Yesterday, NASA’s Space Launch System — the giant, expensive rocket the space agency is building to take astronauts into deep space and onto Mars someday — got a crucial endorsement from an unlikely ally: the commercial space industry.

Alan Stern, the chairman of the board of directors for the Commercial Spaceflight Federation (CSF), publicly announced the organization’s support for the rocket at a conference in DC. The CSF is an association representing more than 70 businesses and organizations in the realm of commercial space, including major players like SpaceX and Blue Origin. Getting the seal of approval from CSF marks a significant attitude shift for the private sector, which has been home to some of the strongest opponents of the Space Launch System, or SLS.

“We see many potential benefits in the development of NASA's Space Launch System.”

“CSF and its members believe strongly in the exploration of space of all kinds, including commercial purposes,” Stern said Tuesday in a speech at the FAA Commercial Space Transportation Conference, according to a CSF spokesperson. “To that end, CSF announced today that we see many potential benefits in the development of NASA's Space Launch System. There are bright futures across the spectrum of commercial space. The SLS can be a resource that benefits commercial spaceflight and makes our future even brighter.”

NASA is currently developing the SLS to get the vehicle ready for its debut flight, slated for fall of 2018. When complete, the rocket will be capable of carrying 70 metric tons, or more than 150,000 pounds, to lower Earth orbit. And that’s just the expected capability of the first iteration of the rocket, known as Block 1. NASA is planning on building multiple variants of SLS, which will increase the rocket’s lift capacity and make it one of the most powerful vehicles that’s ever been built. The next evolution of SLS is called Block 1B, which will include a more powerful upper stage that can loft 105 metric tons, or more than 230,000 pounds, into lower Earth orbit. And the final version of SLS, Block 2, will have even more powerful boosters attached to it during launch, giving it a lift capacity of 130 metric tons, or close to 290,000 pounds.

While the rocket’s stats may seem impressive, the SLS has suffered a lot of criticism since it was first announced in 2011. It represents an old way of doing business at NASA, where the space agency heavily oversees the design and development of the rocket. But the main issue has always been the rocket’s costs. Initially, NASA estimated that developing SLS would cost $18 billion through 2017. And in 2014, the space agency estimated that it would cost $7 billion just to develop the SLS from February of that year through the rocket’s first launch in 2018. Many early opponents, including the Space Frontier Foundation, called for the cancellation of the program, arguing that the vehicle’s development would suck up a sizable portion of NASA’s already limited budget. That would leave very little money leftover for other projects at NASA, including new, innovative partnerships with the private sector.

Another critique was that commercial companies are developing new, heavy-lift rockets that could be just as capable as the SLS but would be potentially much cheaper. For instance, SpaceX is currently developing a heavy-lift version of its Falcon 9 rocket called the Falcon Heavy. It has yet to fly, though, and SpaceX claims it will be able to lift 54 metric tons, or more than 119,000 pounds — less capability than what NASA promises for SLS. However, SpaceX says the starting cost of the Falcon Heavy is $90 million, whereas one launch of the SLS is estimated to be $1 billion, according to Bill Gerstenmaier, the associate administrator for NASA’s human exploration and operations, who spoke at the FAA conference yesterday.

Stern wanted to get this perception “off the table” that the CSF is strongly against the vehicle

However, Stern says that the extra capability of SLS will enable missions and partnerships with the private sector that cannot be achieved on commercial heavy-lift vehicles that are currently in development. Because of this, he wanted to get this perception “off the table” that the Commercial Spaceflight Federation is strongly against the vehicle when the organization is actually in favor of it. Stern sees the potential of the SLS being used to put something like a commercial lunar outpost on the surface of the Moon (that is if NASA sets its sights on returning to the Moon again).

It’s a crucial affirmation from the private sector, since public-private partnerships are poised to be a major focus of NASA moving forward. Under the Obama administration, the space agency experimented with new models of doing business with the commercial spaceflight industry, by doing a more hands-off approach when working with the private sector; instead of intense oversight of vehicle design, NASA has tried purchasing spaceflight services from private companies with less scrutiny on how the vehicles are made. Some of President Trump’s space advisors have heralded this new way of partnering with spaceflight companies, so it’s something we could see more of in the future.