NASA is building a super-heavy-lift rocket called the Space Launch System to send astronauts back to the moon.

The SLS program has seen multiple delays and cost overruns, and the rocket is not reusable.

Elon Musk’s and Jeff Bezos’ aerospace companies, SpaceX and Blue Origin, are developing comparable yet reusable (and presumably more affordable) giant rocket ships.

If SpaceX’s Big Falcon Rocket or Blue Origin’s New Glenn rockets come online, one NASA executive said the agency would “eventually retire” SLS.

For now, though, NASA says it’s focused on completing its Commercial Crew Program to test-launch American spaceships.

NASA is building a giant rocket ship to return astronauts to the moon and, later on, ferry the first crews to and from Mars.

But agency leaders are already contemplating the retirement of the Space Launch System (SLS), as the towering and yet-to-fly government rocket is called, and the Orion space capsule that’ll ride on top.

NASA is anticipating the emergence of two reusable and presumably more affordable mega-rockets that private aerospace companies are creating. Those systems are the Big Falcon Rocket (BFR), which is being built by Elon Musk’s SpaceX; and the New Glenn, a launcher being built by Jeff Bezos’ Blue Origin.

Read more: Elon Musk and SpaceX are building a monster rocket for Mars. Here’s how big it is compared to 20 familiar objects.

“I think our view is that if those commercial capabilities come online, we will eventually retire the government system, and just move to a buying launch capacity on those [rockets],” Stephen Jurczyk, NASA’s associate administrator, told Business Insider at The Economist Space Summit on November 1.

However, Jim Bridenstine, the administrator of NASA, appears to have publicly denied his colleague’s statement.

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“In case there is any confusion, @NASA will NOT be retiring @NASA_SLS in 2022 or any foreseeable date. It is the backbone of America’s return to the Moon with international and commercial partners,” Bridenstine tweeted on Monday, following the initial publication of this story on Saturday.

In any case, NASA may soon find itself in a strange position, since the upcoming launch vehicles of SpaceX and Blue Origin may beat SLS back to the moon – and one of them may be the first to send humans to Mars.

The super-size struggles with SLS

Foto: Patrick Shea inspects a 1.3% scale model of the NASA’s Space Launch System (SLS) in a wind tunnel.sourceNASA/Ames/Dominic Hart

Space Launch System is often called a super-heavy-lift rocket. This means it’s designed to heave a payload of more than 55 tons (roughly the mass of a battle tank) into low-Earth orbit.

“We need a [super-]heavy lift launch capability,” Jurczyk said. “Without it, we’re not going to have a safe, reliable, and affordable architecture and implementation for human exploration.”

Several iterations of SLS are planned through the 2020s, and the first is called Block 1. This rocket is expected to stand about 322 feet tall and be able to lift about 70 tons of spacecraft hardware and supplies into orbit.

NASA’s hopes to test-launch the first Block 1 rocket in June 2020 on a flight called Exploration Mission-1 (or EM-1). The mission would prove SLS is safe and reliable by flying an uncrewed Orion crew capsule around the moon and back to Earth.

A crewed Exploration Mission-2 (EM-2) would follow several years later.

Foto: How NASA plans to pull off its Exploration Mission-2 flight with the Space Launch System rocket and Orion spaceship.sourceNASA

It is unknown how much an SLS launch might cost. The same is also true for SpaceX’s BFR and Blue Origin’s New Glenn, which have yet to announce mission pricing.

The figure for NASA’s program depends on the types of missions it pursues, how many and how frequently SLS rockets are launched, and how development costs are accounted for. For example, the space shuttle’s per-mission raw cost was about $500 million, but averaging in the entire program’s development costs and accounting for inflation brings the per-mission figure closer to about $1.5 billion.

So far NASA has spent about $11.9 billion on SLS, and the agency is projected to need $4-5 billion more than it has planned by 2021. Relatedly, the scheduled launch date for EM-1 in June 2021 is about 2.5 years behind-schedule.

An internal audit of NASA’s program found that preventable accidents, contract management problems, and other performance issues related to Boeing, the prime contractor, is largely responsible for the cost overruns and delays.

