WASHINGTON, May 2 (Reuters) - U.S. President Donald

Trump's administration is seeking to axe key parts of NASA's

moon program in favor of commercial alternatives and his

Mars-focused agenda, targeting an array of established projects

in a proposed $6 billion cut to the space agency's overall

budget for next year.

The "skinny" - or outline - version of Trump's proposed 2026

budget, released on Friday, would cancel NASA's over-budget

Space Launch System (SLS), a gigantic rocket built by Boeing ( BA ) and

Northrop Grumman ( NOC ), and its Lockheed Martin ( LMT )-built Orion crew

capsule after their third mission in 2027 under the agency's

Artemis program.

The proposal, cutting 24% of NASA's current $24.8 billion

budget, threatens to upend active contracts defended for years

in Washington by an array of established NASA contractors, as

well as overturn missions and programs in which U.S. allies play

key roles, such as the European Space Agency, Canada and Japan.

The Artemis program was spawned by Trump during his first

administration to accelerate a pre-existing effort to return

humans to the moon before Chinese astronauts get there in 2030,

growing into a multi-billion dollar effort on the frontline of

an emerging global space race.

But in his new administration, Trump has instead fixated on

getting humans to Mars, the long-sought destination for SpaceX

CEO Elon Musk, the president's outgoing adviser who spent $250

million on Trump's effort to return to the White House.

"The Budget phases out the grossly expensive and delayed

Space Launch System (SLS) rocket and Orion capsule after three

flights," the budget summary said, noting SLS's per-launch

pricetag of $4 billion. The rocket's development cost of roughly

$23 billion since 2010 is "140 percent over budget," it added.

"The Budget funds a program to replace SLS and Orion flights

to the Moon with more cost-effective commercial systems that

would support more ambitious subsequent lunar missions," the

summary added.