After a record-breaking week in space, the four astronauts on NASA’s 10-day lunar flyby Artemis II mission are getting ready for the most intense part of their journey: the return to Earth.
In 13 minutes, the Orion spacecraft will fall over 400,000 feet (121 kilometres) and travel almost 2,000 miles (3,218 kilometres) over the Pacific Ocean to a special “splashdown” site off the coast of California.
For almost half of this time, their communication with NASA’s ground crew will be cut off entirely, and they will endure temperatures up to 2,760 degrees Celsius.
Astronaut Victor Glover said he’s been thinking about this re-entry from the Artemis II mission since the day he was selected over three years ago.
He described re-entry as “riding a fireball through the atmosphere” in a press conference on Wednesday.
Here’s a closer look at what the astronauts are doing right now to prepare for their fiery arrival back to Earth, and what comes after.
Preparing for descent
To get ready for re-entry, the crew has already carried out a return trajectory correction manoeuvre, a small engine burn to adjust the spacecraft’s trajectory for a more precise route back to Earth, according to Rick Henfling, the director of Artemis II’s entry flight.
The astronauts also tested suits that help them combat orthostatic intolerance, a condition that makes it difficult for astronauts to maintain blood pressure and blood flow when standing up after returning from space.
On the ninth day of the 10-day flyby, the crew will manually drive the vehicle to centre the Earth in one of the windows and then fly it to an altitude where the tail of the ship points towards the sun, so it can generate more power, Henfling added.
Then, on Artemis II’s tenth day, the astronauts get ready for the final descent.
About 20 minutes before re-entry, the service module that supported and powered the crew during the mission will separate from Orion. It will eventually burn up in the atmosphere before coming down to Earth on its own.
Then, the crew is ready for a last “raise burn,” a final opportunity to change the flight path before their descent, which starts southeast of Hawaii and will eventually see them land off the coast of California, Henfling said.
The crew then lowers their visors to cover their eyes and will be “in an isolated environment in their launch and entry suit” until they reach the Earth’s surface.
How will they perform the re-entry?
The capsule will re-enter the Earth’s atmosphere at about 400,000 feet (121,920 metres) and will have to travel 1,950 miles (3,138 kilometres) to its landing site.
“That’s where the fun really begins,” Henfling said.
Only 24 seconds after entering the Earth’s atmosphere, Orion will hit a “blackout,” when plasma builds up around the spacecraft, which will cut the communications between the astronauts and NASA control for about six minutes.
Orion has the world’s largest heat shield on its body, which will protect the astronauts from the extreme heat and plasma.
After the six-minute blackout is over, Orion will be at an altitude of 150,000 feet (45,720 metres), travelling at a “very quick” speed towards the landing site, so the next focus will be on deploying parachutes, Henfling said.
Two small drogue parachutes — designed for deployment from a rapidly moving object — that are seven metres in diameter will unfurl at an altitude of 25,000 feet (7,620 metres) to slow Orion down to 494 km/h. Three larger parachutes will slow Orion down even further to 38 km/h, the speed it will maintain to splash down into the Pacific Ocean.
Once the craft is in the water, a system of five orange airbags will inflate around the top of the spacecraft and will flip it into an upright position, so the crew can get out.
The re-entry will take 13 minutes from start to finish, Henfling said. “It’s going to start quickly, and it’s going to be over even faster,” he added.
The Artemis II is scheduled to splash down off the coast of San Diego on Friday 10 April at approximately 8:07 p.m. EDT (2:07 a.m. CEST), according to NASA
NASA has some “contingency” trajectories, where the crew could be landing further away than planned, based on any problems that might come up during descent, Henfling said.
What happens after the mission?
Liliana Villarreal, the Artemis landing and recovery director, is leading a team to sea aboard the USS John P. Murtha, a transport dock ship that will be used to recover the astronauts after their landing.
The ship, along with small boats, will be stationed “at a safe distance” away from Orion’s landing place. After a quick assessment of the air and water around the capsule, the boats will open the Orion hatch and help the astronauts out into an inflatable raft called the “Front Porch,” Villarreal said.
The astronauts wait on the “Front Porch” for two helicopters to come and bring them to medical facilities, where they receive immediate medical checkups.
“We expect to recover the crew and deliver them to the medical bay within two hours of splashdown,” Villarreal said. “We had a very successful recovery […] during the Artemis I mission, and we feel confident during our testing and training […] Artemis II will be just as successful.”
The Orion capsule will be loaded onto the USS John P. Murtha and will return to the closest Navy base within 24 hours after splashdown.
The capsule then undergoes some quick inspections, but it will quickly be loaded onto a truck and driven back to NASA in Florida.