After more than a decade of development, NASA’s new moon rocket will finally attempt to shed the shackles of Earth’s gravity and soar into space.

The space agency has officially set August 29 as the launch date for its Artemis I mission. This flight will be the beginning of an intricate series of spaceflights that could send humans back to the moon’s surface—and on a tortuous path to Mars—for the first time since the final Apollo mission in 1972. Artemis I will blast off from launch pad 39B at NASA’s Kennedy Space Center near Cape Canaveral, Fla., as early as 8:33 A.M. ET, with backup dates set for September 2 and 5.

“We are ‘go’ for launch, which is absolutely outstanding. This day has been a long time coming,” NASA’s associate administrator Bob Cabana told reporters during an August 22 press briefing that followed Artemis I’s flight readiness review.

But Cabana and others were quick to stress that this mission is not without risk. Artemis I is a test flight—a journey of more than a million miles that will put the space agency’s new crew-rated hardware through its paces. It’s the first time NASA’s Space Launch System (SLS) will fly, the first time the Orion crew capsule will feel the tug of the moon’s gravity and the first time the spacecraft’s heat shield will experience a blistering plunge through Earth’s atmosphere. Invariably, not everything will perform exactly according to expectations. So no humans will be onboard—that will have to wait until the follow-up flight of Artemis II, optimistically scheduled for 2024. But the mission will still have some ride alongs—a few secondary science payloads that will help researchers better understand the quirks and challenges of exploring deep space and lunar environments.

“We use the word ‘exploration’ in this discussion, and I think sometimes we forget what exploration is. And that is—we don’t know all the answers,” says Daniel Dumbacher, who oversaw the SLS’s initial development while he was at NASA and now serves as executive director of the American Institute of Aeronautics and Astronautics. “This launch system is going to give us the capability to put humans and equipment into space that we haven’t had in a long time.”

Despite the lofty goals of broadening humankind’s off-world horizons, NASA has faced years of criticism for its handling of the SLS and Orion. Complaints have mostly focused on the ballooning costs of developing and building the hardware, now known to exceed $40 billion, which some critics say are a consequence of the traditional way in which the agency assembled the spacecraft. Instead of working with more nimble, less expensive commercial companies such as SpaceX or Blue Origin, NASA turned to a handful of legacy aerospace contractors—such as Boeing, Lockheed Martin and Northrop Grumman—that have a habit of delivering results that, while reliable, are also reliably behind schedule and over budget.

“We see these two competing elements going on at once now: SLS, which represents a previous model of space contracting, and, in contrast, the commercial programs,” says Teasel Muir-Harmony, a historian and curator of the Apollo collection at the Smithsonian Institution’s National Air and Space Museum. Those two competing camps somewhat merged in April 2021, when NASA announced that the first moonwalking astronauts of the Artemis program—at least one of whom will be the first woman on the moon—would launch from Earth inside an Orion capsule atop an SLS rocket but would use SpaceX’s in-development Starship spacecraft as a lunar lander.

According to Muir-Harmony, however, the greatest immediate impact of the Artemis program may not be the revamping of NASA’s aerospace contracting but rather the inspiration it provides for future scientists, engineers and explorers around the globe—the so-called Artemis generation.

“For people who were really interested and enthusiastic about lunar exploration with the Apollo program—and now it’s been 50 years since the last Apollo mission in December of 1972—it’s exciting to see this important step in that process of a return to human lunar exploration,” she says. “And just seeing the evolution of this program and all the different players—it’s a great example of the ways that space exploration gets done in the U.S.”

Fly Me to the Moon

In its grandest realization, the Artemis program—named after Apollo’s sister in Greek mythology—could lead to new space station orbiting the moon called Gateway and outposts on the lunar surface where humans could safely live and work for extended periods. Outfitted with far more capable tools and scientific instruments than their Apollo-era predecessors, astronauts on the lunar surface could rapidly deliver major new discoveries about Earth’s nearest neighbor—or harvest its as-yet-untapped natural resources. And of course, Artemis could ultimately be a pathway for launching humans even farther afield.

“We’re going to Mars, and we’re going back to the moon in order to learn to live, to work, to survive,” NASA administrator Bill Nelson said during an August 3 briefing. “How do you keep humans alive in those hostile conditions? We’re going to learn how to use the resources on the moon in order to be able to build things in the future as we go.”

