Why the U.S. Needs a Backup for GPS

By: Tracy Staedter

The U.S. federal government maintains at least 24 operational GPS satellites at any given time. That critical network of satellites helps people with everything from navigating across town to determining when, exactly, they got cash from the ATM. And some think we're way overdue to make that network more resilient. John Greim/LightRocket via Getty Images
The U.S. federal government maintains at least 24 operational GPS satellites at any given time. That critical network of satellites helps people with everything from navigating across town to determining when, exactly, they got cash from the ATM. And some think we're way overdue to make that network more resilient. John Greim/LightRocket via Getty Images

If you think GPS is there only to help you navigate to that new restaurant or find the fastest route across town, you'd be wrong. The signals from GPS satellites are fundamental to every network in the United States — internet, power grid, financial trading, telecommunications and, yes, transportation. But there's no backup to the system, which means a big disruption, spoof or hack could bring the entire country to its knees.

A new system called eLoran, which has its origin in World War II ground-based radio technology, could complement GPS and give it the resilience it needs. Other countries have such a backup, including China and Russia. But despite administrations as far back as 2008 announcing the U.S. would build such a system, it has yet to do so.

"This is a national infrastructure issue," says Dana Goward, president of Resilient Navigation and Timing Foundation, a nonprofit organization that supports policies and systems to make GPS more resilient.

GPS satellite orbits
That constellation coverage ensures that you can spot at least four different satellites from pretty much anywhere on Earth.

For GPS and the systems that depend on it, it's all about the timing. Literally. The 24 operational satellites in orbit around Earth each carry as many as four atomic clocks onboard that keep precise time down to the nanosecond and are all synchronized with each other and to Coordinated Universal Time. When satellites broadcast signals, they're broadcasting their time and position to receivers on Earth, like your smartphone, located along those critical networks. The receivers use the differences in arrival time of those signals to determine position.

The signals are why you get an alert when your Lyft driver is about to arrive. Nodes in the internet use the signals to keep track of packets of information moving at light speed across the network. They need to know what time it is so that they can reassemble the packets of information that originated in Omaha onto your laptop in Boston. On the electrical grid, phase measurement units use GPS signals to make sure that sine waves of electricity match up where two grids come together. A mismatch can generate too much heat and create energy loss.

Telecommunication networks use GPS signals to keep their cellphone towers synchronized to prevent your call from dropping on that train ride to grandma's house. Your credit card purchases, ATM withdrawals and financial market transactions all have precise time-stamps thanks to GPS.

You can see where we're going here. A snafu in GPS can create some seriously snarly problems. And it's not too difficult to do. GPS satellites transmit weak, very high-frequency signals that travel to Earth through 12,645 miles (20,350 kilometers) of space and atmosphere. Space weather can mess them up by accident. People can mess them up on purpose. There are products sold online that, depending on cost and quality, can illegally jam GPS signals in a radius anywhere between 100 feet (30 meters) and 30 miles (48 kilometers).

"It's not a problem until it's a problem," says Goward.


And There Have Been Problems

In April 2016, Reuters reported that dozens of South Korean fish vessels had to return to port because their GPS devices had been jammed — evidently by North Korea.

On Jan. 12, 2016, two U.S. Navy boats sailed 50 miles (80 kilometers) into Iranian territorial waters and were seized by Iran's Islamic Revolutionary Guard Corps Navy. Goward wrote an editorial for the Christian Science Monitor suggesting that Iran may have spoofed the boats' GPS devices with fake signals, purposely throwing the vessels off course.

Last January 2016, the U.S. Air Force decommissioned a GPS satellite, something it's routinely doing, and in the process introduced a 13.7-microsecond error to ripple through half of the GPS satellites still in orbit. The error created thousands of disruptions around the globe for the next 12 hours, including system errors in telecommunication networks, the Automatic Dependent Surveillance-Broadcast (ADS-B), an aircraft tracking safety system and first responder networks in North America.

"Fortunately, as far as we can tell, nobody died and unfortunately, there were no headlines. So things have pretty much continued on as they were," says Goward. "But it is evidence that these systems are all linked and these faults and failures occur even when there's a really, really small discrepancy in GPS."


The Backup

The eLoran system provides a backup plan. The system, first called LORAN — which stood for "Long Range Aid to Navigation" — was originally a secret system deployed by the U.S. across much of the globe during World War II. After the war, the U.S. Coast Guard maintained a number of transmitter sites overseas in support of the Department of Defense, and a network of more than 25 in the United States. Each of the transmitters used atomic clocks synchronized to the Naval Observatory's Coordinated Universal Time and broadcast precise time signals.

But then the more accurate GPS came along and the United States set Loran aside. An enhanced Loran, or eLoran, under development by the U.S. Coast Guard, was picked up, perfected, and demonstrated by commercial entities and the British maritime navigation authorities.

The plan in the United States is to reuse the same terrestrial infrastructure as the previous Loran system to broadcast low-frequency, very high-power time signals that are 1.3 million times stronger than those coming from GPS satellites, says Goward.

The combination of low-frequency radio waves transmitted at a super high power make them virtually impossible to jam. They can penetrate buildings, underground and even go underwater — which could help with navigational apps in these places. Research has shown, says Goward, that when eLoran is used in tandem with GPS, the combination is more accurate than either alone.

This past July, the U.S. House of Representatives passed a bill stating that, "Subject to the availability of appropriations, the Secretary shall provide for the establishment, sustainment, and operation of a reliable land-based enhanced LORAN, or eLORAN, positioning, navigation, and timing system." The same month, the House also passed the National Defense Authorization Act for Fiscal Year 2018, which allocated $10 million to build a proof-of-concept system to complement and back up GPS.

Goward thinks that money could go toward a first phase of the final system, which could involve enhancing four of the eight remaining towers across the middle of the continental United States.

"You could immediately establish a time signal to provide protection for critical infrastructure," he said. "It could be done in less than a year. The $10 million dollars would be a good start on that effort."

The rest of it may cost between $400 million and $500 million to build. But Goward doesn't think the government should do it. His foundation advocates for a private-public partnership between government and business. The idea is that a company would build out the rest of the infrastructure, sell a subscription to the government and sell higher resolution services to private companies — which the government would get a cut of — while also providing basic service to the public for free.

At this stage, it's unclear how the U.S. government will proceed. But technology marches on without the government, and as the world grows increasingly dependent on networks and automation, something will have to give.

"We're relying on what the Department of Homeland Security calls a single-point-of-failure for critical infrastructure" says Goward. "That means when it fails, that has the potential to cause even bigger failures."