THEY have almost made it to the moon and back, but now the crew on board Artemis II face their greatest moment of jeopardy.
Travelling at a barely comprehensible 25,000mph — seven miles a second — their 15ft-by-9ft will catapult back into the Earth’s atmosphere in the early hours of Saturday.
The crew of Artemis face a perilous 16-minute plunge back to EarthCredit: AP
Christina Koch, Victor Glover (top) Reid Wiseman (bottom) and Jeremy Hansen ventured farther than humankind has ever beenCredit: AP
Transforming the craft into a meteorite, it will be subjected to temperatures of more than 2,760C — way hotter than a blast furnace.
All that protects the four astronauts from being burned alive is a three-inch thick heat-resistant shield.
It is a -age physics experiment that ominously went wrong when the uncrewed Artemis I tested the in 2022.
Back then, chunks of material unexpectedly flew off the shield and its bolts partially melted.
Dr Ed Macaulay, a lecturer in physics and data science at Queen Mary University of London, warned of the potential peril the crew now face.
He said: “During the final phase of the Artemis II mission, there’s no backup, no contingency and no chance of escape. The four astronauts on board will be depending on a few inches of resin-coated silica to shield themselves from temperatures app-roaching half that of the surface of the sun.”
and a few computer glitches, the Artemis II’s mission has been a resounding triumph.
No human has gone deeper into space than Reid Wiseman, Victor Glover, Christina Koch and Jeremy Hansen aboard the vessel as they journeyed to the far side of the moon.
On Monday, they were 252,756 miles away from Earth, beating the record 248,655 miles set by Apollo 13 in 1970.
Glancing homewards, the world resembled a tiny blue and white marble.
No one else has ever seen the fragile-looking planet in all its beauty from such a distance with the naked eye.
In wonderment, they witnessed an Earthset — Earth dipping behind the moon’s cratered surface like a sunset.
And they experienced a lunar eclipse as the moon blocked out the sun.
Pilot Victor described it as “sci-fi” and “unreal”.
Commander Reid revealed the crew “saw sights that no human has ever seen”.
When the Orion craft, named Integrity, was on the far side of the moon, its radio and laser connections to Earth were cut off.
Apollo 13 crew splash down in the Pacific in 1970Credit: Getty
The moon is seen through the window of the Orion spacecraftCredit: AP
It meant a lonely 40 minutes when the astronauts had no contact with Nasa.
Then,, Integrity was propelled on its journey home.
It is a free ride. Moving too fast to remain in the moon’s orbit, its momentum allows the capsule to wing back home with little help from its rocket engines.
After travelling 700,000 miles, Integrity will approach the Earth’s atmosphere at 13 times the speed of a bullet as gravity draws it in.
Then it will take 16 harrowing minutes before hopefully flopping into the Pacific Ocean off .
Scientists have had to address how to prevent the capsule burning up as it re-enters the atmosphere.
Using rocket power to slow Integrity would mean being weighed down with more fuel, making blast-off harder.
Instead, Nasa is relying on a heat shield for the craft, then trusting Earth’s atmosphere to act as a brake pad.
‘Dangerous levels’
During 2022’s unmanned Artemis I mission, Orion made what was known as a “skip entry” — briefly dipping in and out of the atmosphere like a stone being skimmed on a lake.
The idea was to reduce the G-force experienced by the craft and subject it to two blasts of heat rather than a single, more intense one.
Jeremy Hansen, Reid Wiseman, Christina Koch and Victor Glover launched into the sky on April 1Credit: AFP
With lives at stake this time, Nasa has decided to attempt re-entry in one go to minimise the time the craft will be subjected to the extreme temperatures.
Integrity will be protected by a heat shield made from a material known as Avcoat, made of silica fibres and epoxy resin, encased in a fibreglass honeycomb mesh.
Attached to the underside of the craft, the 16.5ft shield, built from 186 blocks of Avcoat, is designed to burn away in a “controlled fashion” to redirect the heat of re-entry away from the capsule.
Yet when Artemis I tested it, instead of wearing to a fine powder, it cracked and broke off in chunks.
The reason? Gases from the burn-off became trapped in the Avcoat because temperatures were too low.
Dr Ed Macaulay explained: “Instead of burning away evenly over the whole surface, parts of the Artemis I heat shield were lost unexpectedly in uneven chunks.”
He added that it “raises the possibility the Orion capsule could be exposed to dangerous levels of heating”.
Former Nasa astronaut Dr Danny Olivas, part of a team who reviewed the incident, said, “this is not the heat shield that Nasa would want to give astronauts”, though he was satisfied later modifications made it safe.
The Artemis astronauts are being protected by just a 3inch heat shieldCredit: Getty
Hansen shaving in zero gravity while using an iPhone as a mirrorCredit: AP
Nasa’s solution for Artemis II was to scrap the “skip entry” and direct Integrity on a steeper, more direct route through the atmosphere to make sure the shield is subjected to a more consistent heat.
But former Nasa astronaut Charlie Camarda, an expert on heat shields, warned in a January letter to agency administrator Jared Isaacman: “The technical and organisational issues associated with the Orion heat shield represent a serious risk.
History shows accidents occur when organisations convince themselves they understand problems they do not.
This issue exhibits the same patterns that preceded past catastrophes.”
‘Holding their breath’
Yet Isaacman, who has twice flown to space, and Artemis II’s crew say they are happy with the solution.
The mission’s Commander Reid Wiseman said: “The investigators discovered the root cause, which was the key. If we stick to the new re- entry path Nasa has planned then this heat shield will be safe to fly.”
Preparing for their return to Earth, the astronauts will load up on fluids mixed with salt tablets to bulk up their blood volume.
It will help them withstand the massive G-force and prevent them blacking out as gravity causes blood to rush to their feet.
Everything in the capsule has to be locked away as even a loose pen at 25,000mph could become a life-threatening projectile.
Then the crew will don their pressurised Orion crew survival system orange suits.
Underneath, they will wear special compression clothing to help maintain their blood pressure.
Artemis II commander Reid Wiseman looks out of the window at the moonCredit: AP
Then the craft is ready to plunge back to Earth, relying on 11 parachutes deployed in a precise order to slam the brakes on Integrity.
Drifting at just 20mph, it will then hopefully land gently in the Pacific off San Diego at around 1.07am on Saturday.
Pilot Victor Glover said the splashdown — the landing method also deployed by Apollo 13 — is the moment of the mission he will most relish.
The dad-of-four, a former US Navy test pilot, admitted: “It’s a risky thing and it’s important to be honest about that.
“I don’t spend a lot of time feeling nervous or anxious about it. There is one thing I do feel that about — my family being there to watch the whole thing the entire time.
“They’re holding their breath. And I know that it’s not until we’re safely back on Earth that they really, truly can exhale and be comfortable and so that’s the part that gives me the most hesitation.”
The watching world will also breathe a collective sigh of relief to see Integrity bobbing in the waves.
It will mean that humanity has not only reached for the stars once more — but has found its way home safely.
A snap of the earth taken from the moon mission vesselCredit: Alamy
Eze Chidiebere Paul
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