A private company is aiming to heave a microwave oven-size spacecraft toward an asteroid later this week, its goal to kick off a future where precious metals are mined around the solar system to create vast fortunes on Earth.

“If this works out, this will probably be the biggest business ever conceived of,” said Matt Gialich, the founder and chief executive of AstroForge, the builder and operator of the robotic probe.

That may sound familiar: A decade ago, news stories were aflutter about the wealth promised by asteroid mining companies. But things didn’t quite work out.

“We blossomed three or four years too early for the big gold rush of investor enthusiasm for space projects,” said David Gump, the former chief executive of Deep Space Industries, one of the earlier batch of would-be asteroid miners. Eventually the money dried up; Deep Space Industries was sold off in 2019 and never reached an asteroid.

AstroForge is betting on things being different this time around. The California company has already launched a demonstration spacecraft into Earth orbit and raised $55 million in funding. Now the company is set to actually travel toward a near-Earth asteroid in deep space.

AstroForge’s second robotic spacecraft, called Odin, is bundled into a SpaceX Falcon 9 rocket that will also launch a privately built moon lander and a NASA-operated lunar orbiter as soon as Wednesday from Florida. About 45 minutes after the launch, Odin will separate and begin its solo journey into deep space, while the moon missions — the Athena lander from Intuitive Machines and NASA’s Lunar Trailblazer — take off on their own separate journeys.

No commercial company has ever launched an operational mission beyond the moon, and AstroForge is the first company to receive a license from the Federal Communications Commission that allows it to transmit from deep space. AstroForge will communicate with the spacecraft using undisclosed dishes in India, South Africa, Australia and the United States.

At first, AstroForge kept its target asteroid a secret, fearing competitors. But in January, the company announced the destination, an object called 2022 OB5. Mr. Gialich said he was more confident of AstroForge’s advantage.

“We’re the only one that’s actually doing anything,” he said. “Who else is preparing to go to an asteroid?”

Asteroid 2022 OB5 is small, no more than 330 feet across, about the size of a football field. AstroForge’s science team assessed the asteroid by using telescopes, including the Lowell Observatory and the Large Binocular Telescope in Arizona, to estimate its metallic content. They believe that 2022 OB5 is an M-type, a class of asteroids comprising 5 percent of known space rocks that may have a high amount of metal. The analysis of the asteroid has not yet been published.

Stephanie Jarmak, a planetary scientist at the Harvard-Smithsonian Center for Astrophysics, said the company’s analysis was plausible.

“There are several different ways to determine whether it’s an M-type or not,” she said, including studying the asteroid’s brightness, or albedo. A higher brightness suggests the presence of more metal. She lauded the company for being more open about its target asteroid. “I thought that was really nice,” she said.

M-type asteroids are thought to be rich in metals such as iron and nickel. These could be useful as a resource for construction in space, perhaps to build new spacecraft and machinery. However, some M-types may also be rich in more valuable platinum group metals, or P.G.M.s, used in devices such as smartphones. The windfall would be huge if these could be mined in abundance and brought to Earth.

“A single one-kilometer-diameter asteroid, if it was platinum-bearing, would contain about 117,000 tons of platinum,” said Mitch Hunter-Scullion, the founder and chief executive of the Asteroid Mining Corporation in Britain. His company is taking a slower approach and plans to demonstrate technologies on the moon later this decade.

“That’s about 680 years of global supply. You’re talking about centuries of platinum demand from a single asteroid,” Mr. Hunter-Scullion said. “Even if you get 1,000 tons of platinum, you’re sitting there with the next half century of mobile phones.”

Not everyone is convinced that so much valuable metal will be found inside M-type asteroids.

“There’s not enough P.G.M.s in asteroids to justify that as a stand-alone business,” said Joel C. Sercel, the founder and chief executive of TransAstra, a company that is developing a giant bag that could be used to grab and extract resources from asteroids in the future. The company will test a small mock-up of the technology aboard the International Space Station following a launch to the station this summer.

The legalities of mining asteroids and selling their resources remain uncertain.

In 2015, President Obama signed a law allowing asteroid resources to be sold on Earth. But no one has yet put this law to the test.

