NASA's moon megarocket is going to get a heckuva lot… mega-er.

Though the U.S. space agency has only completed the crewless Artemis I mission around the moon and back so far, engineers are busy working on enhancements for the Space Launch System rocket, or SLS, for expeditions beyond Artemis IX.

The rocket is expected to one day put millions of miles on the odometer for the first astronaut flight to Mars. Robotic journeys to Saturn and Jupiter also could be in its future.

To see where NASA and its contractors are in the process, watch a recent hot-fire test of a small-scale solid rocket motor at Marshall Space Flight Center in Huntsville, Alabama. The motor produced over 82,000 pounds of scorching thrust.

SEE ALSO: Get ready: SpaceX Starship will try to fly again soon

The test was part of an ongoing series to study different possible materials for the nozzle and motor insulation, according to NASA.

Engineers hope the upgraded booster design will support heavier loads of cargo and people headed to the moon and deep space, said Jim Free, NASA's associate administrator for exploration systems, on X, formerly known as Twitter.

NASA designed the Space Launch System as the foundation for a generation of human exploration missions to deep space. Credit: NASA

The megarocket became the most powerful space-worthy rocket when it blasted to the moon in November 2022. But Elon Musk's SpaceX could outperform it if the rocket company succeeds at launching Starship into space. The commercial rocket under development has 33 Raptor engines capable of 16.7 million pounds of thrust — double that of SLS.

NASA has planned for SLS to evolve into increasingly powerful configurations as its Artemis missions become more complex.

But the space agency has often faced criticism for the cost to develop and operate SLS. Inspector General Paul Martin, NASA's federal watchdog, said the ballooning expense imperils the entire deep spaceflight program. He estimated the first four Artemis missions would cost about $4.1 billion each, with roughly half of the cost just for the new rocket system. By 2025, NASA will have spent about $93 billion on the Artemis program.

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The first rocket assembly, the same which was used for Artemis I, is called "Block 1." It uses the central (orange) core booster with four main engines and can send over 59,500 pounds around the moon. A pair of solid rocket boosters and liquid fuel-fed engines provide much of the thrust.

After leaving Earth's atmosphere, a final rocket booster — the Interim Cryogenic Propulsion Stage — sent the Orion capsule onward to the moon. This is the configuration NASA plans to use for the first three Artemis missions, including a moon landing.

Later missions carrying astronauts will see the rocket evolve, including the powerful Exploration Upper Stage. Known as "Block 1B," this rocket design can transport crew and large amounts of cargo — up to 83,700 pounds.

The final iteration of SLS, aka "Block 2," is estimated to provide 9.5 million pounds of thrust. NASA expects this to be the workhorse vehicle for sending cargo to the moon, Mars, and other deep-space destinations, an eight percent increase over Artemis I's 8.8 million pounds of thrust. This rocket should be able to lift a whopping 101,400 pounds.

To carry the supplies needed to mine the moon for water ice or build human habitats, NASA will need the extra oomph.