The agency is now likely to be at least three years late in delivering its new booster.

After Donald Trump moved into the White House in January, his advisers asked NASA to consider the possibility of a splashy achievement during the president's first term. Shortly following that, the space agency announced that it had begun to study the possibility of adding crew members to the maiden launch of the Space Launch System (SLS) rocket.

This seemed an ambitious ask for 2019. Not only was the agency already scrambling to meet a November 2018 deadline for an uncrewed test flight of the SLS rocket and Orion spacecraft, but few of the life support systems needed to keep crew members alive during a spaceflight were planned to be ready before 2021. Also, it's rare to launch crew on the first flight of any rocket, as engineers like to have confidence in their launch system before adding humans.

On Friday afternoon, the agency's acting administrator, Robert Lightfoot, and chief of human spaceflight, William Gerstenmaier, announced that NASA had completed the study. And while it was technically feasible to put crew on the first SLS launch, it would cost $600 million to $900 million above the existing budget, and it would not appreciably advance the agency's long-term goals of deep spaceflight. "We’re in this for the long haul, and we want to make sure we’re focusing on that," Lightfoot said in a conference call with reporters.

In the face of political pressure, then, NASA chose prudence. Yet the evidently shrewd short-term decision to hold crew off the maiden flight of the SLS rocket could not mask a larger political problem that NASA has grappled with for nearly this entire decade. Simply, it has been tasked with building a massive, complicated rocket that it can't really afford.

Too expensive

The SLS rocket was born in 2010 with the budget authorization bill signed into law by President Obama in October. In doing so, the president bowed to the will of Congress, and, more specifically, the US Senate, which wanted NASA to build a big rocket. However, after that legislation was signed into law, NASA engineers and their consultants began studying the rocket and how best to build it. What they found is that the SLS rocket would not fit within the agency's budget run-out, and its costs would be too high for the agency to handle.

Notably, an August 2011 analysis by the consulting firm Booz Allen Hamilton offered a stark warning for any rosy SLS cost estimates. "There are many instances of unjustified cost reductions in the program estimates," the analysis said. "This exposes the programs to cost risk and undermines the credibility of the estimate." Inevitably, this would lead to delays and force NASA to cut any funding that would go toward payloads to fly on the rocket.

In 2011, when NASA officials pushed back on these budget questions with congressional staffers, Senator Kay Bailey Hutchison, a Texas Republican, had a message for the agency's chief financial officer, Beth Robinson: don't worry about the money—I'll get you the money. Hutchison, however, would leave the Senate about a year later.

By then, other senators had taken up the cause. These included Richard Shelby from Alabama, whose home-state Marshall Space Flight Center was in charge of managing the rocket program and who had begun to appreciate the value of the program for local jobs. Thanks to his support, and others, the rocket regularly received large "plus ups" in NASA's budget over what the president provided for rocket building. (Typically, the president's budget offered about $1.3 billion annually, and Congress appropriated $2 billion for the SLS.) But this still wasn't enough.

Delays, and more delays

Even with the extra funding, the unfortunate result of these decisions has come home to NASA. On Friday, agency officials confirmed that not only would crew not fly on the rocket's first mission, but the maiden launch date would also be delayed—again. The original NASA Authorization legislation that created the rocket in 2010 required the agency to launch the rocket and Orion by December 31, 2016. That date slipped into 2017, and then for the last couple of years, NASA has been targeting September to November, 2018.

Now, NASA says the launch will not occur before 2019, but the agency will require another one or two months to finalize a 2019 date. (Ars has heard from two sources that the most likely timeframe will be November 2019 for the uncrewed launch of the rocket and spacecraft.)

During the teleconference, Ars asked Gerstenmaier to step back and take a big-picture look at the SLS rocket. Even with all of the funding—about $10 billion through next year—how was the agency likely to miss the original deadline by as much as three years, if not more?

"I don’t know," Gerstenmaier replied. "I don’t know—I would just say it’s really kind of the complexity of what we’re trying to go do, and to build these systems. We weren’t pushing state-of-the-art technology, like main engines sitting underneath the rocket or new solid rocket boosters. But we were pushing a lot of new manufacturing, and I think that new manufacturing has caused some of the delays we’ve seen. No one welds the way that we’re welding material at the thicknesses we’re welding."

He also mentioned problems with the Orion spacecraft's service module provided by the European Space Agency, tornado damage at NASA's Michoud Assembly Facility in Louisiana, and other causes of delays. But at the end of the day, it's just a big rocket, which takes a lot of time and money to build. "Again, I think if you look at the amount of work that we’ve accomplished, it's pretty phenomenal overall, and that has caused some of the delays," Gerstenmaier said.

Later, the NASA officials were asked about private companies such as SpaceX and Blue Origin, which are also building heavy-lift rockets but at a very limited cost to taxpayers. What would they have to say about just buying those vehicles off the shelf, at significantly lower cost than an SLS launch, and preserving NASA's funds to execute in-space missions?

Lightfoot responded that he welcomed commercial participation in NASA's journey back into deep space, near the Moon, and then potentially on to Mars. "I've been saying for a while this is an 'and' proposition; it is not an 'or' proposition," he said. "If you look at what we're trying to do, it's going to take both. It's going to take really all of us, frankly, to get this done."

That may well be so, but the latest delay of the SLS rocket raises the distinct possibility that not only will SpaceX's Falcon Heavy rocket fly well before the first SLS launch but that Blue Origin's New Glenn heavy vehicle may as well. If these private launchers are viable even before the NASA vehicle enters service, it may raise new questions about the need for the government's own gold-plated capability.