Members of Congress on Wednesday expressed growing concern that delays in NASA’s Artemis moon program and its immense cost could threaten the United States’ goal of returning astronauts to the moon before China, a rising space superpower, gets there.

Last week, NASA Administrator Bill Nelson announced that the space agency’s first attempt to send astronauts around the moon in more than 50 years would be delayed from later this year to September 2025. The first lunar landing since the Apollo era would also be pushed back by nearly a year, he said, to September 2026.

The postponements come as the space agency studies why the heat shield of its Orion spacecraft, the vehicle that will carry Artemis astronauts to the moon, showed more charring than anticipated during an uncrewed test flight in late 2022. NASA also said delays in developing the spacecraft that would ferry astronauts to and from the lunar surface, as well as in developing the spacesuits they would wear while there, are affecting the timeline.

In addition to those delays, NASA’s inspector general said in a report released Wednesday that the total cost of the program, between 2012 and 2025, could reach $93 billion.

“NASA faces additional challenges to meeting its Artemis goals. Of utmost importance is resolving technical issues that could threaten astronaut safety,” George Scott, NASA’s acting inspector general, told lawmakers during a hearing of the House Science, Space and Technology Committee. “The agency will need to do this while also addressing long-standing concerns such as unsustainable costs, unreliable project schedules, and the lack of transparency into funding needs.”

Taken together, those challenges could allow China, which is also aiming for the lunar surface, to send its astronauts there before NASA is able to return, Rep. Frank Lucas (R-Okla.), the committee’s chair, said during the hearing.

“I remind my colleagues that we are not the only country interested in sending humans to the moon,” he said. “The Chinese Communist Party is actively soliciting international partners for a lunar mission, a lunar research station, and has stated its ambition to have human astronauts on the surface by 2030. The country that lands first will have the ability to set a precedent for whether future lunar activities are conducted with openness and transparency or in a more restricted manner.”

Former NASA administrator Mike Griffin, who has also served in key roles at the Pentagon, said the United States has not demonstrated a sense of urgency that would keep it ahead of China. “Our self-declared adversaries, the Chinese Communist Party, together with their Russian partner, fully understand the role that being on the space frontier has in the world of global power politics,” he said. “We seem no longer to understand that. For the United States and its partners not to be on the moon when others are on the moon, is unacceptable.”

NASA completed the first flight of its Orion crew capsule in late 2022, when it flew around the moon without anyone on board in a mission known as Artemis I. Since then, however, NASA has been studying some unexpected erosion of the heat shield as the capsule returned through the atmosphere at some 25,000 mph and hit temperatures of nearly 5,000 degrees Fahrenheit.

Last week, NASA officials said they were also working to understand an issue with the circuitry in the capsule’s life support system, as well as the emergency abort system that would propel the capsule away from the rocket in the event of an emergency.

Those problems need to be fixed before NASA flies the Artemis II mission, sending NASA astronauts Christina Koch, Victor Glover and Reid Wiseman, as well as Canadian astronaut Jeremy Hansen, on a 10-day trip around the moon.

“I want to emphasize that safety is our Number One priority,” Jim Free, NASA’s associate administrator, said during a briefing about last week’s delay announcement. “As we prepare to send our friends and colleagues on this mission, we’re committed to launching as safely as possible. And we will launch when we’re ready.”

Even with the delays, NASA should be in a position to land its astronauts on the moon in the Artemis III mission before China, Nelson said at the briefing.

“I do not have a concern that China is going to land before us,” he said. “I think that China has a very aggressive plan. I think they would like to land before us because that might give them some PR coup. But the fact is that I don’t think they will.”

After sending a spacecraft to orbit the moon in 2007 and again in 2010, China landed the Chang’e-3 spacecraft in 2013, becoming the first nation to soft-land on the lunar surface since the U.S.-Soviet Union rivalry of five decades ago. In early 2019, China became the first country to land a spacecraft on the moon’s far side. And in 2020 it brought back samples from the lunar surface.

Later this year, it is planning to land a craft on the far side again, this time in an effort to bring samples back to Earth, in what would be another impressive demonstration of its growing prowess and ambition. Ultimately, China has said it plans to establish a base near the lunar south pole, where there is water in the form of ice in the permanently shadowed craters. The south pole is also where NASA intends to go as part of its Artemis program.

The race with China is one of the main reasons the Biden administration embraced Artemis, which was born during the Trump administration, making it the first deep-space human exploration program to survive the transition of presidential administrations since the Apollo era. Initially, the Trump administration directed NASA to land astronauts on the moon by 2024, a schedule that the Biden White House pushed back to 2025 after it assessed the program.

Despite the delay, Artemis continues to have bipartisan support in Congress, which is eager to see the first woman and first person of color walk on the moon, as NASA has promised. But China’s presence looms over the program.

“I support Artemis, but I want it to be successful,” Rep. Zoe Lofgren, D-Calif., said during Wednesday’s hearing — “especially with China at our heels.”