For the first time in more than 50 years, astronauts are on their way to the moon.

NASA’s colossal Space Launch System rocket lifted off at 3:35 p.m. Pacific time from the Kennedy Space Center in Florida, marking the start of the 10-day Artemis II mission.

In the hours and minutes leading up to launch, as the astronauts waited aboard, NASA engineers troubleshooted minor issues with the 30-story-tall rocket. First, the teams identified an issue with the hardware that communicates with a system designed to detonate the rocket to protect public safety if the rocket veers off course. Next, there was a fluke temperature reading on the Launch Abort System, designed to pull the crew to safety during such an event. Finally, they managed a brief telemetry issue with the capsule.

All were ultimately resolved, and the agency proceeded.

“On this historic mission, you take with you the heart of this Artemis team, the daring spirit of the American people and our partners across the globe, and the hopes and dreams of a new generation,” Artemis II launch director Charlie Blackwell-Thompson said to the crew minutes before launch. “Good luck. Godspeed, Artemis II. Let’s go.”

In a few days’ time, the four astronauts aboard will perform a flyby of the moon — they will not land on the surface nor will they enter the moon’s orbit. Instead, the flyby is designed as an essential stepping-stone mission to test the rocket, human life support systems and flight procedures ahead of a lunar landing, which NASA hopes to pull off in 2028.

This includes studies on the astronauts’ sleep and mental health, as well as how deep-space radiation and microgravity affect organs and immune system. The crew will also practice manually piloting the spacecraft while still close to Earth.

NASA expects the crew to reach the moon Monday morning, around 10 a.m. Pacific time. As the astronauts pass the far side of the moon, NASA expects to temporarily lose communication with the crew, who will focus on documenting and analyzing the rugged lunar surface. Around this point, NASA anticipates the crew will break the Apollo 13 crew’s record for the farthest distance any human has traveled from Earth.

The crew will then begin their four-day return. The crew capsule is set to slam into the Earth’s atmosphere at roughly 30 times the speed of sound — potentially making it the fastest reentry of a crewed capsule in history — on April 10. NASA anticipates the crew will splash down off the coast of San Diego around 5 p.m. Pacific time.

The mission, made possible by scientists, engineers and support crews across the country and world, has a touch of Southern California, too.

Victor Glover, the astronaut piloting the mission, was once a kid in the Pomona Valley, watching the space shuttle launch on TV and dreaming of driving the thing. He cut his teeth as a test pilot out in the Mojave, attending test pilot school at Edwards Air Force Base and serving on a Navy test pilot squadron in China Lake, Calif.

If the mission is successful, Glover will become the first Black person to travel to the moon. With him will be the first woman to do so, NASA astronaut Christina Koch, and the first non-American to do so, Jeremy Hansen of the Canadian Space Agency. Not to be outdone by his crewmates, mission commander Reid Wiseman, at 50, will be the oldest to do so.

NASA’s Armstrong Flight Research Center inside Edwards Air Force Base is also conducting critical research and testing for the mission. They supported two tests of the rocket’s Launch Abort System — designed to accelerate from 0 to 500 mph in just two seconds to literally outrun the debris of an exploding rocket — in the 2010s. (The rocket discarded the abort system after the crew safely escaped the majority of Earth’s atmosphere.)

During reentry, the center will participate in a high-speed relay of military and civilian planes to chase the capsule and measure how the heat shield performs with high-tech telescopes and sensors. Artemis II is testing out a new reentry trajectory after an uncrewed test mission in 2022 resulted in unexpected damage to the heat shield.

Finally, once the capsule safely splashes down off San Diego, NASA and U.S. Navy divers will secure the capsule, with medical staff from both on standby. A Navy ship will then bring the capsule back to Naval Base San Diego, right next to the city’s downtown.

The Artemis program ultimately aims to land humans back on the moon, help the space agency establish a lunar base and serve as the testing grounds for future missions to Mars.

NASA plans to launch Artemis III, a mission in Earth’s orbit to test docking the NASA spacecraft with SpaceX’s and Blue Origin’s lunar landers, in 2027. It aspires to launch Artemis IV, which would put humans on the surface of the moon, in 2028.

“Artemis II is the opening act,” said NASA Administrator Jared Isaacman shortly before launch. “We’re going into the golden age of science and discovery right now.”

On Wednesday, for the first time since 1972, NASA is attempting to launch astronauts to the moon.

The space agency is targeting a 3:24 p.m. Pacific time launch of the colossal Space Launch System rocket with four astronauts aboard. Once off the ground, the crew — including Southern California native Victor Glover — will fly past the moon (but not land on the lunar surface or enter its orbit) and splash down off the coast of San Diego in roughly 10 days.

How to watch

NASA has already begun around-the-clock coverage of the entire mission — including launch preparations, liftoff, the lunar flyby and splashdown — on its YouTube page.

NASA is also livestreaming major milestones, including the launch, on its X account, Facebook page, Twitch profile and website.

If cable television is more your speed, C-SPAN is covering the launch (featuring its famous viewer calls).

