D-Backs: Chase Field ball humidor is almost operational.

Nevada has Area 51. Chase Field has Trunk Storage 1526.

Both places are highly secretive and so sensitive that their contents and even existence aren’t discussed or acknowledged.

The “phantom” Air Force base at Groom Lake has long been the subject of cloak-and-dagger suspicion and fascination. Until recently, no one really cared what was behind the green double doors of a simple storage room at field level of the downtown Phoenix ballpark.

Except that’s where the Diamondbacks are housing their new humidor, which is in the process of getting built and, soon, will have at least two inspectors from Major League Baseball visiting to check on the status of baseballs the device will be humidifying.

“Oh, is that where it’s going to be?” Diamondbacks manager Torey Lovullo asked on Saturday, moments after wrapping up his pregame news conference in the interview room directly across from Trunk Storage 1526.

“I have not been in there.”

Lovullo is free to visit if he wishes, but the room and its contents are strictly off limits to any and all other visitors – although on Saturday it doubled as a staging area for boxes of Paul Goldschmidt bobbleheads and a place for game-day staff to dress up in their garb for Star Wars Night.

Since it was learned in April that the Diamondbacks were adding a humidor, team officials have been reluctant to talk about it publicly, at least in any detail. Initially, there were groans from skeptics who wondered if this was a way to appease pitcher Zack Greinke and make his numbers look good to justify the $206.5 million it cost to sign him.

Team President and CEO Derrick Hall flatly denied that at the time, suggesting Greinke was unaware the team was even considering adding a humidor. But since they’ve gone ahead with it, rarely will you find anyone connected with the team willing to discuss it in specifics.

Recently, azcentral sports learned there had been tentative plans for the humidor to be up and running this weekend during Arizona’s four-game series against the visiting Philadelphia Phillies. Construction and installation got pushed back and now, according to Diamondbacks General Manager Mike Hazen, the project won’t be operational until “somewhere around or after the All-Star break.”

The Diamondbacks will become just the second MLB team to use a humidor, which regulates the temperature and relative humidity of baseballs. Because of Arizona’s heat and elevation, it can be difficult to store baseballs at the optimum range of 70 degrees with 50 percent relative humidity, which MLB requires of all its teams.

Some physics professors have speculated the Diamondbacks will regret adding a humidor to Chase Field, however, suggesting the ball’s coefficient of restitution – or its bounciness along with its weight from water absorption – will decrease the ball’s exit speed and thus, reduce the number of home runs hit in the stadium.

A dip in homers and run production overall occurred for a period of time at Coors Field after the Colorado Rockies became the first team to install a humidor. The power numbers more or less have since returned to normal in recent seasons.

“We won’t really know that until we put this in place and see what the actual impact is,” Hazen said. “I think that’s the only answer I can give. We don’t know at this point in time what the impact will be … but it probably will have an impact.”