SpaceX has never flown a person into space in its Crew Dragon, its first crew-capable spacecraft. But already the company is showing off its much bigger, much shinier cousin: the Starship, built in Boca Chica, a coastal village at the southeastern tip of Texas, as part of a plan to carry giant crews into deep space. And NASA's administrator is bristling.

That's because, even though the Crew Dragon — which consists of a capsule for carrying cargo and crew into space on top of a Falcon 9 rocket — is still very much in the works, it's well behind schedule. Awarded a NASA contract in 2014, SpaceX initially said it would deliver an operational vehicle that astronauts could fly in by 2017. But that still hasn't happened. As of March, SpaceX has completed one uncrewed mission to the International Space Station using the Crew Dragon. It planned to launch a crewed mission later in 2019. But when a Crew Dragon capsule exploded during engine testing in April, SpaceX and NASA put off the planned first crewed mission.

On Sept. 30, Elon Musk, CEO of SpaceX, told CNN that the Crew Dragon would be ready to carry astronauts into space in three to four months. But NASA Administrator Jim Bridenstine told CNN he wasn't convinced, and due to delays from SpaceX and Boeing (which is at work on a similarly delayed, competitor capsule called Starliner), he anticipated NASA buying more seats aboard Russian capsules.

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The public friction followed an incident just days earlier in which Bridenstine undermined a much-ballyhooed Musk presentation of the completed Starship prototype with a critical tweet.

"I am looking forward to the SpaceX announcement. In the meantime, Commercial Crew is years behind schedule. NASA expects to see the same level of enthusiasm focused on the investments of the American taxpayer. It's time to deliver," he said, referring to the NASA-funded Commercial Crew Program that is tasked with these joint government-private partnerships for crewed space transportation.

So why is SpaceX building two ships, and why is the company in a public tiff with the NASA administrator?

Crew Dragon is SpaceX's answer to a problem that began after NASA retired its space shuttle program, with its last flight in July 2011. At the time, the space agency didn't have any other space vehicle ready to ferry people and supplies into low Earth orbit where the International Space Station sits. (Since then, NASA has relied on Russian vehicles to travel to the ISS.)

Starship is something else entirely: a vehicle that, if it works as intended could serve Musk's stated goal of permanent settlement on Mars. It wasn't built to fulfill any NASA goals or contracts, won't launch from NASA facilities (at least at first), and appears to have been funded in large part by a Japanese billionaire looking to hitch a ride to the moon.

Under President Barack Obama, NASA farmed out the future of American low Earth orbital operations to the Commercial Crew program, which contracts with private companies to build spacecraft capable of ferrying both people and supplies to and from low Earth orbit, and transporting people on more distant missions to the moon and beyond. NASA has essentially hired SpaceX and Boeing to act as taxi services under its oversight, under the theory that the private companies could operate more efficiently than the bureaucratic space agency. Meanwhile, NASA has thrown its own engineering might behind a different project: the Space Launch System (SLS), a giant, heavy-lifting rocket, designed in-house at NASA, that's scheduled to form the backbone of crewed missions beyond low Earth orbit: a moon base, trips to Mars and potentially visits to asteroids.

Bridenstine, appointed under President Donald Trump, has continued to cheerlead for both of these projects. NASA wants Commercial Crew operational now, and, as Vice President Mike Pence announced in March 2019, it wants to return to the moon and land the first woman on the lunar surface by 2024 (i.e., the end of Trump's presidency, if he were to win a second term). In NASA's new vision, this 2024 mission will be the first step in establishing a permanent station in lunar orbit, and eventually a base at the moon's south pole.

But SLS's near-term prospects may not be so sunny. In October 2018, NASA's Office of the Inspector General reported that SLS is over budget and behind schedule. Bridenstine said in March that if the system isn't up to the task in time, NASA might rely on commercial rockets for a lunar mission, according to Spaceflight Now.

But that was before the Crew Dragon capsule exploded, setting back Commercial Crew Program plans as well. There have also been concerns about the safety of the Crew Dragon’s parachutes, according to SpaceNews.

So why build the shiny Starship (meant for travel beyond low Earth orbit) when Crew Dragon is still being perfected?

In theory, Crew Dragon should really be as cheap and efficient as promised. The spacecraft is reusable, and it can ferry up to seven passengers into orbit aboard reusable Falcon 9 rockets — pointing to per-seat costs far less than the $85 million NASA spends for each person ferried into space in a rented spot aboard a cramped Russian ship. But the Dragon is little more than a scaled-up version of the little, round, flat-bottomed capsules that (with the notable exception of the big, gliding space shuttle) have dominated spacecraft design for decades.

For years, Musk has brought up Starship in his talks — SpaceX's vision for a vehicle to accomplish more or less what NASA has wanted to achieve with SLS, but on an even grander scale. And on Friday night (Sept. 28), he showed off the prototype MK-1 on the field where it had been assembled in South Texas.

At 30 feet (9 meters) across and a full 160 feet (50 m) tall even before mounting on its booster rocket, the giant, reusable, stainless steel vehicle represents an idea of how to do deep-space travel unmatched by anything else in the human playbook. (Once mounted on a not-yet-constructed reusable Super Heavy rocket, the whole assembly will stand over 380 feet, or 115 m tall.)

SpaceX says Starship in its final form will be able to carry at least 100 tons (90 metric tons) of cargo into low Earth orbit. And, perhaps carrying smaller loads, it's expected to be able to land on the moon and return to Earth. The company has also suggested Starship will one day carry up to 100 people, though that number would mean cramped quarters. Saturn V rockets of the Apollo era could lift similar masses, but their crew capsules were comparably tiny, and never carried more than three people at a time into space. The planned Orion capsule, still the primary crew vehicle for the first stage of planned SLS missions, is expected to have a maximum crew capacity of six. (The Russian capsule maxes out at three.)

If Crew Dragon were on schedule and offering NASA a way into space without pricey, embarrassing Russian assistance, Bridenstine might have been happier to see Musk standing in a field in front of his giant, shiny new rocket ship telling the world it would perform a 12-mile (19 kilometer) test hop in a month or two, and reach orbit within six months. It's relatively cheap, big enough for long-haul mission, and built by engineers able to bypass NASA's conservative, plodding culture ⁠— in sharp contrast to SLS. (SpaceX builders slapped the MK-1 together in just a few months, out in the open, exposed to the elements — a far cry from the giant, sterile hangars where NASA constructs its multiyear projects.) But Starship isn't on track to fill the gaps in NASA's It doesn't have a booster rocket yet — needed to carry the Starship capsule into space — let alone life-support systems, the equipment needed to keep humans alive and well on the craft.

Bridenstine tweeted Thursday (Oct. 3) that the two had spoken on the phone, suggesting they'd reconciled. And Musk has said that SpaceX is still focused on Crew Dragon, estimating that Starship takes up just 5% of the company's resources.

Originally published on Live Science.