to 12 hours to complete.

The massive rocket will be carried to the launch pad by the crawler-transporter 2, a behemoth of a vehicle the size of a baseball field and weighing in at 6.6 million pounds, the weight of a thousand pickup trucks. The monster vehicle is over 50 years old and clocks in at a top speed of one mile per hour when loaded and has a fuel efficiency of 125 gallons of diesel fuel per mile (about 0.008 miles per gallon). It’s capable of carrying 18 million pounds. The platform atop the crawler-transporter is designed to keep the launch vehicle it’s carrying completely level at all times.

The Space Shuttle Atlantis atop the crawler-transporter. Note the person on the right for scale.

Even once the rocket reaches the launchpad, it won’t be time to launch yet. Upon arrival, NASA will begin a long and thorough checklist of preparations to ensure that all is in working order. Once that list is complete, it’s time for a wet dress rehearsal. A wet dress rehearsal is a full-scale launch simulation of a rocket, including the loading of the rocket’s liquid fuel—hence the “wet” rehearsal. During this simulation, everything from the equipment to the ground crew to the astronauts will be put through a test run as many times as are necessary. If necessary, the launch can be delayed and the SLS and Orion returned to the assembly building for further work.

Currently, NASA is aiming for one of three launch periods for Artemis II, with the earliest being from February 6 through 11, then March 6 through 11, and the latest on April 1 through 6. If all three of these fail, a later launch window in May could also be scheduled. NASA’s current goal is the early February window. These dates are determined by the complex relationship between the Earth and Moon. Both the Earth and Moon are moving on their own paths, while also spinning about their axes. Given that the lunar cycle lasts about a month, that leads to approximately a week of possible launch times followed by three weeks without.

NASA may be forced to miss the first launch period due to technological issues discovered during their checklist of wet dress rehearsal, in which case they would delay to the next launch period and try again. It’s also possible that the weather might get in the way. Due to all these complex factors at play, NASA won’t actually give a finalized launch date and time days, or even hours, beforehand. And even then, last-minute problems could further delay the launch. Artemis I, predecessor of Artemis II, had its launch pushed back three times after issues with engine temperature readings and a hydrogen leak during fueling.

If you want to witness the launch for yourself, you’re going to have to be flexible. When NASA has a launch date, it will be published on the Artemis II page of their website and likely show up on their social media accounts but be ready for even that to change on a whim.

Launching from the Kennedy Space Center, the Artemis II liftoff will be visible across the east coast of Florida and up into the Carolinas, even further if it’s a night launch. If you can’t travel that far, you can still view it using NASA’s livestreams through platforms like NASA+ or YouTube. Feeds usually begin several hours before the launch and feature countdown commentary.

As early as February 6, four astronauts will begin their voyage further than any have gone in the past fifty years. The voyage will take them on a ten-day round trip to the Moon and back, finally ending our absence from nearest celestial neighbor.