WASHINGTON — NASA is considering moving the Orion spacecraft that was to fly on the first Space Launch System mission to a commercial rocket to keep that mission on schedule for mid-2020.

During a hearing of the Senate Commerce Committee here March 13, NASA Administrator Jim Bridenstine said the agency would decide in the coming weeks about whether to fly the Orion spacecraft and its European service module on a pair of commercial launch vehicles.

That mission, known as Exploration Mission (EM) 1, was intended to be the first flight of the SLS. However, problems with the launch vehicle’s development have pushed that mission’s launch to the middle of 2020, and agency officials recently indicated that it could slip again.

“SLS is struggling to meet its schedule,” Bridenstine said in response to a line of questions from the committee’s chairman, Sen. Roger Wicker (R-Miss.) “We’re now understanding better how difficult this project is and that it is going to take some additional time.”

“I think we, as an agency, need to stick to our commitments,” he added, referring to the earlier plan to launch EM-1 no later than mid-2020. “If we tell you and others we’re going to launch in June of 2020 around the moon, which is what EM-1 is, then we should launch around the moon in June of 2020, and I think it can be done. We need to consider as an agency all options to accomplish that objective.”

That included, he said, launching the Orion spacecraft being built for EM-1 on commercial vehicles. “It’s been done before,” he said, referring to Exploration Flight Test 1 in December 2014, when a Delta 4 Heavy launched an Orion spacecraft, with a boilerplate service module, on a two-orbit mission around the Earth.

“There are opportunities to utilize commercial capabilities to put the Orion crew capsule and the European service module in orbit around the moon by June of 2020, which was our originally stated objective,” he said. “I have tasked the agency to look into how we might accomplish that objective.”

Bridenstine, upon further questioning by Wicker, said that no commercial launch vehicle available today could carry out the EM-1 mission. Instead, he said, the mission would require two launches: one to place the Orion into orbit the Earth, and a second carrying an upper stage. The two would then dock and the upper stage ignited to send Orion to the moon.

One challenge, he said, would be carrying out that docking. “We do not have, right now, an ability to dock the Orion crew capsule with anything in orbit,” he said. “So between now and June of 2020, we would have to make that a reality.”

“This is 2019,” Wicker noted.

“We have amazing capabilities that exist right now that we can use off the shelf in order to accomplish this objective,” he said, such as the Delta 4 Heavy that launched Orion on the earlier test flight. “We can use off-the-shelf capabilities, sir, to accomplish this objective for EM-1 but not change the direction of the SLS for EM-2.”

After the hearing, Bridenstine said he had not talked with United Launch Alliance or SpaceX about the use of their vehicles for this alternative approach to EM-1. He said he’s asking NASA’s Launch Services Program to see “what would be in the realm of possibilities” and provide a report to him on the various options.

One issue will be the availability of vehicles like ULA’s Delta 4 Heavy and Atlas 5, or SpaceX’s Falcon Heavy, to carry out a mission in just 15 months. Lead times for new launch vehicles are typically significantly longer than that, but vehicles already under development for other missions could be reassigned to this.

A decision on this alternative approach, he said, “can be done in the next couple of weeks.” He didn’t discuss the cost of this approach other than to say that, if exercised, “it might require some help from the Congress.”

Even while considering this alternative approach to EM-1, Bridenstine said the agency remained committed to developing SLS for EM-2 and subsequent missions. The SLS, he said, “is a critical piece of what the United States of America needs to build” given its advertised payload performance. “It is a critical capability.”

If that alternative approach is exercised, it could mean that the first SLS mission, EM-2, would also be the first mission to carry a crew. That may not change despite hesitations about placing astronauts on the first launch of a new rocket.

“It’s well within the realm of possibility,” he said of a crewed first SLS launch after the hearing. “If we can do a full-up ‘green run’ test on SLS, and we have an Orion crew capsule and a European service module that have been tested, I think that that is something we should absolutely consider, and that’s what would put us back on track.”