“Is AstroForge going to make a claim? Does the fact they reach this asteroid before anybody else mean nobody else can go to it?” asked Michelle Hanlon, a law professor specializing in space at the University of Mississippi. “It’s going to be interesting to see the international reaction.”

Odin will arrive in late 2025 after a journey of about 300 days to 2022 OB5. The asteroid follows an orbit around the sun similar to Earth’s. The probe will fly past the asteroid at a distance of 0.6 miles, using two black-and-white cameras to snap pictures. Zooming by the object at thousands of miles per hour, the spacecraft will have an encounter that will last five and a half hours.

“And it’s probably only the last 10 minutes that we’re getting pictures bigger than a pixel,” Mr. Gialich said.

The goal is for these pictures to be enough to tell if the asteroid is metallic.

“Hopefully it looks shiny,” Mr. Gialich said. However, it’s very possible that any metal could be mixed into the asteroid’s soil and not be visible.

“I’m not sure how much compositional information they can get purely from images,” Dr. Jarmak, the planetary scientist, said.

Craters on the surface may hint at hidden metal though, Mr. Gialich said, adding: “We expect to see cracking on the surface” that could be indicative of metallic content.

The spacecraft will also precisely track the asteroid’s position in space during the flyby. Doing so could allow the density of the asteroid to be calculated, based on its gravitational tug on the spacecraft. Higher density would hint at more metallic content.

Success is not guaranteed. AstroForge’s first mission, Brokkr-1, was launched into low-Earth orbit in April 2023 to test the company’s planned asteroid refining technology. But the mission encountered problems and burned up in the atmosphere. Mr. Gialich said that AstroForge had improved its technologies on the Odin spacecraft by relying on components produced in-house.

Vestri, the third mission of AstroForge, will be its most ambitious. That spacecraft, the size of a refrigerator, will be designed to land on an asteroid as soon as next year, possibly even 2022 OB5 if the metallic content is confirmed. Vestri’s landing legs would be equipped with magnets designed to stick to the surface of the asteroid and be capable of estimating how many P.G.M.s are present.

It’s unclear how successful this mission will be. “If it’s made out of solid metal it will stick,” said Benjamin Weiss, a planetary scientist at the Massachusetts Institute of Technology. However, many asteroids are known to be rubble piles, essentially collections of rocks held together loosely by gravity, such as the asteroid Bennu that was visited by NASA’s ORISIS-REx spacecraft.

“They are barely held together,” Dr. Weiss said, meaning that the magnets might just end up pulling a few rocks away from the surface as the lander drifts away.

Only one spacecraft, the Rosetta spacecraft from the European Space Agency, has visited a suspected M-type asteroid before, a flyby of the asteroid 21 Lutetia in 2010. The presence of metal at that time was inconclusive. A much more capable mission, NASA’s $1.2 billion Psyche spacecraft, is currently on its way to an asteroid bearing the same name by 2029. Astronomers think the asteroid may be a fragment of a failed planet’s core and is rich in metal.

Results from the Odin mission’s analysis of 2022 OB5 could be a tantalizing tease for Psyche. “If it turns out it’s made of solid metal, that would support the idea that some of these larger bodies like Psyche could be the cores of differentiated bodies,” Dr. Weiss said.

Lindy Elkins-Tanton at Arizona State University, the principal investigator on Psyche and also an adviser to AstroForge, said that the opportunities afforded by commercial deep space missions like Odin are exciting, enabling small and fast missions at low cost. “It’s going to be a bit of a game-changer,” she said.

Others are more focused on what Odin means for asteroid mining in the present tense.

“It’s probably the highest achievement in the sector so far,” Mr. Hunter-Scullion of Asteroid Mining Corporation said. Mr. Sercel of TransAstra also applauded the company.

“We’re gung-ho for AstroForge and wish them the best of luck,” he said. “We’re behind them 100 percent.”

Now there’s just the small matter of the launch and journey to the asteroid, and the hope that what Odin finds will lead to the riches long touted from asteroid mining.

“If we make it, I’m popping champagne,” Mr. Gialich said.