Lunar departure: NASA's Orion spacecraft begins journey back to Earth

Orion is scheduled to splash down off the coast of San Diego on Dec. 11. First, the Artemis 1 spacecraft must complete a series of engine burns to set it on the correct trajectory for Earth.

The final leg of the Artemis 1 test flight is now underway after the Orion spacecraft fired up its engines, beginning the journey from the moon back to Earth. 

NASA is in the home stretch of its 25.5-day Artemis 1 mission, the first end-to-end test of the Orion and Space Launch System (SLS) rocket.

NASA plans to use Orion and the SLS rocket to send astronauts back to the moon under the Artemis III mission in 2025. If this first test flight is successful, two astronauts will launch on the Artemis II flight around the moon in 2024. 

It all started on Nov. 16 with the SLS launch from Kennedy Space Center in Florida.

Early on in its test flight, Orion flew by the far side of the moon, sending back detailed images of craters on the lunar surface. More than halfway into its mission, Orion has flown nearly 270,000 miles from Earth, a new record for a spacecraft designed to carry humans. 

Orion will need to complete a series of engine burns to get back to Earth. The first happened Thursday evening, setting the spacecraft up to begin its flight home.

Orion conducted a 45-second distant retrograde orbit (DRO) departure burn on Thursday around 4:53 p.m. EST.

"That basically takes us out of the distant retrograde orbit and brings us on a close trajectory to the moon," NASA Deputy Chief Flight Director Zeb Scoville said ahead of the milestone.

According to NASA, the burn was "nominal," and Orion is now set up for the second burn needed to return to Earth.

WATCH: NASA'S ORION SPACECRAFT VIEWS AN ECLIPSE OF THE MOON AND EARTH

On Dec. 5, the spacecraft will swing by the moon and complete the most crucial maneuver of the journey home: the return power flyby (RPF) burn. Depending on the weather at the splashdown sites in the Pacific Ocean, mission control can modify this burn slightly to land where the forecast is more favorable.

"We're going to be looking at what the weather systems are like off of the coast. And there is some variability that we can have on different trajectory lines. Basically by how much we dip down will affect how much we approach from the south or more from the west," Scoville explained. "So we can target different approach factors into the coast to pick the best weather and timing."

However, the small modifications made through a series of correction trajectory burns will change the return by hours, not days. 

On its last moon flyby, the side of the moon that faces Earth will be lit up, providing an opportunity to see some of the Apollo landing sites. At that point, Orion will be about 6,000 miles above the moon.

The final test: Surviving the return to Earth

One of Orion's final and most critical tests will be how its heat shield withstands the 5,000-degree Fahrenheit temperatures as it blasts back through Earth's atmosphere.

IMPROVED SPACE WEATHER FORECASTS NEEDED TO AVOID DESTRUCTION OF SATELLITES

There are two expected communication blackouts during reentry due to plasma heating the spacecraft.

At about 24,000 feet, three small drogue parachutes will deploy from Orion, followed by the main parachute at 6,800 feet. Eleven parachutes deploy, slowing Orion from 350 mph to about 20 mph for landing. At 1,500 feet, Orion will roll to hit the waves at the proper angle. 

Orion will splash down off the coast of San Diego, California, on Dec. 11 around 11 a.m., where U.S. Navy recovery teams will be waiting.

It's still too early to be sure what the forecast around the splashdown zone will be, but conversations around the weather off the coast of San Diego also began this week, according to Artemis 1 mission manager Mike Sarafin. 

NASA will be looking for calm seas, minimal wind and a low chance of precipitation for a safe recovery of the Orion capsule. 

Loading.