If more hiccups come with the SLS program, NASA may be watching SpaceX beat the agency to the moon with a crewed mission. That’s because Musk, the company’s founder, is pursuing aggressive timelines to reach the moon and Mars with BFR.

How SpaceX could beat NASA back to the moon

Foto: An illustration of the SpaceX’s Big Falcon Rocket, or BFR, launching into space. Here, the spaceship is shown detaching from the booster.sourceSpaceX

SpaceX employees have been toiling under a tent in Los Angeles to build the top half of the system, called the Big Falcon Spaceship.

Musk and Gwynne Shotwell, SpaceX’s president, have both said the spaceship could be doing short launches called “hops” as soon as late 2019. Musk is also planning to modify his mainstay Falcon 9 rocket into a “mini-BFR ship” to test some of the more challenging aspects of the ship, like blazing-hot reentry into Earth’s atmosphere.

Foto: The planned dimensions of SpaceX’s Big Falcon Rocket.sourceOlivia Reaney/Business Insider

In 2020 or 2021, he aims to launch a fully integrated version of BFR – a Big Falcon Booster with the Big Falcon Spaceship on top – into orbit around Earth. (Around the same time, Blue Origin is planning to use New Glenn to deliver a lander to the surface of the moon to scout for ice to make rocket fuel.)

If SpaceX’s first orbital launch and later uncrewed missions fly without an explosion or other incident, the company intends to fly a Japanese billionaire and a group of artists around the moon in 2023.

It remains to be seen how the space agency would react to such a feat, which is essentially a creative reprise of the Apollo 8 mission of 1968. In fact, 2023 is the same timeframe in which NASA plans to launch EM-2 around the moon.

Foto: An illustration of the spaceship of SpaceX’s Big Falcon Rocket, or BFR, flying around the moon.sourceSpaceX

It’s also unknown what NASA would do if SpaceX launches its first uncrewed missions to Mars with BFR in 2022, followed by the first crewed missions in 2024. That’s several years ahead of when the space agency hopes to land people on the moon, and perhaps a decade sooner than NASA would attempt a crewed Mars landing.

“We haven’t really engaged SpaceX on how we’d work together on BFR, and eventually get to a Mars mission – yet,” Jurczyk said of NASA’s leadership. “My guess is that it’s coming.”

A US space agency without an American spaceship

Foto: Nine astronauts will fly the first four crewed missions inside SpaceX and Boeing’s new spaceships for NASA, called Crew Dragon and CST-100 Starliner, respectively.sourceNASA via AP

Right now, Jurczyk said, the space agency’s leadership is laser-focused on test launches for its Commercial Crew Program, a competition for private companies to build and launch American spaceships.

The ultimate goal of Commercial Crew is to revive US spaceflight capabilities that the agency lost when it retired the space shuttle fleet in 2011. (Ever since then, NASA has relied solely on Russia to taxi its astronauts to and from the $150 billion International Space Station.)

Boeing and SpaceX have each designed and built seven-person space capsules, which are each nearing approval for uncrewed and crewed test launches. SpaceX is currently looking to fly first with its Crew Dragon ship.

“Their first uncrewed flight test, right now, is scheduled for January, followed by, not many months later, maybe in the springtime, their first crewed flight test to the space station,” Jurczyk said.

Read more: Boeing may have used a lobbying firm to plant a scathing opinion piece about SpaceX in US news outlets. At stake is billions of dollars in NASA contracts.

Once the Crew Dragon and Boeing’s CST-100 Starliner ships prove they can launch safely and reliably, the agency’s leadership should have more energy to contemplate its deep-space future with BFR and Blue Origin’s New Glenn.

“How we engage will depend a lot on the pace at which those systems and capabilities develop,” Jurczyk said.

The key for NASA is to get as quickly as possible to some kind of super-heavy-lift capability.

“Right now we see the way to do that is through SLS, because we kind of have the head-start and use these legacy technologies and systems,” he said, referring to the fact that SLS will use space shuttle engines and other well-understood hardware.

Jurczyk added: “That’s kind of where we are. We know we need that kind of BFR – and whatever evolves from New Glenn – heavy-lift capability if we’re going to do human exploration of the solar system. We don’t think another approach is going to be as safe, affordable, and reliable.”

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This story has been updated to include a response from NASA’s administrator. It was originally published on November 17, 2018.