NASA is building the most powerful rocket in history, called Space Launch System (SLS).

The new rocket will use retrofitted space shuttle engines to send people to the moon, Mars, and beyond.

NASA recently test-fired one modified RS-25 space shuttle engine at "113% thrust" to observe its behavior for SLS.

The first SLS mission is supposed to fly a space capsule around the moon, but the program is behind schedule and ballooning in cost.



NASA fired up a rocket engine pulled from a space shuttle on Wednesday — then cranked the power up to 11.

But this hot fire, as such rocket engine tests are known, wasn't done out of nostalgia for the space shuttle program, which retired in July 2011.

The purpose was to see how the engine, known as an RS-25, behaved after NASA modified it to power a brand-new mega-rocket called the Space Launch System (SLS).

One of NASA's RS-25 rocket engines being trucked out to a test-firing mount in Mississippi. NASA SLS is a 321-foot-tall rocket that will outperform the Saturn V rockets that sent Apollo astronauts on the first lunar missions. SLS may take astronauts to the moon, Mars, and beyond.

Four RS-25 engines — each 14 feet tall and weighing 3.9 tons — will line the base of the rocket's core boosters. Combined with two side boosters, the engines will help make SLS the most powerful rocket ever built.

For the Feb. 21 test at Stennis Space Center in Mississippi, the engines were outfitted with new 3D-printed parts to reach "113 percent thrust level" — 13% beyond what the engines were designed to achieve some 40 years ago.

"Increased engine performance is crucial for enabling SLS missions to deep space as the rocket evolves to be larger and carry astronauts and heavy cargo on a single flight," NASA wrote in a story about the hot-fire test.

Funding a maiden flight and astronaut-less lunar voyage

An artist's depiction of NASA's Space Launch System rocketing a crew toward orbit. NASA/MSFC

NASA is working toward a maiden flight with SLS called "Exploration Mission 1." While that test mission won't launch any people, it will rocket NASA's Orion space capsule around the moon and back to Earth on a roughly three-week voyage, according to the space agency.

The SLS rocket for the mission is designed to haul nearly 29 tons out to the moon, or about two school buses' worth of mass. The final version of SLS could lift as much as 50 tons on a lunar mission.

Exploration Mission 1 (also known as EM-1) was originally planned to lift off in December 2017, but NASA has delayed the mission multiple times. This is primarily due to the program's multi-billion-dollar cost and a flat NASA budget, according to a Government Accountability Office report.

The space agency faces a $200 million annual budget cut if President Donald Trump's proposed $19.1-billion request is enacted. However, a Senate-led NASA funding bill that Trump signed into law in March 2017 calls for $19.5 billion — a $200 million increase in space-agency funding. (Congressional appropriators will ultimately have to reconcile the difference.)

NASA recently said it expects to launch the rocket for the first time in 2020 at the earliest.

SpaceX's Falcon Heavy rocket launches toward space for the first time on February 6, 2018. Dave Mosher/Business Insider By the end of 2018, NASA will have spent about $23 billion on the SLS program, according to an April 2017 report by NASA's Office of Inspector General. Part of that cost is sunk into retrofitting a mobile launch tower originally built for NASA's cancelled Ares rocket program.

By the time the tower gets used for EM-1, NASA will have spent eight years and $912 million on it. Even then, as Ars Technica reported, it will only be good for one launch because it's leaning.

To reach Mars, NASA will need more than $210 billion in funding, according to the Office of Inspector General. And that's not even to set foot on the planet's surface — just orbit it. (Though the first Mars astronauts might explore the moon Phobos.)

Meanwhile, private companies like Elon Musk's SpaceX, Jeff Bezos' Blue Origin, ULA, and others are working on colossal new launch systems that may come close to rivaling SLS. Their launch power may even exceed it, and for far less money.

But rockets are not easy to design, build, and make safe to launch, so the major players are still emerging in what's quickly becoming a new space race.