It's the Second Korean War of 2020, and things aren't looking good for the U.S.-South Korean side. North Korea has used its jamming gear to disrupt low-power GPS signals accessible in South Korea for navigation. Luckily for Washington and Seoul, in 2013, the Pentagon's blue-sky researchers created a positioning tool for use when GPS goes down – and even back then, it was smaller than a penny.

At the University of Michigan on Wednesday, researchers for Darpa announced they'd created a very small chip containing a timing and inertial measurement unit, or TIMU, that's as thick as a couple human hairs. When the satellites we rely on for navigation can't be reached – whether they've been jammed or you're in a densely packed city – the chip contains everything you'll need to figure out how to get from place to place. It's got gyroscopes, accelerometers and a master clock, to calculate orientation, acceleration and time.

The TIMU is fabricated from silicon dioxide and contained within a 10 cubic millimeter package – meaning it can just about fit within the Lincoln Memorial rendered on the back of a penny. All of this came out of a Darpa effort to compensate for the weaknesses of global satellite positioning through the possibilities of microtechnology.

"The resulting TIMU is small enough and should be robust enough for applications (when GPS is unavailable or limited for a short period of time) such as personnel tracking, handheld navigation, small diameter munitions and small airborne platforms," Darpa program manager Andrei Shkel said in the researchers' announcement. In other words, further development could not only help ground units find optimal battlefield routes in the absence of GPS, they could make ever smaller bombs and missiles smart enough to find accurate targets, and equip gliders like the ones the Naval Research Lab 3D-prints with miniature navigation.

Notice that Darpa isn't saying the penny-sized chip will replace GPS. For now, the Pentagon futurists are only talking about compensating for satellite positioning when the satellite signals are inaccessible. The Defense Department remains heavily invested in GPS: the budget it unveiled yesterday proposes $1.27 billion to procure and develop the next four satellites in the Block III GPS constellation. Darpa just wants a GPS workaround so the satellites don't become a single point of failure for the U.S. military.

Oh, and don't freak out, but reportedly, North Korea is already capable of jamming GPS signals in South Korea. The Pentagon wants to make the follow-on GPS satellites harder to jam, but even those satellites will still be vulnerable, and commercially-accessible (if illegal)GPS jamming and spoofing devices are proliferating. There may be some urgency behind Darpa's tiny navigation chip.