By Jordan Schraeder in 40 Acres, July | August 2012 on |

In the beginning of the 2006 blockbuster The Da Vinci Code, Professor Robert Langdon, played by Tom Hanks, reaches cautiously into his pants pocket, delicately retrieving a circular silver object no bigger than a dime.

“It’s a GPS dot, accurate within two feet anywhere on the globe,” he’s told.

Without his knowledge, French investigators—suspecting Langdon of murder—had slipped it on his person to track his movements across Europe. Because of its size, he never even knew it was there.

Four years after the movie’s release, aerospace engineering assistant professor Todd Humphreys receives a phone call. A panicked woman explains that her ex-boyfriend from California has somehow tracked her down in Texas, showing up wherever she goes too often for it to be a coincidence. The kicker: each time she runs into him, an open laptop is sitting on his car’s dashboard. He had planted a GPS tracking device somewhere on her car.

The mechanic she took her car to couldn’t locate the device; the police department she called lacked the technical support to find it. Even the FBI couldn’t help. So as a last resort, she picked up the phone and dialed UT’s navigation expert.

What was just years ago a figment of an author’s imagination is now a freaky but all-too-real possibility. GPS devices are getting smaller and easier to conceal. In fact, something similar to The Da Vinci Code dot already exists. Not quite as small as a dime, today’s fully functioning tracking devices come as small as a car key fob.

“After that phone call, it dawned on me,” says Humphreys, director of UT’s Radionavigation Lab. “What I saw as a normal evolution of GPS technology was potentially a threat.”

Humphreys is sounding the alarm bells for a problem that many people aren’t aware exists. Global positioning system te chnology has advanced dramatically over the last decade, and the proof is in the meter-level accuracy of our TomToms, Garmins, and iPhones. With very little effort, an angry ex-spouse could easily follow in your footsteps—literally. Though not yet accessible via cell phone or car GPS system, the evolution of GPS technology has now led to millimeter-level accuracy.

“The GPS dot is going to be a wonderful and terrible thing,” Humphreys says. “It will be beneficial for those of us who lose things. The barriers to sharing with neighbors will decrease. But the possibilities for invasion of privacy are endless.”

And that invasion of privacy is, in some states, not illegal. In Texas, it’s a Class A misdemeanor offense to place a tracking device on a vehicle owned or leased by another person, but in many other states, the practice is perfectly legal. No federal statute addresses the legality of GPS tracking.

There’s no doubt the ability to slap a GPS dot on your phone, wallet, or keys would save time. Humphreys even imagines a world where we’ll be able to search through a database of belongings just as we search our email inboxes. “It’ll prevent all wives across the world from getting into fights with their husbands about losing the keys,” Humphreys laughs.

But does the bad outweigh the good? A desire for personal privacy has already prompted the development of jammers, which block GPS signals, and spoofers, which trick a GPS receiver into thinking you’re somewhere you’re not.

These devices for confounding GPS signals have their own terrifying implications: without proper GPS guidance, planes would veer off course, ships would collide, and cell phone towers would fail. With a little hacking, a full-blown terrorist attack could affect both homeland security and the economy—though Humphreys says the probability of that happening is low.

The scholars in Humphrey’s Radionavigation Lab have made this type of subversive technology, particularly spoofers, a priority in their research, attempting to create the best defenses to these devices.

“It’s like we’ve got both our black hat and white hat on,” says graduate student Daniel Shepard, who has worked in the Radionavigation Lab for two years, one as an undergrad. “We have to learn how to attack others in order to determine how we can protect ourselves.”

The lab has a few years to figure out the good and the bad of GPS—according to Humphreys, the tiny dot at the heart of all the chaos won’t really be consumer-friendly for five more years or so. The holdup: GPS signals rarely work indoors, and the price of data plans makes buying dots in bulk impractical for some.

Harmful or helpful, GPS dots are on their way, and UT’s Radionavigation Lab is on the leading edge. “Not very many institutions have an entire lab dedicated to navigation research,” Shepard says. “Robotics, space applications—it’s exciting because our research is very valuable to society.”

No one knows the value of this research better than Humphreys’ frantic female caller, whom not even he could help.

“The easiest solution wasn’t legal, so I wasn’t going to suggest it,” Humphreys says. “I ended up just telling her to switch cars with a really big, mean guy friend for a while. Even if the tracking is illegal, it’s practically unenforceable and anonymous.”

Illustration by Brown Bird Design, Photo by Robin Peeples