NASA’s towering 98-meter-tall Space Launch System (SLS) rocket and Orion spacecraft have made a slow but steady journey from the Vehicle Assembly Building (VAB) at Kennedy Space Center in Florida to Pad 39B. This marks the second time the Artemis II rocket has been moved to the launch site, following a March delay caused by a problem with the rocket’s helium system.

The Slow Journey to the Launch Pad

The move. Which began at 00:20 local time (04:20 GMT), involved a four-mile trek across the Kennedy Space Center. The SLS and its launch platform. Weighing approximately 5. 000 tonnes. Were transported by the Crawler-Transporter-2, a massive, tank-like vehicle built in 1965 to move Saturn V rockets to the launch site during the Apollo era.

The Crawler-Transporter-2 moves at a maximum speed of about 1 mph (1.6 km/h), and it crawls even more slowly on bends and up the gentle ramp to the launch pad. This deliberate pace ensures minimal stress on the rocket and launch tower, which cost billions of dollars to build — the slow movement also allows engineers to detect and stop any unexpected movement of the mobile skyscraper.

Which stands taller than Big Ben’s clock tower, was moved out of the VAB after engineers repaired the helium system that had previously forced a rollback in March. The four-mile journey can take up to 12 hours, depending on the terrain. The SLS. The helium system is critical for pressurizing propellant tanks, and any fault could affect the performance of the upper stage engine or the safe draining of fuel.

Final Tests and Launch Window

Now at the launch pad. Engineers will spend several days checking that the repairs carried out in the VAB have worked as intended and that nothing has shifted during the slow journey. They will reconnect the launch tower to the rocket, run pressure tests on the helium system, and rehearse parts of the countdown using the same computers and networks that will be used on launch day, without filling the tanks with fuel.

Once those tests are complete. NASA’s mission management team will meet a few days before the earliest launch opportunity on 1 April to review the data and decide whether to proceed. If all goes well, Artemis II could launch on 1 April at 18:24 Eastern Daylight Time (23:24 UK time), with additional opportunities on 2, 3, 4, 5, and 6 April. If those are missed, the final chance in April would be on 30 April.

The Artemis II crew—Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen—have entered pre-flight quarantine and will travel to Florida closer to launch to participate in various rehearsals, including suiting up and traveling to the pad. This mission, expected to last about 10 days, would be a major step toward returning humans to the Moon’s surface, a goal set by President Donald Trump in his first term.

Delays and Technical Challenges

The March launch attempt was called off after engineers detected an issue with the helium flow during a fuelling test. This forced NASA to roll the Artemis II stack back into the VAB for repairs. Before that setback, NASA had already faced other technical problems, including a liquid hydrogen leak that interrupted a “wet dress rehearsal” for the launch.

Inside the VAB, work platforms were raised around the upper stage so specialists could reach valves and plumbing in the helium circuit. Engineers replaced suspect components, swapped batteries in several critical systems, and repeated their tests to confirm the fault had been cleared. After reviewing the data, NASA managers signed off on a second rollout and the next phase of checks, which take place at the launch pad.

If the tests are completed without incident, Artemis II will become the first crewed mission in the Artemis program. This will pave the way for another crewed test flight, Artemis III, which is scheduled for 2027, and Artemis IV, planned for 2028, which aims to see astronauts set foot on the Moon.

The Artemis program, which aims to establish a sustainable human presence on the Moon, is a key part of NASA’s long-term space exploration strategy. The first crewed lunar mission in over 50 years would mark a significant milestone in space exploration and could help lay the groundwork for future missions to Mars.

For the first launch opportunity for Artemis II, NASA is targeting 18:24 Eastern Daylight Time on 1 April, which is 23:24 in the UK. If that attempt is delayed, further launch windows currently run on 2, 3, 4, 5, and 6 April. If those are missed, the month’s final opportunity would be on 30 April.