WASHINGTON (Reuters) -Elon Musk was expected on Tuesday to present an update on SpaceX's plan to launch missions to Mars ahead of a high-stakes Starship test flight later in the day.

Musk, the world's richest person and a key supporter of U.S. President Donald Trump, has indicated he will be spending less time in government and on political campaigns in the future in order to focus on his business empire.

He is scheduled to speak at 1 p.m. EDT (1700 GMT) from SpaceX's Starbase rocket facility in Texas, where he is expected to offer ambitious new timelines for sending SpaceX's Starship rocket system to Mars. The Red Planet, tens of millions of miles away from Earth, has been a long-sought but challenging destination for SpaceX, as well as U.S. government astronauts in recent years.

SpaceX has posted a placeholder for its livestream of the talk on platform X titled "The Road to Making Life Multiplanetary." Hours later, the company will attempt the ninth Starship test launch, after its last two Starship launches exploded early in flight.

The speech could offer clues about the trajectory of NASA's cosmic strategy. While Musk has been known to make overly ambitious projections in past talks regarding SpaceX's development timelines, the billionaire has since amassed significantly more power and influence over the Trump administration's space agenda.

His Starship program has had difficulties lately. The rocket was grounded for nearly two months after a testing explosion in March over Caribbean islands, prompting the Federal Aviation Administration to expand its debris hazard zones.

Starship is poised to attempt its ninth test flight from Starbase hours after Musk's speech. The rocket's hour-long launch window opens at 7:30 p.m. EDT (2330 GMT).

The 400-foot-tall (122 m) Starship rocket system is the centerpiece of Musk's vision to ferry humans to Mars and expand SpaceX's global dominance in the satellite launch market, a foothold the company has gained with its reusable Falcon 9. 

The rocket, picked by NASA in 2021 to land humans on the moon later this decade, is expected to play an even bigger role in the U.S. space program. Trump attended a Starship test launch in November and has publicly regaled Musk's Mars vision.

Musk and SpaceX remain influential over U.S. space policy despite the billionaire's shift away from government and signals to cut political spending.

Trump's choice to lead NASA, Jared Isaacman, a billionaire private astronaut and SpaceX customer for whom Musk advocated, testified before a U.S. Senate committee in April but has not advanced through the full confirmation process, while significant changes loom at the U.S. space agency.

A White House budget blueprint released earlier this month proposed $6 billion in cuts at NASA, bolstering the agency's Mars focus and threatening programs that Musk and Isaacman have criticized.

During a tense May 22 White House event with Trump and South African President Cyril Ramaphosa, South African-born Musk stood among Trump's cabinet officials in the room and was pointed out by the U.S. president.

"He actually came here on a different subject: sending rockets to Mars," Trump said. "He likes that subject better."