Backup dates

The launch is ultimately dependent on the weather. The forecast shows an 80% chance of favorable weather for launch, with some potential for clouds and high winds at ground level that could delay the mission. Wednesday’s launch opportunity is open for two hours, until 5:24 p.m.

If weather or minor technical concerns prevent launch Wednesday, NASA has additional two-hour launch windows every evening through April 6. After that, it would have to wait until at least April 30.

The historical significance

Artemis II is the first mission since Apollo 17 in 1972 to carry humans to the moon. The capsule will carry the first Black person, first woman and first non-American to travel around the moon — potentially traveling farther and reentering the Earth’s atmosphere faster than any other human mission in history.

Although the astronauts will not land on the moon, Artemis II mimics early Apollo missions that were designed as a stepping stone to test all of the equipment and procedures before making the daring landing.

A springboard to Mars

The Artemis program ultimately aims to land humans back on the moon, help the space agency establish a lunar base and serve as the testing grounds for future missions to Mars.

NASA plans to launch Artemis III, a mission in Earth’s orbit to test docking the NASA spacecraft with SpaceX’s and Blue Origin’s lunar landers, in 2027. It aspires to launch Artemis IV, which would put humans on the surface of the moon, in 2028.

In an earlier era, the American Heart Assn. and the U.S. federal government were very closely aligned on what the American public should eat and why.

Dietary guidelines from the cardiovascular research nonprofit largely mirrored those published by the U.S. Department of Health and Human Services. American Heart Assn. representatives advised the government on the science behind its dietary advice.

But as is the case with many public health issues these days, the distance between the policies recommended by established medical groups and those endorsed by Department of Health and Human Services Secretary Robert F. Kennedy Jr. appears to be growing wider.

On Tuesday, American Heart Assn. released its updated guidelines for a heart-healthy diet. Like the new federal dietary guidelines released back in January, the document cautions against processed foods and refined sugars.

But the group pressed back on some nutrition claims that Kennedy and Make America Healthy Again influencers have touted in public statements and written into federal policy.

Unlike the new federally authorized inverted food pyramid, which gives top billing to an enormous cut of steak, a tray of ground meat, a hunk of cheese and carton of whole milk, the American Heart Assn. urges plant-based proteins over red meat, and low- or nonfat dairy products over whole-fat options.

In contrast to Kennedy’s declaration in January that the U.S. was “ending the war on saturated fat,” the heart association continues to recommend unsaturated fat sources over saturated ones for the sake of cardiovascular health.

The heart association also pushes back on Kennedy’s well-publicized passion for beef tallow as a replacement for seed oils, which he has accused (despite shaky evidence) of “poisoning” Americans.

“Animal fats (eg, beef tallow and butter) and tropical oils (eg, coconut oil, cocoa butter, and palm oil) are relatively high in saturated fat, whereas nontropical plant oils (eg, soybean, canola, and olive oils) are relatively high in unsaturated fat,” the American Heart Assn. paper reads. “In summary, as part of heart-healthy dietary patterns, nontropical plant sources of fat should be used as part of food preparation in place of animal fats and tropical oils.”

In response to questions, both the American Heart Assn. and Department of Health and Human Services emphasized their shared objectives over any differences.

“The American Heart Association’s [paper] is aligned with the Dietary Guidelines on the major issues: eat real food, avoid highly processed food, and limit refined grains and added sugar,” said Andrew Nixon, a health department spokesman. “We look forward to working collaboratively with the [American Heart Assn.] to evangelize these core principles and reverse the diet-related chronic disease epidemic.”

The heart association and the federal government have different purposes when drafting their recommendations, said Dr. Simin Liu, director of UC Irvine’s Center for Global Cardiometabolic Health & Nutrition and a professor at the UC Irvine School of Medicine.

The heart association’s guidelines are intended to reflect the best available evidence on nutrition and cardiovascular health outcomes, whereas federal nutrition standards inform the content of federally funded meals served in schools, hospitals and military dining facilities, and help determine foods included under assistance plans like the Supplemental Nutrition Assistance Program.

The two sets of guidelines aren’t totally at odds. The heart association applauded the government’s warnings against added sugars, refined grains and processed foods in January, noting that the advice aligns with the organization’s long-standing recommendations.

“Those of us in the field have been pushing for food-based dietary recommendations, like advocating people eat actual foods instead of [processed] food products,” Liu said, but “the focus on animal product consumption is a bit off the mark.”

The administration’s hearty endorsement of animal protein sources surprised many health groups, as a diet rich in red meat is strongly associated with poorer cardiovascular health.

A supplemental report published alongside the federal guidelines noted that several members of the government’s advisory panel had financial ties to meat and dairy industry groups, including the National Cattlemen’s Beef Assn., the National Pork Board and the California Dairy Research Foundation.

The heart association’s guidelines better reflect the current scientific consensus on the relationship between food and cardiovascular health, said a spokesperson for the nonprofit Center for Science in the Public Interest, and “will be a valuable resource for anyone who was confused by the mixed messages” in the government’s earlier advice.