The SLS is often billed as the most powerful rocket ever built—projected to be even more muscular in its final form than Saturn V, which delivered Apollo astronauts to the lunar surface in the 1960s and 1970s. Like the Saturn V rocket, the SLS’s main stage uses a mix of liquid fuels. But unlike its forebear, it also relies on a pair of solid rocket boosters to give it the extra oomph needed to climb out of Earth’s gravity well. The 322-foot-tall rocket can launch 59,000 pounds of payload into lunar orbit and beyond, allowing crew and cargo to reach deep space in one step, which minimizes cost and the risk of repeated launches.

“Every launch is a risk, no matter what, so from a mission reliability perspective—from a cost perspective—this system gave us the most flexibility to accomplish the most missions,” Dumbacher says. The SLS is also meant to be capable of launching astronauts to Mars, he says, should such a mission materialize.

“The question is: Is Artemis a priority for this nation? Do we feel we must, as we felt during Apollo, get people on the moon in the next few years?” asks Lori Garver, former deputy administrator of NASA. “If this program were being done in a way that was different from Apollo—really lowering the costs and really advancing technology and being reusable and being sustainable—I think it would be exciting.”

The SLS and Orion have been something of a ball and chain for the space agency since 2010, when President Barack Obama elected to cancel a George W. Bush–era program called Constellation that would have been the space shuttle’s successor. Powerful members of Congress pushed back, including then senator Nelson, as Garver recounts in her recent memoir Escaping Gravity. They pushed for existing Constellation contracts to remain essentially intact, providing funds for aerospace companies in their districts, and mandated that the SLS launch by the end of 2016.

Instead reaching the launch pad would take more than a decade and billions of dollars of additional expenditures.

“I think, when it comes to space exploration, it’s really important to recognize that it has always been closely tied to politics and political incentives,” Muir-Harmony says. “If we’re asking taxpayers to fund it, and we’re asking for congressional support and for this to be one of the national priorities, it makes sense that it’s going to be tied to politics.”

As a result of those congressional machinations, the SLS is somewhat of a “Frankenstein” rocket, assembled from variously sourced components, some of which were state-of-the-art decades ago, when they were used in support of NASA’s space shuttle fleet. Boeing provides the rocket’s core and upper stages, Northrop Grumman makes the twin solid rocket boosters, and Aerojet Rocketdyne built the main and upper-stage engines, along with the main and auxiliary engines of the Orion crew capsule. Lockheed Martin designed and built the Orion spacecraft, which now has a price tag exceeding $8 billion.

If that sounds like a hefty amount of money, that’s because it is. A recent report from NASA’s Office of Inspector General estimates the total cost of a single SLS launch at circa $4 billion. And the report suggests that spending on Artemis could exceed $90 billion by the end of 2025, before astronauts have even landed on the lunar surface.

“It’s a substantial price tag. But when it comes to human spaceflight, I think it’s within the range of what we [historically] spend,” Muir-Harmony says. “It’s much more comparable to what we were spending on [the] space shuttle. It’s not even close to the same as Apollo.”

Despite being cheaper than the Apollo program—at least so far—the pressure for Artemis to deliver results is nearly as high as it was in the 1960s. Unlike back then, when only the U.S. and the Soviet Union were attempting to reach the moon, today numerous nations and even private companies are pursuing ambitious plans for lunar voyages. The consequences of a major catastrophe unfolding during Artemis I could easily prove disastrous for NASA and the broader endeavor of federally funded human spaceflight beyond low-Earth orbit.

To the Moon and Back

If all goes well, the SLS rocket will launch the Orion capsule to a 42-day exploratory journey into space. Tracing a serpentine path known as a distant retrograde orbit, the spacecraft will loop 1.5 times around the moon, coming to within 60 miles of the cratered lunar surface at closest approach. Before returning to Earth, Orion will boomerang out to 40,000 miles beyond the lunar far side—where it will set a new distance record. “On this mission, Orion will venture farther than any spacecraft built for humans has ever flown,” Nelson told reporters on August 3.

