Artemis II enters moon's sphere of influence ahead of lunar flyby

April 6 (UPI) -- The four crew members of the Artemis II mission entered the moon's sphere of influence early Monday, marking the start of their lunar flyby.

The Orion spacecraft reached what is called the lunar sphere of influence at about 12:41 a.m. ET Monday, meaning the moon's gravitational forces on the capsule were greater than those of Earth.

The mission launched Wednesday from Florida, and it took the spacecraft four days, six hours, two minutes and 54 seconds to cross the important gravitational milestone, the first crewed mission to enter the moon's sphere of influence since Apollo 17 in 1972.

About 13 hours later, at 1:56 p.m., the four-person crew of NASA astronauts Reid Wiseman, Victor Glover and Cristina Koch, and Canadian Space Agency astronaut Jeremy Hansen will have surpassed the record for the farthest humans have traveled from Earth, which was previously set by Apollo 13 in 1970.

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The spacecraft is expected to start its flyby of the moon at about 2:45 p.m. Monday, when a seven-hour lunar observation period will begin.

NASA said the crew will see both the near and far sides of the moon during this period. As window space is limited, the crew will be divided into pairs that will conduct between 55- and 85-minute observation shifts, it said.

Mission control sent the crew the final list of lunar surface features to be observed and photographed during the flyby early Sunday, according to NASA.

The astronauts will be tasked with observing about 30 targets, including the Orientale basin, a nearly 600-mile-wide crater that spans the boundary between the moon's near and far sides, NASA said.

"The crew will study Orientale's features up close and from multiple angles as they pass by," the space agency said in a Sunday evening blog post.

Orion is expected to reach its closest approach to the moon at 4,070 miles at 7:02 p.m. only to reach its maximum distance from Earth during the mission minutes later.

The lunar observation period is expected to come to an end at 9:20 p.m.

At about 1:25 p.m. Tuesday, Orion will have exited the lunar sphere of influence en route home.

The 10-day moon flyby mission is to conclude with a splashdown off the coast of San Diego at about 8:07 p.m. Friday.