The US Congress championed the creation of NASA's Space Launch System rocket in 2010, at which time its members also successfully beat back an effort by the Obama administration to end support for the Orion spacecraft. Since then, Republicans and Democrats in the House and Senate have patiently spent $3 billion to $4 billion annually for continued development of these deep space vehicles.

However, in recent years the projected launch date of the first flight of the SLS rocket and Orion spacecraft has slipped to the right, from 2017 to 2018 and now likely into mid-2020. While overall support remains strong for these space vehicles, delays in their development may have begun to break the almost uniform congressional approbation for these exploration programs.

During a hearing Thursday before a House subcommittee over NASA, some of those concerns spilled into the public. "It is very disappointing to hear about delays caused by poor execution when the US taxpayer has invested so much in these programs," said Rep. Lamar Smith (R-Texas), chairman of the House Science, Space, and Technology Committee. "NASA and the contractors should not assume future delays and cost overruns will have no consequences."

Smith, who recently announced that this will be his last term in Congress, perhaps felt more free to discuss his concerns about the delays in work being done by NASA and its large contractors, such as Boeing, Lockheed Martin, Orbital ATK, Aerojet, and others on the SLS and Orion programs. "That confidence is ebbing," he said of congressional faith in NASA's exploration systems. "If it slips much further, NASA and the contractors will have a hard time regaining their credibility."

Commercial solutions?

The Texas congressman also tiptoed around an issue that, until now, lawmakers have almost never mentioned in public: SpaceX, Blue Origin, and United Launch Alliance are all developing competitive launch vehicles that would be useful for a lunar surface program. SpaceX's Dragon spacecraft is also being built with a heat shield capable of returning from the Moon, much like NASA's own much more expensive Orion spacecraft.

"Alternatives to SLS and Orion almost certainly would involve significant taxpayer funding and lead to further delays," Smith said during his prepared remarks. "But the more setbacks SLS and Orion face, the more support builds for other options."

The chairman of the subcommittee, another Texas Republican, Brian Babin, did not go as far as Smith in his criticism of NASA. But he, too, said the space agency must now execute on its program. "Failure to do so could have dire consequences for the program, and there will be no one else to blame," Babin said. "The administration has demonstrated its renewed support. Congress consistently funds the program at healthy levels. It is time for NASA and the contractors to deliver."

Both of the witnesses at Thursday's hearing, NASA's chief of human spaceflight, William Gerstenmaier, and the executive director of the American Institute of Aeronautics and Astronautics, Sandy Magnus, defended the status quo. They urged Congress to stay the course with NASA and continue to fund the program between now and 2023, when the first crewed flight of SLS and Orion may take place.

"I repeat, because this is critical, to be successful in our space endeavors it is imperative that we commit, as a nation, with a constancy of purpose for the long term—it is the nature of the space business that it takes time, patience, and constant purpose to make advancements," Magnus said.