WASHINGTON, Dec 6 (Reuters) - U.S. President-elect

Donald Trump's pick to helm NASA, a private astronaut and close

ally of Elon Musk's SpaceX, is a central figure of a speedy,

commercial-focused side of the space industry who would face

unfamiliar political challenges as an administrator.

Jared Isaacman, the CEO of payment processing company Shift4

Payments ( FOUR ), has made landmark visits to space on two

ambitious SpaceX missions, including the first-ever privately

funded spacewalk in September.

In accepting Trump's decision, he envisioned a "thriving

space economy" and vowed to "usher in an era where humanity

becomes a true spacefaring civilization."

But the path to pursuing a faster, more privatized human

spaceflight agenda is expected to involve a delicate political

tango of trimming costly, entrenched programs and wooing

lawmakers to increase the space agency's $25 billion budget.

"He's going to definitely push NASA, but he'll do it in

a positive way," said Garrett Reisman, a retired NASA astronaut

who has been an adviser to SpaceX.

Musk had recommended Trump pick Isaacman and has since told

associates he sees the tech billionaire as someone who will get

things done at NASA, according to two people familiar with the

discussions.

"He is a man (of) high ability and integrity," Musk said

Wednesday of Isaacman on his X platform.

Targets at NASA for Trump and Musk's cost-cutting agenda

that Isaacman is expected to eye include the agency's

over-budget, $24 billion Space Launch System rocket and the

in-development Gateway space station poised to sit in a lunar

orbit, according to people familiar with the transition team's

space plans.

Other projects expected to face scrutiny include the

agency's goal to return soil samples from Mars - another top

NASA priority alongside its Artemis moon program.

While likely to face pushback from lawmakers, cuts to

expensive NASA programs could mean boosts to companies such as

SpaceX that have embraced cheaper and faster means of getting to

space and offering rockets to the government as a privately

owned service.

That approach has contrasted with the space agency's

traditional method of company contracting where companies like

Boeing ( BA ) and Lockheed Martin ( LMT ) build spacecraft that

the agency itself owns, controls and fully funds.

Trump's first NASA administrator, former Oklahoma

congressman Jim Bridenstine, proved adept at navigating those

political challenges. He was instrumental in winning budget

boosts for NASA's flagship crewed space exploration program and

upping its dependence on private companies.

Bridenstine in a statement Wednesday night urged for

Isaacman's Senate confirmation, saying his "vision for pushing

boundaries, paired with his proven track record of success in

private industry, positions him as an ideal candidate to lead

NASA into a bold new era of exploration and discovery."

Since Trump's first term, NASA has focused heavily on

returning humans to the moon. But the Artemis program using

NASA's powerful Space Launch System (SLS) rocket to send

astronauts to space and Musk's Starship rocket to land them on

the moon has faced budget blowouts and delays, pushing the

planned landing back to 2027.

NASA's reliance on SpaceX's Crew Dragon capsule, providing

astronaut rides to the International Space Station at a cheaper

price than previous options, has reinforced the agency's

commercial cost-savings strategy. It has also galvanized a

industry culture that threatens the future of NASA's older and

far more expensive SLS rocket, built mainly by Boeing ( BA ) and

Northrop Grumman ( NOC ) with a countrywide workforce of 28,000.

"Administrator-nominee Isaacman, if confirmed, will face

challenges as he leads NASA into the future," said Dan Stohr,

CEO of the industry group Coalition for Deep Space Exploration,

which counts Boeing ( BA ) and Lockheed Martin ( LMT ) as members.

"Budget limitations, workforce, and infrastructure needs

will all play a role in shaping NASA's future," Stohr added.

NASA's current administrator, Bill Nelson, said he spoke

with Isaacman to congratulate his tentative nomination and feels

"basically optimistic" about the future of NASA under Trump.

"I think the relationship between Elon Musk and the

president-elect is going to be a benefit to making sure that the

funding for NASA is there, so I see that as a positive," Nelson

told a press conference on Thursday.

(Reporting by Joey Roulette; Editing by Lincoln Feast.)