NASA’s ambitious initiative to fly astronauts on commercial spacecraft continues to suffer from schedule delays, as well as questions regarding the program’s safety — and Congress isn’t happy about it. Members of the House Subcommittee on Space held a hearing today in which they grilled representatives from NASA and its commercial partners about the program, known as Commercial Crew. They voiced concerns that the commercial vehicles might put human crew members at risk, and that the companies will miss crucial deadlines by two to three years.

As part of the program, two companies — Boeing and SpaceX — are developing spacecraft to ferry NASA astronauts to and from the International Space Station. When these two companies were selected by NASA back in 2014, the goal was to start flying crews to the station as early as 2017. But 2017 has come and gone, and the target dates keep moving. Just this month, SpaceX’s timeline for its first Commercial Crews flight was pushed back four months, and NASA says that both companies are still a year away from flying astronauts for the first time.

Experts think that’s a generous expectation. Today’s hearing coincided with the release of a critical report on the Commercial Crew program from the Government Accountability Office, which does periodic audits of NASA’s agendas. The authors of the report claim that SpaceX won’t be certified to fly astronauts to the ISS until December 2019, while Boeing’s certification will happen in February 2020. NASA plans to certify the company’s vehicles only after they’ve done an uncrewed test flight and a crewed test flight, meaning the first astronauts likely won’t fly until late next year at the earliest. The vehicles can only start performing regular trips to the ISS once they’re certified.

The report also raises doubts that Boeing and SpaceX will meet the safety standards that NASA has set for the program. NASA is requiring that both companies prove that there is only a 1 in 270 chance of a flight going catastrophically wrong and losing crew members on board. In other words, 99.6 percent of the Commercial Crew missions should keep astronauts safe during flight. It’s a particularly stringent requirement, especially since each Space Shuttle flight had a 1 in 80 chance of loss of life. The GAO report argues that the two companies may not meet this hard standard, and that NASA may have to accept a higher level of risk for the astronauts on board.

But Congress is refusing to give NASA and its commercial partners any more wiggle room. The subcommittee members made it clear that NASA should not expect more money to help the companies meet their deadlines, and that changing the safety standards is not a good idea. “Both companies are making progress, but certainly not at the rate that was expected, and not without significant challenges to safety and reliability,” Rep. Brian Babin (R-TX), chairman of the House Subcommittee on Space, said at the hearing. “In order to remedy these problems, NASA may seek additional funding or accept significant risks. Neither of those options is viable.”

The Commercial Crew program was originally envisioned as a more cost-effective way to develop new vehicles for NASA. Instead of NASA investing billions and heavily overseeing the development of a spacecraft — as it did with the Shuttle — the space agency would let commercial companies develop their own vehicles with minimal oversight and partial government funding. The idea was that this more “hands off” approach would save taxpayers’ money and allow companies more flexibility when creating their vehicles. The companies could also conceivably work faster, since they wouldn’t be restricted by as much government red tape.

While it’s true that NASA is saving potentially millions of dollars by investing in these commercial vehicles, the Commercial Crew program isn’t moving as quickly as expected. One reason may be that the companies set super aggressive target dates (something the GAO notes in its report). The strict safety standards may also play a roll, requiring the companies to do lots of additional testing to prove that their vehicles are reliable and safe. Plus, other unforeseen challenges have cropped up, throwing timelines off track.

NASA says that ultimately, the schedule isn’t the agency’s biggest priority. “NASA is aware of the schedule but not driven by the schedule,” Bill Gerstenmaier, the associate administrator for Human Exploration and Operations for NASA, said at the hearing. Of course, as the dates for the program move to the right, NASA continues its reliance on Russia to send US astronauts to space. Currently, NASA astronauts can only fly on Russia’s Soyuz rocket to get to the ISS, and the space agency has already purchased extra Soyuz seats through 2019 because of delays in Commercial Crew. Additionally, the ISS program is only slated to last through 2024 at the moment, meaning the commercial vehicles may not be transporting astronauts for very long.

Both the authors of the GAO report and members of Congress agree that safety should be the top priority, and that’s why lots of questions were raised at the hearing today regarding SpaceX’s launch record. Congress members repeatedly asked if SpaceX’s recent classified Zuma mission failed, as some reports have indicated, and if the company was to blame. “We relayed the information that Falcon 9 performed as specified, and it actually performed very well as specified,” Hans Koenigsmann, vice president of Build and Flight Reliability at SpaceX, said at the hearing.

The subcommittee also brought up SpaceX’s failure from 2016, in which one of the company’s Falcon 9 rockets exploded while it was being loaded with propellant. Safety experts have been on edge about the failure, since SpaceX wants astronauts to board the rocket before the propellant is loaded — which could pose a safety hazard. SpaceX insists that this method will be safe and that its abort system will be able to safely carry crew members away from a malfunctioning rocket. Additionally, NASA’s Gerstenmaier is still looking at the best time to put people on SpaceX’s vehicles.

Meanwhile, Boeing has its own problems with its abort system, which may not meet NASA’s safety standards, according to the GAO report. And there’s a risk that when the company’s vehicle falls back to Earth, part of the spacecraft’s heat shield might actually damage its parachutes. If NASA refuses to accept this possibility, then Boeing will likely need to redesign its parachutes, according to the GAO.

Addressing these problems will be a top priority for NASA as it moves forward with the program this year. At some point in 2018, the agency will need to decide what level of risk it’s willing to accept for the program, despite Congress’ misgivings — and that means potentially more delays are on the horizon. Despite the negativity from today’s GAO report and hearing, however, one member of the subcommittee offered some praise and hope for Commercial Crew. “So it looks like the program is going along as we thought it would, even though there have been glitches,” Rep. Dana Rohrabacher (R-CA) said at the hearing. “But there are the glitches in the development of any new technology.”