The Artemis II crew is set to enter a nerve-wracking communications blackout Monday evening as the spacecraft slips behind the Moon’s far side.

NASA said the expected signal loss should last roughly 40 minutes, beginning at 6:44 p.m. ET.

During this unprecedented moment, the crew — Reid Wiseman, Victor Glover, Christina Koch, and Canadian astronaut Jeremy Hansen — will be more isolated than any humans in deep space history.

The blackout occurs as the spacecraft loses line of sight to Earth, with the Moon blocking satellite communications entirely.

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Contact is expected to return around 7:25 p.m. ET, when Earth reemerges on the other side of the Moon’s horizon in a moment known as "Earthrise."

Ground control has emphasized that NASA does not anticipate any specific dangers during the mission but is prepared for potential contingencies.

For example, the astronauts recently practiced performing essential tasks, such as drinking protein shakes or administering medication,  while wearing their bulky orange launch and entry suits in case they must remain in the gear for an extended period.

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NASA also noted that if the spacecraft were punctured, Orion is equipped to continuously pump oxygen to maintain cabin pressure, giving the crew ample time to safely don their pressurized suits.

The Artemis II crew will also reach several major milestones during the blackout, including becoming the first humans to witness never-before-seen views of the Moon’s far side. 

At 7:05 p.m. ET, the spacecraft is expected to reach its farthest point from Earth at 252,760 miles, marking another key milestone and surpassing the Apollo 13 record by roughly 4,105 miles.

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At their nearest point, roughly 4,070 miles from the lunar surface, the Moon is expected to appear about the size of a basketball held at arm’s length, according to NASA.

While ground control and the science evaluation room will not be able to interact with the astronauts during this specific period, the crew will continue to execute their lunar targeting plan and conduct science observations throughout the blackout.

The astronauts are expected to track historic Apollo sites, scout future landing zones and photograph rare views of nearby planets, including Mercury, Venus, Mars and Saturn, while also observing a solar eclipse from Orion’s unique vantage point.

Earlier in the afternoon, the crew broke a record for distance traveled from Earth set by Apollo 13 in 1970, NASA announced.