The Artemis I test orbit is different than the path a crewed mission would take. Artemis II, if it flies, will be a much shorter 10-day mission with as many as four crew members onboard. But as Orion loops through space on this initial flight, teams will be testing all the onboard systems—making sure that the spacecraft can communicate with Earth; that its guidance, navigation and control systems are up to snuff; that its propulsion system can perform the necessary maneuvers to stay on course; and that life support systems powered by a European-built service module are running correctly. The long-duration mission will push the spacecraft to its limits and potentially challenge it to survive situations that would automatically be avoided if astronauts were onboard—but that’s part of the plan.

“We are pushing the vehicle to its limits, really stressing it to get ready for crew,” NASA’s associate administrator of exploration systems development Jim Free said during the Artemis I flight readiness briefing on August 22. “It is incredibly risky.”

Perhaps the most crucial part of Orion’s journey begins as the spacecraft returns from beyond the moon, and Earth is once again in view: atmospheric reentry. As it rounds the moon’s far side, Orion’s thrusters will fire and set it on a course for Earth.

“That is our most critical burn of the mission. If something happens with that one, and we don’t execute it, then it’s a loss of the Orion capsule,” NASA’s Rick LaBrode, lead Artemis I flight director, said during a preflight briefing on August 5. “We have to do that one.”

The reentry burn will set up Orion for a splashdown in the Pacific Ocean, optimally within 50 or 60 nautical miles of San Diego, Calif. And as it hurtles home, the mettle of Orion’s protective heat shield will, in a very real sense, be put to the test in a fiery crucible of glowing plasma formed from frictional heating between the capsule and molecules of air. Traveling 32 times faster than the speed of sound, the spacecraft will dip into the top layers of the atmosphere, shed some of that speed and skip like a rock back into space. Then it will make its final plunge to the planet’s surface, enveloped by a fireball that, at 5,000 degrees Fahrenheit, will be half as hot as the sun’s surface. If the heat shield does its job, Orion will endure the descent and deploy its parachutes. If it doesn’t, searing gases seeping into the capsule will obliterate the spacecraft just as it nears the “mission success” finish line.

Scientific Hitchhikers

Artemis I will also be carrying science payloads that will help scientists better understand the complexities of the deep-space environment.

Orion will be the temporary home to three onboard mannequins (and to a Shaun the Sheep doll, provided by the European Space Agency). One, dubbed Commander Moonikin Campos, wears a space suit and sensors that will measure the forces a human might encounter during a lunar journey. The other two—called phantoms—simulate human female torsos, and they will be used to measure the amount of radiation astronauts might absorb. As Orion swings around the moon, the spacecraft will be flying far beyond Earth’s protective magnetic field, in a realm relatively riddled with high-energy cosmic particles that can damage cells and DNA. Scientists already know that radiation is harmful to humans, and to female biology in particular, so one of the phantoms will be testing a special radiation-shielding vest.

“Radiation is one of the top challenges for human exploration beyond [low-Earth orbit], which is why there is such a focus on understanding the radiation environment to and at the moon,” said NASA’s Bhavya Lal, associate administrator for technology, policy and strategy, during the briefing on August 3.

Also onboard are 10 CubeSats—shoebox-size science experiments, each weighing less than 30 pounds, that will be deployed about two hours after launch. The CubeSats’ objectives include mapping the moon, searching for sources of lunar water ice, monitoring space weather, testing plasma thrusters and propulsion, and more. One CubeSat, called NEA Scout, will travel to a near-Earth asteroid using energy harvested by solar sails. Another, BioSentinel, will measure the effects of radiation on the single-celled yeast Saccharomyces cerevisiae. And a third, OMOTENASHI, will intentionally crash-land on the lunar surface. In a twist, though, repeated launch delays have meant that half of the CubeSats—which were loaded onto SLS last year—will be launching with less than fully charged batteries.

“These lightweight platforms enable us to conduct research at lower cost but higher risk. Of course, that is the point,” Lal told reporters. “When it comes to CubeSats, failure is an option.”

That’s in contrast to the SLS and Orion. If they don’t function as expected, the outlines of any “Plan B” that would then emerge are murky at best.

“This is a big system—there’s been a large investment to get us to where we are today,” Dumbacher says. “The stakes are pretty high, and that’s why the team is making sure they’re doing it right.”