The building that houses Google's Advanced Technology and Products division offers a few subtle hints that something weird is going on inside. The pirate flags in the bathroom. The big sign reminding ATAP employees to always erase their whiteboards after a meeting. The workers who encounter me milling around in the entryway on a warm day just before the big Google I/O conference, each more worried than the last about what a stranger is doing here. Rick Osterloh, Google's newly hired hardware boss, comes rushing out of the building to head to his next meeting with a big smile on his face, but even he won't let me in.

Eventually, a handler shows up and ushers me into a conference room. The whiteboards are indeed empty, except for a single phrase that appears to have been written in something permanent: "Aim High." Dan Kaufman, once the director of innovation at Darpa and the new head of ATAP, sits across the table along with three of the men in charge of one of the most ambitious ideas inside Google's haven for ambitious ideas: Project Ara, the modular smartphone. Depending on who you ask, and maybe on the day, Ara is either the future of the phone—a forever-lasting, totally personal device—or an impossible pipe dream.

It's been more than a year since Google showed Ara to the public, and a lot has changed. The mission hasn't: Build a smartphone out of interchangeable parts that you can swap on the fly to make your phone exactly what you want right this second. Add a wide-angle camera module for your hike. Swap it for a telephoto—and add a larger battery—for the soccer game. Replace the screen with an E Ink display for reading on a long flight. The idea is, the ability to swap modules would lengthen the life of a smartphone—devices can last five years instead of two—and lessen the waste accrued in the rush to upgrade.

After years of failed demos, public sputters, and worrisome silence, Ara works. About 30 people within ATAP are using Ara as their primary phone.

It's the how, not the what, that was problematic. Today, Rafa Camargo, Ara's technical project lead, wants to show me what he's made. He picks the black phone up from the white table in front of him, flips it over, and taps the power button. It turns on. Next, he picks up a camera module from the table, pops it into the phone, opens the camera app, and quickly takes a crisp photo. "There's your camera, live," Camargo says.

Hang on. You caught that, right? It works! After years of failed demos, public sputters, and worrisome silence, Ara works. About 30 people within ATAP are using Ara as their primary phone. Camargo actually has the luxury of worrying about things like aesthetics, rather than whether it'll turn on. "Please pay no attention to how it looks," he tells me, flipping the blocky smartphone over in his hands, "because it's a prototype." It's not a concept, not an idea, not a YouTube video. It's a prototype. Developer kits for Ara will be shipping later this year, and a consumer version is coming in 2017. "We have now built all the key components of the platform," Camargo says. Ara is no longer an experimental part of ATAP: It just became its own division within Google. Now it's time to find out if there's room left for another smartphone revolution.

Google

Finding the Starting Point

Google wants to open up smartphone innovation by creating an ecosystem anyone can contribute to. Mobile is the largest technology platform in history, but to get in, you either need the resources and experience of an Apple or a Samsung, or you need to be convincing enough to get Apple or Samsung to bet on your technology. "What currently happens in the market is, you get great products that are all set for you, like, 'Oh, that's what you want, right?'" says Blaise Bertrand, ATAP's master of creative. (That's really his title.)

Ara could blow all that up by blowing your smartphone up: It wouldn't have to one be one thing you buy in full every two years, it could be a dozen pieces you replace if and when you need them. You could buy a better speaker, and I could buy a better camera. It all sounds wonderful, but Ara's path to completion was anything but clear. They made enough progress that at last year's Google I/O, Camargo managed to snap a grainy photo of the audience with a hot-swapped camera module. And then the team went dark. Other than a few stray tweets, that photo was the last anyone saw of Ara.

Since then, Paul Eremenko, the team's leader, left Google. So did Regina Dugan, who quit running ATAP to start something similar at Facebook. Google reorganized and consolidated its hardware efforts under Osterloh. Within Ara, the team scrapped testing and rollout plans, which (weirdly) involved selling Ara modules out of a converted food truck in Puerto Rico. After lots of research and testing, they made a big decision: rather than turn every single piece of the phone into modules, from the processor to the RAM to the hard drive, they'd consolidate all that into the standard frame. They found that people don't care about, or want to think about, the processor in their phone. And they especially don't want to worry about it being compatible with all their apps. Users just want a good phone with good specs that does all the basics well, and then they want a place to play on top of that.

