What to expect ahead of Artemis II’s splashdown

The cynthia II missionary post is go down to terminate in simply a few hours. 

NASA astronauts Reid Wiseman, Victor Glover, Christina Koch and Canadian Space Agency astronaut Jeremy Hansen are in their Orion spacecraft — named Integrity — have had a trip of a lifetime as they travelled around the moon, the farthest any humans have ever been.

But now, they're coming back to terra firma.

The four are expected to splashdown in the Pacific Ocean off the coast of San Diego, Calif., tonight at 8:07 p.m. ET.

The return to Earth is harrowing, as they reach speeds of nearly 40,000 kilometres an hour, their capsule heating to 3,000 C. 

Now imagine what that might feel like.

Their bodies will be going through almost 4 Gs. That means that they will feel four times heavier than normal. It's like being crushed.

In a press briefing Wednesday evening, Glover said it all: "Riding a fireball through the atmosphere is profound, as well. I'm gonna be thinking about and talking about all of these things for the rest of my life."

Indeed.

But before we get to that point, there’s a lot that will happen before the four set foot on solid ground.

The European Space Agency’s European Space Module has been providing power to Orion. That needs to separate before re-entry, which happens roughly 20 minutes before it begins. 

Then there may be a crew module raise burn to fine-tune Orion’s trajectory. Orion will then conduct a few roll manoeuvres that will take it farther from the service module. 

The astronauts, who will be in their spacesuits, will put their visors down. The spacecraft will be about 16,000 kilometres from their landing site.

“That’s when the fun really begins,” said Artemis II fight director Rick Henfling in a press conference on Wednesday.

As the capsule re-enters Earth’s atmosphere, plasma that has built up around the spacecraft will hinder any communication between NASA ground control and the astronauts. This is expected to last roughly six minutes. It's what they call LOS, or loss of signal.

“Once that six-minute blackout is done, Orion is going to be about 150,000 feet [45,720 m]. So, still falling pretty quickly,” Henfling said. €œWe've got two drogue parachutes that will deploy. It'll be at about 22,000 feet [6,705 m]. That'll slow us down to about 200 miles an hour [322 km/h].”

The crew withstands that heat build-up thanks to a heat shield called Avcoat.

However, after the uncrewed Artemis I mission, NASA engineers noticed that some of that material broke off as gas was unable to property vent and built up causing some of that charred material to break apart.

While NASA didn't change the heat shield for Artemis II, they conducted an investigation and modified the re-entry procedures.

At about 1,800 metres, the three main parachutes will deploy and slow the spacecraft down to just 32 km/h, to a splashdown off San Diego.

The whole sequence of events will take only 14 minutes.

The astronauts will be met by the ship USS John P. Murtha, which departed days ahead of the expected splashdown.

"After ensuring the area is safe, they're going to go ahead and open the Orion hatch and help the astronauts from their seats to a large inflatable raft that we call the front porch," Liliana Villarreal, Artemis II landing and recovery director, said in Wednesday's press conference.

"Once all four astronauts are on the front porch, we will tow the capsule away from the front porch, and the team will wait…. Two helicopters are going to rotate, picking up all four crew members before they return to the recovery ship within a few minutes of each other. "

If it all goes to plan, Koch will exit first, followed by Glover, Hansen and then Reid.

After medical evaluations the astronauts will return to the Johnson Space Center in Houston.

But there's also all the science that they've collected.

Some of that will be sent to the space centre right away, while others will take time to collect.

Senior Science Reporter

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