The Artemis II astronauts, on track for a flight around the dark side of the moon Monday, faced a relatively quiet day aboard their Orion crew capsule Saturday while engineers on the ground worked to solve a toilet issue.

Overnight, Artemis II commander Reid Wiseman, Victor Glover, Christina Koch and Canadian astronaut Jeremy Hansen reached a milestone of sorts on their historic voyage to the moon.

"And Integrity, (this is) Houston, we have some news to share with you," called spacecraft communicator Jackie Mahafey in mission control. "As of 30 seconds ago, you are now closer to the moon than you are to us on Earth."

"Wow, Jackie, thank you for sharing that with us," replied Koch. "We all kind of had a collective, I guess, expression of joy at that. It's hard to imagine, but we can see here on our (instrumentation) that we are at 118,000 nautical miles (from the moon). So yeah, you can do the math."

She said the crew was enjoying views of the moon through Orion's docking hatch window.

"It is a beautiful sight," Koch said. "We're seeing more and more of the far side, and it's just a thrill to be here."

The crew has had intermittent problems with their space toilet since launch on Wednesday, occasionally being told to avoid its use in favor of collapsible contingency urinals, or CCUs, bags used for urine collection that can be emptied to space later.

Early Saturday, as the crew was preparing for bed, flight controllers were unable to dump the toilet's stored urine overboard as needed, possibly because of a frozen vent line. The astronauts were told, once again, to use their CCUs until the problem was resolved.

Later in the day, after crew wakeup, flight controllers re-oriented the Orion capsule to allow sunlight to warm up the waste water vent line in hopes of thawing any frozen material. The procedure was referred to as a "bake out."

"We have increased the heater temperatures on the nozzle and the lines themselves, and we're hoping that if the problem is the freezing of the vent lines ... then this will give us a chance to see if we're able to solve that," mission control radioed the crew.

"We'll have the cameras on it and we'll be able to take pictures of that. Due to all of this, we've replanned overnight, your timeline is going to be a little bit in flux. We're working on pulling some things forward. Some things might have to move off of the morning because of this maneuver."

Veteran astronaut Don Pettit said in a social media post on X that a CCU is "essentially an open container (reusable, sealable and drainable) that controls the urine-air interface using capillary forces like my Space Cup does coffee," he said, referring to a cup he designed for drinking coffee in weightlessness.

"When you are in cislunar space with a broken toilet," he continued, "you need contingencies, and the CCU replaces the need for about 25 pounds of diapers."

Otherwise, Orion was performing well. For the second day in a row, a planned trajectory correction thruster firing was called off after analysis showed the spacecraft was still on a near-perfect trajectory.

Later Saturday, Wiseman and Glover planned to take a turn at manually piloting the Orion capsule to help engineers better understand how the spacecraft performs in flight and to provide hands-on feedback for future Artemis astronauts.

All four crew members were expected to spend time late in the day reviewing their plans for video and camera mapping of the lunar surface when they pass behind the moon on Monday. Close approach on the far side, at an altitude of about 4,100 miles, is expected at 7:03 p.m. EDT.

The moon has been observed in great detail by satellites at lower altitudes, but the Artemis II crew will have a unique chance to observe features on the lunar far side that no human has ever directly experienced.

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