Can private-sector space business be profitable, or is it just an exciting way for billionaires to live out their fantasies?

Testy lawmakers peppered executives from Boeing and SpaceX with questions at a hearing yesterday about delayed efforts to launch humans into space from the United States.

The US is paying billions to both companies to build cheap, efficient spacecraft to ferry astronauts to the International Space Station (ISS) orbiting 250 miles above the earth, but plans to begin operations have slipped from last year into 2020 due to under-funding and the challenges of safely flying people into space.

SpaceX is now scheduled to fly its first crewed test flight in December 2018, while Boeing is planning to do so in January 2019. But both dates are optimistic; NASA believes they could slip another year, into 2020. Until then, the US and the rest of the world are dependent on Russia’s Soyuz rockets to access the ISS.

Undergirding the entire project is a controversial debate about whether the companies that build space hardware for the government should be guaranteed a profit, or asked to operate within the bounds of a fixed-price contract. NASA and SpaceX pioneered the latter approach with a successful partnership that developed spacecraft and rockets to bring cargo, but not humans, to the ISS.

Here are three key takeaways from the hearing:

SpaceX and Boeing are (slowly) solving engineering challenges

Both companies have put forward aggressive schedules that have slipped since the final contracts were awarded in 2014, and both have questions left to answer. NASA and government auditors say they are confident that both will accomplish their missions eventually, but they are running out patience. Kathy Lueders, the NASA executive responsible for the program, told auditors that “she relies on her prior experience for a better sense of schedule timeframes as opposed to relying on the contractors’ schedules.”

For Boeing, there are several issues: The rocket it will use to fly its Starliner space capsule, the Atlas V, is one of the most reliable in the world, but its engine is constructed in Russia and NASA wants to know more about its design and construction to be assured it will be safe to fly people. The abort system that will launch the Starliner clear of its rocket in the event of an accident may prove too violent to carry astronauts to safety. Finally, the parachutes that will carry the capsule safely back to earth could be damaged by its own heat shielding in some circumstances; NASA is considering a re-design that might add six months to the schedule.

SpaceX, meanwhile, has its own to-do list. The primary job is upgrading its workhorse Falcon 9 rocket to meet NASA’s safety concerns, particularly around cracks appearing in a key engine part called a turbopump. It will also redesign another component, called a “carbon over-wrap pressure vessel,” or COPV, that led to the destruction of a SpaceX rocket in 2016. The new version of the rocket, known as Block V, is expected to be finalized before the end of the quarter. The company is also negotiating with NASA about how to load propellant into its launch vehicle when flying people; NASA’s safety advisers fear that a proposal to fuel the rocket while astronauts are on board is unsafe.

But the upset lawmakers also deserve a hefty share of the blame for the delays: According to the NASA Inspector General, the Commercial Crew program received less than 40% of the required funding from 2011 to 2013, which created a two year delay in the schedule.

SpaceX is still facing a double standard

Elon Musk’s scrappy space start-up has stepped on plenty of toes as it disrupted the moribund US launch industry, and that was apparent in a hearing where several lawmakers harped on the company’s reliability.

It’s undoubtedly fair to ask questions about the company’s two failures, which occurred in 2015 and 2016. In particular, the unexpected fire linked to filling COPVs with ultra-chilled propellants is a new enough technology, and presents a clear enough safety risk, that NASA is running its own independent test program on the design at its White Sands, New Mexico test facility.

But the tone of the hearing was captured when Rep. Mo Brooks read aloud an op-ed published by the chief operating officer of the Lexington Institute, which is funded by SpaceX competitors Boeing and Lockheed Martin. One assumption of the op-ed was that SpaceX was responsible for the failure of a recently launched spy satellite, though the company has repeatedly said that its vehicle performed correctly, and NASA associate administrator Bill Gerstenmaier confirmed that NASA would be told if the launch was a failure, and said he had not been so informed.

In practice, this plays out in more test requirements. SpaceX will need to fly its new COPVs on seven of its own flights before it can convince NASA that the rocket can safely carry astronauts. Meanwhile, astronauts are scheduled to fly on just the second flight of the new rocket being designed by NASA and built by Boeing, the Space Launch System. Astronauts on Boeing’s commercial vehicle will also fly on just the second flight of a re-designed second stage of the Atlas rocket.

The US space program is still figuring out risk and reliability

“NASA may seek additional funding or accept significant risks,” Rep. Brian Babin said today. “Neither of those options is viable.”

That leaves just one option: SpaceX and Boeing eating the costs of schedule delays as they re-engineer their vehicles and re-plan operations to keep astronauts as safe as possible. At the same time, it’s worth recognizing that NASA is pushing the two companies to meet a safety standard that is far higher than that met by the Space Shuttle while it served as America’s ride to space. The metric, known as Loss of Crew, requires that the new vehicles have only a 1-in-270 chance of an astronaut being killed, versus the 1-in-90 standard met by the Space Shuttle. (The first Space Shuttle launch was flown with a loss of crew probability of 1-in-12, NASA determined later.)

NASA officials tell Quartz they expect that the final designs of the private vehicles to carry astronauts will wind up somewhere below the 1-in-270 standard. Much of the problem isn’t with design choices but with the nature of the space environment, with micrometeoroids and other space debris the largest source of concern. There is also quite a bit of uncertainty in these estimates that is masked by the simple output. ”We never simply accept it, but NASA, our stakeholders and the public must acknowledge the risk as we move forward and field these new systems,” Gerstenmaier wrote last year in an article urging a more realistic relationship with risk.

Typically, NASA—and Congress—have preferred to try to eliminate risk than live with it. They guaranteed a profit to companies building its space vehicles to compensate them for the expense of developing path-breaking technology. This has led to hugely costly programs, but not necessarily to safe and reliable spacecraft delivered on time. The development of cargo service to the ISS was seen as evidence that there was another way. But can this new approach produce a safe, human-carrying spacecraft without an unlimited budget, in time for its cost-savings to matter?