As ever, the plan for Ara is to have more modules than anyone could possibly imagine. Google

Your Dream Machine

The Ara Developer Edition shipping later this year is a 5.3-inch, fairly high-end smartphone. You'll be able to take it out of the box, turn it on, and use it like a normal Android phone. A big, thick Android phone with a bunch of weird exposed ports, but normal nonetheless.

The parts required to make a good smartphone are pretty cheap and entirely commoditized; instead of "screen" being the base module, now "phone parts" is the starting point. "The key here," Camargo says, "is to develop the functionality you don't get on your smartphone today. I'll give you the smartphone, so you don't have to worry about it."

Over the last year or so, the team also worked to standardize the modules, so that developers could actually start to build them. The key bit was redesigning the connectors on the back. Each one has to support constant connecting and reconnecting, charge things when they get plugged in, and, you know, not break or fall off. They created a proprietary port, but one that uses an open standard, UniPro. The phone has six, and each one can push up to 11.9 gigabits of data per second, in both directions. Ara chief Richard Woolridge spits out crazy edit-video-while-you-computer-vision use cases, but says the spec boils down to this: It can handle anything. And it only consumes a third as much power as USB 3.

Press a button on the right side of the phone to bring up a map of all your modules, tap on the picture of the one you want to release, then flip over your phone, A moment later, it releases. Or do it like Camargo and say, "OK Google, eject the camera." Doing everything in software prevents mechanical accidents or failures, and even lets users do things like password-protect sensitive modules. And, of course, there's nothing to adding a new one: just pop it in.

Modular Thinking

Which brings us to the most important question still facing Project Ara: what the hell kind of modules are people going to build? Woolridge and his team took their user research to the Mobile World Congress conference in Barcelona in February, where they started showing it to potential partners: carriers, tech companies, fashion brands, everyone.

It's been years since we've had anything like true experimentation and newness in smartphones. The stakes are so high and the scale is so big, no one can afford to take chances.

Turns out they all have ideas. Better speakers, flashlights, panic buttons, fitness trackers, projectors, app-shortcut buttons, kickstands, a million other things. Some are incredibly high-tech—pro-level cameras clearly fascinate the Ara team, and they all get excited at the idea of replacing my hideous tape recorder with a microphone module—but some aren't. Bertrand shows me a small compact case for storing makeup, and a small hollow pillbox. They're also building "style" modules, which don't do anything except look nice. Apparently, when given the opportunity to make anything that plugs into their phone, people come up with some pretty useless ideas.

And that's OK: it's the whole point. It's been years since the smartphone industry has seen anything like true experimentation and newness. The stakes are so high and the scale is so big, no one can afford to take chances. With Ara, the industry can go back to throwing shit against the wall, looking to see what else might work.

Ultimately, the modules are much more important than the frame they go in. The first Ara device is a smartphone because that's the biggest market. But Camargo reminds me that anything bigger than the smallest module, which right now is about half the size of a stick of gum, could be an Ara device. An Ara tablet isn't a crazy idea, nor is a teeny-tiny Internet of Things Ara device. Anything with a connector works, Camargo says. "That allows us to be somewhat form-factor independent."

For right now, though, the smartphone is the thing. While we talk, Bertrand slides another Ara phone over to me, a non-working prototype that looks more like what they're going for. It's still thicker and chunkier than they'd like, but Bertrand is confident than thin and clean are adjectives he can work with. The phone is wearing a light blue backplate that I can swap out, and has a dozen or so modules to choose from. Screens, cameras, one that's the color of (but hopefully not made of) concrete, a picture of someone's dog. I start playing with options, trying to figure out exactly what works for me. I need a camera, obviously. And the E Ink screen is cool. But I don't want to clutter it too much, so I drop in two wooden modules just to keep things looking nice.

Before he handed it to me, Bertrand had it set up completely differently. And whoever tries it next will do something else. There are thousands of combinations possible. Of all the people the team has invited so far to build their own Ara phone as part of its research, no two people have picked exactly the same things.

Ara has come a long way, but the biggest test comes later this year. Woolridge doesn't know how many Developer Editions he expects to sell, except that he expects a lot. It's going to be a high-end device, at least at first, because that's where they feel like the market really needs a kick in the pants. (That, and making cool new stuff for cheap is hard to do.) There's lots more to do, on design and software and branding and ecosystem-building. And, of course, they have to find out if anyone actually wants to buy this thing. But they've already done something special. Toward the end of our conversation, I look over and see Camargo just idly fiddling with his Ara. Not testing, not debugging, fiddling. It's just his phone now.