NASA is considering using a commercial rocket to launch its Orion crew capsule around the Moon next year, instead of the agency’s future multibillion-dollar Space Launch System (SLS). NASA administrator Jim Bridenstine floated the idea for the first time today during a Senate hearing. The change may occur, as it becomes increasingly likely that the SLS may not be ready to fly the crew capsule by June 2020.

Bridenstine argued that NASA needs to stick to its commitment of sending the Orion crew capsule around the Moon by next year. One way to do that would be using a rocket other than the SLS. “We need to consider, as an agency, all options to accomplish that objective,” Bridenstine said during the hearing. “Some of those options would include launching the Orion crew capsule... on a commercial rocket.”

“We need to consider, as an agency, all options to accomplish that objective.”

NASA has long planned to send the Orion crew capsule on a three-week trip around the Moon on a mission dubbed Exploration Mission 1, or EM-1. The flight is meant to serve as the debut launch of the SLS, which has been in development for the last decade and will be the most powerful rocket available when it’s finished. But the target date for EM-1 has been consistently delayed due to technical challenges and cost overruns with the rocket. At one point, NASA targeted 2017 for the flight, but the agency is now working toward June 2020. Recently, NASA officials admitted that they are reassessing the 2020 date since the rocket probably won’t be ready to fly next year either.

This expected date change was something that Bridenstine mentioned during today’s Senate hearing, which addressed how the US could maintain its dominance in space. “We’re now understanding better how difficult this project is and that it is going to take some additional time,” he said, regarding the SLS development.

However, Bridenstine noted that no current commercial rocket has the extreme power needed to launch both the Orion and its European Service Module — a cylindrical piece of hardware that provides support and power for the capsule during flight — around the Moon. “The challenge is we don’t have a rocket right now that can launch Orion and the European Service Module around the Moon,” Bridenstine said. “That rocket doesn’t exist ... That’s what the SLS is all about.”

Instead, NASA is considering doing EM-1 in two launches with two heavy-lift commercial vehicles. One rocket would launch the Orion and European Service Module together, placing them in orbit, and another rocket would then launch an upper stage, which is a rocket with an engine capable of providing enough power to boost the capsule and module to the Moon. The upper stage would dock with Orion and the module in orbit, in order to complete the mission.

“The challenge is we don’t have a rocket right now that can launch Orion and the European Service Module around the Moon.”

Bridenstine did not mention which rockets are being considered for the job, but there are currently two heavy-lift vehicles in the US that can launch large amounts of cargo to orbit. Those include SpaceX’s Falcon Heavy, which debuted last year, and the Delta IV Heavy, which is manufactured by the United Launch Alliance.

However, making all of this happen by 2020 would still require some great feats of engineering. For one, the Orion capsule does not have the ability to dock with anything in orbit right now. “Between now and June of 2020, we would have to make that a reality,” Bridenstine said about docking. However, he noted that using a commercial vehicle is ideal since these rockets are already available — unlike the SLS. “We have amazing capability that exists right now that we can use off the shelf in order to accomplish this objective,” Bridenstine said.

It also wouldn’t be the first time that Orion has launched on a commercial vehicle into space. In 2014, a Delta IV Heavy rocket launched the capsule on a four-hour trip into a stretched orbit around Earth on an experimental flight known as Exploration Flight Test-1.

Switching to a commercial rocket for EM-1 would serve as another big blow to the SLS, which has been heavily criticized for being over budget and slow to develop. It’s estimated that NASA has spent $14 billion on developing the vehicle. And while it will be a powerful rocket, it won’t be that much more capable than other vehicles that are currently on the market. For instance, the Falcon Heavy is capable of putting up to 140,700 pounds (63.8 metric tons) into low Earth orbit, while the SLS will be able to put 209,000 pounds (95 metric tons) into the same region of space.

“NASA has a history of not meeting launch dates and I’m trying to change that.”

Additionally, the future of the SLS became even more uncertain this week with the release of the president’s budget request. In the request, the administration called for stopping development on the second version of the SLS that NASA was planning to build, one that would make the vehicle even more powerful. By canceling that upgrade, the SLS will no longer be able to boast the incredible strength that NASA has long been touting. The power of the SLS is perhaps the biggest asset the vehicle had.

Bridenstine noted during the hearing that NASA will decide soon whether to make this massive change for EM-1. “I think it can be done, sir, in the next couple of weeks, and every moment counts,” he said addressing Sen. Roger Wicker (R-MS). “Because I want to be clear: NASA has a history of not meeting launch dates and I’m trying to change that.”

Despite this change, Bridenstine maintained that the SLS is still needed for the future of NASA’s space efforts. “The Space Launch System, SLS, the largest rocket that’s ever been built in American history, is a critical piece of what the United States of America needs to build,” he said.