Artemis II: Countdown to Launch

The countdown is underway at Kennedy Space Center in Florida as four astronauts prepare for the Artemis II mission – a historic journey to circumnavigate the moon and mark humanity’s return to deep space after five decades. NASA is poised to launch its 322-foot-tall Space Launch System (SLS) rocket, with a two-hour launch window opening at 6:24 p.m. ET on Wednesday.

Key Moments to Watch

Rocket launches are frequent from Florida’s Space Coast, but Artemis II is a particularly significant event. Astronauts Reid Wiseman, Victor Glover, Christina Koch, and Canadian Space Agency astronaut Jeremy Hansen will board the Orion spacecraft atop the SLS rocket and accelerate to supersonic speeds – 768 miles per hour – within the first minute of flight.

Understanding the Countdown

The countdown clock displays “T minus” time, where “T” represents the “terminal count.” It’s important to note that the clock will intentionally pause during pre-planned holds at the 40-minute and 10-minute marks. The real-time launch target is referred to as “L minus” time, currently set at 6:24 p.m. ET. NASA may issue a new “L minus” time if technical issues or external factors, like boat traffic, arise.

Fueling the Rocket

The SLS rocket requires millions of gallons of super-chilled liquid hydrogen for fuel. Fueling will begin approximately 10 hours and 20 minutes before liftoff. Launch controllers will closely monitor for leaks, as hydrogen is prone to seepage. According to NASA launch director Charlie Blackwell-Thompson, a leak rate below 16% is acceptable for a safe launch.

Astronaut Walkout and Boarding

Around four hours and 40 minutes before launch, the four astronauts will emerge from the Neil Armstrong Operations & Checkout Building. They will be greeted by their families before boarding futuristic “astrovans” to the launchpad. Victor Glover shared that this moment will be special, allowing him to personally express his love to his family. Jeremy Hansen’s wife, Catherine, described her husband as the family’s “grounding rod” and acknowledged the difficulty of his absence during a stressful time.

Final Checks and Liftoff Decision

As the countdown progresses, NASA will conduct extensive vehicle checks and monitor the fueling process. At T - 16 minutes, a final “go/no-go” poll will be conducted. At the 10-minute mark, the “Ground Launch Sequencer” software will assess the rocket’s health. A reset and another launch attempt are possible if issues arise, provided at least 75 minutes remain in the launch window and the clock hasn’t reached 33 seconds.

Taking the Wheel: Manual Control Test

Once in a stable low-Earth orbit, the crew will conduct a “Proximity Operations Demonstration,” a manual test drive of the Orion spacecraft. They will practice docking and piloting the capsule, using the interim cryogenic propulsion stage (ICPS) as a docking target. Howard Hu, manager of NASA’s Orion Program, emphasized the importance of verifying manual capabilities alongside automated systems. Victor Glover likened the test to self-driving cars, highlighting the need for a crew to intervene if necessary. The crew’s views from the docking camera will be shared live with the public, according to Rachel Kraft with NASA Communications.