Four astronauts aboard NASA's Orion spacecraft will vanish from all human contact Monday evening, passing behind the Moon's far side in a 40-minute window of complete isolation that no simulation can replicate. When Mission Control says goodbye at 6:47 p.m. ET, the crew will be truly alone — farther from home than any humans have traveled in over 50 years.
The blackout begins as Artemis II swings behind the lunar far side, where the Moon itself blocks every radio signal and laser communication link between the spacecraft and Earth. For 40 minutes, the four crew members will experience something no amount of training can prepare them for: the knowledge that if anything goes wrong, Houston cannot help.
The crew makes their closest lunar approach at 7:02 p.m., skimming within 4,066 miles of the Moon's surface while completely cut off from ground control. According to BBC News, they'll spend the blackout "dedicated to lunar observation — taking images, studying the Moon's geology and simply gazing at its splendour."
The psychological weight of that isolation echoes the Apollo missions, when astronauts first experienced what Michael Collins called feeling "truly alone" and "isolated from any known life." Collins, who orbited the Moon alone while Neil Armstrong and Buzz Aldrin walked on the surface in 1969, endured 48 minutes of radio silence — eight minutes longer than the Artemis crew will face.
Artemis II pilot Victor Glover told BBC News before the mission that he hopes the world will use those 40 minutes for collective reflection. The crew's radio silence represents more than a technical limitation — it's a profound reminder of humanity's isolation in the cosmos.
Back on Earth, the tension will be palpable at tracking stations worldwide. At the Goonhilly Earth Station in Cornwall, engineers have been carefully tracking Orion's position throughout its journey. Matt Cosby, the facility's chief technology officer, told the BBC the stakes feel different this time.
"This is the first time we're tracking a spacecraft with humans on it," Cosby said. "We're going to get slightly nervous as it goes behind the Moon, and then we'll be very excited when we see it again, because we know that they're all safe."
The lunar flyby includes a seven-hour observation period that began at 2:45 p.m. ET Monday, during which the crew observes both the near and far sides of the Moon in rotating pairs every 55 to 85 minutes. NASA's live coverage runs from 1 p.m. to 9:45 p.m. ET on the agency's YouTube channel — though viewers will share in the silence when communications cease.
When the signal returns at 7:27 p.m., the crew will have already made history, completing their closest approach to the Moon entirely on their own. The moment marks a crucial test not just of spacecraft systems, but of human psychology in the deepest reaches of space.
Collins later described the peace and tranquility of his radio silence, saying it offered "a break from the constant requests from mission control." For the Artemis crew, those 40 minutes may provide the same respite — a chance to absorb the magnitude of their journey without the chatter of ground control.
The communication blackouts that seem daunting today may become routine as space agencies build lunar infrastructure. Cosby notes that "for a sustainable presence on the Moon, you need the full comms — you need the full 24 hours a day, even on the far side, because the far side will want to be explored as well."
But for now, those 40 minutes represent something irreplaceable: a window of pure human experience in the most isolated environment our species can reach. When Earth disappears behind the lunar horizon and the last radio signal fades, four humans will be more alone than anyone has been since 1972.
The Artemis II mission is scheduled to splashdown off the coast of San Diego at approximately 8:07 p.m. ET on Friday, April 10. The crew will return with unprecedented imagery and scientific observations from humanity's first deep space journey in over five decades.
