Artemis II: A Return to the Moon

Tomorrow evening at 6:24 PM EDT (11:24 PM BST), NASA is opening the launch window for Artemis II. Barring any last-minute weather issues or hydrogen leaks at Kennedy Space Center, four astronauts are going to strap into the Orion capsule on top of the massive Space Launch System rocket and leave low Earth orbit. Assuming the countdown goes smoothly, it will be the first crewed deep-space launch since Apollo 17 in December 1972.

Because it’s been over 50 years, a common question is why we are repeating something we already accomplished. But Artemis has a completely different goal than Apollo. The 1960s missions were a sprint to the surface to prove we could do it. The Artemis program is focused on long-term infrastructure. The ultimate plan is to build a sustained presence near the lunar South Pole, mine water-ice, and figure out how to keep humans alive long enough to attempt a Mars mission down the line.

This mission is technical validation. But it is also a reignition. Humans are leaving Earth for deep space again for the first time since Apollo 17. The next era of exploration begins.

The crew, Commander Reid Wiseman, Victor Glover, Christina Koch, and Canadian astronaut Jeremy Hansen, won’t be touching down. They are essentially taking the spacecraft on a massive stress test to make sure the hardware holds up.

How the Flight Actually Works

After launch, they won’t head straight for the Moon. Orion will stay in a high Earth orbit for roughly 24 hours. This gives the astronauts time to test the manual controls and verify the capsule’s systems are stable close to home. Once they get the all-clear from mission control, the upper stage engines will fire for the translunar injection burn, pushing them out of Earth’s gravity well and across the 238,000-mile gap.

They are flying what is called a free-return trajectory. They won’t fire their engines to brake and enter lunar orbit. Instead, they will simply swing around the far side of the Moon and let its gravity slingshot them straight back toward Earth. Because of how this wide loop works, the crew will fly roughly 4,700 miles past the far side, putting them further into deep space than anyone in history.

After the gravity assist, they coast back toward Earth for a few days. The final hurdle is the reentry. Orion will hit the atmosphere at 25,000 miles per hour (roughly Mach 32). The friction will push the capsule’s new heat shield to temperatures hotter than the surface of the sun before the parachutes deploy for a Pacific Ocean splashdown.

NASA’s launch coverage starts well before the 6:24 PM target tomorrow (11:24 PM BST). It’s been half a century since humans have gone this far out, making it a launch worth watching.