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It’s go time at the Hirshhorn Museum. With the museum’s self-imposed spring deadline for committing to building the Bloomberg Balloon just months away, last Thursday the museum’s board of trustees met to discuss, among other topics, the seasonal addition’s fate. In the run-up to the meeting, the board identified consultants to perform a fundraising feasibility study, which more or less means finding the money to inflate the Balloon (otherwise known as the Bubble or Seasonal Inflatable Structure). The consultancy’s work is tantamount to a crash fundraising drive, one that has to run its course on a ludicrous schedule: The Hirshhorn delivers its go/no-go recommendation to the Castle in July. That means raising several million more dollars for the Bubble, Hirshhorn Director Richard Koshalek‘s big bet on architecture.

That’s just one of three Inflatable feasibility studies—-the other two relate to its construction and operations—-that are now converging, according to Richard Kurin, the Smithsonian Institution’s undersecretary for history, art, and culture.

One study was performed in large part by the Smithsonian’s Office of Facilities Engineering and Operations in order to determine the project’s real costs: $8.5 million for construction, with another $3 million going to architects Diller Scofidio + Renfro for design fees and to engineers, plus any undisclosed costs. OFEO was key in nudging the early estimate of $5 million (reported by The New York Times in December 2009) northward to about $15 million.

“Nobody’s ever done this before,” Kurin says of the Bubble. “It took a long time—you have to spend some money, because you’ve got engineers and architects and designers looking at this—to figure out what this is going to cost. That’s the cost that was presented to the board [of the Hirshhorn Museum and Sculpture Garden] two meetings ago.”

Kurin says he has asked a group within the Smithsonian to perform an operations feasibility study. It would include a set of recommendations and assessments that gauge the mix of performances, conferences, sponsorship, and other uses of the facility that will make the Bubble float—”the money in, money out,” as Kurin puts it. Those recommendations are not yet finalized, and Kurin hopes to present the results of the study to the Hirshhorn’s board in May.

The final feasibility study is out of the Castle’s hands. The Hirshhorn won’t name the consultancy looking at fundraising until the final contract’s been signed.

The work happening at the Castle and the Hirshhorn boardroom between now and May is about rising to the occasion—the occasion being rising costs, a fuzzy mission, and a lack of money. But at one point, the Castle was looking not to raise funds but rather to cut the cost of the Bubble. As recently as August of last year, Secretary of the Smithsonian G. Wayne Clough told the Smithsonian’s executive committee that a new design from Inflatable architects Diller Scofidio + Renfro could drop the project’s overall cost to $10 million. The new Bubble would still feature a bulbous blue dome emanating from the top of the cylindrical Hirshhorn museum, but the part of the Bubble protruding from the bottom of the raised drum out over the courtyard and north plaza would be gone. This alternative design would also cut out annual inflation and deflation costs, though museum officials won’t say how, because the alternative design was dropped. It sounds as though the Hirshhorn almost got a blobular hat—-but now it’s Bubble or nothing.

The only design going forward now is the one the public knows, says Kurin, the one that readers and viewers immediately dubbed the Bubble. With no real doubt lingering over the design or its construction, the questions that remain involve programming and funding. Beyond the $4 million that the Castle has committed to facilities costs for the Bubble once it’s built, there’s no more Smithsonian money lined up for the Hirshhorn project, Kurin reiterates. “This is a more discretionary project,” he says, “so it really has to be more of a private effort.”