The Orion spacecraft successfully fired its main engine for 5 minutes and 50 seconds on Thursday, sending four astronauts on a free-return trajectory around the Moon. For NASA and the Artemis II crew members, this marked a point of no return for more than week.

Most Americans, indeed about three-quarters of the population around the world, have not witnessed humans leaving low-Earth orbit in their lifetimes. The last time this occurred was 1972, with the final Apollo Moon mission.

The “translunar injection” burn of Orion’s main engine occurred about one day after the successful launch of the mission on NASA’s Space Launch System rocket from Kennedy Space Center on Wednesday. This burn was the last major firing of Orion’s main engine, and sets the crew on a course to fly around the Moon on Monday, slingshot back toward Earth under lunar gravity, and splash down in the Pacific Ocean on Friday, April 10.

“Things are going really well right now,” said Lori Glaze, NASA’s senior official over exploration, during a news conference on Thursday evening. “I don’t think we could be more pleased.”

First day is filled with activity

The decision to leave Earth orbit followed a busy day on board Orion during which the four person crew; Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen, pushed the spacecraft’s life support and propulsion systems to ensure the vehicle was ready for a prolonged mission in deep space.

Orion’s life support functioned very well, said Howard Hu, NASA’s Program Manager for the Orion spacecraft. This included critical systems such as the carbon dioxide “scrubbers” that remove the exhaled gas from the cabin’s atmosphere as well as water systems. There was a minor kerfuffle with Orion’s toilet during the initial checkout when it was supposed to be “wetted” with water to prime the pump. Not enough water was introduced, so the pump was non-responsive. Once more water was added, it began functioning fine.