A number of entrepreneurs are taking their shot. The splashiest space-mining startup, Planetary Resources, was founded in 2012 and boasts investors including movie director James Cameron and Google cofounder Larry Page.

At the start of 2018, Planetary Resources was literally flying high. It had just launched a brand-new miniature satellite of its own design, one that would use a mid-wave infrared imager to sniff out sources of water beyond Earth’s atmosphere. It was the first step toward its longer-term mission to eventually stake the first asteroid-mining claim.

Courtesy of Planetary Resources

Two years earlier, the company had raised $21 million, and then another $28 million through a partnership deal with the government of Luxembourg—a country trying to position itself as the Earth-based hub for all things interplanetary mining–related.

But the commercial space venture based in Redmond, Wash., soon found itself in trouble: A fundraising shortfall led to employee cutbacks—reportedly shrinking a staff of about 70 workers to roughly 10—and to Luxembourg selling its 10% stake in the company. By the end of August, CEO Chris Lewicki, who declined an interview for this story, was planning to auction off laptops and other equipment.

While asteroid mining is a potentially lucrative business—a Goldman Sachs report estimated the platinum found on one asteroid to be worth as much as $50 billion—the technical challenges of mining them are still being figured out. Outside observers say that any company interested in drilling space rock had best be prepared for a long wait.

“There are going to be a lot of bumps in the road to create this entirely new field, so any startup company that had these grand ambitions has to be pragmatic about establishing a revenue stream,” says George Sowers, a professor in the space resources program at the Colorado School of Mines.

A Planetary Resources competitor, Deep Space Industries (DSI), in San Jose, has abandoned its focus on mining asteroids until it can be reliably certain that the cost of traveling to them won’t bankrupt the business.

For the past 18 months, DSI has instead been developing spacecraft that will cost less than $10 million. “There’s a big need for low-cost transportation to deep space,” says its CEO, Bill Miller. “A commercially viable strategy; that’s what we’re focused on today.”

Then, in October, the asteroid-mining industry collided with another technology vying to define the rest of the century. Planetary Resources’ assets were acquired by ConsenSys, a Brooklyn-based blockchain company founded by Joe Lubin, cofounder of the cryptocurrency Ethereum.

Just what, exactly, a blockchain startup wants with a space-­mining company is anyone’s guess. Details about the transaction are confidential, and in a statement, Lubin made it sound as if adventuring into space is a natural outgrowth for his company, noting that the purchase “reflects our belief in democratizing and decentralizing space endeavors.” For the broad endeavor of fracking the galaxy for profit, however, the underlying message is a simple one: Find an alternative source of funding, at least for the time being.

According to University of Arizona professor Dante Lauretta, a principal investigator for NASA’s Osiris-Rex asteroid mission, the idea of space mining within the next decade seemed like a viable goal—last year. This year, he says, it feels much more lofty.

“It takes a long time to get up to an asteroid, to process material, to deliver that material. It’s a multi-decade kind of prospect,” says Lauretta, who serves on Planetary Resources’ scientific advisory board (which last met in December 2017).

But that doesn’t mean a future in which asteroids are mined for resources is out of reach. The Osiris spacecraft is approaching an asteroid named Bennu and will attempt to land on its surface in the summer of 2020 to collect a sample to return to Earth.

“I’m still of the opinion that the scientific and engineering challenges of asteroid mining are completely surmountable. There’s nothing we can’t solve,” Lauretta says. “It’s just a matter of getting the business case in place.”

A version of this article appears in the December 1, 2018 issue of Fortune with the headline “Space Mining Comes Down To Earth.”