To cover its expected annual operating costs of $20.7 million, including paying a staff of 150 people, the Frost museum must attract 725,000 visitors a year, an estimate that officials hope to exceed, said Paola Villanueva, a museum spokeswoman.
The project’s financial footing, though, has been rocky for years. In 2015 and last year, fund-raising was so underwhelming that almost the entire board of trustees was fired.
Phillip and Patricia Frost, whose wealth comes mainly from pharmaceuticals and whose names already adorn buildings at the University of Miami and Florida International University, initially gave $35 million toward the science museum and converted a loan guarantee for $10 million to a gift in 2015 when the project’s finances went awry.
“I never thought it would go off the road, but of course we were concerned because they had got to the point where the path forward was not clear,” Mr. Frost said in a telephone interview. “The county came to the rescue and we were able to pitch in a bit.”
Over the course of the museum’s design and construction, Miami-Dade County provided $205 million — some of it as part of a general obligation bond — to enable the project’s completion. Private donations and sponsorships provided most of the rest. Museum officials hope to attract an additional $50 million from naming rights to parts of the facility, which was designed by the British architect Nicholas Grimshaw.
From Mr. Frost’s point of view, the museum was almost too large an enterprise to succeed without pain.
“Through no fault of their own, the people who conceived of it originally were not experienced enough in the area to realize how complex an undertaking it was,” Mr. Frost said. “They might have gone for a less complicated version of the museum, which would have been fine as well. But we have this magnificent institution now and it’s up to the community to support it.”