On Sunday, after a 25-day voyage around the Moon, NASA’s Orion spacecraft will return to Earth. This Sunday, December 11th, the unmanned spacecraft will make a splash landing in the Pacific.

After leaving Earth’s atmosphere on November 16th, Orion has completed a near flyby of the Moon and entered a distant orbit, with its furthest point being more than 43,000 miles from the Moon. Orion has completed a full round of the Moon and is currently returning to Earth after doing a second close flyby of the Moon during its trip around the planet.

The spaceship’s next significant task is to reach Earth’s atmosphere and land in the ocean without causing any damage.

In a news conference on Thursday, Artemis mission manager Mike Sarafin said, “At present, we are on schedule to have a totally successful Mission with some additional objectives that we’ve fulfilled along the way.” He continued by saying that on the day of the splashdown, they would mostly be practising the retrieval of Orion from the water and testing the re-entry of the spacecraft.

Orion will use a technique termed a “skip entry” to assist it land precisely at the splashdown site. The first time a human-capable spaceship has tried this manoeuvre. The spaceship will reach Earth’s upper atmosphere, draw up, and re-enter the atmosphere, completing the loop. After being slowed by parachutes, it will crash into the water. The spacecraft will be able to land in a very specific area of the Pacific Ocean because of this.

NASA‘s Orion guidance, navigation, and control subsystem manager Chris Madsen wrote last year that the manoeuvre, known as a “skip entry,” would bring the spaceship down closer to the coast of the United States, where recovery personnel would be ready to bring it back to solid ground. “When we fly personnel in Orion starting with Artemis II, landing precision will significantly help make sure that we can rescue the crew swiftly and minimises the amount of resources we will need to have stationed in the Pacific Ocean to help with recovery,” said the project manager.

When Orion returns to Earth, it will do so travelling at a staggering 25,000 miles per hour; but, once it passes through the atmosphere, its speed will drop to just 325 miles per hour. Starting at a height of roughly 5 miles, it will release its 11-parachute system, reducing its speed to less than 20 mph before it splashes down.

Orion’s heat shield, which must protect the capsule from the temperatures of re-entry, which can reach up to 5,000 degrees Fahrenheit, will be put to the test on the return to Earth. Since there is no way to recreate this occurrence on Earth, Sarafin emphasised the need of conducting heat shield tests in space. The shield will be crucial in protecting future astronauts on the Artemis II mission and beyond as they transit through Orion.